include demumble without submodule

9 files changed, 7595 insertions, 0 deletions

diff --git a/demangle/third_party/llvm/include/llvm/Demangle/Compiler.h b/demangle/third_party/llvm/include/llvm/Demangle/Compiler.h
new file mode 100644
index 00000000..c17ff4ca
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/Compiler.h
@@ -0,0 +1,549 @@
+//===--- Compiler.h ---------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//
+// This file contains a variety of feature test macros copied from
+// include/llvm/Support/Compiler.h so that LLVMDemangle does not need to take
+// a dependency on LLVMSupport.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_COMPILER_H
+#define LLVM_DEMANGLE_COMPILER_H
+
+#ifdef __cplusplus
+#include <new>
+#endif
+#include <stddef.h>
+
+#if defined(_MSC_VER)
+#include <sal.h>
+#endif
+
+#ifndef __has_feature
+# define __has_feature(x) 0
+#endif
+
+#ifndef __has_extension
+# define __has_extension(x) 0
+#endif
+
+#ifndef __has_attribute
+# define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+# define __has_builtin(x) 0
+#endif
+
+// Only use __has_cpp_attribute in C++ mode. GCC defines __has_cpp_attribute in
+// C mode, but the :: in __has_cpp_attribute(scoped::attribute) is invalid.
+#ifndef LLVM_HAS_CPP_ATTRIBUTE
+#if defined(__cplusplus) && defined(__has_cpp_attribute)
+# define LLVM_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
+#else
+# define LLVM_HAS_CPP_ATTRIBUTE(x) 0
+#endif
+#endif
+
+/// \macro LLVM_GNUC_PREREQ
+/// Extend the default __GNUC_PREREQ even if glibc's features.h isn't
+/// available.
+#ifndef LLVM_GNUC_PREREQ
+# if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
+#  define LLVM_GNUC_PREREQ(maj, min, patch) \
+    ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >= \
+     ((maj) << 20) + ((min) << 10) + (patch))
+# elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+#  define LLVM_GNUC_PREREQ(maj, min, patch) \
+    ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
+# else
+#  define LLVM_GNUC_PREREQ(maj, min, patch) 0
+# endif
+#endif
+
+/// \macro LLVM_MSC_PREREQ
+/// Is the compiler MSVC of at least the specified version?
+/// The common \param version values to check for are:
+/// * 1910: VS2017, version 15.1 & 15.2
+/// * 1911: VS2017, version 15.3 & 15.4
+/// * 1912: VS2017, version 15.5
+/// * 1913: VS2017, version 15.6
+/// * 1914: VS2017, version 15.7
+/// * 1915: VS2017, version 15.8
+/// * 1916: VS2017, version 15.9
+/// * 1920: VS2019, version 16.0
+/// * 1921: VS2019, version 16.1
+#ifdef _MSC_VER
+#define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version))
+
+// We require at least MSVC 2017.
+#if !LLVM_MSC_PREREQ(1910)
+#error LLVM requires at least MSVC 2017.
+#endif
+
+#else
+#define LLVM_MSC_PREREQ(version) 0
+#endif
+
+/// Does the compiler support ref-qualifiers for *this?
+///
+/// Sadly, this is separate from just rvalue reference support because GCC
+/// and MSVC implemented this later than everything else. This appears to be
+/// corrected in MSVC 2019 but not MSVC 2017.
+#if __has_feature(cxx_rvalue_references) || LLVM_GNUC_PREREQ(4, 8, 1) ||       \
+    LLVM_MSC_PREREQ(1920)
+#define LLVM_HAS_RVALUE_REFERENCE_THIS 1
+#else
+#define LLVM_HAS_RVALUE_REFERENCE_THIS 0
+#endif
+
+/// Expands to '&' if ref-qualifiers for *this are supported.
+///
+/// This can be used to provide lvalue/rvalue overrides of member functions.
+/// The rvalue override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
+#if LLVM_HAS_RVALUE_REFERENCE_THIS
+#define LLVM_LVALUE_FUNCTION &
+#else
+#define LLVM_LVALUE_FUNCTION
+#endif
+
+/// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
+/// into a shared library, then the class should be private to the library and
+/// not accessible from outside it.  Can also be used to mark variables and
+/// functions, making them private to any shared library they are linked into.
+/// On PE/COFF targets, library visibility is the default, so this isn't needed.
+///
+/// LLVM_EXTERNAL_VISIBILITY - classes, functions, and variables marked with
+/// this attribute will be made public and visible outside of any shared library
+/// they are linked in to.
+#if (__has_attribute(visibility) || LLVM_GNUC_PREREQ(4, 0, 0)) &&              \
+    !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(_WIN32)
+#define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
+#define LLVM_EXTERNAL_VISIBILITY __attribute__ ((visibility("default")))
+#else
+#define LLVM_LIBRARY_VISIBILITY
+#define LLVM_EXTERNAL_VISIBILITY
+#endif
+
+#if defined(__GNUC__)
+#define LLVM_PREFETCH(addr, rw, locality) __builtin_prefetch(addr, rw, locality)
+#else
+#define LLVM_PREFETCH(addr, rw, locality)
+#endif
+
+#if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0)
+#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
+#else
+#define LLVM_ATTRIBUTE_USED
+#endif
+
+/// LLVM_NODISCARD - Warn if a type or return value is discarded.
+
+// Use the 'nodiscard' attribute in C++17 or newer mode.
+#if defined(__cplusplus) && __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(nodiscard)
+#define LLVM_NODISCARD [[nodiscard]]
+#elif LLVM_HAS_CPP_ATTRIBUTE(clang::warn_unused_result)
+#define LLVM_NODISCARD [[clang::warn_unused_result]]
+// Clang in C++14 mode claims that it has the 'nodiscard' attribute, but also
+// warns in the pedantic mode that 'nodiscard' is a C++17 extension (PR33518).
+// Use the 'nodiscard' attribute in C++14 mode only with GCC.
+// TODO: remove this workaround when PR33518 is resolved.
+#elif defined(__GNUC__) && LLVM_HAS_CPP_ATTRIBUTE(nodiscard)
+#define LLVM_NODISCARD [[nodiscard]]
+#else
+#define LLVM_NODISCARD
+#endif
+
+// Indicate that a non-static, non-const C++ member function reinitializes
+// the entire object to a known state, independent of the previous state of
+// the object.
+//
+// The clang-tidy check bugprone-use-after-move recognizes this attribute as a
+// marker that a moved-from object has left the indeterminate state and can be
+// reused.
+#if LLVM_HAS_CPP_ATTRIBUTE(clang::reinitializes)
+#define LLVM_ATTRIBUTE_REINITIALIZES [[clang::reinitializes]]
+#else
+#define LLVM_ATTRIBUTE_REINITIALIZES
+#endif
+
+// Some compilers warn about unused functions. When a function is sometimes
+// used or not depending on build settings (e.g. a function only called from
+// within "assert"), this attribute can be used to suppress such warnings.
+//
+// However, it shouldn't be used for unused *variables*, as those have a much
+// more portable solution:
+//   (void)unused_var_name;
+// Prefer cast-to-void wherever it is sufficient.
+#if __has_attribute(unused) || LLVM_GNUC_PREREQ(3, 1, 0)
+#define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
+#else
+#define LLVM_ATTRIBUTE_UNUSED
+#endif
+
+// FIXME: Provide this for PE/COFF targets.
+#if (__has_attribute(weak) || LLVM_GNUC_PREREQ(4, 0, 0)) &&                    \
+    (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(_WIN32))
+#define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
+#else
+#define LLVM_ATTRIBUTE_WEAK
+#endif
+
+// Prior to clang 3.2, clang did not accept any spelling of
+// __has_attribute(const), so assume it is supported.
+#if defined(__clang__) || defined(__GNUC__)
+// aka 'CONST' but following LLVM Conventions.
+#define LLVM_READNONE __attribute__((__const__))
+#else
+#define LLVM_READNONE
+#endif
+
+#if __has_attribute(pure) || defined(__GNUC__)
+// aka 'PURE' but following LLVM Conventions.
+#define LLVM_READONLY __attribute__((__pure__))
+#else
+#define LLVM_READONLY
+#endif
+
+#if __has_builtin(__builtin_expect) || LLVM_GNUC_PREREQ(4, 0, 0)
+#define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
+#define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
+#else
+#define LLVM_LIKELY(EXPR) (EXPR)
+#define LLVM_UNLIKELY(EXPR) (EXPR)
+#endif
+
+/// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
+/// mark a method "not for inlining".
+#if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0)
+#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
+#else
+#define LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+/// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
+/// so, mark a method "always inline" because it is performance sensitive. GCC
+/// 3.4 supported this but is buggy in various cases and produces unimplemented
+/// errors, just use it in GCC 4.0 and later.
+#if __has_attribute(always_inline) || LLVM_GNUC_PREREQ(4, 0, 0)
+#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
+#else
+#define LLVM_ATTRIBUTE_ALWAYS_INLINE inline
+#endif
+
+#ifdef __GNUC__
+#define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
+#else
+#define LLVM_ATTRIBUTE_NORETURN
+#endif
+
+#if __has_attribute(returns_nonnull) || LLVM_GNUC_PREREQ(4, 9, 0)
+#define LLVM_ATTRIBUTE_RETURNS_NONNULL __attribute__((returns_nonnull))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_RETURNS_NONNULL _Ret_notnull_
+#else
+#define LLVM_ATTRIBUTE_RETURNS_NONNULL
+#endif
+
+/// \macro LLVM_ATTRIBUTE_RETURNS_NOALIAS Used to mark a function as returning a
+/// pointer that does not alias any other valid pointer.
+#ifdef __GNUC__
+#define LLVM_ATTRIBUTE_RETURNS_NOALIAS __attribute__((__malloc__))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_RETURNS_NOALIAS __declspec(restrict)
+#else
+#define LLVM_ATTRIBUTE_RETURNS_NOALIAS
+#endif
+
+/// LLVM_FALLTHROUGH - Mark fallthrough cases in switch statements.
+#if defined(__cplusplus) && __cplusplus > 201402L && LLVM_HAS_CPP_ATTRIBUTE(fallthrough)
+#define LLVM_FALLTHROUGH [[fallthrough]]
+#elif LLVM_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
+#define LLVM_FALLTHROUGH [[gnu::fallthrough]]
+#elif __has_attribute(fallthrough)
+#define LLVM_FALLTHROUGH __attribute__((fallthrough))
+#elif LLVM_HAS_CPP_ATTRIBUTE(clang::fallthrough)
+#define LLVM_FALLTHROUGH [[clang::fallthrough]]
+#else
+#define LLVM_FALLTHROUGH
+#endif
+
+/// LLVM_REQUIRE_CONSTANT_INITIALIZATION - Apply this to globals to ensure that
+/// they are constant initialized.
+#if LLVM_HAS_CPP_ATTRIBUTE(clang::require_constant_initialization)
+#define LLVM_REQUIRE_CONSTANT_INITIALIZATION                                   \
+  [[clang::require_constant_initialization]]
+#else
+#define LLVM_REQUIRE_CONSTANT_INITIALIZATION
+#endif
+
+/// LLVM_GSL_OWNER - Apply this to owning classes like SmallVector to enable
+/// lifetime warnings.
+#if LLVM_HAS_CPP_ATTRIBUTE(gsl::Owner)
+#define LLVM_GSL_OWNER [[gsl::Owner]]
+#else
+#define LLVM_GSL_OWNER
+#endif
+
+/// LLVM_GSL_POINTER - Apply this to non-owning classes like
+/// StringRef to enable lifetime warnings.
+#if LLVM_HAS_CPP_ATTRIBUTE(gsl::Pointer)
+#define LLVM_GSL_POINTER [[gsl::Pointer]]
+#else
+#define LLVM_GSL_POINTER
+#endif
+
+/// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
+/// pedantic diagnostics.
+#ifdef __GNUC__
+#define LLVM_EXTENSION __extension__
+#else
+#define LLVM_EXTENSION
+#endif
+
+// LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
+// This macro will be removed.
+// Use C++14's attribute instead: [[deprecated("message")]]
+#define LLVM_ATTRIBUTE_DEPRECATED(decl, message) [[deprecated(message)]] decl
+
+/// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
+/// to an expression which states that it is undefined behavior for the
+/// compiler to reach this point.  Otherwise is not defined.
+#if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0)
+# define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
+#elif defined(_MSC_VER)
+# define LLVM_BUILTIN_UNREACHABLE __assume(false)
+#endif
+
+/// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
+/// which causes the program to exit abnormally.
+#if __has_builtin(__builtin_trap) || LLVM_GNUC_PREREQ(4, 3, 0)
+# define LLVM_BUILTIN_TRAP __builtin_trap()
+#elif defined(_MSC_VER)
+// The __debugbreak intrinsic is supported by MSVC, does not require forward
+// declarations involving platform-specific typedefs (unlike RaiseException),
+// results in a call to vectored exception handlers, and encodes to a short
+// instruction that still causes the trapping behavior we want.
+# define LLVM_BUILTIN_TRAP __debugbreak()
+#else
+# define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
+#endif
+
+/// LLVM_BUILTIN_DEBUGTRAP - On compilers which support it, expands to
+/// an expression which causes the program to break while running
+/// under a debugger.
+#if __has_builtin(__builtin_debugtrap)
+# define LLVM_BUILTIN_DEBUGTRAP __builtin_debugtrap()
+#elif defined(_MSC_VER)
+// The __debugbreak intrinsic is supported by MSVC and breaks while
+// running under the debugger, and also supports invoking a debugger
+// when the OS is configured appropriately.
+# define LLVM_BUILTIN_DEBUGTRAP __debugbreak()
+#else
+// Just continue execution when built with compilers that have no
+// support. This is a debugging aid and not intended to force the
+// program to abort if encountered.
+# define LLVM_BUILTIN_DEBUGTRAP
+#endif
+
+/// \macro LLVM_ASSUME_ALIGNED
+/// Returns a pointer with an assumed alignment.
+#if __has_builtin(__builtin_assume_aligned) || LLVM_GNUC_PREREQ(4, 7, 0)
+# define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
+#elif defined(LLVM_BUILTIN_UNREACHABLE)
+# define LLVM_ASSUME_ALIGNED(p, a) \
+           (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
+#else
+# define LLVM_ASSUME_ALIGNED(p, a) (p)
+#endif
+
+/// \macro LLVM_PACKED
+/// Used to specify a packed structure.
+/// LLVM_PACKED(
+///    struct A {
+///      int i;
+///      int j;
+///      int k;
+///      long long l;
+///   });
+///
+/// LLVM_PACKED_START
+/// struct B {
+///   int i;
+///   int j;
+///   int k;
+///   long long l;
+/// };
+/// LLVM_PACKED_END
+#ifdef _MSC_VER
+# define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop))
+# define LLVM_PACKED_START __pragma(pack(push, 1))
+# define LLVM_PACKED_END   __pragma(pack(pop))
+#else
+# define LLVM_PACKED(d) d __attribute__((packed))
+# define LLVM_PACKED_START _Pragma("pack(push, 1)")
+# define LLVM_PACKED_END   _Pragma("pack(pop)")
+#endif
+
+/// \macro LLVM_PTR_SIZE
+/// A constant integer equivalent to the value of sizeof(void*).
+/// Generally used in combination with alignas or when doing computation in the
+/// preprocessor.
+#ifdef __SIZEOF_POINTER__
+# define LLVM_PTR_SIZE __SIZEOF_POINTER__
+#elif defined(_WIN64)
+# define LLVM_PTR_SIZE 8
+#elif defined(_WIN32)
+# define LLVM_PTR_SIZE 4
+#elif defined(_MSC_VER)
+# error "could not determine LLVM_PTR_SIZE as a constant int for MSVC"
+#else
+# define LLVM_PTR_SIZE sizeof(void *)
+#endif
+
+/// \macro LLVM_MEMORY_SANITIZER_BUILD
+/// Whether LLVM itself is built with MemorySanitizer instrumentation.
+#if __has_feature(memory_sanitizer)
+# define LLVM_MEMORY_SANITIZER_BUILD 1
+# include <sanitizer/msan_interface.h>
+# define LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE __attribute__((no_sanitize_memory))
+#else
+# define LLVM_MEMORY_SANITIZER_BUILD 0
+# define __msan_allocated_memory(p, size)
+# define __msan_unpoison(p, size)
+# define LLVM_NO_SANITIZE_MEMORY_ATTRIBUTE
+#endif
+
+/// \macro LLVM_ADDRESS_SANITIZER_BUILD
+/// Whether LLVM itself is built with AddressSanitizer instrumentation.
+#if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
+# define LLVM_ADDRESS_SANITIZER_BUILD 1
+# include <sanitizer/asan_interface.h>
+#else
+# define LLVM_ADDRESS_SANITIZER_BUILD 0
+# define __asan_poison_memory_region(p, size)
+# define __asan_unpoison_memory_region(p, size)
+#endif
+
+/// \macro LLVM_THREAD_SANITIZER_BUILD
+/// Whether LLVM itself is built with ThreadSanitizer instrumentation.
+#if __has_feature(thread_sanitizer) || defined(__SANITIZE_THREAD__)
+# define LLVM_THREAD_SANITIZER_BUILD 1
+#else
+# define LLVM_THREAD_SANITIZER_BUILD 0
+#endif
+
+#if LLVM_THREAD_SANITIZER_BUILD
+// Thread Sanitizer is a tool that finds races in code.
+// See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations .
+// tsan detects these exact functions by name.
+#ifdef __cplusplus
+extern "C" {
+#endif
+void AnnotateHappensAfter(const char *file, int line, const volatile void *cv);
+void AnnotateHappensBefore(const char *file, int line, const volatile void *cv);
+void AnnotateIgnoreWritesBegin(const char *file, int line);
+void AnnotateIgnoreWritesEnd(const char *file, int line);
+#ifdef __cplusplus
+}
+#endif
+
+// This marker is used to define a happens-before arc. The race detector will
+// infer an arc from the begin to the end when they share the same pointer
+// argument.
+# define TsanHappensBefore(cv) AnnotateHappensBefore(__FILE__, __LINE__, cv)
+
+// This marker defines the destination of a happens-before arc.
+# define TsanHappensAfter(cv) AnnotateHappensAfter(__FILE__, __LINE__, cv)
+
+// Ignore any races on writes between here and the next TsanIgnoreWritesEnd.
+# define TsanIgnoreWritesBegin() AnnotateIgnoreWritesBegin(__FILE__, __LINE__)
+
+// Resume checking for racy writes.
+# define TsanIgnoreWritesEnd() AnnotateIgnoreWritesEnd(__FILE__, __LINE__)
+#else
+# define TsanHappensBefore(cv)
+# define TsanHappensAfter(cv)
+# define TsanIgnoreWritesBegin()
+# define TsanIgnoreWritesEnd()
+#endif
+
+/// \macro LLVM_NO_SANITIZE
+/// Disable a particular sanitizer for a function.
+#if __has_attribute(no_sanitize)
+#define LLVM_NO_SANITIZE(KIND) __attribute__((no_sanitize(KIND)))
+#else
+#define LLVM_NO_SANITIZE(KIND)
+#endif
+
+/// Mark debug helper function definitions like dump() that should not be
+/// stripped from debug builds.
+/// Note that you should also surround dump() functions with
+/// `#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)` so they do always
+/// get stripped in release builds.
+// FIXME: Move this to a private config.h as it's not usable in public headers.
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
+#else
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+/// \macro LLVM_PRETTY_FUNCTION
+/// Gets a user-friendly looking function signature for the current scope
+/// using the best available method on each platform.  The exact format of the
+/// resulting string is implementation specific and non-portable, so this should
+/// only be used, for example, for logging or diagnostics.
+#if defined(_MSC_VER)
+#define LLVM_PRETTY_FUNCTION __FUNCSIG__
+#elif defined(__GNUC__) || defined(__clang__)
+#define LLVM_PRETTY_FUNCTION __PRETTY_FUNCTION__
+#else
+#define LLVM_PRETTY_FUNCTION __func__
+#endif
+
+/// \macro LLVM_THREAD_LOCAL
+/// A thread-local storage specifier which can be used with globals,
+/// extern globals, and static globals.
+///
+/// This is essentially an extremely restricted analog to C++11's thread_local
+/// support. It uses thread_local if available, falling back on gcc __thread
+/// if not. __thread doesn't support many of the C++11 thread_local's
+/// features. You should only use this for PODs that you can statically
+/// initialize to some constant value. In almost all circumstances this is most
+/// appropriate for use with a pointer, integer, or small aggregation of
+/// pointers and integers.
+#if LLVM_ENABLE_THREADS
+#if __has_feature(cxx_thread_local) || defined(_MSC_VER)
+#define LLVM_THREAD_LOCAL thread_local
+#else
+// Clang, GCC, and other compatible compilers used __thread prior to C++11 and
+// we only need the restricted functionality that provides.
+#define LLVM_THREAD_LOCAL __thread
+#endif
+#else // !LLVM_ENABLE_THREADS
+// If threading is disabled entirely, this compiles to nothing and you get
+// a normal global variable.
+#define LLVM_THREAD_LOCAL
+#endif
+
+/// \macro LLVM_ENABLE_EXCEPTIONS
+/// Whether LLVM is built with exception support.
+#if __has_feature(cxx_exceptions)
+#define LLVM_ENABLE_EXCEPTIONS 1
+#elif defined(__GNUC__) && defined(__EXCEPTIONS)
+#define LLVM_ENABLE_EXCEPTIONS 1
+#elif defined(_MSC_VER) && defined(_CPPUNWIND)
+#define LLVM_ENABLE_EXCEPTIONS 1
+#endif
+
+#endif
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/Demangle.h b/demangle/third_party/llvm/include/llvm/Demangle/Demangle.h
new file mode 100644
index 00000000..6133d0b9
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/Demangle.h
@@ -0,0 +1,133 @@
+//===--- Demangle.h ---------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_DEMANGLE_H
+#define LLVM_DEMANGLE_DEMANGLE_H
+
+#include <cstddef>
+#include <string>
+
+namespace llvm {
+/// This is a llvm local version of __cxa_demangle. Other than the name and
+/// being in the llvm namespace it is identical.
+///
+/// The mangled_name is demangled into buf and returned. If the buffer is not
+/// large enough, realloc is used to expand it.
+///
+/// The *status will be set to a value from the following enumeration
+enum : int {
+  demangle_unknown_error = -4,
+  demangle_invalid_args = -3,
+  demangle_invalid_mangled_name = -2,
+  demangle_memory_alloc_failure = -1,
+  demangle_success = 0,
+};
+
+char *itaniumDemangle(const char *mangled_name, char *buf, size_t *n,
+                      int *status);
+
+enum MSDemangleFlags {
+  MSDF_None = 0,
+  MSDF_DumpBackrefs = 1 << 0,
+  MSDF_NoAccessSpecifier = 1 << 1,
+  MSDF_NoCallingConvention = 1 << 2,
+  MSDF_NoReturnType = 1 << 3,
+  MSDF_NoMemberType = 1 << 4,
+  MSDF_NoVariableType = 1 << 5,
+};
+
+/// Demangles the Microsoft symbol pointed at by mangled_name and returns it.
+/// Returns a pointer to the start of a null-terminated demangled string on
+/// success, or nullptr on error.
+/// If n_read is non-null and demangling was successful, it receives how many
+/// bytes of the input string were consumed.
+/// buf can point to a *n_buf bytes large buffer where the demangled name is
+/// stored. If the buffer is too small, it is grown with realloc(). If buf is
+/// nullptr, then this malloc()s memory for the result.
+/// *n_buf stores the size of buf on input if buf is non-nullptr, and it
+/// receives the size of the demangled string on output if n_buf is not nullptr.
+/// status receives one of the demangle_ enum entries above if it's not nullptr.
+/// Flags controls various details of the demangled representation.
+char *microsoftDemangle(const char *mangled_name, size_t *n_read, char *buf,
+                        size_t *n_buf, int *status,
+                        MSDemangleFlags Flags = MSDF_None);
+
+// Demangles a Rust v0 mangled symbol.
+char *rustDemangle(const char *MangledName);
+
+// Demangles a D mangled symbol.
+char *dlangDemangle(const char *MangledName);
+
+/// Attempt to demangle a string using different demangling schemes.
+/// The function uses heuristics to determine which demangling scheme to use.
+/// \param MangledName - reference to string to demangle.
+/// \returns - the demangled string, or a copy of the input string if no
+/// demangling occurred.
+std::string demangle(const std::string &MangledName);
+
+bool nonMicrosoftDemangle(const char *MangledName, std::string &Result);
+
+/// "Partial" demangler. This supports demangling a string into an AST
+/// (typically an intermediate stage in itaniumDemangle) and querying certain
+/// properties or partially printing the demangled name.
+struct ItaniumPartialDemangler {
+  ItaniumPartialDemangler();
+
+  ItaniumPartialDemangler(ItaniumPartialDemangler &&Other);
+  ItaniumPartialDemangler &operator=(ItaniumPartialDemangler &&Other);
+
+  /// Demangle into an AST. Subsequent calls to the rest of the member functions
+  /// implicitly operate on the AST this produces.
+  /// \return true on error, false otherwise
+  bool partialDemangle(const char *MangledName);
+
+  /// Just print the entire mangled name into Buf. Buf and N behave like the
+  /// second and third parameters to itaniumDemangle.
+  char *finishDemangle(char *Buf, size_t *N) const;
+
+  /// Get the base name of a function. This doesn't include trailing template
+  /// arguments, ie for "a::b<int>" this function returns "b".
+  char *getFunctionBaseName(char *Buf, size_t *N) const;
+
+  /// Get the context name for a function. For "a::b::c", this function returns
+  /// "a::b".
+  char *getFunctionDeclContextName(char *Buf, size_t *N) const;
+
+  /// Get the entire name of this function.
+  char *getFunctionName(char *Buf, size_t *N) const;
+
+  /// Get the parameters for this function.
+  char *getFunctionParameters(char *Buf, size_t *N) const;
+  char *getFunctionReturnType(char *Buf, size_t *N) const;
+
+  /// If this function has any any cv or reference qualifiers. These imply that
+  /// the function is a non-static member function.
+  bool hasFunctionQualifiers() const;
+
+  /// If this symbol describes a constructor or destructor.
+  bool isCtorOrDtor() const;
+
+  /// If this symbol describes a function.
+  bool isFunction() const;
+
+  /// If this symbol describes a variable.
+  bool isData() const;
+
+  /// If this symbol is a <special-name>. These are generally implicitly
+  /// generated by the implementation, such as vtables and typeinfo names.
+  bool isSpecialName() const;
+
+  ~ItaniumPartialDemangler();
+
+private:
+  void *RootNode;
+  void *Context;
+};
+} // namespace llvm
+
+#endif
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/DemangleConfig.h b/demangle/third_party/llvm/include/llvm/Demangle/DemangleConfig.h
new file mode 100644
index 00000000..2ff95dd8
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/DemangleConfig.h
@@ -0,0 +1,92 @@
+//===--- DemangleConfig.h ---------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains a variety of feature test macros copied from
+// include/llvm/Support/Compiler.h so that LLVMDemangle does not need to take
+// a dependency on LLVMSupport.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_DEMANGLECONFIG_H
+#define LLVM_DEMANGLE_DEMANGLECONFIG_H
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#ifndef __has_cpp_attribute
+#define __has_cpp_attribute(x) 0
+#endif
+
+#ifndef __has_attribute
+#define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifndef DEMANGLE_GNUC_PREREQ
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
+#define DEMANGLE_GNUC_PREREQ(maj, min, patch)                           \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >=          \
+   ((maj) << 20) + ((min) << 10) + (patch))
+#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+#define DEMANGLE_GNUC_PREREQ(maj, min, patch)                           \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
+#else
+#define DEMANGLE_GNUC_PREREQ(maj, min, patch) 0
+#endif
+#endif
+
+#if __has_attribute(used) || DEMANGLE_GNUC_PREREQ(3, 1, 0)
+#define DEMANGLE_ATTRIBUTE_USED __attribute__((__used__))
+#else
+#define DEMANGLE_ATTRIBUTE_USED
+#endif
+
+#if __has_builtin(__builtin_unreachable) || DEMANGLE_GNUC_PREREQ(4, 5, 0)
+#define DEMANGLE_UNREACHABLE __builtin_unreachable()
+#elif defined(_MSC_VER)
+#define DEMANGLE_UNREACHABLE __assume(false)
+#else
+#define DEMANGLE_UNREACHABLE
+#endif
+
+#if __has_attribute(noinline) || DEMANGLE_GNUC_PREREQ(3, 4, 0)
+#define DEMANGLE_ATTRIBUTE_NOINLINE __attribute__((noinline))
+#elif defined(_MSC_VER)
+#define DEMANGLE_ATTRIBUTE_NOINLINE __declspec(noinline)
+#else
+#define DEMANGLE_ATTRIBUTE_NOINLINE
+#endif
+
+#if !defined(NDEBUG)
+#define DEMANGLE_DUMP_METHOD DEMANGLE_ATTRIBUTE_NOINLINE DEMANGLE_ATTRIBUTE_USED
+#else
+#define DEMANGLE_DUMP_METHOD DEMANGLE_ATTRIBUTE_NOINLINE
+#endif
+
+#if __cplusplus > 201402L && __has_cpp_attribute(fallthrough)
+#define DEMANGLE_FALLTHROUGH [[fallthrough]]
+#elif __has_cpp_attribute(gnu::fallthrough)
+#define DEMANGLE_FALLTHROUGH [[gnu::fallthrough]]
+#elif !__cplusplus
+// Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious
+// error when __has_cpp_attribute is given a scoped attribute in C mode.
+#define DEMANGLE_FALLTHROUGH
+#elif __has_cpp_attribute(clang::fallthrough)
+#define DEMANGLE_FALLTHROUGH [[clang::fallthrough]]
+#else
+#define DEMANGLE_FALLTHROUGH
+#endif
+
+#define DEMANGLE_NAMESPACE_BEGIN namespace llvm { namespace itanium_demangle {
+#define DEMANGLE_NAMESPACE_END } }
+
+#endif
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/ItaniumDemangle.h b/demangle/third_party/llvm/include/llvm/Demangle/ItaniumDemangle.h
new file mode 100644
index 00000000..ea55f4a6
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -0,0 +1,5500 @@
+//===--- ItaniumDemangle.h -----------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Generic itanium demangler library.
+// There are two copies of this file in the source tree.  The one under
+// libcxxabi is the original and the one under llvm is the copy.  Use
+// cp-to-llvm.sh to update the copy.  See README.txt for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_ITANIUMDEMANGLE_H
+#define DEMANGLE_ITANIUMDEMANGLE_H
+
+#include "DemangleConfig.h"
+#include "StringView.h"
+#include "Utility.h"
+#include <algorithm>
+#include <cassert>
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <limits>
+#include <new>
+#include <utility>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+template <class T, size_t N> class PODSmallVector {
+  static_assert(std::is_pod<T>::value,
+                "T is required to be a plain old data type");
+
+  T *First = nullptr;
+  T *Last = nullptr;
+  T *Cap = nullptr;
+  T Inline[N] = {0};
+
+  bool isInline() const { return First == Inline; }
+
+  void clearInline() {
+    First = Inline;
+    Last = Inline;
+    Cap = Inline + N;
+  }
+
+  void reserve(size_t NewCap) {
+    size_t S = size();
+    if (isInline()) {
+      auto *Tmp = static_cast<T *>(std::malloc(NewCap * sizeof(T)));
+      if (Tmp == nullptr)
+        std::terminate();
+      std::copy(First, Last, Tmp);
+      First = Tmp;
+    } else {
+      First = static_cast<T *>(std::realloc(First, NewCap * sizeof(T)));
+      if (First == nullptr)
+        std::terminate();
+    }
+    Last = First + S;
+    Cap = First + NewCap;
+  }
+
+public:
+  PODSmallVector() : First(Inline), Last(First), Cap(Inline + N) {}
+
+  PODSmallVector(const PODSmallVector &) = delete;
+  PODSmallVector &operator=(const PODSmallVector &) = delete;
+
+  PODSmallVector(PODSmallVector &&Other) : PODSmallVector() {
+    if (Other.isInline()) {
+      std::copy(Other.begin(), Other.end(), First);
+      Last = First + Other.size();
+      Other.clear();
+      return;
+    }
+
+    First = Other.First;
+    Last = Other.Last;
+    Cap = Other.Cap;
+    Other.clearInline();
+  }
+
+  PODSmallVector &operator=(PODSmallVector &&Other) {
+    if (Other.isInline()) {
+      if (!isInline()) {
+        std::free(First);
+        clearInline();
+      }
+      std::copy(Other.begin(), Other.end(), First);
+      Last = First + Other.size();
+      Other.clear();
+      return *this;
+    }
+
+    if (isInline()) {
+      First = Other.First;
+      Last = Other.Last;
+      Cap = Other.Cap;
+      Other.clearInline();
+      return *this;
+    }
+
+    std::swap(First, Other.First);
+    std::swap(Last, Other.Last);
+    std::swap(Cap, Other.Cap);
+    Other.clear();
+    return *this;
+  }
+
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  void push_back(const T &Elem) {
+    if (Last == Cap)
+      reserve(size() * 2);
+    *Last++ = Elem;
+  }
+
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  void pop_back() {
+    assert(Last != First && "Popping empty vector!");
+    --Last;
+  }
+
+  void dropBack(size_t Index) {
+    assert(Index <= size() && "dropBack() can't expand!");
+    Last = First + Index;
+  }
+
+  T *begin() { return First; }
+  T *end() { return Last; }
+
+  bool empty() const { return First == Last; }
+  size_t size() const { return static_cast<size_t>(Last - First); }
+  T &back() {
+    assert(Last != First && "Calling back() on empty vector!");
+    return *(Last - 1);
+  }
+  T &operator[](size_t Index) {
+    assert(Index < size() && "Invalid access!");
+    return *(begin() + Index);
+  }
+  void clear() { Last = First; }
+
+  ~PODSmallVector() {
+    if (!isInline())
+      std::free(First);
+  }
+};
+
+// Base class of all AST nodes. The AST is built by the parser, then is
+// traversed by the printLeft/Right functions to produce a demangled string.
+class Node {
+public:
+  enum Kind : unsigned char {
+#define NODE(NodeKind) K##NodeKind,
+#include "ItaniumNodes.def"
+  };
+
+  /// Three-way bool to track a cached value. Unknown is possible if this node
+  /// has an unexpanded parameter pack below it that may affect this cache.
+  enum class Cache : unsigned char { Yes, No, Unknown, };
+
+  /// Operator precedence for expression nodes. Used to determine required
+  /// parens in expression emission.
+  enum class Prec {
+    Primary,
+    Postfix,
+    Unary,
+    Cast,
+    PtrMem,
+    Multiplicative,
+    Additive,
+    Shift,
+    Spaceship,
+    Relational,
+    Equality,
+    And,
+    Xor,
+    Ior,
+    AndIf,
+    OrIf,
+    Conditional,
+    Assign,
+    Comma,
+    Default,
+  };
+
+private:
+  Kind K;
+
+  Prec Precedence : 6;
+
+  // FIXME: Make these protected.
+public:
+  /// Tracks if this node has a component on its right side, in which case we
+  /// need to call printRight.
+  Cache RHSComponentCache : 2;
+
+  /// Track if this node is a (possibly qualified) array type. This can affect
+  /// how we format the output string.
+  Cache ArrayCache : 2;
+
+  /// Track if this node is a (possibly qualified) function type. This can
+  /// affect how we format the output string.
+  Cache FunctionCache : 2;
+
+public:
+  Node(Kind K_, Prec Precedence_ = Prec::Primary,
+       Cache RHSComponentCache_ = Cache::No, Cache ArrayCache_ = Cache::No,
+       Cache FunctionCache_ = Cache::No)
+      : K(K_), Precedence(Precedence_), RHSComponentCache(RHSComponentCache_),
+        ArrayCache(ArrayCache_), FunctionCache(FunctionCache_) {}
+  Node(Kind K_, Cache RHSComponentCache_, Cache ArrayCache_ = Cache::No,
+       Cache FunctionCache_ = Cache::No)
+      : Node(K_, Prec::Primary, RHSComponentCache_, ArrayCache_,
+             FunctionCache_) {}
+
+  /// Visit the most-derived object corresponding to this object.
+  template<typename Fn> void visit(Fn F) const;
+
+  // The following function is provided by all derived classes:
+  //
+  // Call F with arguments that, when passed to the constructor of this node,
+  // would construct an equivalent node.
+  //template<typename Fn> void match(Fn F) const;
+
+  bool hasRHSComponent(OutputBuffer &OB) const {
+    if (RHSComponentCache != Cache::Unknown)
+      return RHSComponentCache == Cache::Yes;
+    return hasRHSComponentSlow(OB);
+  }
+
+  bool hasArray(OutputBuffer &OB) const {
+    if (ArrayCache != Cache::Unknown)
+      return ArrayCache == Cache::Yes;
+    return hasArraySlow(OB);
+  }
+
+  bool hasFunction(OutputBuffer &OB) const {
+    if (FunctionCache != Cache::Unknown)
+      return FunctionCache == Cache::Yes;
+    return hasFunctionSlow(OB);
+  }
+
+  Kind getKind() const { return K; }
+
+  Prec getPrecedence() const { return Precedence; }
+
+  virtual bool hasRHSComponentSlow(OutputBuffer &) const { return false; }
+  virtual bool hasArraySlow(OutputBuffer &) const { return false; }
+  virtual bool hasFunctionSlow(OutputBuffer &) const { return false; }
+
+  // Dig through "glue" nodes like ParameterPack and ForwardTemplateReference to
+  // get at a node that actually represents some concrete syntax.
+  virtual const Node *getSyntaxNode(OutputBuffer &) const { return this; }
+
+  // Print this node as an expression operand, surrounding it in parentheses if
+  // its precedence is [Strictly] weaker than P.
+  void printAsOperand(OutputBuffer &OB, Prec P = Prec::Default,
+                      bool StrictlyWorse = false) const {
+    bool Paren =
+        unsigned(getPrecedence()) >= unsigned(P) + unsigned(StrictlyWorse);
+    if (Paren)
+      OB.printOpen();
+    print(OB);
+    if (Paren)
+      OB.printClose();
+  }
+
+  void print(OutputBuffer &OB) const {
+    printLeft(OB);
+    if (RHSComponentCache != Cache::No)
+      printRight(OB);
+  }
+
+  // Print the "left" side of this Node into OutputBuffer.
+  virtual void printLeft(OutputBuffer &) const = 0;
+
+  // Print the "right". This distinction is necessary to represent C++ types
+  // that appear on the RHS of their subtype, such as arrays or functions.
+  // Since most types don't have such a component, provide a default
+  // implementation.
+  virtual void printRight(OutputBuffer &) const {}
+
+  virtual StringView getBaseName() const { return StringView(); }
+
+  // Silence compiler warnings, this dtor will never be called.
+  virtual ~Node() = default;
+
+#ifndef NDEBUG
+  DEMANGLE_DUMP_METHOD void dump() const;
+#endif
+};
+
+class NodeArray {
+  Node **Elements;
+  size_t NumElements;
+
+public:
+  NodeArray() : Elements(nullptr), NumElements(0) {}
+  NodeArray(Node **Elements_, size_t NumElements_)
+      : Elements(Elements_), NumElements(NumElements_) {}
+
+  bool empty() const { return NumElements == 0; }
+  size_t size() const { return NumElements; }
+
+  Node **begin() const { return Elements; }
+  Node **end() const { return Elements + NumElements; }
+
+  Node *operator[](size_t Idx) const { return Elements[Idx]; }
+
+  void printWithComma(OutputBuffer &OB) const {
+    bool FirstElement = true;
+    for (size_t Idx = 0; Idx != NumElements; ++Idx) {
+      size_t BeforeComma = OB.getCurrentPosition();
+      if (!FirstElement)
+        OB += ", ";
+      size_t AfterComma = OB.getCurrentPosition();
+      Elements[Idx]->printAsOperand(OB, Node::Prec::Comma);
+
+      // Elements[Idx] is an empty parameter pack expansion, we should erase the
+      // comma we just printed.
+      if (AfterComma == OB.getCurrentPosition()) {
+        OB.setCurrentPosition(BeforeComma);
+        continue;
+      }
+
+      FirstElement = false;
+    }
+  }
+};
+
+struct NodeArrayNode : Node {
+  NodeArray Array;
+  NodeArrayNode(NodeArray Array_) : Node(KNodeArrayNode), Array(Array_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Array); }
+
+  void printLeft(OutputBuffer &OB) const override { Array.printWithComma(OB); }
+};
+
+class DotSuffix final : public Node {
+  const Node *Prefix;
+  const StringView Suffix;
+
+public:
+  DotSuffix(const Node *Prefix_, StringView Suffix_)
+      : Node(KDotSuffix), Prefix(Prefix_), Suffix(Suffix_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Prefix, Suffix); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Prefix->print(OB);
+    OB += " (";
+    OB += Suffix;
+    OB += ")";
+  }
+};
+
+class VendorExtQualType final : public Node {
+  const Node *Ty;
+  StringView Ext;
+  const Node *TA;
+
+public:
+  VendorExtQualType(const Node *Ty_, StringView Ext_, const Node *TA_)
+      : Node(KVendorExtQualType), Ty(Ty_), Ext(Ext_), TA(TA_) {}
+
+  const Node *getTy() const { return Ty; }
+  StringView getExt() const { return Ext; }
+  const Node *getTA() const { return TA; }
+
+  template <typename Fn> void match(Fn F) const { F(Ty, Ext, TA); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Ty->print(OB);
+    OB += " ";
+    OB += Ext;
+    if (TA != nullptr)
+      TA->print(OB);
+  }
+};
+
+enum FunctionRefQual : unsigned char {
+  FrefQualNone,
+  FrefQualLValue,
+  FrefQualRValue,
+};
+
+enum Qualifiers {
+  QualNone = 0,
+  QualConst = 0x1,
+  QualVolatile = 0x2,
+  QualRestrict = 0x4,
+};
+
+inline Qualifiers operator|=(Qualifiers &Q1, Qualifiers Q2) {
+  return Q1 = static_cast<Qualifiers>(Q1 | Q2);
+}
+
+class QualType final : public Node {
+protected:
+  const Qualifiers Quals;
+  const Node *Child;
+
+  void printQuals(OutputBuffer &OB) const {
+    if (Quals & QualConst)
+      OB += " const";
+    if (Quals & QualVolatile)
+      OB += " volatile";
+    if (Quals & QualRestrict)
+      OB += " restrict";
+  }
+
+public:
+  QualType(const Node *Child_, Qualifiers Quals_)
+      : Node(KQualType, Child_->RHSComponentCache,
+             Child_->ArrayCache, Child_->FunctionCache),
+        Quals(Quals_), Child(Child_) {}
+
+  Qualifiers getQuals() const { return Quals; }
+  const Node *getChild() const { return Child; }
+
+  template<typename Fn> void match(Fn F) const { F(Child, Quals); }
+
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return Child->hasRHSComponent(OB);
+  }
+  bool hasArraySlow(OutputBuffer &OB) const override {
+    return Child->hasArray(OB);
+  }
+  bool hasFunctionSlow(OutputBuffer &OB) const override {
+    return Child->hasFunction(OB);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Child->printLeft(OB);
+    printQuals(OB);
+  }
+
+  void printRight(OutputBuffer &OB) const override { Child->printRight(OB); }
+};
+
+class ConversionOperatorType final : public Node {
+  const Node *Ty;
+
+public:
+  ConversionOperatorType(const Node *Ty_)
+      : Node(KConversionOperatorType), Ty(Ty_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "operator ";
+    Ty->print(OB);
+  }
+};
+
+class PostfixQualifiedType final : public Node {
+  const Node *Ty;
+  const StringView Postfix;
+
+public:
+  PostfixQualifiedType(const Node *Ty_, StringView Postfix_)
+      : Node(KPostfixQualifiedType), Ty(Ty_), Postfix(Postfix_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Postfix); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Ty->printLeft(OB);
+    OB += Postfix;
+  }
+};
+
+class NameType final : public Node {
+  const StringView Name;
+
+public:
+  NameType(StringView Name_) : Node(KNameType), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name); }
+
+  StringView getName() const { return Name; }
+  StringView getBaseName() const override { return Name; }
+
+  void printLeft(OutputBuffer &OB) const override { OB += Name; }
+};
+
+class BitIntType final : public Node {
+  const Node *Size;
+  bool Signed;
+
+public:
+  BitIntType(const Node *Size_, bool Signed_)
+      : Node(KBitIntType), Size(Size_), Signed(Signed_) {}
+
+  template <typename Fn> void match(Fn F) const { F(Size, Signed); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (!Signed)
+      OB += "unsigned ";
+    OB += "_BitInt";
+    OB.printOpen();
+    Size->printAsOperand(OB);
+    OB.printClose();
+  }
+};
+
+class ElaboratedTypeSpefType : public Node {
+  StringView Kind;
+  Node *Child;
+public:
+  ElaboratedTypeSpefType(StringView Kind_, Node *Child_)
+      : Node(KElaboratedTypeSpefType), Kind(Kind_), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Kind, Child); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Kind;
+    OB += ' ';
+    Child->print(OB);
+  }
+};
+
+struct AbiTagAttr : Node {
+  Node *Base;
+  StringView Tag;
+
+  AbiTagAttr(Node* Base_, StringView Tag_)
+      : Node(KAbiTagAttr, Base_->RHSComponentCache,
+             Base_->ArrayCache, Base_->FunctionCache),
+        Base(Base_), Tag(Tag_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Base, Tag); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Base->printLeft(OB);
+    OB += "[abi:";
+    OB += Tag;
+    OB += "]";
+  }
+};
+
+class EnableIfAttr : public Node {
+  NodeArray Conditions;
+public:
+  EnableIfAttr(NodeArray Conditions_)
+      : Node(KEnableIfAttr), Conditions(Conditions_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Conditions); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += " [enable_if:";
+    Conditions.printWithComma(OB);
+    OB += ']';
+  }
+};
+
+class ObjCProtoName : public Node {
+  const Node *Ty;
+  StringView Protocol;
+
+  friend class PointerType;
+
+public:
+  ObjCProtoName(const Node *Ty_, StringView Protocol_)
+      : Node(KObjCProtoName), Ty(Ty_), Protocol(Protocol_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Protocol); }
+
+  bool isObjCObject() const {
+    return Ty->getKind() == KNameType &&
+           static_cast<const NameType *>(Ty)->getName() == "objc_object";
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Ty->print(OB);
+    OB += "<";
+    OB += Protocol;
+    OB += ">";
+  }
+};
+
+class PointerType final : public Node {
+  const Node *Pointee;
+
+public:
+  PointerType(const Node *Pointee_)
+      : Node(KPointerType, Pointee_->RHSComponentCache),
+        Pointee(Pointee_) {}
+
+  const Node *getPointee() const { return Pointee; }
+
+  template<typename Fn> void match(Fn F) const { F(Pointee); }
+
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return Pointee->hasRHSComponent(OB);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    // We rewrite objc_object<SomeProtocol>* into id<SomeProtocol>.
+    if (Pointee->getKind() != KObjCProtoName ||
+        !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
+      Pointee->printLeft(OB);
+      if (Pointee->hasArray(OB))
+        OB += " ";
+      if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
+        OB += "(";
+      OB += "*";
+    } else {
+      const auto *objcProto = static_cast<const ObjCProtoName *>(Pointee);
+      OB += "id<";
+      OB += objcProto->Protocol;
+      OB += ">";
+    }
+  }
+
+  void printRight(OutputBuffer &OB) const override {
+    if (Pointee->getKind() != KObjCProtoName ||
+        !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
+      if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
+        OB += ")";
+      Pointee->printRight(OB);
+    }
+  }
+};
+
+enum class ReferenceKind {
+  LValue,
+  RValue,
+};
+
+// Represents either a LValue or an RValue reference type.
+class ReferenceType : public Node {
+  const Node *Pointee;
+  ReferenceKind RK;
+
+  mutable bool Printing = false;
+
+  // Dig through any refs to refs, collapsing the ReferenceTypes as we go. The
+  // rule here is rvalue ref to rvalue ref collapses to a rvalue ref, and any
+  // other combination collapses to a lvalue ref.
+  //
+  // A combination of a TemplateForwardReference and a back-ref Substitution
+  // from an ill-formed string may have created a cycle; use cycle detection to
+  // avoid looping forever.
+  std::pair<ReferenceKind, const Node *> collapse(OutputBuffer &OB) const {
+    auto SoFar = std::make_pair(RK, Pointee);
+    // Track the chain of nodes for the Floyd's 'tortoise and hare'
+    // cycle-detection algorithm, since getSyntaxNode(S) is impure
+    PODSmallVector<const Node *, 8> Prev;
+    for (;;) {
+      const Node *SN = SoFar.second->getSyntaxNode(OB);
+      if (SN->getKind() != KReferenceType)
+        break;
+      auto *RT = static_cast<const ReferenceType *>(SN);
+      SoFar.second = RT->Pointee;
+      SoFar.first = std::min(SoFar.first, RT->RK);
+
+      // The middle of Prev is the 'slow' pointer moving at half speed
+      Prev.push_back(SoFar.second);
+      if (Prev.size() > 1 && SoFar.second == Prev[(Prev.size() - 1) / 2]) {
+        // Cycle detected
+        SoFar.second = nullptr;
+        break;
+      }
+    }
+    return SoFar;
+  }
+
+public:
+  ReferenceType(const Node *Pointee_, ReferenceKind RK_)
+      : Node(KReferenceType, Pointee_->RHSComponentCache),
+        Pointee(Pointee_), RK(RK_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Pointee, RK); }
+
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return Pointee->hasRHSComponent(OB);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Printing)
+      return;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    std::pair<ReferenceKind, const Node *> Collapsed = collapse(OB);
+    if (!Collapsed.second)
+      return;
+    Collapsed.second->printLeft(OB);
+    if (Collapsed.second->hasArray(OB))
+      OB += " ";
+    if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
+      OB += "(";
+
+    OB += (Collapsed.first == ReferenceKind::LValue ? "&" : "&&");
+  }
+  void printRight(OutputBuffer &OB) const override {
+    if (Printing)
+      return;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    std::pair<ReferenceKind, const Node *> Collapsed = collapse(OB);
+    if (!Collapsed.second)
+      return;
+    if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
+      OB += ")";
+    Collapsed.second->printRight(OB);
+  }
+};
+
+class PointerToMemberType final : public Node {
+  const Node *ClassType;
+  const Node *MemberType;
+
+public:
+  PointerToMemberType(const Node *ClassType_, const Node *MemberType_)
+      : Node(KPointerToMemberType, MemberType_->RHSComponentCache),
+        ClassType(ClassType_), MemberType(MemberType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(ClassType, MemberType); }
+
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return MemberType->hasRHSComponent(OB);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    MemberType->printLeft(OB);
+    if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
+      OB += "(";
+    else
+      OB += " ";
+    ClassType->print(OB);
+    OB += "::*";
+  }
+
+  void printRight(OutputBuffer &OB) const override {
+    if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
+      OB += ")";
+    MemberType->printRight(OB);
+  }
+};
+
+class ArrayType final : public Node {
+  const Node *Base;
+  Node *Dimension;
+
+public:
+  ArrayType(const Node *Base_, Node *Dimension_)
+      : Node(KArrayType,
+             /*RHSComponentCache=*/Cache::Yes,
+             /*ArrayCache=*/Cache::Yes),
+        Base(Base_), Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Base, Dimension); }
+
+  bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
+  bool hasArraySlow(OutputBuffer &) const override { return true; }
+
+  void printLeft(OutputBuffer &OB) const override { Base->printLeft(OB); }
+
+  void printRight(OutputBuffer &OB) const override {
+    if (OB.back() != ']')
+      OB += " ";
+    OB += "[";
+    if (Dimension)
+      Dimension->print(OB);
+    OB += "]";
+    Base->printRight(OB);
+  }
+};
+
+class FunctionType final : public Node {
+  const Node *Ret;
+  NodeArray Params;
+  Qualifiers CVQuals;
+  FunctionRefQual RefQual;
+  const Node *ExceptionSpec;
+
+public:
+  FunctionType(const Node *Ret_, NodeArray Params_, Qualifiers CVQuals_,
+               FunctionRefQual RefQual_, const Node *ExceptionSpec_)
+      : Node(KFunctionType,
+             /*RHSComponentCache=*/Cache::Yes, /*ArrayCache=*/Cache::No,
+             /*FunctionCache=*/Cache::Yes),
+        Ret(Ret_), Params(Params_), CVQuals(CVQuals_), RefQual(RefQual_),
+        ExceptionSpec(ExceptionSpec_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(Ret, Params, CVQuals, RefQual, ExceptionSpec);
+  }
+
+  bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
+  bool hasFunctionSlow(OutputBuffer &) const override { return true; }
+
+  // Handle C++'s ... quirky decl grammar by using the left & right
+  // distinction. Consider:
+  //   int (*f(float))(char) {}
+  // f is a function that takes a float and returns a pointer to a function
+  // that takes a char and returns an int. If we're trying to print f, start
+  // by printing out the return types's left, then print our parameters, then
+  // finally print right of the return type.
+  void printLeft(OutputBuffer &OB) const override {
+    Ret->printLeft(OB);
+    OB += " ";
+  }
+
+  void printRight(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Params.printWithComma(OB);
+    OB.printClose();
+    Ret->printRight(OB);
+
+    if (CVQuals & QualConst)
+      OB += " const";
+    if (CVQuals & QualVolatile)
+      OB += " volatile";
+    if (CVQuals & QualRestrict)
+      OB += " restrict";
+
+    if (RefQual == FrefQualLValue)
+      OB += " &";
+    else if (RefQual == FrefQualRValue)
+      OB += " &&";
+
+    if (ExceptionSpec != nullptr) {
+      OB += ' ';
+      ExceptionSpec->print(OB);
+    }
+  }
+};
+
+class NoexceptSpec : public Node {
+  const Node *E;
+public:
+  NoexceptSpec(const Node *E_) : Node(KNoexceptSpec), E(E_) {}
+
+  template<typename Fn> void match(Fn F) const { F(E); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "noexcept";
+    OB.printOpen();
+    E->printAsOperand(OB);
+    OB.printClose();
+  }
+};
+
+class DynamicExceptionSpec : public Node {
+  NodeArray Types;
+public:
+  DynamicExceptionSpec(NodeArray Types_)
+      : Node(KDynamicExceptionSpec), Types(Types_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Types); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "throw";
+    OB.printOpen();
+    Types.printWithComma(OB);
+    OB.printClose();
+  }
+};
+
+class FunctionEncoding final : public Node {
+  const Node *Ret;
+  const Node *Name;
+  NodeArray Params;
+  const Node *Attrs;
+  Qualifiers CVQuals;
+  FunctionRefQual RefQual;
+
+public:
+  FunctionEncoding(const Node *Ret_, const Node *Name_, NodeArray Params_,
+                   const Node *Attrs_, Qualifiers CVQuals_,
+                   FunctionRefQual RefQual_)
+      : Node(KFunctionEncoding,
+             /*RHSComponentCache=*/Cache::Yes, /*ArrayCache=*/Cache::No,
+             /*FunctionCache=*/Cache::Yes),
+        Ret(Ret_), Name(Name_), Params(Params_), Attrs(Attrs_),
+        CVQuals(CVQuals_), RefQual(RefQual_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(Ret, Name, Params, Attrs, CVQuals, RefQual);
+  }
+
+  Qualifiers getCVQuals() const { return CVQuals; }
+  FunctionRefQual getRefQual() const { return RefQual; }
+  NodeArray getParams() const { return Params; }
+  const Node *getReturnType() const { return Ret; }
+
+  bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
+  bool hasFunctionSlow(OutputBuffer &) const override { return true; }
+
+  const Node *getName() const { return Name; }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Ret) {
+      Ret->printLeft(OB);
+      if (!Ret->hasRHSComponent(OB))
+        OB += " ";
+    }
+    Name->print(OB);
+  }
+
+  void printRight(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Params.printWithComma(OB);
+    OB.printClose();
+    if (Ret)
+      Ret->printRight(OB);
+
+    if (CVQuals & QualConst)
+      OB += " const";
+    if (CVQuals & QualVolatile)
+      OB += " volatile";
+    if (CVQuals & QualRestrict)
+      OB += " restrict";
+
+    if (RefQual == FrefQualLValue)
+      OB += " &";
+    else if (RefQual == FrefQualRValue)
+      OB += " &&";
+
+    if (Attrs != nullptr)
+      Attrs->print(OB);
+  }
+};
+
+class LiteralOperator : public Node {
+  const Node *OpName;
+
+public:
+  LiteralOperator(const Node *OpName_)
+      : Node(KLiteralOperator), OpName(OpName_) {}
+
+  template<typename Fn> void match(Fn F) const { F(OpName); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "operator\"\" ";
+    OpName->print(OB);
+  }
+};
+
+class SpecialName final : public Node {
+  const StringView Special;
+  const Node *Child;
+
+public:
+  SpecialName(StringView Special_, const Node *Child_)
+      : Node(KSpecialName), Special(Special_), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Special, Child); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Special;
+    Child->print(OB);
+  }
+};
+
+class CtorVtableSpecialName final : public Node {
+  const Node *FirstType;
+  const Node *SecondType;
+
+public:
+  CtorVtableSpecialName(const Node *FirstType_, const Node *SecondType_)
+      : Node(KCtorVtableSpecialName),
+        FirstType(FirstType_), SecondType(SecondType_) {}
+
+  template<typename Fn> void match(Fn F) const { F(FirstType, SecondType); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "construction vtable for ";
+    FirstType->print(OB);
+    OB += "-in-";
+    SecondType->print(OB);
+  }
+};
+
+struct NestedName : Node {
+  Node *Qual;
+  Node *Name;
+
+  NestedName(Node *Qual_, Node *Name_)
+      : Node(KNestedName), Qual(Qual_), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Qual, Name); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Qual->print(OB);
+    OB += "::";
+    Name->print(OB);
+  }
+};
+
+struct ModuleName : Node {
+  ModuleName *Parent;
+  Node *Name;
+  bool IsPartition;
+
+  ModuleName(ModuleName *Parent_, Node *Name_, bool IsPartition_ = false)
+      : Node(KModuleName), Parent(Parent_), Name(Name_),
+        IsPartition(IsPartition_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Parent, Name, IsPartition);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Parent)
+      Parent->print(OB);
+    if (Parent || IsPartition)
+      OB += IsPartition ? ':' : '.';
+    Name->print(OB);
+  }
+};
+
+struct ModuleEntity : Node {
+  ModuleName *Module;
+  Node *Name;
+
+  ModuleEntity(ModuleName *Module_, Node *Name_)
+      : Node(KModuleEntity), Module(Module_), Name(Name_) {}
+
+  template <typename Fn> void match(Fn F) const { F(Module, Name); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Name->print(OB);
+    OB += '@';
+    Module->print(OB);
+  }
+};
+
+struct LocalName : Node {
+  Node *Encoding;
+  Node *Entity;
+
+  LocalName(Node *Encoding_, Node *Entity_)
+      : Node(KLocalName), Encoding(Encoding_), Entity(Entity_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Encoding, Entity); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Encoding->print(OB);
+    OB += "::";
+    Entity->print(OB);
+  }
+};
+
+class QualifiedName final : public Node {
+  // qualifier::name
+  const Node *Qualifier;
+  const Node *Name;
+
+public:
+  QualifiedName(const Node *Qualifier_, const Node *Name_)
+      : Node(KQualifiedName), Qualifier(Qualifier_), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Qualifier, Name); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Qualifier->print(OB);
+    OB += "::";
+    Name->print(OB);
+  }
+};
+
+class VectorType final : public Node {
+  const Node *BaseType;
+  const Node *Dimension;
+
+public:
+  VectorType(const Node *BaseType_, const Node *Dimension_)
+      : Node(KVectorType), BaseType(BaseType_), Dimension(Dimension_) {}
+
+  const Node *getBaseType() const { return BaseType; }
+  const Node *getDimension() const { return Dimension; }
+
+  template<typename Fn> void match(Fn F) const { F(BaseType, Dimension); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    BaseType->print(OB);
+    OB += " vector[";
+    if (Dimension)
+      Dimension->print(OB);
+    OB += "]";
+  }
+};
+
+class PixelVectorType final : public Node {
+  const Node *Dimension;
+
+public:
+  PixelVectorType(const Node *Dimension_)
+      : Node(KPixelVectorType), Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Dimension); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    // FIXME: This should demangle as "vector pixel".
+    OB += "pixel vector[";
+    Dimension->print(OB);
+    OB += "]";
+  }
+};
+
+class BinaryFPType final : public Node {
+  const Node *Dimension;
+
+public:
+  BinaryFPType(const Node *Dimension_)
+      : Node(KBinaryFPType), Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Dimension); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "_Float";
+    Dimension->print(OB);
+  }
+};
+
+enum class TemplateParamKind { Type, NonType, Template };
+
+/// An invented name for a template parameter for which we don't have a
+/// corresponding template argument.
+///
+/// This node is created when parsing the <lambda-sig> for a lambda with
+/// explicit template arguments, which might be referenced in the parameter
+/// types appearing later in the <lambda-sig>.
+class SyntheticTemplateParamName final : public Node {
+  TemplateParamKind Kind;
+  unsigned Index;
+
+public:
+  SyntheticTemplateParamName(TemplateParamKind Kind_, unsigned Index_)
+      : Node(KSyntheticTemplateParamName), Kind(Kind_), Index(Index_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Kind, Index); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    switch (Kind) {
+    case TemplateParamKind::Type:
+      OB += "$T";
+      break;
+    case TemplateParamKind::NonType:
+      OB += "$N";
+      break;
+    case TemplateParamKind::Template:
+      OB += "$TT";
+      break;
+    }
+    if (Index > 0)
+      OB << Index - 1;
+  }
+};
+
+/// A template type parameter declaration, 'typename T'.
+class TypeTemplateParamDecl final : public Node {
+  Node *Name;
+
+public:
+  TypeTemplateParamDecl(Node *Name_)
+      : Node(KTypeTemplateParamDecl, Cache::Yes), Name(Name_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name); }
+
+  void printLeft(OutputBuffer &OB) const override { OB += "typename "; }
+
+  void printRight(OutputBuffer &OB) const override { Name->print(OB); }
+};
+
+/// A non-type template parameter declaration, 'int N'.
+class NonTypeTemplateParamDecl final : public Node {
+  Node *Name;
+  Node *Type;
+
+public:
+  NonTypeTemplateParamDecl(Node *Name_, Node *Type_)
+      : Node(KNonTypeTemplateParamDecl, Cache::Yes), Name(Name_), Type(Type_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name, Type); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Type->printLeft(OB);
+    if (!Type->hasRHSComponent(OB))
+      OB += " ";
+  }
+
+  void printRight(OutputBuffer &OB) const override {
+    Name->print(OB);
+    Type->printRight(OB);
+  }
+};
+
+/// A template template parameter declaration,
+/// 'template<typename T> typename N'.
+class TemplateTemplateParamDecl final : public Node {
+  Node *Name;
+  NodeArray Params;
+
+public:
+  TemplateTemplateParamDecl(Node *Name_, NodeArray Params_)
+      : Node(KTemplateTemplateParamDecl, Cache::Yes), Name(Name_),
+        Params(Params_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name, Params); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+    OB += "template<";
+    Params.printWithComma(OB);
+    OB += "> typename ";
+  }
+
+  void printRight(OutputBuffer &OB) const override { Name->print(OB); }
+};
+
+/// A template parameter pack declaration, 'typename ...T'.
+class TemplateParamPackDecl final : public Node {
+  Node *Param;
+
+public:
+  TemplateParamPackDecl(Node *Param_)
+      : Node(KTemplateParamPackDecl, Cache::Yes), Param(Param_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Param); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Param->printLeft(OB);
+    OB += "...";
+  }
+
+  void printRight(OutputBuffer &OB) const override { Param->printRight(OB); }
+};
+
+/// An unexpanded parameter pack (either in the expression or type context). If
+/// this AST is correct, this node will have a ParameterPackExpansion node above
+/// it.
+///
+/// This node is created when some <template-args> are found that apply to an
+/// <encoding>, and is stored in the TemplateParams table. In order for this to
+/// appear in the final AST, it has to referenced via a <template-param> (ie,
+/// T_).
+class ParameterPack final : public Node {
+  NodeArray Data;
+
+  // Setup OutputBuffer for a pack expansion, unless we're already expanding
+  // one.
+  void initializePackExpansion(OutputBuffer &OB) const {
+    if (OB.CurrentPackMax == std::numeric_limits<unsigned>::max()) {
+      OB.CurrentPackMax = static_cast<unsigned>(Data.size());
+      OB.CurrentPackIndex = 0;
+    }
+  }
+
+public:
+  ParameterPack(NodeArray Data_) : Node(KParameterPack), Data(Data_) {
+    ArrayCache = FunctionCache = RHSComponentCache = Cache::Unknown;
+    if (std::all_of(Data.begin(), Data.end(), [](Node* P) {
+          return P->ArrayCache == Cache::No;
+        }))
+      ArrayCache = Cache::No;
+    if (std::all_of(Data.begin(), Data.end(), [](Node* P) {
+          return P->FunctionCache == Cache::No;
+        }))
+      FunctionCache = Cache::No;
+    if (std::all_of(Data.begin(), Data.end(), [](Node* P) {
+          return P->RHSComponentCache == Cache::No;
+        }))
+      RHSComponentCache = Cache::No;
+  }
+
+  template<typename Fn> void match(Fn F) const { F(Data); }
+
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasRHSComponent(OB);
+  }
+  bool hasArraySlow(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasArray(OB);
+  }
+  bool hasFunctionSlow(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasFunction(OB);
+  }
+  const Node *getSyntaxNode(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() ? Data[Idx]->getSyntaxNode(OB) : this;
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    if (Idx < Data.size())
+      Data[Idx]->printLeft(OB);
+  }
+  void printRight(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    if (Idx < Data.size())
+      Data[Idx]->printRight(OB);
+  }
+};
+
+/// A variadic template argument. This node represents an occurrence of
+/// J<something>E in some <template-args>. It isn't itself unexpanded, unless
+/// one of it's Elements is. The parser inserts a ParameterPack into the
+/// TemplateParams table if the <template-args> this pack belongs to apply to an
+/// <encoding>.
+class TemplateArgumentPack final : public Node {
+  NodeArray Elements;
+public:
+  TemplateArgumentPack(NodeArray Elements_)
+      : Node(KTemplateArgumentPack), Elements(Elements_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Elements); }
+
+  NodeArray getElements() const { return Elements; }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Elements.printWithComma(OB);
+  }
+};
+
+/// A pack expansion. Below this node, there are some unexpanded ParameterPacks
+/// which each have Child->ParameterPackSize elements.
+class ParameterPackExpansion final : public Node {
+  const Node *Child;
+
+public:
+  ParameterPackExpansion(const Node *Child_)
+      : Node(KParameterPackExpansion), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child); }
+
+  const Node *getChild() const { return Child; }
+
+  void printLeft(OutputBuffer &OB) const override {
+    constexpr unsigned Max = std::numeric_limits<unsigned>::max();
+    ScopedOverride<unsigned> SavePackIdx(OB.CurrentPackIndex, Max);
+    ScopedOverride<unsigned> SavePackMax(OB.CurrentPackMax, Max);
+    size_t StreamPos = OB.getCurrentPosition();
+
+    // Print the first element in the pack. If Child contains a ParameterPack,
+    // it will set up S.CurrentPackMax and print the first element.
+    Child->print(OB);
+
+    // No ParameterPack was found in Child. This can occur if we've found a pack
+    // expansion on a <function-param>.
+    if (OB.CurrentPackMax == Max) {
+      OB += "...";
+      return;
+    }
+
+    // We found a ParameterPack, but it has no elements. Erase whatever we may
+    // of printed.
+    if (OB.CurrentPackMax == 0) {
+      OB.setCurrentPosition(StreamPos);
+      return;
+    }
+
+    // Else, iterate through the rest of the elements in the pack.
+    for (unsigned I = 1, E = OB.CurrentPackMax; I < E; ++I) {
+      OB += ", ";
+      OB.CurrentPackIndex = I;
+      Child->print(OB);
+    }
+  }
+};
+
+class TemplateArgs final : public Node {
+  NodeArray Params;
+
+public:
+  TemplateArgs(NodeArray Params_) : Node(KTemplateArgs), Params(Params_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Params); }
+
+  NodeArray getParams() { return Params; }
+
+  void printLeft(OutputBuffer &OB) const override {
+    ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+    OB += "<";
+    Params.printWithComma(OB);
+    OB += ">";
+  }
+};
+
+/// A forward-reference to a template argument that was not known at the point
+/// where the template parameter name was parsed in a mangling.
+///
+/// This is created when demangling the name of a specialization of a
+/// conversion function template:
+///
+/// \code
+/// struct A {
+///   template<typename T> operator T*();
+/// };
+/// \endcode
+///
+/// When demangling a specialization of the conversion function template, we
+/// encounter the name of the template (including the \c T) before we reach
+/// the template argument list, so we cannot substitute the parameter name
+/// for the corresponding argument while parsing. Instead, we create a
+/// \c ForwardTemplateReference node that is resolved after we parse the
+/// template arguments.
+struct ForwardTemplateReference : Node {
+  size_t Index;
+  Node *Ref = nullptr;
+
+  // If we're currently printing this node. It is possible (though invalid) for
+  // a forward template reference to refer to itself via a substitution. This
+  // creates a cyclic AST, which will stack overflow printing. To fix this, bail
+  // out if more than one print* function is active.
+  mutable bool Printing = false;
+
+  ForwardTemplateReference(size_t Index_)
+      : Node(KForwardTemplateReference, Cache::Unknown, Cache::Unknown,
+             Cache::Unknown),
+        Index(Index_) {}
+
+  // We don't provide a matcher for these, because the value of the node is
+  // not determined by its construction parameters, and it generally needs
+  // special handling.
+  template<typename Fn> void match(Fn F) const = delete;
+
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    if (Printing)
+      return false;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->hasRHSComponent(OB);
+  }
+  bool hasArraySlow(OutputBuffer &OB) const override {
+    if (Printing)
+      return false;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->hasArray(OB);
+  }
+  bool hasFunctionSlow(OutputBuffer &OB) const override {
+    if (Printing)
+      return false;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->hasFunction(OB);
+  }
+  const Node *getSyntaxNode(OutputBuffer &OB) const override {
+    if (Printing)
+      return this;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->getSyntaxNode(OB);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Printing)
+      return;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    Ref->printLeft(OB);
+  }
+  void printRight(OutputBuffer &OB) const override {
+    if (Printing)
+      return;
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    Ref->printRight(OB);
+  }
+};
+
+struct NameWithTemplateArgs : Node {
+  // name<template_args>
+  Node *Name;
+  Node *TemplateArgs;
+
+  NameWithTemplateArgs(Node *Name_, Node *TemplateArgs_)
+      : Node(KNameWithTemplateArgs), Name(Name_), TemplateArgs(TemplateArgs_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Name, TemplateArgs); }
+
+  StringView getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Name->print(OB);
+    TemplateArgs->print(OB);
+  }
+};
+
+class GlobalQualifiedName final : public Node {
+  Node *Child;
+
+public:
+  GlobalQualifiedName(Node* Child_)
+      : Node(KGlobalQualifiedName), Child(Child_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Child); }
+
+  StringView getBaseName() const override { return Child->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "::";
+    Child->print(OB);
+  }
+};
+
+enum class SpecialSubKind {
+  allocator,
+  basic_string,
+  string,
+  istream,
+  ostream,
+  iostream,
+};
+
+class SpecialSubstitution;
+class ExpandedSpecialSubstitution : public Node {
+protected:
+  SpecialSubKind SSK;
+
+  ExpandedSpecialSubstitution(SpecialSubKind SSK_, Kind K_)
+      : Node(K_), SSK(SSK_) {}
+public:
+  ExpandedSpecialSubstitution(SpecialSubKind SSK_)
+      : ExpandedSpecialSubstitution(SSK_, KExpandedSpecialSubstitution) {}
+  inline ExpandedSpecialSubstitution(SpecialSubstitution const *);
+
+  template<typename Fn> void match(Fn F) const { F(SSK); }
+
+protected:
+  bool isInstantiation() const {
+    return unsigned(SSK) >= unsigned(SpecialSubKind::string);
+  }
+
+  StringView getBaseName() const override {
+    switch (SSK) {
+    case SpecialSubKind::allocator:
+      return StringView("allocator");
+    case SpecialSubKind::basic_string:
+      return StringView("basic_string");
+    case SpecialSubKind::string:
+      return StringView("basic_string");
+    case SpecialSubKind::istream:
+      return StringView("basic_istream");
+    case SpecialSubKind::ostream:
+      return StringView("basic_ostream");
+    case SpecialSubKind::iostream:
+      return StringView("basic_iostream");
+    }
+    DEMANGLE_UNREACHABLE;
+  }
+
+private:
+  void printLeft(OutputBuffer &OB) const override {
+    OB << "std::" << getBaseName();
+    if (isInstantiation()) {
+      OB << "<char, std::char_traits<char>";
+      if (SSK == SpecialSubKind::string)
+        OB << ", std::allocator<char>";
+      OB << ">";
+    }
+  }
+};
+
+class SpecialSubstitution final : public ExpandedSpecialSubstitution {
+public:
+  SpecialSubstitution(SpecialSubKind SSK_)
+      : ExpandedSpecialSubstitution(SSK_, KSpecialSubstitution) {}
+
+  template<typename Fn> void match(Fn F) const { F(SSK); }
+
+  StringView getBaseName() const override {
+    auto SV = ExpandedSpecialSubstitution::getBaseName ();
+    if (isInstantiation()) {
+      // The instantiations are typedefs that drop the "basic_" prefix.
+      assert(SV.startsWith("basic_"));
+      SV = SV.dropFront(sizeof("basic_") - 1);
+    }
+    return SV;
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB << "std::" << getBaseName();
+  }
+};
+
+inline ExpandedSpecialSubstitution::ExpandedSpecialSubstitution(
+    SpecialSubstitution const *SS)
+    : ExpandedSpecialSubstitution(SS->SSK) {}
+
+class CtorDtorName final : public Node {
+  const Node *Basename;
+  const bool IsDtor;
+  const int Variant;
+
+public:
+  CtorDtorName(const Node *Basename_, bool IsDtor_, int Variant_)
+      : Node(KCtorDtorName), Basename(Basename_), IsDtor(IsDtor_),
+        Variant(Variant_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Basename, IsDtor, Variant); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (IsDtor)
+      OB += "~";
+    OB += Basename->getBaseName();
+  }
+};
+
+class DtorName : public Node {
+  const Node *Base;
+
+public:
+  DtorName(const Node *Base_) : Node(KDtorName), Base(Base_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Base); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "~";
+    Base->printLeft(OB);
+  }
+};
+
+class UnnamedTypeName : public Node {
+  const StringView Count;
+
+public:
+  UnnamedTypeName(StringView Count_) : Node(KUnnamedTypeName), Count(Count_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Count); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "'unnamed";
+    OB += Count;
+    OB += "\'";
+  }
+};
+
+class ClosureTypeName : public Node {
+  NodeArray TemplateParams;
+  NodeArray Params;
+  StringView Count;
+
+public:
+  ClosureTypeName(NodeArray TemplateParams_, NodeArray Params_,
+                  StringView Count_)
+      : Node(KClosureTypeName), TemplateParams(TemplateParams_),
+        Params(Params_), Count(Count_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(TemplateParams, Params, Count);
+  }
+
+  void printDeclarator(OutputBuffer &OB) const {
+    if (!TemplateParams.empty()) {
+      ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+      OB += "<";
+      TemplateParams.printWithComma(OB);
+      OB += ">";
+    }
+    OB.printOpen();
+    Params.printWithComma(OB);
+    OB.printClose();
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "\'lambda";
+    OB += Count;
+    OB += "\'";
+    printDeclarator(OB);
+  }
+};
+
+class StructuredBindingName : public Node {
+  NodeArray Bindings;
+public:
+  StructuredBindingName(NodeArray Bindings_)
+      : Node(KStructuredBindingName), Bindings(Bindings_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Bindings); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen('[');
+    Bindings.printWithComma(OB);
+    OB.printClose(']');
+  }
+};
+
+// -- Expression Nodes --
+
+class BinaryExpr : public Node {
+  const Node *LHS;
+  const StringView InfixOperator;
+  const Node *RHS;
+
+public:
+  BinaryExpr(const Node *LHS_, StringView InfixOperator_, const Node *RHS_,
+             Prec Prec_)
+      : Node(KBinaryExpr, Prec_), LHS(LHS_), InfixOperator(InfixOperator_),
+        RHS(RHS_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(LHS, InfixOperator, RHS, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    bool ParenAll = OB.isGtInsideTemplateArgs() &&
+                    (InfixOperator == ">" || InfixOperator == ">>");
+    if (ParenAll)
+      OB.printOpen();
+    // Assignment is right associative, with special LHS precedence.
+    bool IsAssign = getPrecedence() == Prec::Assign;
+    LHS->printAsOperand(OB, IsAssign ? Prec::OrIf : getPrecedence(), !IsAssign);
+    // No space before comma operator
+    if (!(InfixOperator == ","))
+      OB += " ";
+    OB += InfixOperator;
+    OB += " ";
+    RHS->printAsOperand(OB, getPrecedence(), IsAssign);
+    if (ParenAll)
+      OB.printClose();
+  }
+};
+
+class ArraySubscriptExpr : public Node {
+  const Node *Op1;
+  const Node *Op2;
+
+public:
+  ArraySubscriptExpr(const Node *Op1_, const Node *Op2_, Prec Prec_)
+      : Node(KArraySubscriptExpr, Prec_), Op1(Op1_), Op2(Op2_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Op1, Op2, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Op1->printAsOperand(OB, getPrecedence());
+    OB.printOpen('[');
+    Op2->printAsOperand(OB);
+    OB.printClose(']');
+  }
+};
+
+class PostfixExpr : public Node {
+  const Node *Child;
+  const StringView Operator;
+
+public:
+  PostfixExpr(const Node *Child_, StringView Operator_, Prec Prec_)
+      : Node(KPostfixExpr, Prec_), Child(Child_), Operator(Operator_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Child, Operator, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Child->printAsOperand(OB, getPrecedence(), true);
+    OB += Operator;
+  }
+};
+
+class ConditionalExpr : public Node {
+  const Node *Cond;
+  const Node *Then;
+  const Node *Else;
+
+public:
+  ConditionalExpr(const Node *Cond_, const Node *Then_, const Node *Else_,
+                  Prec Prec_)
+      : Node(KConditionalExpr, Prec_), Cond(Cond_), Then(Then_), Else(Else_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Cond, Then, Else, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Cond->printAsOperand(OB, getPrecedence());
+    OB += " ? ";
+    Then->printAsOperand(OB);
+    OB += " : ";
+    Else->printAsOperand(OB, Prec::Assign, true);
+  }
+};
+
+class MemberExpr : public Node {
+  const Node *LHS;
+  const StringView Kind;
+  const Node *RHS;
+
+public:
+  MemberExpr(const Node *LHS_, StringView Kind_, const Node *RHS_, Prec Prec_)
+      : Node(KMemberExpr, Prec_), LHS(LHS_), Kind(Kind_), RHS(RHS_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(LHS, Kind, RHS, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    LHS->printAsOperand(OB, getPrecedence(), true);
+    OB += Kind;
+    RHS->printAsOperand(OB, getPrecedence(), false);
+  }
+};
+
+class SubobjectExpr : public Node {
+  const Node *Type;
+  const Node *SubExpr;
+  StringView Offset;
+  NodeArray UnionSelectors;
+  bool OnePastTheEnd;
+
+public:
+  SubobjectExpr(const Node *Type_, const Node *SubExpr_, StringView Offset_,
+                NodeArray UnionSelectors_, bool OnePastTheEnd_)
+      : Node(KSubobjectExpr), Type(Type_), SubExpr(SubExpr_), Offset(Offset_),
+        UnionSelectors(UnionSelectors_), OnePastTheEnd(OnePastTheEnd_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(Type, SubExpr, Offset, UnionSelectors, OnePastTheEnd);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    SubExpr->print(OB);
+    OB += ".<";
+    Type->print(OB);
+    OB += " at offset ";
+    if (Offset.empty()) {
+      OB += "0";
+    } else if (Offset[0] == 'n') {
+      OB += "-";
+      OB += Offset.dropFront();
+    } else {
+      OB += Offset;
+    }
+    OB += ">";
+  }
+};
+
+class EnclosingExpr : public Node {
+  const StringView Prefix;
+  const Node *Infix;
+  const StringView Postfix;
+
+public:
+  EnclosingExpr(StringView Prefix_, const Node *Infix_,
+                Prec Prec_ = Prec::Primary)
+      : Node(KEnclosingExpr, Prec_), Prefix(Prefix_), Infix(Infix_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Prefix, Infix, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Prefix;
+    OB.printOpen();
+    Infix->print(OB);
+    OB.printClose();
+    OB += Postfix;
+  }
+};
+
+class CastExpr : public Node {
+  // cast_kind<to>(from)
+  const StringView CastKind;
+  const Node *To;
+  const Node *From;
+
+public:
+  CastExpr(StringView CastKind_, const Node *To_, const Node *From_, Prec Prec_)
+      : Node(KCastExpr, Prec_), CastKind(CastKind_), To(To_), From(From_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(CastKind, To, From, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += CastKind;
+    {
+      ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+      OB += "<";
+      To->printLeft(OB);
+      OB += ">";
+    }
+    OB.printOpen();
+    From->printAsOperand(OB);
+    OB.printClose();
+  }
+};
+
+class SizeofParamPackExpr : public Node {
+  const Node *Pack;
+
+public:
+  SizeofParamPackExpr(const Node *Pack_)
+      : Node(KSizeofParamPackExpr), Pack(Pack_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Pack); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "sizeof...";
+    OB.printOpen();
+    ParameterPackExpansion PPE(Pack);
+    PPE.printLeft(OB);
+    OB.printClose();
+  }
+};
+
+class CallExpr : public Node {
+  const Node *Callee;
+  NodeArray Args;
+
+public:
+  CallExpr(const Node *Callee_, NodeArray Args_, Prec Prec_)
+      : Node(KCallExpr, Prec_), Callee(Callee_), Args(Args_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Callee, Args, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Callee->print(OB);
+    OB.printOpen();
+    Args.printWithComma(OB);
+    OB.printClose();
+  }
+};
+
+class NewExpr : public Node {
+  // new (expr_list) type(init_list)
+  NodeArray ExprList;
+  Node *Type;
+  NodeArray InitList;
+  bool IsGlobal; // ::operator new ?
+  bool IsArray;  // new[] ?
+public:
+  NewExpr(NodeArray ExprList_, Node *Type_, NodeArray InitList_, bool IsGlobal_,
+          bool IsArray_, Prec Prec_)
+      : Node(KNewExpr, Prec_), ExprList(ExprList_), Type(Type_),
+        InitList(InitList_), IsGlobal(IsGlobal_), IsArray(IsArray_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(ExprList, Type, InitList, IsGlobal, IsArray, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (IsGlobal)
+      OB += "::";
+    OB += "new";
+    if (IsArray)
+      OB += "[]";
+    if (!ExprList.empty()) {
+      OB.printOpen();
+      ExprList.printWithComma(OB);
+      OB.printClose();
+    }
+    OB += " ";
+    Type->print(OB);
+    if (!InitList.empty()) {
+      OB.printOpen();
+      InitList.printWithComma(OB);
+      OB.printClose();
+    }
+  }
+};
+
+class DeleteExpr : public Node {
+  Node *Op;
+  bool IsGlobal;
+  bool IsArray;
+
+public:
+  DeleteExpr(Node *Op_, bool IsGlobal_, bool IsArray_, Prec Prec_)
+      : Node(KDeleteExpr, Prec_), Op(Op_), IsGlobal(IsGlobal_),
+        IsArray(IsArray_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Op, IsGlobal, IsArray, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (IsGlobal)
+      OB += "::";
+    OB += "delete";
+    if (IsArray)
+      OB += "[]";
+    OB += ' ';
+    Op->print(OB);
+  }
+};
+
+class PrefixExpr : public Node {
+  StringView Prefix;
+  Node *Child;
+
+public:
+  PrefixExpr(StringView Prefix_, Node *Child_, Prec Prec_)
+      : Node(KPrefixExpr, Prec_), Prefix(Prefix_), Child(Child_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Prefix, Child, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Prefix;
+    Child->printAsOperand(OB, getPrecedence());
+  }
+};
+
+class FunctionParam : public Node {
+  StringView Number;
+
+public:
+  FunctionParam(StringView Number_) : Node(KFunctionParam), Number(Number_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Number); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "fp";
+    OB += Number;
+  }
+};
+
+class ConversionExpr : public Node {
+  const Node *Type;
+  NodeArray Expressions;
+
+public:
+  ConversionExpr(const Node *Type_, NodeArray Expressions_, Prec Prec_)
+      : Node(KConversionExpr, Prec_), Type(Type_), Expressions(Expressions_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Type, Expressions, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Type->print(OB);
+    OB.printClose();
+    OB.printOpen();
+    Expressions.printWithComma(OB);
+    OB.printClose();
+  }
+};
+
+class PointerToMemberConversionExpr : public Node {
+  const Node *Type;
+  const Node *SubExpr;
+  StringView Offset;
+
+public:
+  PointerToMemberConversionExpr(const Node *Type_, const Node *SubExpr_,
+                                StringView Offset_, Prec Prec_)
+      : Node(KPointerToMemberConversionExpr, Prec_), Type(Type_),
+        SubExpr(SubExpr_), Offset(Offset_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Type, SubExpr, Offset, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Type->print(OB);
+    OB.printClose();
+    OB.printOpen();
+    SubExpr->print(OB);
+    OB.printClose();
+  }
+};
+
+class InitListExpr : public Node {
+  const Node *Ty;
+  NodeArray Inits;
+public:
+  InitListExpr(const Node *Ty_, NodeArray Inits_)
+      : Node(KInitListExpr), Ty(Ty_), Inits(Inits_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Inits); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Ty)
+      Ty->print(OB);
+    OB += '{';
+    Inits.printWithComma(OB);
+    OB += '}';
+  }
+};
+
+class BracedExpr : public Node {
+  const Node *Elem;
+  const Node *Init;
+  bool IsArray;
+public:
+  BracedExpr(const Node *Elem_, const Node *Init_, bool IsArray_)
+      : Node(KBracedExpr), Elem(Elem_), Init(Init_), IsArray(IsArray_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Elem, Init, IsArray); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (IsArray) {
+      OB += '[';
+      Elem->print(OB);
+      OB += ']';
+    } else {
+      OB += '.';
+      Elem->print(OB);
+    }
+    if (Init->getKind() != KBracedExpr && Init->getKind() != KBracedRangeExpr)
+      OB += " = ";
+    Init->print(OB);
+  }
+};
+
+class BracedRangeExpr : public Node {
+  const Node *First;
+  const Node *Last;
+  const Node *Init;
+public:
+  BracedRangeExpr(const Node *First_, const Node *Last_, const Node *Init_)
+      : Node(KBracedRangeExpr), First(First_), Last(Last_), Init(Init_) {}
+
+  template<typename Fn> void match(Fn F) const { F(First, Last, Init); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += '[';
+    First->print(OB);
+    OB += " ... ";
+    Last->print(OB);
+    OB += ']';
+    if (Init->getKind() != KBracedExpr && Init->getKind() != KBracedRangeExpr)
+      OB += " = ";
+    Init->print(OB);
+  }
+};
+
+class FoldExpr : public Node {
+  const Node *Pack, *Init;
+  StringView OperatorName;
+  bool IsLeftFold;
+
+public:
+  FoldExpr(bool IsLeftFold_, StringView OperatorName_, const Node *Pack_,
+           const Node *Init_)
+      : Node(KFoldExpr), Pack(Pack_), Init(Init_), OperatorName(OperatorName_),
+        IsLeftFold(IsLeftFold_) {}
+
+  template<typename Fn> void match(Fn F) const {
+    F(IsLeftFold, OperatorName, Pack, Init);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    auto PrintPack = [&] {
+      OB.printOpen();
+      ParameterPackExpansion(Pack).print(OB);
+      OB.printClose();
+    };
+
+    OB.printOpen();
+    // Either '[init op ]... op pack' or 'pack op ...[ op init]'
+    // Refactored to '[(init|pack) op ]...[ op (pack|init)]'
+    // Fold expr operands are cast-expressions
+    if (!IsLeftFold || Init != nullptr) {
+      // '(init|pack) op '
+      if (IsLeftFold)
+        Init->printAsOperand(OB, Prec::Cast, true);
+      else
+        PrintPack();
+      OB << " " << OperatorName << " ";
+    }
+    OB << "...";
+    if (IsLeftFold || Init != nullptr) {
+      // ' op (init|pack)'
+      OB << " " << OperatorName << " ";
+      if (IsLeftFold)
+        PrintPack();
+      else
+        Init->printAsOperand(OB, Prec::Cast, true);
+    }
+    OB.printClose();
+  }
+};
+
+class ThrowExpr : public Node {
+  const Node *Op;
+
+public:
+  ThrowExpr(const Node *Op_) : Node(KThrowExpr), Op(Op_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Op); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "throw ";
+    Op->print(OB);
+  }
+};
+
+class BoolExpr : public Node {
+  bool Value;
+
+public:
+  BoolExpr(bool Value_) : Node(KBoolExpr), Value(Value_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Value); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Value ? StringView("true") : StringView("false");
+  }
+};
+
+class StringLiteral : public Node {
+  const Node *Type;
+
+public:
+  StringLiteral(const Node *Type_) : Node(KStringLiteral), Type(Type_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "\"<";
+    Type->print(OB);
+    OB += ">\"";
+  }
+};
+
+class LambdaExpr : public Node {
+  const Node *Type;
+
+public:
+  LambdaExpr(const Node *Type_) : Node(KLambdaExpr), Type(Type_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "[]";
+    if (Type->getKind() == KClosureTypeName)
+      static_cast<const ClosureTypeName *>(Type)->printDeclarator(OB);
+    OB += "{...}";
+  }
+};
+
+class EnumLiteral : public Node {
+  // ty(integer)
+  const Node *Ty;
+  StringView Integer;
+
+public:
+  EnumLiteral(const Node *Ty_, StringView Integer_)
+      : Node(KEnumLiteral), Ty(Ty_), Integer(Integer_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Ty, Integer); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Ty->print(OB);
+    OB.printClose();
+
+    if (Integer[0] == 'n')
+      OB << "-" << Integer.dropFront(1);
+    else
+      OB << Integer;
+  }
+};
+
+class IntegerLiteral : public Node {
+  StringView Type;
+  StringView Value;
+
+public:
+  IntegerLiteral(StringView Type_, StringView Value_)
+      : Node(KIntegerLiteral), Type(Type_), Value(Value_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Type, Value); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Type.size() > 3) {
+      OB.printOpen();
+      OB += Type;
+      OB.printClose();
+    }
+
+    if (Value[0] == 'n') {
+      OB += '-';
+      OB += Value.dropFront(1);
+    } else
+      OB += Value;
+
+    if (Type.size() <= 3)
+      OB += Type;
+  }
+};
+
+template <class Float> struct FloatData;
+
+namespace float_literal_impl {
+constexpr Node::Kind getFloatLiteralKind(float *) {
+  return Node::KFloatLiteral;
+}
+constexpr Node::Kind getFloatLiteralKind(double *) {
+  return Node::KDoubleLiteral;
+}
+constexpr Node::Kind getFloatLiteralKind(long double *) {
+  return Node::KLongDoubleLiteral;
+}
+}
+
+template <class Float> class FloatLiteralImpl : public Node {
+  const StringView Contents;
+
+  static constexpr Kind KindForClass =
+      float_literal_impl::getFloatLiteralKind((Float *)nullptr);
+
+public:
+  FloatLiteralImpl(StringView Contents_)
+      : Node(KindForClass), Contents(Contents_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Contents); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    const char *first = Contents.begin();
+    const char *last = Contents.end() + 1;
+
+    const size_t N = FloatData<Float>::mangled_size;
+    if (static_cast<std::size_t>(last - first) > N) {
+      last = first + N;
+      union {
+        Float value;
+        char buf[sizeof(Float)];
+      };
+      const char *t = first;
+      char *e = buf;
+      for (; t != last; ++t, ++e) {
+        unsigned d1 = isdigit(*t) ? static_cast<unsigned>(*t - '0')
+                                  : static_cast<unsigned>(*t - 'a' + 10);
+        ++t;
+        unsigned d0 = isdigit(*t) ? static_cast<unsigned>(*t - '0')
+                                  : static_cast<unsigned>(*t - 'a' + 10);
+        *e = static_cast<char>((d1 << 4) + d0);
+      }
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+      std::reverse(buf, e);
+#endif
+      char num[FloatData<Float>::max_demangled_size] = {0};
+      int n = snprintf(num, sizeof(num), FloatData<Float>::spec, value);
+      OB += StringView(num, num + n);
+    }
+  }
+};
+
+using FloatLiteral = FloatLiteralImpl<float>;
+using DoubleLiteral = FloatLiteralImpl<double>;
+using LongDoubleLiteral = FloatLiteralImpl<long double>;
+
+/// Visit the node. Calls \c F(P), where \c P is the node cast to the
+/// appropriate derived class.
+template<typename Fn>
+void Node::visit(Fn F) const {
+  switch (K) {
+#define NODE(X)                                                                \
+  case K##X:                                                                   \
+    return F(static_cast<const X *>(this));
+#include "ItaniumNodes.def"
+  }
+  assert(0 && "unknown mangling node kind");
+}
+
+/// Determine the kind of a node from its type.
+template<typename NodeT> struct NodeKind;
+#define NODE(X)                                                                \
+  template <> struct NodeKind<X> {                                             \
+    static constexpr Node::Kind Kind = Node::K##X;                             \
+    static constexpr const char *name() { return #X; }                         \
+  };
+#include "ItaniumNodes.def"
+
+template <typename Derived, typename Alloc> struct AbstractManglingParser {
+  const char *First;
+  const char *Last;
+
+  // Name stack, this is used by the parser to hold temporary names that were
+  // parsed. The parser collapses multiple names into new nodes to construct
+  // the AST. Once the parser is finished, names.size() == 1.
+  PODSmallVector<Node *, 32> Names;
+
+  // Substitution table. Itanium supports name substitutions as a means of
+  // compression. The string "S42_" refers to the 44nd entry (base-36) in this
+  // table.
+  PODSmallVector<Node *, 32> Subs;
+
+  using TemplateParamList = PODSmallVector<Node *, 8>;
+
+  class ScopedTemplateParamList {
+    AbstractManglingParser *Parser;
+    size_t OldNumTemplateParamLists;
+    TemplateParamList Params;
+
+  public:
+    ScopedTemplateParamList(AbstractManglingParser *TheParser)
+        : Parser(TheParser),
+          OldNumTemplateParamLists(TheParser->TemplateParams.size()) {
+      Parser->TemplateParams.push_back(&Params);
+    }
+    ~ScopedTemplateParamList() {
+      assert(Parser->TemplateParams.size() >= OldNumTemplateParamLists);
+      Parser->TemplateParams.dropBack(OldNumTemplateParamLists);
+    }
+  };
+
+  // Template parameter table. Like the above, but referenced like "T42_".
+  // This has a smaller size compared to Subs and Names because it can be
+  // stored on the stack.
+  TemplateParamList OuterTemplateParams;
+
+  // Lists of template parameters indexed by template parameter depth,
+  // referenced like "TL2_4_". If nonempty, element 0 is always
+  // OuterTemplateParams; inner elements are always template parameter lists of
+  // lambda expressions. For a generic lambda with no explicit template
+  // parameter list, the corresponding parameter list pointer will be null.
+  PODSmallVector<TemplateParamList *, 4> TemplateParams;
+
+  // Set of unresolved forward <template-param> references. These can occur in a
+  // conversion operator's type, and are resolved in the enclosing <encoding>.
+  PODSmallVector<ForwardTemplateReference *, 4> ForwardTemplateRefs;
+
+  bool TryToParseTemplateArgs = true;
+  bool PermitForwardTemplateReferences = false;
+  size_t ParsingLambdaParamsAtLevel = (size_t)-1;
+
+  unsigned NumSyntheticTemplateParameters[3] = {};
+
+  Alloc ASTAllocator;
+
+  AbstractManglingParser(const char *First_, const char *Last_)
+      : First(First_), Last(Last_) {}
+
+  Derived &getDerived() { return static_cast<Derived &>(*this); }
+
+  void reset(const char *First_, const char *Last_) {
+    First = First_;
+    Last = Last_;
+    Names.clear();
+    Subs.clear();
+    TemplateParams.clear();
+    ParsingLambdaParamsAtLevel = (size_t)-1;
+    TryToParseTemplateArgs = true;
+    PermitForwardTemplateReferences = false;
+    for (int I = 0; I != 3; ++I)
+      NumSyntheticTemplateParameters[I] = 0;
+    ASTAllocator.reset();
+  }
+
+  template <class T, class... Args> Node *make(Args &&... args) {
+    return ASTAllocator.template makeNode<T>(std::forward<Args>(args)...);
+  }
+
+  template <class It> NodeArray makeNodeArray(It begin, It end) {
+    size_t sz = static_cast<size_t>(end - begin);
+    void *mem = ASTAllocator.allocateNodeArray(sz);
+    Node **data = new (mem) Node *[sz];
+    std::copy(begin, end, data);
+    return NodeArray(data, sz);
+  }
+
+  NodeArray popTrailingNodeArray(size_t FromPosition) {
+    assert(FromPosition <= Names.size());
+    NodeArray res =
+        makeNodeArray(Names.begin() + (long)FromPosition, Names.end());
+    Names.dropBack(FromPosition);
+    return res;
+  }
+
+  bool consumeIf(StringView S) {
+    if (StringView(First, Last).startsWith(S)) {
+      First += S.size();
+      return true;
+    }
+    return false;
+  }
+
+  bool consumeIf(char C) {
+    if (First != Last && *First == C) {
+      ++First;
+      return true;
+    }
+    return false;
+  }
+
+  char consume() { return First != Last ? *First++ : '\0'; }
+
+  char look(unsigned Lookahead = 0) const {
+    if (static_cast<size_t>(Last - First) <= Lookahead)
+      return '\0';
+    return First[Lookahead];
+  }
+
+  size_t numLeft() const { return static_cast<size_t>(Last - First); }
+
+  StringView parseNumber(bool AllowNegative = false);
+  Qualifiers parseCVQualifiers();
+  bool parsePositiveInteger(size_t *Out);
+  StringView parseBareSourceName();
+
+  bool parseSeqId(size_t *Out);
+  Node *parseSubstitution();
+  Node *parseTemplateParam();
+  Node *parseTemplateParamDecl();
+  Node *parseTemplateArgs(bool TagTemplates = false);
+  Node *parseTemplateArg();
+
+  /// Parse the <expr> production.
+  Node *parseExpr();
+  Node *parsePrefixExpr(StringView Kind, Node::Prec Prec);
+  Node *parseBinaryExpr(StringView Kind, Node::Prec Prec);
+  Node *parseIntegerLiteral(StringView Lit);
+  Node *parseExprPrimary();
+  template <class Float> Node *parseFloatingLiteral();
+  Node *parseFunctionParam();
+  Node *parseConversionExpr();
+  Node *parseBracedExpr();
+  Node *parseFoldExpr();
+  Node *parsePointerToMemberConversionExpr(Node::Prec Prec);
+  Node *parseSubobjectExpr();
+
+  /// Parse the <type> production.
+  Node *parseType();
+  Node *parseFunctionType();
+  Node *parseVectorType();
+  Node *parseDecltype();
+  Node *parseArrayType();
+  Node *parsePointerToMemberType();
+  Node *parseClassEnumType();
+  Node *parseQualifiedType();
+
+  Node *parseEncoding();
+  bool parseCallOffset();
+  Node *parseSpecialName();
+
+  /// Holds some extra information about a <name> that is being parsed. This
+  /// information is only pertinent if the <name> refers to an <encoding>.
+  struct NameState {
+    bool CtorDtorConversion = false;
+    bool EndsWithTemplateArgs = false;
+    Qualifiers CVQualifiers = QualNone;
+    FunctionRefQual ReferenceQualifier = FrefQualNone;
+    size_t ForwardTemplateRefsBegin;
+
+    NameState(AbstractManglingParser *Enclosing)
+        : ForwardTemplateRefsBegin(Enclosing->ForwardTemplateRefs.size()) {}
+  };
+
+  bool resolveForwardTemplateRefs(NameState &State) {
+    size_t I = State.ForwardTemplateRefsBegin;
+    size_t E = ForwardTemplateRefs.size();
+    for (; I < E; ++I) {
+      size_t Idx = ForwardTemplateRefs[I]->Index;
+      if (TemplateParams.empty() || !TemplateParams[0] ||
+          Idx >= TemplateParams[0]->size())
+        return true;
+      ForwardTemplateRefs[I]->Ref = (*TemplateParams[0])[Idx];
+    }
+    ForwardTemplateRefs.dropBack(State.ForwardTemplateRefsBegin);
+    return false;
+  }
+
+  /// Parse the <name> production>
+  Node *parseName(NameState *State = nullptr);
+  Node *parseLocalName(NameState *State);
+  Node *parseOperatorName(NameState *State);
+  bool parseModuleNameOpt(ModuleName *&Module);
+  Node *parseUnqualifiedName(NameState *State, Node *Scope, ModuleName *Module);
+  Node *parseUnnamedTypeName(NameState *State);
+  Node *parseSourceName(NameState *State);
+  Node *parseUnscopedName(NameState *State, bool *isSubstName);
+  Node *parseNestedName(NameState *State);
+  Node *parseCtorDtorName(Node *&SoFar, NameState *State);
+
+  Node *parseAbiTags(Node *N);
+
+  struct OperatorInfo {
+    enum OIKind : unsigned char {
+      Prefix,      // Prefix unary: @ expr
+      Postfix,     // Postfix unary: expr @
+      Binary,      // Binary: lhs @ rhs
+      Array,       // Array index:  lhs [ rhs ]
+      Member,      // Member access: lhs @ rhs
+      New,         // New
+      Del,         // Delete
+      Call,        // Function call: expr (expr*)
+      CCast,       // C cast: (type)expr
+      Conditional, // Conditional: expr ? expr : expr
+      NameOnly,    // Overload only, not allowed in expression.
+      // Below do not have operator names
+      NamedCast, // Named cast, @<type>(expr)
+      OfIdOp,    // alignof, sizeof, typeid
+
+      Unnameable = NamedCast,
+    };
+    char Enc[2];      // Encoding
+    OIKind Kind;      // Kind of operator
+    bool Flag : 1;    // Entry-specific flag
+    Node::Prec Prec : 7; // Precedence
+    const char *Name; // Spelling
+
+  public:
+    constexpr OperatorInfo(const char (&E)[3], OIKind K, bool F, Node::Prec P,
+                           const char *N)
+        : Enc{E[0], E[1]}, Kind{K}, Flag{F}, Prec{P}, Name{N} {}
+
+  public:
+    bool operator<(const OperatorInfo &Other) const {
+      return *this < Other.Enc;
+    }
+    bool operator<(const char *Peek) const {
+      return Enc[0] < Peek[0] || (Enc[0] == Peek[0] && Enc[1] < Peek[1]);
+    }
+    bool operator==(const char *Peek) const {
+      return Enc[0] == Peek[0] && Enc[1] == Peek[1];
+    }
+    bool operator!=(const char *Peek) const { return !this->operator==(Peek); }
+
+  public:
+    StringView getSymbol() const {
+      StringView Res = Name;
+      if (Kind < Unnameable) {
+        assert(Res.startsWith("operator") &&
+               "operator name does not start with 'operator'");
+        Res = Res.dropFront(sizeof("operator") - 1);
+        Res.consumeFront(' ');
+      }
+      return Res;
+    }
+    StringView getName() const { return Name; }
+    OIKind getKind() const { return Kind; }
+    bool getFlag() const { return Flag; }
+    Node::Prec getPrecedence() const { return Prec; }
+  };
+  static const OperatorInfo Ops[];
+  static const size_t NumOps;
+  const OperatorInfo *parseOperatorEncoding();
+
+  /// Parse the <unresolved-name> production.
+  Node *parseUnresolvedName(bool Global);
+  Node *parseSimpleId();
+  Node *parseBaseUnresolvedName();
+  Node *parseUnresolvedType();
+  Node *parseDestructorName();
+
+  /// Top-level entry point into the parser.
+  Node *parse();
+};
+
+const char* parse_discriminator(const char* first, const char* last);
+
+// <name> ::= <nested-name> // N
+//        ::= <local-name> # See Scope Encoding below  // Z
+//        ::= <unscoped-template-name> <template-args>
+//        ::= <unscoped-name>
+//
+// <unscoped-template-name> ::= <unscoped-name>
+//                          ::= <substitution>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseName(NameState *State) {
+  if (look() == 'N')
+    return getDerived().parseNestedName(State);
+  if (look() == 'Z')
+    return getDerived().parseLocalName(State);
+
+  Node *Result = nullptr;
+  bool IsSubst = false;
+
+  Result = getDerived().parseUnscopedName(State, &IsSubst);
+  if (!Result)
+    return nullptr;
+
+  if (look() == 'I') {
+    //        ::= <unscoped-template-name> <template-args>
+    if (!IsSubst)
+      // An unscoped-template-name is substitutable.
+      Subs.push_back(Result);
+    Node *TA = getDerived().parseTemplateArgs(State != nullptr);
+    if (TA == nullptr)
+      return nullptr;
+    if (State)
+      State->EndsWithTemplateArgs = true;
+    Result = make<NameWithTemplateArgs>(Result, TA);
+  } else if (IsSubst) {
+    // The substitution case must be followed by <template-args>.
+    return nullptr;
+  }
+
+  return Result;
+}
+
+// <local-name> := Z <function encoding> E <entity name> [<discriminator>]
+//              := Z <function encoding> E s [<discriminator>]
+//              := Z <function encoding> Ed [ <parameter number> ] _ <entity name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseLocalName(NameState *State) {
+  if (!consumeIf('Z'))
+    return nullptr;
+  Node *Encoding = getDerived().parseEncoding();
+  if (Encoding == nullptr || !consumeIf('E'))
+    return nullptr;
+
+  if (consumeIf('s')) {
+    First = parse_discriminator(First, Last);
+    auto *StringLitName = make<NameType>("string literal");
+    if (!StringLitName)
+      return nullptr;
+    return make<LocalName>(Encoding, StringLitName);
+  }
+
+  if (consumeIf('d')) {
+    parseNumber(true);
+    if (!consumeIf('_'))
+      return nullptr;
+    Node *N = getDerived().parseName(State);
+    if (N == nullptr)
+      return nullptr;
+    return make<LocalName>(Encoding, N);
+  }
+
+  Node *Entity = getDerived().parseName(State);
+  if (Entity == nullptr)
+    return nullptr;
+  First = parse_discriminator(First, Last);
+  return make<LocalName>(Encoding, Entity);
+}
+
+// <unscoped-name> ::= <unqualified-name>
+//                 ::= St <unqualified-name>   # ::std::
+// [*] extension
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseUnscopedName(NameState *State,
+                                                          bool *IsSubst) {
+
+  Node *Std = nullptr;
+  if (consumeIf("St")) {
+    Std = make<NameType>("std");
+    if (Std == nullptr)
+      return nullptr;
+  }
+
+  Node *Res = nullptr;
+  ModuleName *Module = nullptr;
+  if (look() == 'S') {
+    Node *S = getDerived().parseSubstitution();
+    if (!S)
+      return nullptr;
+    if (S->getKind() == Node::KModuleName)
+      Module = static_cast<ModuleName *>(S);
+    else if (IsSubst && Std == nullptr) {
+      Res = S;
+      *IsSubst = true;
+    } else {
+      return nullptr;
+    }
+  }
+
+  if (Res == nullptr || Std != nullptr) {
+    Res = getDerived().parseUnqualifiedName(State, Std, Module);
+  }
+
+  return Res;
+}
+
+// <unqualified-name> ::= [<module-name>] L? <operator-name> [<abi-tags>]
+//                    ::= [<module-name>] <ctor-dtor-name> [<abi-tags>]
+//                    ::= [<module-name>] L? <source-name> [<abi-tags>]
+//                    ::= [<module-name>] L? <unnamed-type-name> [<abi-tags>]
+//			# structured binding declaration
+//                    ::= [<module-name>] L? DC <source-name>+ E
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseUnqualifiedName(
+    NameState *State, Node *Scope, ModuleName *Module) {
+  if (getDerived().parseModuleNameOpt(Module))
+    return nullptr;
+
+  consumeIf('L');
+
+  Node *Result;
+  if (look() >= '1' && look() <= '9') {
+    Result = getDerived().parseSourceName(State);
+  } else if (look() == 'U') {
+    Result = getDerived().parseUnnamedTypeName(State);
+  } else if (consumeIf("DC")) {
+    // Structured binding
+    size_t BindingsBegin = Names.size();
+    do {
+      Node *Binding = getDerived().parseSourceName(State);
+      if (Binding == nullptr)
+        return nullptr;
+      Names.push_back(Binding);
+    } while (!consumeIf('E'));
+    Result = make<StructuredBindingName>(popTrailingNodeArray(BindingsBegin));
+  } else if (look() == 'C' || look() == 'D') {
+    // A <ctor-dtor-name>.
+    if (Scope == nullptr || Module != nullptr)
+      return nullptr;
+    Result = getDerived().parseCtorDtorName(Scope, State);
+  } else {
+    Result = getDerived().parseOperatorName(State);
+  }
+
+  if (Result != nullptr && Module != nullptr)
+    Result = make<ModuleEntity>(Module, Result);
+  if (Result != nullptr)
+    Result = getDerived().parseAbiTags(Result);
+  if (Result != nullptr && Scope != nullptr)
+    Result = make<NestedName>(Scope, Result);
+
+  return Result;
+}
+
+// <module-name> ::= <module-subname>
+// 	 	 ::= <module-name> <module-subname>
+//		 ::= <substitution>  # passed in by caller
+// <module-subname> ::= W <source-name>
+//		    ::= W P <source-name>
+template <typename Derived, typename Alloc>
+bool AbstractManglingParser<Derived, Alloc>::parseModuleNameOpt(
+    ModuleName *&Module) {
+  while (consumeIf('W')) {
+    bool IsPartition = consumeIf('P');
+    Node *Sub = getDerived().parseSourceName(nullptr);
+    if (!Sub)
+      return true;
+    Module =
+        static_cast<ModuleName *>(make<ModuleName>(Module, Sub, IsPartition));
+    Subs.push_back(Module);
+  }
+
+  return false;
+}
+
+// <unnamed-type-name> ::= Ut [<nonnegative number>] _
+//                     ::= <closure-type-name>
+//
+// <closure-type-name> ::= Ul <lambda-sig> E [ <nonnegative number> ] _
+//
+// <lambda-sig> ::= <parameter type>+  # Parameter types or "v" if the lambda has no parameters
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseUnnamedTypeName(NameState *State) {
+  // <template-params> refer to the innermost <template-args>. Clear out any
+  // outer args that we may have inserted into TemplateParams.
+  if (State != nullptr)
+    TemplateParams.clear();
+
+  if (consumeIf("Ut")) {
+    StringView Count = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<UnnamedTypeName>(Count);
+  }
+  if (consumeIf("Ul")) {
+    ScopedOverride<size_t> SwapParams(ParsingLambdaParamsAtLevel,
+                                      TemplateParams.size());
+    ScopedTemplateParamList LambdaTemplateParams(this);
+
+    size_t ParamsBegin = Names.size();
+    while (look() == 'T' &&
+           StringView("yptn").find(look(1)) != StringView::npos) {
+      Node *T = parseTemplateParamDecl();
+      if (!T)
+        return nullptr;
+      Names.push_back(T);
+    }
+    NodeArray TempParams = popTrailingNodeArray(ParamsBegin);
+
+    // FIXME: If TempParams is empty and none of the function parameters
+    // includes 'auto', we should remove LambdaTemplateParams from the
+    // TemplateParams list. Unfortunately, we don't find out whether there are
+    // any 'auto' parameters until too late in an example such as:
+    //
+    //   template<typename T> void f(
+    //       decltype([](decltype([]<typename T>(T v) {}),
+    //                   auto) {})) {}
+    //   template<typename T> void f(
+    //       decltype([](decltype([]<typename T>(T w) {}),
+    //                   int) {})) {}
+    //
+    // Here, the type of v is at level 2 but the type of w is at level 1. We
+    // don't find this out until we encounter the type of the next parameter.
+    //
+    // However, compilers can't actually cope with the former example in
+    // practice, and it's likely to be made ill-formed in future, so we don't
+    // need to support it here.
+    //
+    // If we encounter an 'auto' in the function parameter types, we will
+    // recreate a template parameter scope for it, but any intervening lambdas
+    // will be parsed in the 'wrong' template parameter depth.
+    if (TempParams.empty())
+      TemplateParams.pop_back();
+
+    if (!consumeIf("vE")) {
+      do {
+        Node *P = getDerived().parseType();
+        if (P == nullptr)
+          return nullptr;
+        Names.push_back(P);
+      } while (!consumeIf('E'));
+    }
+    NodeArray Params = popTrailingNodeArray(ParamsBegin);
+
+    StringView Count = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<ClosureTypeName>(TempParams, Params, Count);
+  }
+  if (consumeIf("Ub")) {
+    (void)parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<NameType>("'block-literal'");
+  }
+  return nullptr;
+}
+
+// <source-name> ::= <positive length number> <identifier>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSourceName(NameState *) {
+  size_t Length = 0;
+  if (parsePositiveInteger(&Length))
+    return nullptr;
+  if (numLeft() < Length || Length == 0)
+    return nullptr;
+  StringView Name(First, First + Length);
+  First += Length;
+  if (Name.startsWith("_GLOBAL__N"))
+    return make<NameType>("(anonymous namespace)");
+  return make<NameType>(Name);
+}
+
+// Operator encodings
+template <typename Derived, typename Alloc>
+const typename AbstractManglingParser<
+    Derived, Alloc>::OperatorInfo AbstractManglingParser<Derived,
+                                                         Alloc>::Ops[] = {
+    // Keep ordered by encoding
+    {"aN", OperatorInfo::Binary, false, Node::Prec::Assign, "operator&="},
+    {"aS", OperatorInfo::Binary, false, Node::Prec::Assign, "operator="},
+    {"aa", OperatorInfo::Binary, false, Node::Prec::AndIf, "operator&&"},
+    {"ad", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator&"},
+    {"an", OperatorInfo::Binary, false, Node::Prec::And, "operator&"},
+    {"at", OperatorInfo::OfIdOp, /*Type*/ true, Node::Prec::Unary, "alignof "},
+    {"aw", OperatorInfo::NameOnly, false, Node::Prec::Primary,
+     "operator co_await"},
+    {"az", OperatorInfo::OfIdOp, /*Type*/ false, Node::Prec::Unary, "alignof "},
+    {"cc", OperatorInfo::NamedCast, false, Node::Prec::Postfix, "const_cast"},
+    {"cl", OperatorInfo::Call, false, Node::Prec::Postfix, "operator()"},
+    {"cm", OperatorInfo::Binary, false, Node::Prec::Comma, "operator,"},
+    {"co", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator~"},
+    {"cv", OperatorInfo::CCast, false, Node::Prec::Cast, "operator"}, // C Cast
+    {"dV", OperatorInfo::Binary, false, Node::Prec::Assign, "operator/="},
+    {"da", OperatorInfo::Del, /*Ary*/ true, Node::Prec::Unary,
+     "operator delete[]"},
+    {"dc", OperatorInfo::NamedCast, false, Node::Prec::Postfix, "dynamic_cast"},
+    {"de", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator*"},
+    {"dl", OperatorInfo::Del, /*Ary*/ false, Node::Prec::Unary,
+     "operator delete"},
+    {"ds", OperatorInfo::Member, /*Named*/ false, Node::Prec::PtrMem,
+     "operator.*"},
+    {"dt", OperatorInfo::Member, /*Named*/ false, Node::Prec::Postfix,
+     "operator."},
+    {"dv", OperatorInfo::Binary, false, Node::Prec::Assign, "operator/"},
+    {"eO", OperatorInfo::Binary, false, Node::Prec::Assign, "operator^="},
+    {"eo", OperatorInfo::Binary, false, Node::Prec::Xor, "operator^"},
+    {"eq", OperatorInfo::Binary, false, Node::Prec::Equality, "operator=="},
+    {"ge", OperatorInfo::Binary, false, Node::Prec::Relational, "operator>="},
+    {"gt", OperatorInfo::Binary, false, Node::Prec::Relational, "operator>"},
+    {"ix", OperatorInfo::Array, false, Node::Prec::Postfix, "operator[]"},
+    {"lS", OperatorInfo::Binary, false, Node::Prec::Assign, "operator<<="},
+    {"le", OperatorInfo::Binary, false, Node::Prec::Relational, "operator<="},
+    {"ls", OperatorInfo::Binary, false, Node::Prec::Shift, "operator<<"},
+    {"lt", OperatorInfo::Binary, false, Node::Prec::Relational, "operator<"},
+    {"mI", OperatorInfo::Binary, false, Node::Prec::Assign, "operator-="},
+    {"mL", OperatorInfo::Binary, false, Node::Prec::Assign, "operator*="},
+    {"mi", OperatorInfo::Binary, false, Node::Prec::Additive, "operator-"},
+    {"ml", OperatorInfo::Binary, false, Node::Prec::Multiplicative,
+     "operator*"},
+    {"mm", OperatorInfo::Postfix, false, Node::Prec::Postfix, "operator--"},
+    {"na", OperatorInfo::New, /*Ary*/ true, Node::Prec::Unary,
+     "operator new[]"},
+    {"ne", OperatorInfo::Binary, false, Node::Prec::Equality, "operator!="},
+    {"ng", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator-"},
+    {"nt", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator!"},
+    {"nw", OperatorInfo::New, /*Ary*/ false, Node::Prec::Unary, "operator new"},
+    {"oR", OperatorInfo::Binary, false, Node::Prec::Assign, "operator|="},
+    {"oo", OperatorInfo::Binary, false, Node::Prec::OrIf, "operator||"},
+    {"or", OperatorInfo::Binary, false, Node::Prec::Ior, "operator|"},
+    {"pL", OperatorInfo::Binary, false, Node::Prec::Assign, "operator+="},
+    {"pl", OperatorInfo::Binary, false, Node::Prec::Additive, "operator+"},
+    {"pm", OperatorInfo::Member, /*Named*/ false, Node::Prec::PtrMem,
+     "operator->*"},
+    {"pp", OperatorInfo::Postfix, false, Node::Prec::Postfix, "operator++"},
+    {"ps", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator+"},
+    {"pt", OperatorInfo::Member, /*Named*/ true, Node::Prec::Postfix,
+     "operator->"},
+    {"qu", OperatorInfo::Conditional, false, Node::Prec::Conditional,
+     "operator?"},
+    {"rM", OperatorInfo::Binary, false, Node::Prec::Assign, "operator%="},
+    {"rS", OperatorInfo::Binary, false, Node::Prec::Assign, "operator>>="},
+    {"rc", OperatorInfo::NamedCast, false, Node::Prec::Postfix,
+     "reinterpret_cast"},
+    {"rm", OperatorInfo::Binary, false, Node::Prec::Multiplicative,
+     "operator%"},
+    {"rs", OperatorInfo::Binary, false, Node::Prec::Shift, "operator>>"},
+    {"sc", OperatorInfo::NamedCast, false, Node::Prec::Postfix, "static_cast"},
+    {"ss", OperatorInfo::Binary, false, Node::Prec::Spaceship, "operator<=>"},
+    {"st", OperatorInfo::OfIdOp, /*Type*/ true, Node::Prec::Unary, "sizeof "},
+    {"sz", OperatorInfo::OfIdOp, /*Type*/ false, Node::Prec::Unary, "sizeof "},
+    {"te", OperatorInfo::OfIdOp, /*Type*/ false, Node::Prec::Postfix,
+     "typeid "},
+    {"ti", OperatorInfo::OfIdOp, /*Type*/ true, Node::Prec::Postfix, "typeid "},
+};
+template <typename Derived, typename Alloc>
+const size_t AbstractManglingParser<Derived, Alloc>::NumOps = sizeof(Ops) /
+                                                              sizeof(Ops[0]);
+
+// If the next 2 chars are an operator encoding, consume them and return their
+// OperatorInfo.  Otherwise return nullptr.
+template <typename Derived, typename Alloc>
+const typename AbstractManglingParser<Derived, Alloc>::OperatorInfo *
+AbstractManglingParser<Derived, Alloc>::parseOperatorEncoding() {
+  if (numLeft() < 2)
+    return nullptr;
+
+  // We can't use lower_bound as that can link to symbols in the C++ library,
+  // and this must remain independant of that.
+  size_t lower = 0u, upper = NumOps - 1; // Inclusive bounds.
+  while (upper != lower) {
+    size_t middle = (upper + lower) / 2;
+    if (Ops[middle] < First)
+      lower = middle + 1;
+    else
+      upper = middle;
+  }
+  if (Ops[lower] != First)
+    return nullptr;
+
+  First += 2;
+  return &Ops[lower];
+}
+
+//   <operator-name> ::= See parseOperatorEncoding()
+//                   ::= li <source-name>  # operator ""
+//                   ::= v <digit> <source-name>  # vendor extended operator
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseOperatorName(NameState *State) {
+  if (const auto *Op = parseOperatorEncoding()) {
+    if (Op->getKind() == OperatorInfo::CCast) {
+      //              ::= cv <type>    # (cast)
+      ScopedOverride<bool> SaveTemplate(TryToParseTemplateArgs, false);
+      // If we're parsing an encoding, State != nullptr and the conversion
+      // operators' <type> could have a <template-param> that refers to some
+      // <template-arg>s further ahead in the mangled name.
+      ScopedOverride<bool> SavePermit(PermitForwardTemplateReferences,
+                                      PermitForwardTemplateReferences ||
+                                          State != nullptr);
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      if (State) State->CtorDtorConversion = true;
+      return make<ConversionOperatorType>(Ty);
+    }
+
+    if (Op->getKind() >= OperatorInfo::Unnameable)
+      /* Not a nameable operator.  */
+      return nullptr;
+    if (Op->getKind() == OperatorInfo::Member && !Op->getFlag())
+      /* Not a nameable MemberExpr */
+      return nullptr;
+
+    return make<NameType>(Op->getName());
+  }
+
+  if (consumeIf("li")) {
+    //                   ::= li <source-name>  # operator ""
+    Node *SN = getDerived().parseSourceName(State);
+    if (SN == nullptr)
+      return nullptr;
+    return make<LiteralOperator>(SN);
+  }
+
+  if (consumeIf('v')) {
+    // ::= v <digit> <source-name>        # vendor extended operator
+    if (look() >= '0' && look() <= '9') {
+      First++;
+      Node *SN = getDerived().parseSourceName(State);
+      if (SN == nullptr)
+        return nullptr;
+      return make<ConversionOperatorType>(SN);
+    }
+    return nullptr;
+  }
+
+  return nullptr;
+}
+
+// <ctor-dtor-name> ::= C1  # complete object constructor
+//                  ::= C2  # base object constructor
+//                  ::= C3  # complete object allocating constructor
+//   extension      ::= C4  # gcc old-style "[unified]" constructor
+//   extension      ::= C5  # the COMDAT used for ctors
+//                  ::= D0  # deleting destructor
+//                  ::= D1  # complete object destructor
+//                  ::= D2  # base object destructor
+//   extension      ::= D4  # gcc old-style "[unified]" destructor
+//   extension      ::= D5  # the COMDAT used for dtors
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseCtorDtorName(Node *&SoFar,
+                                                          NameState *State) {
+  if (SoFar->getKind() == Node::KSpecialSubstitution) {
+    // Expand the special substitution.
+    SoFar = make<ExpandedSpecialSubstitution>(
+        static_cast<SpecialSubstitution *>(SoFar));
+    if (!SoFar)
+      return nullptr;
+  }
+
+  if (consumeIf('C')) {
+    bool IsInherited = consumeIf('I');
+    if (look() != '1' && look() != '2' && look() != '3' && look() != '4' &&
+        look() != '5')
+      return nullptr;
+    int Variant = look() - '0';
+    ++First;
+    if (State) State->CtorDtorConversion = true;
+    if (IsInherited) {
+      if (getDerived().parseName(State) == nullptr)
+        return nullptr;
+    }
+    return make<CtorDtorName>(SoFar, /*IsDtor=*/false, Variant);
+  }
+
+  if (look() == 'D' && (look(1) == '0' || look(1) == '1' || look(1) == '2' ||
+                        look(1) == '4' || look(1) == '5')) {
+    int Variant = look(1) - '0';
+    First += 2;
+    if (State) State->CtorDtorConversion = true;
+    return make<CtorDtorName>(SoFar, /*IsDtor=*/true, Variant);
+  }
+
+  return nullptr;
+}
+
+// <nested-name> ::= N [<CV-Qualifiers>] [<ref-qualifier>] <prefix>
+// 			<unqualified-name> E
+//               ::= N [<CV-Qualifiers>] [<ref-qualifier>] <template-prefix>
+//               	<template-args> E
+//
+// <prefix> ::= <prefix> <unqualified-name>
+//          ::= <template-prefix> <template-args>
+//          ::= <template-param>
+//          ::= <decltype>
+//          ::= # empty
+//          ::= <substitution>
+//          ::= <prefix> <data-member-prefix>
+// [*] extension
+//
+// <data-member-prefix> := <member source-name> [<template-args>] M
+//
+// <template-prefix> ::= <prefix> <template unqualified-name>
+//                   ::= <template-param>
+//                   ::= <substitution>
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseNestedName(NameState *State) {
+  if (!consumeIf('N'))
+    return nullptr;
+
+  Qualifiers CVTmp = parseCVQualifiers();
+  if (State) State->CVQualifiers = CVTmp;
+
+  if (consumeIf('O')) {
+    if (State) State->ReferenceQualifier = FrefQualRValue;
+  } else if (consumeIf('R')) {
+    if (State) State->ReferenceQualifier = FrefQualLValue;
+  } else {
+    if (State) State->ReferenceQualifier = FrefQualNone;
+  }
+
+  Node *SoFar = nullptr;
+  while (!consumeIf('E')) {
+    if (State)
+      // Only set end-with-template on the case that does that.
+      State->EndsWithTemplateArgs = false;
+
+    if (look() == 'T') {
+      //          ::= <template-param>
+      if (SoFar != nullptr)
+        return nullptr; // Cannot have a prefix.
+      SoFar = getDerived().parseTemplateParam();
+    } else if (look() == 'I') {
+      //          ::= <template-prefix> <template-args>
+      if (SoFar == nullptr)
+        return nullptr; // Must have a prefix.
+      Node *TA = getDerived().parseTemplateArgs(State != nullptr);
+      if (TA == nullptr)
+        return nullptr;
+      if (SoFar->getKind() == Node::KNameWithTemplateArgs)
+        // Semantically <template-args> <template-args> cannot be generated by a
+        // C++ entity.  There will always be [something like] a name between
+        // them.
+        return nullptr;
+      if (State)
+        State->EndsWithTemplateArgs = true;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+    } else if (look() == 'D' && (look(1) == 't' || look(1) == 'T')) {
+      //          ::= <decltype>
+      if (SoFar != nullptr)
+        return nullptr; // Cannot have a prefix.
+      SoFar = getDerived().parseDecltype();
+    } else {
+      ModuleName *Module = nullptr;
+
+      if (look() == 'S') {
+        //          ::= <substitution>
+        Node *S = nullptr;
+        if (look(1) == 't') {
+          First += 2;
+          S = make<NameType>("std");
+        } else {
+          S = getDerived().parseSubstitution();
+        }
+        if (!S)
+          return nullptr;
+        if (S->getKind() == Node::KModuleName) {
+          Module = static_cast<ModuleName *>(S);
+        } else if (SoFar != nullptr) {
+          return nullptr; // Cannot have a prefix.
+        } else {
+          SoFar = S;
+          continue; // Do not push a new substitution.
+        }
+      }
+
+      //          ::= [<prefix>] <unqualified-name>
+      SoFar = getDerived().parseUnqualifiedName(State, SoFar, Module);
+    }
+
+    if (SoFar == nullptr)
+      return nullptr;
+    Subs.push_back(SoFar);
+
+    // No longer used.
+    // <data-member-prefix> := <member source-name> [<template-args>] M
+    consumeIf('M');
+  }
+
+  if (SoFar == nullptr || Subs.empty())
+    return nullptr;
+
+  Subs.pop_back();
+  return SoFar;
+}
+
+// <simple-id> ::= <source-name> [ <template-args> ]
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSimpleId() {
+  Node *SN = getDerived().parseSourceName(/*NameState=*/nullptr);
+  if (SN == nullptr)
+    return nullptr;
+  if (look() == 'I') {
+    Node *TA = getDerived().parseTemplateArgs();
+    if (TA == nullptr)
+      return nullptr;
+    return make<NameWithTemplateArgs>(SN, TA);
+  }
+  return SN;
+}
+
+// <destructor-name> ::= <unresolved-type>  # e.g., ~T or ~decltype(f())
+//                   ::= <simple-id>        # e.g., ~A<2*N>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseDestructorName() {
+  Node *Result;
+  if (std::isdigit(look()))
+    Result = getDerived().parseSimpleId();
+  else
+    Result = getDerived().parseUnresolvedType();
+  if (Result == nullptr)
+    return nullptr;
+  return make<DtorName>(Result);
+}
+
+// <unresolved-type> ::= <template-param>
+//                   ::= <decltype>
+//                   ::= <substitution>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedType() {
+  if (look() == 'T') {
+    Node *TP = getDerived().parseTemplateParam();
+    if (TP == nullptr)
+      return nullptr;
+    Subs.push_back(TP);
+    return TP;
+  }
+  if (look() == 'D') {
+    Node *DT = getDerived().parseDecltype();
+    if (DT == nullptr)
+      return nullptr;
+    Subs.push_back(DT);
+    return DT;
+  }
+  return getDerived().parseSubstitution();
+}
+
+// <base-unresolved-name> ::= <simple-id>                                # unresolved name
+//          extension     ::= <operator-name>                            # unresolved operator-function-id
+//          extension     ::= <operator-name> <template-args>            # unresolved operator template-id
+//                        ::= on <operator-name>                         # unresolved operator-function-id
+//                        ::= on <operator-name> <template-args>         # unresolved operator template-id
+//                        ::= dn <destructor-name>                       # destructor or pseudo-destructor;
+//                                                                         # e.g. ~X or ~X<N-1>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseBaseUnresolvedName() {
+  if (std::isdigit(look()))
+    return getDerived().parseSimpleId();
+
+  if (consumeIf("dn"))
+    return getDerived().parseDestructorName();
+
+  consumeIf("on");
+
+  Node *Oper = getDerived().parseOperatorName(/*NameState=*/nullptr);
+  if (Oper == nullptr)
+    return nullptr;
+  if (look() == 'I') {
+    Node *TA = getDerived().parseTemplateArgs();
+    if (TA == nullptr)
+      return nullptr;
+    return make<NameWithTemplateArgs>(Oper, TA);
+  }
+  return Oper;
+}
+
+// <unresolved-name>
+//  extension        ::= srN <unresolved-type> [<template-args>] <unresolved-qualifier-level>* E <base-unresolved-name>
+//                   ::= [gs] <base-unresolved-name>                     # x or (with "gs") ::x
+//                   ::= [gs] sr <unresolved-qualifier-level>+ E <base-unresolved-name>
+//                                                                       # A::x, N::y, A<T>::z; "gs" means leading "::"
+// [gs] has been parsed by caller.
+//                   ::= sr <unresolved-type> <base-unresolved-name>     # T::x / decltype(p)::x
+//  extension        ::= sr <unresolved-type> <template-args> <base-unresolved-name>
+//                                                                       # T::N::x /decltype(p)::N::x
+//  (ignored)        ::= srN <unresolved-type>  <unresolved-qualifier-level>+ E <base-unresolved-name>
+//
+// <unresolved-qualifier-level> ::= <simple-id>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedName(bool Global) {
+  Node *SoFar = nullptr;
+
+  // srN <unresolved-type> [<template-args>] <unresolved-qualifier-level>* E <base-unresolved-name>
+  // srN <unresolved-type>                   <unresolved-qualifier-level>+ E <base-unresolved-name>
+  if (consumeIf("srN")) {
+    SoFar = getDerived().parseUnresolvedType();
+    if (SoFar == nullptr)
+      return nullptr;
+
+    if (look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+      if (!SoFar)
+        return nullptr;
+    }
+
+    while (!consumeIf('E')) {
+      Node *Qual = getDerived().parseSimpleId();
+      if (Qual == nullptr)
+        return nullptr;
+      SoFar = make<QualifiedName>(SoFar, Qual);
+      if (!SoFar)
+        return nullptr;
+    }
+
+    Node *Base = getDerived().parseBaseUnresolvedName();
+    if (Base == nullptr)
+      return nullptr;
+    return make<QualifiedName>(SoFar, Base);
+  }
+
+  // [gs] <base-unresolved-name>                     # x or (with "gs") ::x
+  if (!consumeIf("sr")) {
+    SoFar = getDerived().parseBaseUnresolvedName();
+    if (SoFar == nullptr)
+      return nullptr;
+    if (Global)
+      SoFar = make<GlobalQualifiedName>(SoFar);
+    return SoFar;
+  }
+
+  // [gs] sr <unresolved-qualifier-level>+ E   <base-unresolved-name>
+  if (std::isdigit(look())) {
+    do {
+      Node *Qual = getDerived().parseSimpleId();
+      if (Qual == nullptr)
+        return nullptr;
+      if (SoFar)
+        SoFar = make<QualifiedName>(SoFar, Qual);
+      else if (Global)
+        SoFar = make<GlobalQualifiedName>(Qual);
+      else
+        SoFar = Qual;
+      if (!SoFar)
+        return nullptr;
+    } while (!consumeIf('E'));
+  }
+  //      sr <unresolved-type>                 <base-unresolved-name>
+  //      sr <unresolved-type> <template-args> <base-unresolved-name>
+  else {
+    SoFar = getDerived().parseUnresolvedType();
+    if (SoFar == nullptr)
+      return nullptr;
+
+    if (look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+      if (!SoFar)
+        return nullptr;
+    }
+  }
+
+  assert(SoFar != nullptr);
+
+  Node *Base = getDerived().parseBaseUnresolvedName();
+  if (Base == nullptr)
+    return nullptr;
+  return make<QualifiedName>(SoFar, Base);
+}
+
+// <abi-tags> ::= <abi-tag> [<abi-tags>]
+// <abi-tag> ::= B <source-name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseAbiTags(Node *N) {
+  while (consumeIf('B')) {
+    StringView SN = parseBareSourceName();
+    if (SN.empty())
+      return nullptr;
+    N = make<AbiTagAttr>(N, SN);
+    if (!N)
+      return nullptr;
+  }
+  return N;
+}
+
+// <number> ::= [n] <non-negative decimal integer>
+template <typename Alloc, typename Derived>
+StringView
+AbstractManglingParser<Alloc, Derived>::parseNumber(bool AllowNegative) {
+  const char *Tmp = First;
+  if (AllowNegative)
+    consumeIf('n');
+  if (numLeft() == 0 || !std::isdigit(*First))
+    return StringView();
+  while (numLeft() != 0 && std::isdigit(*First))
+    ++First;
+  return StringView(Tmp, First);
+}
+
+// <positive length number> ::= [0-9]*
+template <typename Alloc, typename Derived>
+bool AbstractManglingParser<Alloc, Derived>::parsePositiveInteger(size_t *Out) {
+  *Out = 0;
+  if (look() < '0' || look() > '9')
+    return true;
+  while (look() >= '0' && look() <= '9') {
+    *Out *= 10;
+    *Out += static_cast<size_t>(consume() - '0');
+  }
+  return false;
+}
+
+template <typename Alloc, typename Derived>
+StringView AbstractManglingParser<Alloc, Derived>::parseBareSourceName() {
+  size_t Int = 0;
+  if (parsePositiveInteger(&Int) || numLeft() < Int)
+    return StringView();
+  StringView R(First, First + Int);
+  First += Int;
+  return R;
+}
+
+// <function-type> ::= [<CV-qualifiers>] [<exception-spec>] [Dx] F [Y] <bare-function-type> [<ref-qualifier>] E
+//
+// <exception-spec> ::= Do                # non-throwing exception-specification (e.g., noexcept, throw())
+//                  ::= DO <expression> E # computed (instantiation-dependent) noexcept
+//                  ::= Dw <type>+ E      # dynamic exception specification with instantiation-dependent types
+//
+// <ref-qualifier> ::= R                   # & ref-qualifier
+// <ref-qualifier> ::= O                   # && ref-qualifier
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseFunctionType() {
+  Qualifiers CVQuals = parseCVQualifiers();
+
+  Node *ExceptionSpec = nullptr;
+  if (consumeIf("Do")) {
+    ExceptionSpec = make<NameType>("noexcept");
+    if (!ExceptionSpec)
+      return nullptr;
+  } else if (consumeIf("DO")) {
+    Node *E = getDerived().parseExpr();
+    if (E == nullptr || !consumeIf('E'))
+      return nullptr;
+    ExceptionSpec = make<NoexceptSpec>(E);
+    if (!ExceptionSpec)
+      return nullptr;
+  } else if (consumeIf("Dw")) {
+    size_t SpecsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *T = getDerived().parseType();
+      if (T == nullptr)
+        return nullptr;
+      Names.push_back(T);
+    }
+    ExceptionSpec =
+      make<DynamicExceptionSpec>(popTrailingNodeArray(SpecsBegin));
+    if (!ExceptionSpec)
+      return nullptr;
+  }
+
+  consumeIf("Dx"); // transaction safe
+
+  if (!consumeIf('F'))
+    return nullptr;
+  consumeIf('Y'); // extern "C"
+  Node *ReturnType = getDerived().parseType();
+  if (ReturnType == nullptr)
+    return nullptr;
+
+  FunctionRefQual ReferenceQualifier = FrefQualNone;
+  size_t ParamsBegin = Names.size();
+  while (true) {
+    if (consumeIf('E'))
+      break;
+    if (consumeIf('v'))
+      continue;
+    if (consumeIf("RE")) {
+      ReferenceQualifier = FrefQualLValue;
+      break;
+    }
+    if (consumeIf("OE")) {
+      ReferenceQualifier = FrefQualRValue;
+      break;
+    }
+    Node *T = getDerived().parseType();
+    if (T == nullptr)
+      return nullptr;
+    Names.push_back(T);
+  }
+
+  NodeArray Params = popTrailingNodeArray(ParamsBegin);
+  return make<FunctionType>(ReturnType, Params, CVQuals,
+                            ReferenceQualifier, ExceptionSpec);
+}
+
+// extension:
+// <vector-type>           ::= Dv <positive dimension number> _ <extended element type>
+//                         ::= Dv [<dimension expression>] _ <element type>
+// <extended element type> ::= <element type>
+//                         ::= p # AltiVec vector pixel
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseVectorType() {
+  if (!consumeIf("Dv"))
+    return nullptr;
+  if (look() >= '1' && look() <= '9') {
+    Node *DimensionNumber = make<NameType>(parseNumber());
+    if (!DimensionNumber)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+    if (consumeIf('p'))
+      return make<PixelVectorType>(DimensionNumber);
+    Node *ElemType = getDerived().parseType();
+    if (ElemType == nullptr)
+      return nullptr;
+    return make<VectorType>(ElemType, DimensionNumber);
+  }
+
+  if (!consumeIf('_')) {
+    Node *DimExpr = getDerived().parseExpr();
+    if (!DimExpr)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+    Node *ElemType = getDerived().parseType();
+    if (!ElemType)
+      return nullptr;
+    return make<VectorType>(ElemType, DimExpr);
+  }
+  Node *ElemType = getDerived().parseType();
+  if (!ElemType)
+    return nullptr;
+  return make<VectorType>(ElemType, /*Dimension=*/nullptr);
+}
+
+// <decltype>  ::= Dt <expression> E  # decltype of an id-expression or class member access (C++0x)
+//             ::= DT <expression> E  # decltype of an expression (C++0x)
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseDecltype() {
+  if (!consumeIf('D'))
+    return nullptr;
+  if (!consumeIf('t') && !consumeIf('T'))
+    return nullptr;
+  Node *E = getDerived().parseExpr();
+  if (E == nullptr)
+    return nullptr;
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<EnclosingExpr>("decltype", E);
+}
+
+// <array-type> ::= A <positive dimension number> _ <element type>
+//              ::= A [<dimension expression>] _ <element type>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseArrayType() {
+  if (!consumeIf('A'))
+    return nullptr;
+
+  Node *Dimension = nullptr;
+
+  if (std::isdigit(look())) {
+    Dimension = make<NameType>(parseNumber());
+    if (!Dimension)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+  } else if (!consumeIf('_')) {
+    Node *DimExpr = getDerived().parseExpr();
+    if (DimExpr == nullptr)
+      return nullptr;
+    if (!consumeIf('_'))
+      return nullptr;
+    Dimension = DimExpr;
+  }
+
+  Node *Ty = getDerived().parseType();
+  if (Ty == nullptr)
+    return nullptr;
+  return make<ArrayType>(Ty, Dimension);
+}
+
+// <pointer-to-member-type> ::= M <class type> <member type>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parsePointerToMemberType() {
+  if (!consumeIf('M'))
+    return nullptr;
+  Node *ClassType = getDerived().parseType();
+  if (ClassType == nullptr)
+    return nullptr;
+  Node *MemberType = getDerived().parseType();
+  if (MemberType == nullptr)
+    return nullptr;
+  return make<PointerToMemberType>(ClassType, MemberType);
+}
+
+// <class-enum-type> ::= <name>     # non-dependent type name, dependent type name, or dependent typename-specifier
+//                   ::= Ts <name>  # dependent elaborated type specifier using 'struct' or 'class'
+//                   ::= Tu <name>  # dependent elaborated type specifier using 'union'
+//                   ::= Te <name>  # dependent elaborated type specifier using 'enum'
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseClassEnumType() {
+  StringView ElabSpef;
+  if (consumeIf("Ts"))
+    ElabSpef = "struct";
+  else if (consumeIf("Tu"))
+    ElabSpef = "union";
+  else if (consumeIf("Te"))
+    ElabSpef = "enum";
+
+  Node *Name = getDerived().parseName();
+  if (Name == nullptr)
+    return nullptr;
+
+  if (!ElabSpef.empty())
+    return make<ElaboratedTypeSpefType>(ElabSpef, Name);
+
+  return Name;
+}
+
+// <qualified-type>     ::= <qualifiers> <type>
+// <qualifiers> ::= <extended-qualifier>* <CV-qualifiers>
+// <extended-qualifier> ::= U <source-name> [<template-args>] # vendor extended type qualifier
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseQualifiedType() {
+  if (consumeIf('U')) {
+    StringView Qual = parseBareSourceName();
+    if (Qual.empty())
+      return nullptr;
+
+    // extension            ::= U <objc-name> <objc-type>  # objc-type<identifier>
+    if (Qual.startsWith("objcproto")) {
+      StringView ProtoSourceName = Qual.dropFront(std::strlen("objcproto"));
+      StringView Proto;
+      {
+        ScopedOverride<const char *> SaveFirst(First, ProtoSourceName.begin()),
+            SaveLast(Last, ProtoSourceName.end());
+        Proto = parseBareSourceName();
+      }
+      if (Proto.empty())
+        return nullptr;
+      Node *Child = getDerived().parseQualifiedType();
+      if (Child == nullptr)
+        return nullptr;
+      return make<ObjCProtoName>(Child, Proto);
+    }
+
+    Node *TA = nullptr;
+    if (look() == 'I') {
+      TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+    }
+
+    Node *Child = getDerived().parseQualifiedType();
+    if (Child == nullptr)
+      return nullptr;
+    return make<VendorExtQualType>(Child, Qual, TA);
+  }
+
+  Qualifiers Quals = parseCVQualifiers();
+  Node *Ty = getDerived().parseType();
+  if (Ty == nullptr)
+    return nullptr;
+  if (Quals != QualNone)
+    Ty = make<QualType>(Ty, Quals);
+  return Ty;
+}
+
+// <type>      ::= <builtin-type>
+//             ::= <qualified-type>
+//             ::= <function-type>
+//             ::= <class-enum-type>
+//             ::= <array-type>
+//             ::= <pointer-to-member-type>
+//             ::= <template-param>
+//             ::= <template-template-param> <template-args>
+//             ::= <decltype>
+//             ::= P <type>        # pointer
+//             ::= R <type>        # l-value reference
+//             ::= O <type>        # r-value reference (C++11)
+//             ::= C <type>        # complex pair (C99)
+//             ::= G <type>        # imaginary (C99)
+//             ::= <substitution>  # See Compression below
+// extension   ::= U <objc-name> <objc-type>  # objc-type<identifier>
+// extension   ::= <vector-type> # <vector-type> starts with Dv
+//
+// <objc-name> ::= <k0 number> objcproto <k1 number> <identifier>  # k0 = 9 + <number of digits in k1> + k1
+// <objc-type> ::= <source-name>  # PU<11+>objcproto 11objc_object<source-name> 11objc_object -> id<source-name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseType() {
+  Node *Result = nullptr;
+
+  switch (look()) {
+  //             ::= <qualified-type>
+  case 'r':
+  case 'V':
+  case 'K': {
+    unsigned AfterQuals = 0;
+    if (look(AfterQuals) == 'r') ++AfterQuals;
+    if (look(AfterQuals) == 'V') ++AfterQuals;
+    if (look(AfterQuals) == 'K') ++AfterQuals;
+
+    if (look(AfterQuals) == 'F' ||
+        (look(AfterQuals) == 'D' &&
+         (look(AfterQuals + 1) == 'o' || look(AfterQuals + 1) == 'O' ||
+          look(AfterQuals + 1) == 'w' || look(AfterQuals + 1) == 'x'))) {
+      Result = getDerived().parseFunctionType();
+      break;
+    }
+    DEMANGLE_FALLTHROUGH;
+  }
+  case 'U': {
+    Result = getDerived().parseQualifiedType();
+    break;
+  }
+  // <builtin-type> ::= v    # void
+  case 'v':
+    ++First;
+    return make<NameType>("void");
+  //                ::= w    # wchar_t
+  case 'w':
+    ++First;
+    return make<NameType>("wchar_t");
+  //                ::= b    # bool
+  case 'b':
+    ++First;
+    return make<NameType>("bool");
+  //                ::= c    # char
+  case 'c':
+    ++First;
+    return make<NameType>("char");
+  //                ::= a    # signed char
+  case 'a':
+    ++First;
+    return make<NameType>("signed char");
+  //                ::= h    # unsigned char
+  case 'h':
+    ++First;
+    return make<NameType>("unsigned char");
+  //                ::= s    # short
+  case 's':
+    ++First;
+    return make<NameType>("short");
+  //                ::= t    # unsigned short
+  case 't':
+    ++First;
+    return make<NameType>("unsigned short");
+  //                ::= i    # int
+  case 'i':
+    ++First;
+    return make<NameType>("int");
+  //                ::= j    # unsigned int
+  case 'j':
+    ++First;
+    return make<NameType>("unsigned int");
+  //                ::= l    # long
+  case 'l':
+    ++First;
+    return make<NameType>("long");
+  //                ::= m    # unsigned long
+  case 'm':
+    ++First;
+    return make<NameType>("unsigned long");
+  //                ::= x    # long long, __int64
+  case 'x':
+    ++First;
+    return make<NameType>("long long");
+  //                ::= y    # unsigned long long, __int64
+  case 'y':
+    ++First;
+    return make<NameType>("unsigned long long");
+  //                ::= n    # __int128
+  case 'n':
+    ++First;
+    return make<NameType>("__int128");
+  //                ::= o    # unsigned __int128
+  case 'o':
+    ++First;
+    return make<NameType>("unsigned __int128");
+  //                ::= f    # float
+  case 'f':
+    ++First;
+    return make<NameType>("float");
+  //                ::= d    # double
+  case 'd':
+    ++First;
+    return make<NameType>("double");
+  //                ::= e    # long double, __float80
+  case 'e':
+    ++First;
+    return make<NameType>("long double");
+  //                ::= g    # __float128
+  case 'g':
+    ++First;
+    return make<NameType>("__float128");
+  //                ::= z    # ellipsis
+  case 'z':
+    ++First;
+    return make<NameType>("...");
+
+  // <builtin-type> ::= u <source-name>    # vendor extended type
+  case 'u': {
+    ++First;
+    StringView Res = parseBareSourceName();
+    if (Res.empty())
+      return nullptr;
+    // Typically, <builtin-type>s are not considered substitution candidates,
+    // but the exception to that exception is vendor extended types (Itanium C++
+    // ABI 5.9.1).
+    Result = make<NameType>(Res);
+    break;
+  }
+  case 'D':
+    switch (look(1)) {
+    //                ::= Dd   # IEEE 754r decimal floating point (64 bits)
+    case 'd':
+      First += 2;
+      return make<NameType>("decimal64");
+    //                ::= De   # IEEE 754r decimal floating point (128 bits)
+    case 'e':
+      First += 2;
+      return make<NameType>("decimal128");
+    //                ::= Df   # IEEE 754r decimal floating point (32 bits)
+    case 'f':
+      First += 2;
+      return make<NameType>("decimal32");
+    //                ::= Dh   # IEEE 754r half-precision floating point (16 bits)
+    case 'h':
+      First += 2;
+      return make<NameType>("half");
+    //                ::= DF <number> _ # ISO/IEC TS 18661 binary floating point (N bits)
+    case 'F': {
+      First += 2;
+      Node *DimensionNumber = make<NameType>(parseNumber());
+      if (!DimensionNumber)
+        return nullptr;
+      if (!consumeIf('_'))
+        return nullptr;
+      return make<BinaryFPType>(DimensionNumber);
+    }
+    //                ::= DB <number> _                             # C23 signed _BitInt(N)
+    //                ::= DB <instantiation-dependent expression> _ # C23 signed _BitInt(N)
+    //                ::= DU <number> _                             # C23 unsigned _BitInt(N)
+    //                ::= DU <instantiation-dependent expression> _ # C23 unsigned _BitInt(N)
+    case 'B':
+    case 'U': {
+      bool Signed = look(1) == 'B';
+      First += 2;
+      Node *Size = std::isdigit(look()) ? make<NameType>(parseNumber())
+                                        : getDerived().parseExpr();
+      if (!Size)
+        return nullptr;
+      if (!consumeIf('_'))
+        return nullptr;
+      return make<BitIntType>(Size, Signed);
+    }
+    //                ::= Di   # char32_t
+    case 'i':
+      First += 2;
+      return make<NameType>("char32_t");
+    //                ::= Ds   # char16_t
+    case 's':
+      First += 2;
+      return make<NameType>("char16_t");
+    //                ::= Du   # char8_t (C++2a, not yet in the Itanium spec)
+    case 'u':
+      First += 2;
+      return make<NameType>("char8_t");
+    //                ::= Da   # auto (in dependent new-expressions)
+    case 'a':
+      First += 2;
+      return make<NameType>("auto");
+    //                ::= Dc   # decltype(auto)
+    case 'c':
+      First += 2;
+      return make<NameType>("decltype(auto)");
+    //                ::= Dn   # std::nullptr_t (i.e., decltype(nullptr))
+    case 'n':
+      First += 2;
+      return make<NameType>("std::nullptr_t");
+
+    //             ::= <decltype>
+    case 't':
+    case 'T': {
+      Result = getDerived().parseDecltype();
+      break;
+    }
+    // extension   ::= <vector-type> # <vector-type> starts with Dv
+    case 'v': {
+      Result = getDerived().parseVectorType();
+      break;
+    }
+    //           ::= Dp <type>       # pack expansion (C++0x)
+    case 'p': {
+      First += 2;
+      Node *Child = getDerived().parseType();
+      if (!Child)
+        return nullptr;
+      Result = make<ParameterPackExpansion>(Child);
+      break;
+    }
+    // Exception specifier on a function type.
+    case 'o':
+    case 'O':
+    case 'w':
+    // Transaction safe function type.
+    case 'x':
+      Result = getDerived().parseFunctionType();
+      break;
+    }
+    break;
+  //             ::= <function-type>
+  case 'F': {
+    Result = getDerived().parseFunctionType();
+    break;
+  }
+  //             ::= <array-type>
+  case 'A': {
+    Result = getDerived().parseArrayType();
+    break;
+  }
+  //             ::= <pointer-to-member-type>
+  case 'M': {
+    Result = getDerived().parsePointerToMemberType();
+    break;
+  }
+  //             ::= <template-param>
+  case 'T': {
+    // This could be an elaborate type specifier on a <class-enum-type>.
+    if (look(1) == 's' || look(1) == 'u' || look(1) == 'e') {
+      Result = getDerived().parseClassEnumType();
+      break;
+    }
+
+    Result = getDerived().parseTemplateParam();
+    if (Result == nullptr)
+      return nullptr;
+
+    // Result could be either of:
+    //   <type>        ::= <template-param>
+    //   <type>        ::= <template-template-param> <template-args>
+    //
+    //   <template-template-param> ::= <template-param>
+    //                             ::= <substitution>
+    //
+    // If this is followed by some <template-args>, and we're permitted to
+    // parse them, take the second production.
+
+    if (TryToParseTemplateArgs && look() == 'I') {
+      Node *TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+      Result = make<NameWithTemplateArgs>(Result, TA);
+    }
+    break;
+  }
+  //             ::= P <type>        # pointer
+  case 'P': {
+    ++First;
+    Node *Ptr = getDerived().parseType();
+    if (Ptr == nullptr)
+      return nullptr;
+    Result = make<PointerType>(Ptr);
+    break;
+  }
+  //             ::= R <type>        # l-value reference
+  case 'R': {
+    ++First;
+    Node *Ref = getDerived().parseType();
+    if (Ref == nullptr)
+      return nullptr;
+    Result = make<ReferenceType>(Ref, ReferenceKind::LValue);
+    break;
+  }
+  //             ::= O <type>        # r-value reference (C++11)
+  case 'O': {
+    ++First;
+    Node *Ref = getDerived().parseType();
+    if (Ref == nullptr)
+      return nullptr;
+    Result = make<ReferenceType>(Ref, ReferenceKind::RValue);
+    break;
+  }
+  //             ::= C <type>        # complex pair (C99)
+  case 'C': {
+    ++First;
+    Node *P = getDerived().parseType();
+    if (P == nullptr)
+      return nullptr;
+    Result = make<PostfixQualifiedType>(P, " complex");
+    break;
+  }
+  //             ::= G <type>        # imaginary (C99)
+  case 'G': {
+    ++First;
+    Node *P = getDerived().parseType();
+    if (P == nullptr)
+      return P;
+    Result = make<PostfixQualifiedType>(P, " imaginary");
+    break;
+  }
+  //             ::= <substitution>  # See Compression below
+  case 'S': {
+    if (look(1) != 't') {
+      bool IsSubst = false;
+      Result = getDerived().parseUnscopedName(nullptr, &IsSubst);
+      if (!Result)
+        return nullptr;
+
+      // Sub could be either of:
+      //   <type>        ::= <substitution>
+      //   <type>        ::= <template-template-param> <template-args>
+      //
+      //   <template-template-param> ::= <template-param>
+      //                             ::= <substitution>
+      //
+      // If this is followed by some <template-args>, and we're permitted to
+      // parse them, take the second production.
+
+      if (look() == 'I' && (!IsSubst || TryToParseTemplateArgs)) {
+        if (!IsSubst)
+          Subs.push_back(Result);
+        Node *TA = getDerived().parseTemplateArgs();
+        if (TA == nullptr)
+          return nullptr;
+        Result = make<NameWithTemplateArgs>(Result, TA);
+      } else if (IsSubst) {
+        // If all we parsed was a substitution, don't re-insert into the
+        // substitution table.
+        return Result;
+      }
+      break;
+    }
+    DEMANGLE_FALLTHROUGH;
+  }
+  //        ::= <class-enum-type>
+  default: {
+    Result = getDerived().parseClassEnumType();
+    break;
+  }
+  }
+
+  // If we parsed a type, insert it into the substitution table. Note that all
+  // <builtin-type>s and <substitution>s have already bailed out, because they
+  // don't get substitutions.
+  if (Result != nullptr)
+    Subs.push_back(Result);
+  return Result;
+}
+
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parsePrefixExpr(StringView Kind,
+                                                              Node::Prec Prec) {
+  Node *E = getDerived().parseExpr();
+  if (E == nullptr)
+    return nullptr;
+  return make<PrefixExpr>(Kind, E, Prec);
+}
+
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseBinaryExpr(StringView Kind,
+                                                              Node::Prec Prec) {
+  Node *LHS = getDerived().parseExpr();
+  if (LHS == nullptr)
+    return nullptr;
+  Node *RHS = getDerived().parseExpr();
+  if (RHS == nullptr)
+    return nullptr;
+  return make<BinaryExpr>(LHS, Kind, RHS, Prec);
+}
+
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseIntegerLiteral(StringView Lit) {
+  StringView Tmp = parseNumber(true);
+  if (!Tmp.empty() && consumeIf('E'))
+    return make<IntegerLiteral>(Lit, Tmp);
+  return nullptr;
+}
+
+// <CV-Qualifiers> ::= [r] [V] [K]
+template <typename Alloc, typename Derived>
+Qualifiers AbstractManglingParser<Alloc, Derived>::parseCVQualifiers() {
+  Qualifiers CVR = QualNone;
+  if (consumeIf('r'))
+    CVR |= QualRestrict;
+  if (consumeIf('V'))
+    CVR |= QualVolatile;
+  if (consumeIf('K'))
+    CVR |= QualConst;
+  return CVR;
+}
+
+// <function-param> ::= fp <top-level CV-Qualifiers> _                                     # L == 0, first parameter
+//                  ::= fp <top-level CV-Qualifiers> <parameter-2 non-negative number> _   # L == 0, second and later parameters
+//                  ::= fL <L-1 non-negative number> p <top-level CV-Qualifiers> _         # L > 0, first parameter
+//                  ::= fL <L-1 non-negative number> p <top-level CV-Qualifiers> <parameter-2 non-negative number> _   # L > 0, second and later parameters
+//                  ::= fpT      # 'this' expression (not part of standard?)
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseFunctionParam() {
+  if (consumeIf("fpT"))
+    return make<NameType>("this");
+  if (consumeIf("fp")) {
+    parseCVQualifiers();
+    StringView Num = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<FunctionParam>(Num);
+  }
+  if (consumeIf("fL")) {
+    if (parseNumber().empty())
+      return nullptr;
+    if (!consumeIf('p'))
+      return nullptr;
+    parseCVQualifiers();
+    StringView Num = parseNumber();
+    if (!consumeIf('_'))
+      return nullptr;
+    return make<FunctionParam>(Num);
+  }
+  return nullptr;
+}
+
+// cv <type> <expression>                               # conversion with one argument
+// cv <type> _ <expression>* E                          # conversion with a different number of arguments
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseConversionExpr() {
+  if (!consumeIf("cv"))
+    return nullptr;
+  Node *Ty;
+  {
+    ScopedOverride<bool> SaveTemp(TryToParseTemplateArgs, false);
+    Ty = getDerived().parseType();
+  }
+
+  if (Ty == nullptr)
+    return nullptr;
+
+  if (consumeIf('_')) {
+    size_t ExprsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *E = getDerived().parseExpr();
+      if (E == nullptr)
+        return E;
+      Names.push_back(E);
+    }
+    NodeArray Exprs = popTrailingNodeArray(ExprsBegin);
+    return make<ConversionExpr>(Ty, Exprs);
+  }
+
+  Node *E[1] = {getDerived().parseExpr()};
+  if (E[0] == nullptr)
+    return nullptr;
+  return make<ConversionExpr>(Ty, makeNodeArray(E, E + 1));
+}
+
+// <expr-primary> ::= L <type> <value number> E                          # integer literal
+//                ::= L <type> <value float> E                           # floating literal
+//                ::= L <string type> E                                  # string literal
+//                ::= L <nullptr type> E                                 # nullptr literal (i.e., "LDnE")
+//                ::= L <lambda type> E                                  # lambda expression
+// FIXME:         ::= L <type> <real-part float> _ <imag-part float> E   # complex floating point literal (C 2000)
+//                ::= L <mangled-name> E                                 # external name
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseExprPrimary() {
+  if (!consumeIf('L'))
+    return nullptr;
+  switch (look()) {
+  case 'w':
+    ++First;
+    return getDerived().parseIntegerLiteral("wchar_t");
+  case 'b':
+    if (consumeIf("b0E"))
+      return make<BoolExpr>(0);
+    if (consumeIf("b1E"))
+      return make<BoolExpr>(1);
+    return nullptr;
+  case 'c':
+    ++First;
+    return getDerived().parseIntegerLiteral("char");
+  case 'a':
+    ++First;
+    return getDerived().parseIntegerLiteral("signed char");
+  case 'h':
+    ++First;
+    return getDerived().parseIntegerLiteral("unsigned char");
+  case 's':
+    ++First;
+    return getDerived().parseIntegerLiteral("short");
+  case 't':
+    ++First;
+    return getDerived().parseIntegerLiteral("unsigned short");
+  case 'i':
+    ++First;
+    return getDerived().parseIntegerLiteral("");
+  case 'j':
+    ++First;
+    return getDerived().parseIntegerLiteral("u");
+  case 'l':
+    ++First;
+    return getDerived().parseIntegerLiteral("l");
+  case 'm':
+    ++First;
+    return getDerived().parseIntegerLiteral("ul");
+  case 'x':
+    ++First;
+    return getDerived().parseIntegerLiteral("ll");
+  case 'y':
+    ++First;
+    return getDerived().parseIntegerLiteral("ull");
+  case 'n':
+    ++First;
+    return getDerived().parseIntegerLiteral("__int128");
+  case 'o':
+    ++First;
+    return getDerived().parseIntegerLiteral("unsigned __int128");
+  case 'f':
+    ++First;
+    return getDerived().template parseFloatingLiteral<float>();
+  case 'd':
+    ++First;
+    return getDerived().template parseFloatingLiteral<double>();
+  case 'e':
+    ++First;
+#if defined(__powerpc__) || defined(__s390__)
+    // Handle cases where long doubles encoded with e have the same size
+    // and representation as doubles.
+    return getDerived().template parseFloatingLiteral<double>();
+#else
+    return getDerived().template parseFloatingLiteral<long double>();
+#endif
+  case '_':
+    if (consumeIf("_Z")) {
+      Node *R = getDerived().parseEncoding();
+      if (R != nullptr && consumeIf('E'))
+        return R;
+    }
+    return nullptr;
+  case 'A': {
+    Node *T = getDerived().parseType();
+    if (T == nullptr)
+      return nullptr;
+    // FIXME: We need to include the string contents in the mangling.
+    if (consumeIf('E'))
+      return make<StringLiteral>(T);
+    return nullptr;
+  }
+  case 'D':
+    if (consumeIf("Dn") && (consumeIf('0'), consumeIf('E')))
+      return make<NameType>("nullptr");
+    return nullptr;
+  case 'T':
+    // Invalid mangled name per
+    //   http://sourcerytools.com/pipermail/cxx-abi-dev/2011-August/002422.html
+    return nullptr;
+  case 'U': {
+    // FIXME: Should we support LUb... for block literals?
+    if (look(1) != 'l')
+      return nullptr;
+    Node *T = parseUnnamedTypeName(nullptr);
+    if (!T || !consumeIf('E'))
+      return nullptr;
+    return make<LambdaExpr>(T);
+  }
+  default: {
+    // might be named type
+    Node *T = getDerived().parseType();
+    if (T == nullptr)
+      return nullptr;
+    StringView N = parseNumber(/*AllowNegative=*/true);
+    if (N.empty())
+      return nullptr;
+    if (!consumeIf('E'))
+      return nullptr;
+    return make<EnumLiteral>(T, N);
+  }
+  }
+}
+
+// <braced-expression> ::= <expression>
+//                     ::= di <field source-name> <braced-expression>    # .name = expr
+//                     ::= dx <index expression> <braced-expression>     # [expr] = expr
+//                     ::= dX <range begin expression> <range end expression> <braced-expression>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseBracedExpr() {
+  if (look() == 'd') {
+    switch (look(1)) {
+    case 'i': {
+      First += 2;
+      Node *Field = getDerived().parseSourceName(/*NameState=*/nullptr);
+      if (Field == nullptr)
+        return nullptr;
+      Node *Init = getDerived().parseBracedExpr();
+      if (Init == nullptr)
+        return nullptr;
+      return make<BracedExpr>(Field, Init, /*isArray=*/false);
+    }
+    case 'x': {
+      First += 2;
+      Node *Index = getDerived().parseExpr();
+      if (Index == nullptr)
+        return nullptr;
+      Node *Init = getDerived().parseBracedExpr();
+      if (Init == nullptr)
+        return nullptr;
+      return make<BracedExpr>(Index, Init, /*isArray=*/true);
+    }
+    case 'X': {
+      First += 2;
+      Node *RangeBegin = getDerived().parseExpr();
+      if (RangeBegin == nullptr)
+        return nullptr;
+      Node *RangeEnd = getDerived().parseExpr();
+      if (RangeEnd == nullptr)
+        return nullptr;
+      Node *Init = getDerived().parseBracedExpr();
+      if (Init == nullptr)
+        return nullptr;
+      return make<BracedRangeExpr>(RangeBegin, RangeEnd, Init);
+    }
+    }
+  }
+  return getDerived().parseExpr();
+}
+
+// (not yet in the spec)
+// <fold-expr> ::= fL <binary-operator-name> <expression> <expression>
+//             ::= fR <binary-operator-name> <expression> <expression>
+//             ::= fl <binary-operator-name> <expression>
+//             ::= fr <binary-operator-name> <expression>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseFoldExpr() {
+  if (!consumeIf('f'))
+    return nullptr;
+
+  bool IsLeftFold = false, HasInitializer = false;
+  switch (look()) {
+  default:
+    return nullptr;
+  case 'L':
+    IsLeftFold = true;
+    HasInitializer = true;
+    break;
+  case 'R':
+    HasInitializer = true;
+    break;
+  case 'l':
+    IsLeftFold = true;
+    break;
+  case 'r':
+    break;
+  }
+  ++First;
+
+  const auto *Op = parseOperatorEncoding();
+  if (!Op)
+    return nullptr;
+  if (!(Op->getKind() == OperatorInfo::Binary
+        || (Op->getKind() == OperatorInfo::Member
+            && Op->getName().back() == '*')))
+    return nullptr;
+
+  Node *Pack = getDerived().parseExpr();
+  if (Pack == nullptr)
+    return nullptr;
+
+  Node *Init = nullptr;
+  if (HasInitializer) {
+    Init = getDerived().parseExpr();
+    if (Init == nullptr)
+      return nullptr;
+  }
+
+  if (IsLeftFold && Init)
+    std::swap(Pack, Init);
+
+  return make<FoldExpr>(IsLeftFold, Op->getSymbol(), Pack, Init);
+}
+
+// <expression> ::= mc <parameter type> <expr> [<offset number>] E
+//
+// Not yet in the spec: https://github.com/itanium-cxx-abi/cxx-abi/issues/47
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parsePointerToMemberConversionExpr(
+    Node::Prec Prec) {
+  Node *Ty = getDerived().parseType();
+  if (!Ty)
+    return nullptr;
+  Node *Expr = getDerived().parseExpr();
+  if (!Expr)
+    return nullptr;
+  StringView Offset = getDerived().parseNumber(true);
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<PointerToMemberConversionExpr>(Ty, Expr, Offset, Prec);
+}
+
+// <expression> ::= so <referent type> <expr> [<offset number>] <union-selector>* [p] E
+// <union-selector> ::= _ [<number>]
+//
+// Not yet in the spec: https://github.com/itanium-cxx-abi/cxx-abi/issues/47
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSubobjectExpr() {
+  Node *Ty = getDerived().parseType();
+  if (!Ty)
+    return nullptr;
+  Node *Expr = getDerived().parseExpr();
+  if (!Expr)
+    return nullptr;
+  StringView Offset = getDerived().parseNumber(true);
+  size_t SelectorsBegin = Names.size();
+  while (consumeIf('_')) {
+    Node *Selector = make<NameType>(parseNumber());
+    if (!Selector)
+      return nullptr;
+    Names.push_back(Selector);
+  }
+  bool OnePastTheEnd = consumeIf('p');
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<SubobjectExpr>(
+      Ty, Expr, Offset, popTrailingNodeArray(SelectorsBegin), OnePastTheEnd);
+}
+
+// <expression> ::= <unary operator-name> <expression>
+//              ::= <binary operator-name> <expression> <expression>
+//              ::= <ternary operator-name> <expression> <expression> <expression>
+//              ::= cl <expression>+ E                                   # call
+//              ::= cv <type> <expression>                               # conversion with one argument
+//              ::= cv <type> _ <expression>* E                          # conversion with a different number of arguments
+//              ::= [gs] nw <expression>* _ <type> E                     # new (expr-list) type
+//              ::= [gs] nw <expression>* _ <type> <initializer>         # new (expr-list) type (init)
+//              ::= [gs] na <expression>* _ <type> E                     # new[] (expr-list) type
+//              ::= [gs] na <expression>* _ <type> <initializer>         # new[] (expr-list) type (init)
+//              ::= [gs] dl <expression>                                 # delete expression
+//              ::= [gs] da <expression>                                 # delete[] expression
+//              ::= pp_ <expression>                                     # prefix ++
+//              ::= mm_ <expression>                                     # prefix --
+//              ::= ti <type>                                            # typeid (type)
+//              ::= te <expression>                                      # typeid (expression)
+//              ::= dc <type> <expression>                               # dynamic_cast<type> (expression)
+//              ::= sc <type> <expression>                               # static_cast<type> (expression)
+//              ::= cc <type> <expression>                               # const_cast<type> (expression)
+//              ::= rc <type> <expression>                               # reinterpret_cast<type> (expression)
+//              ::= st <type>                                            # sizeof (a type)
+//              ::= sz <expression>                                      # sizeof (an expression)
+//              ::= at <type>                                            # alignof (a type)
+//              ::= az <expression>                                      # alignof (an expression)
+//              ::= nx <expression>                                      # noexcept (expression)
+//              ::= <template-param>
+//              ::= <function-param>
+//              ::= dt <expression> <unresolved-name>                    # expr.name
+//              ::= pt <expression> <unresolved-name>                    # expr->name
+//              ::= ds <expression> <expression>                         # expr.*expr
+//              ::= sZ <template-param>                                  # size of a parameter pack
+//              ::= sZ <function-param>                                  # size of a function parameter pack
+//              ::= sP <template-arg>* E                                 # sizeof...(T), size of a captured template parameter pack from an alias template
+//              ::= sp <expression>                                      # pack expansion
+//              ::= tw <expression>                                      # throw expression
+//              ::= tr                                                   # throw with no operand (rethrow)
+//              ::= <unresolved-name>                                    # f(p), N::f(p), ::f(p),
+//                                                                       # freestanding dependent name (e.g., T::x),
+//                                                                       # objectless nonstatic member reference
+//              ::= fL <binary-operator-name> <expression> <expression>
+//              ::= fR <binary-operator-name> <expression> <expression>
+//              ::= fl <binary-operator-name> <expression>
+//              ::= fr <binary-operator-name> <expression>
+//              ::= <expr-primary>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseExpr() {
+  bool Global = consumeIf("gs");
+
+  const auto *Op = parseOperatorEncoding();
+  if (Op) {
+    auto Sym = Op->getSymbol();
+    switch (Op->getKind()) {
+    case OperatorInfo::Binary:
+      // Binary operator: lhs @ rhs
+      return getDerived().parseBinaryExpr(Sym, Op->getPrecedence());
+    case OperatorInfo::Prefix:
+      // Prefix unary operator: @ expr
+      return getDerived().parsePrefixExpr(Sym, Op->getPrecedence());
+    case OperatorInfo::Postfix: {
+      // Postfix unary operator: expr @
+      if (consumeIf('_'))
+        return getDerived().parsePrefixExpr(Sym, Op->getPrecedence());
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return nullptr;
+      return make<PostfixExpr>(Ex, Sym, Op->getPrecedence());
+    }
+    case OperatorInfo::Array: {
+      // Array Index:  lhs [ rhs ]
+      Node *Base = getDerived().parseExpr();
+      if (Base == nullptr)
+        return nullptr;
+      Node *Index = getDerived().parseExpr();
+      if (Index == nullptr)
+        return nullptr;
+      return make<ArraySubscriptExpr>(Base, Index, Op->getPrecedence());
+    }
+    case OperatorInfo::Member: {
+      // Member access lhs @ rhs
+      Node *LHS = getDerived().parseExpr();
+      if (LHS == nullptr)
+        return nullptr;
+      Node *RHS = getDerived().parseExpr();
+      if (RHS == nullptr)
+        return nullptr;
+      return make<MemberExpr>(LHS, Sym, RHS, Op->getPrecedence());
+    }
+    case OperatorInfo::New: {
+      // New
+      // # new (expr-list) type [(init)]
+      // [gs] nw <expression>* _ <type> [pi <expression>*] E
+      // # new[] (expr-list) type [(init)]
+      // [gs] na <expression>* _ <type> [pi <expression>*] E
+      size_t Exprs = Names.size();
+      while (!consumeIf('_')) {
+        Node *Ex = getDerived().parseExpr();
+        if (Ex == nullptr)
+          return nullptr;
+        Names.push_back(Ex);
+      }
+      NodeArray ExprList = popTrailingNodeArray(Exprs);
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      bool HaveInits = consumeIf("pi");
+      size_t InitsBegin = Names.size();
+      while (!consumeIf('E')) {
+        if (!HaveInits)
+          return nullptr;
+        Node *Init = getDerived().parseExpr();
+        if (Init == nullptr)
+          return Init;
+        Names.push_back(Init);
+      }
+      NodeArray Inits = popTrailingNodeArray(InitsBegin);
+      return make<NewExpr>(ExprList, Ty, Inits, Global,
+                           /*IsArray=*/Op->getFlag(), Op->getPrecedence());
+    }
+    case OperatorInfo::Del: {
+      // Delete
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return nullptr;
+      return make<DeleteExpr>(Ex, Global, /*IsArray=*/Op->getFlag(),
+                              Op->getPrecedence());
+    }
+    case OperatorInfo::Call: {
+      // Function Call
+      Node *Callee = getDerived().parseExpr();
+      if (Callee == nullptr)
+        return nullptr;
+      size_t ExprsBegin = Names.size();
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseExpr();
+        if (E == nullptr)
+          return nullptr;
+        Names.push_back(E);
+      }
+      return make<CallExpr>(Callee, popTrailingNodeArray(ExprsBegin),
+                            Op->getPrecedence());
+    }
+    case OperatorInfo::CCast: {
+      // C Cast: (type)expr
+      Node *Ty;
+      {
+        ScopedOverride<bool> SaveTemp(TryToParseTemplateArgs, false);
+        Ty = getDerived().parseType();
+      }
+      if (Ty == nullptr)
+        return nullptr;
+
+      size_t ExprsBegin = Names.size();
+      bool IsMany = consumeIf('_');
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseExpr();
+        if (E == nullptr)
+          return E;
+        Names.push_back(E);
+        if (!IsMany)
+          break;
+      }
+      NodeArray Exprs = popTrailingNodeArray(ExprsBegin);
+      if (!IsMany && Exprs.size() != 1)
+        return nullptr;
+      return make<ConversionExpr>(Ty, Exprs, Op->getPrecedence());
+    }
+    case OperatorInfo::Conditional: {
+      // Conditional operator: expr ? expr : expr
+      Node *Cond = getDerived().parseExpr();
+      if (Cond == nullptr)
+        return nullptr;
+      Node *LHS = getDerived().parseExpr();
+      if (LHS == nullptr)
+        return nullptr;
+      Node *RHS = getDerived().parseExpr();
+      if (RHS == nullptr)
+        return nullptr;
+      return make<ConditionalExpr>(Cond, LHS, RHS, Op->getPrecedence());
+    }
+    case OperatorInfo::NamedCast: {
+      // Named cast operation, @<type>(expr)
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      Node *Ex = getDerived().parseExpr();
+      if (Ex == nullptr)
+        return nullptr;
+      return make<CastExpr>(Sym, Ty, Ex, Op->getPrecedence());
+    }
+    case OperatorInfo::OfIdOp: {
+      // [sizeof/alignof/typeid] ( <type>|<expr> )
+      Node *Arg =
+          Op->getFlag() ? getDerived().parseType() : getDerived().parseExpr();
+      if (!Arg)
+        return nullptr;
+      return make<EnclosingExpr>(Sym, Arg, Op->getPrecedence());
+    }
+    case OperatorInfo::NameOnly: {
+      // Not valid as an expression operand.
+      return nullptr;
+    }
+    }
+    DEMANGLE_UNREACHABLE;
+  }
+
+  if (numLeft() < 2)
+    return nullptr;
+
+  if (look() == 'L')
+    return getDerived().parseExprPrimary();
+  if (look() == 'T')
+    return getDerived().parseTemplateParam();
+  if (look() == 'f') {
+    // Disambiguate a fold expression from a <function-param>.
+    if (look(1) == 'p' || (look(1) == 'L' && std::isdigit(look(2))))
+      return getDerived().parseFunctionParam();
+    return getDerived().parseFoldExpr();
+  }
+  if (consumeIf("il")) {
+    size_t InitsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *E = getDerived().parseBracedExpr();
+      if (E == nullptr)
+        return nullptr;
+      Names.push_back(E);
+    }
+    return make<InitListExpr>(nullptr, popTrailingNodeArray(InitsBegin));
+  }
+  if (consumeIf("mc"))
+    return parsePointerToMemberConversionExpr(Node::Prec::Unary);
+  if (consumeIf("nx")) {
+    Node *Ex = getDerived().parseExpr();
+    if (Ex == nullptr)
+      return Ex;
+    return make<EnclosingExpr>("noexcept ", Ex, Node::Prec::Unary);
+  }
+  if (consumeIf("so"))
+    return parseSubobjectExpr();
+  if (consumeIf("sp")) {
+    Node *Child = getDerived().parseExpr();
+    if (Child == nullptr)
+      return nullptr;
+    return make<ParameterPackExpansion>(Child);
+  }
+  if (consumeIf("sZ")) {
+    if (look() == 'T') {
+      Node *R = getDerived().parseTemplateParam();
+      if (R == nullptr)
+        return nullptr;
+      return make<SizeofParamPackExpr>(R);
+    }
+    Node *FP = getDerived().parseFunctionParam();
+    if (FP == nullptr)
+      return nullptr;
+    return make<EnclosingExpr>("sizeof... ", FP);
+  }
+  if (consumeIf("sP")) {
+    size_t ArgsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+    auto *Pack = make<NodeArrayNode>(popTrailingNodeArray(ArgsBegin));
+    if (!Pack)
+      return nullptr;
+    return make<EnclosingExpr>("sizeof... ", Pack);
+  }
+  if (consumeIf("tl")) {
+    Node *Ty = getDerived().parseType();
+    if (Ty == nullptr)
+      return nullptr;
+    size_t InitsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *E = getDerived().parseBracedExpr();
+      if (E == nullptr)
+        return nullptr;
+      Names.push_back(E);
+    }
+    return make<InitListExpr>(Ty, popTrailingNodeArray(InitsBegin));
+  }
+  if (consumeIf("tr"))
+    return make<NameType>("throw");
+  if (consumeIf("tw")) {
+    Node *Ex = getDerived().parseExpr();
+    if (Ex == nullptr)
+      return nullptr;
+    return make<ThrowExpr>(Ex);
+  }
+  if (consumeIf('u')) {
+    Node *Name = getDerived().parseSourceName(/*NameState=*/nullptr);
+    if (!Name)
+      return nullptr;
+    // Special case legacy __uuidof mangling. The 't' and 'z' appear where the
+    // standard encoding expects a <template-arg>, and would be otherwise be
+    // interpreted as <type> node 'short' or 'ellipsis'. However, neither
+    // __uuidof(short) nor __uuidof(...) can actually appear, so there is no
+    // actual conflict here.
+    bool IsUUID = false;
+    Node *UUID = nullptr;
+    if (Name->getBaseName() == "__uuidof") {
+      if (consumeIf('t')) {
+        UUID = getDerived().parseType();
+        IsUUID = true;
+      } else if (consumeIf('z')) {
+        UUID = getDerived().parseExpr();
+        IsUUID = true;
+      }
+    }
+    size_t ExprsBegin = Names.size();
+    if (IsUUID) {
+      if (UUID == nullptr)
+        return nullptr;
+      Names.push_back(UUID);
+    } else {
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseTemplateArg();
+        if (E == nullptr)
+          return E;
+        Names.push_back(E);
+      }
+    }
+    return make<CallExpr>(Name, popTrailingNodeArray(ExprsBegin),
+                          Node::Prec::Postfix);
+  }
+
+  // Only unresolved names remain.
+  return getDerived().parseUnresolvedName(Global);
+}
+
+// <call-offset> ::= h <nv-offset> _
+//               ::= v <v-offset> _
+//
+// <nv-offset> ::= <offset number>
+//               # non-virtual base override
+//
+// <v-offset>  ::= <offset number> _ <virtual offset number>
+//               # virtual base override, with vcall offset
+template <typename Alloc, typename Derived>
+bool AbstractManglingParser<Alloc, Derived>::parseCallOffset() {
+  // Just scan through the call offset, we never add this information into the
+  // output.
+  if (consumeIf('h'))
+    return parseNumber(true).empty() || !consumeIf('_');
+  if (consumeIf('v'))
+    return parseNumber(true).empty() || !consumeIf('_') ||
+           parseNumber(true).empty() || !consumeIf('_');
+  return true;
+}
+
+// <special-name> ::= TV <type>    # virtual table
+//                ::= TT <type>    # VTT structure (construction vtable index)
+//                ::= TI <type>    # typeinfo structure
+//                ::= TS <type>    # typeinfo name (null-terminated byte string)
+//                ::= Tc <call-offset> <call-offset> <base encoding>
+//                    # base is the nominal target function of thunk
+//                    # first call-offset is 'this' adjustment
+//                    # second call-offset is result adjustment
+//                ::= T <call-offset> <base encoding>
+//                    # base is the nominal target function of thunk
+//                # Guard variable for one-time initialization
+//                ::= GV <object name>
+//                                     # No <type>
+//                ::= TW <object name> # Thread-local wrapper
+//                ::= TH <object name> # Thread-local initialization
+//                ::= GR <object name> _             # First temporary
+//                ::= GR <object name> <seq-id> _    # Subsequent temporaries
+//                # construction vtable for second-in-first
+//      extension ::= TC <first type> <number> _ <second type>
+//      extension ::= GR <object name> # reference temporary for object
+//      extension ::= GI <module name> # module global initializer
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSpecialName() {
+  switch (look()) {
+  case 'T':
+    switch (look(1)) {
+    // TA <template-arg>    # template parameter object
+    //
+    // Not yet in the spec: https://github.com/itanium-cxx-abi/cxx-abi/issues/63
+    case 'A': {
+      First += 2;
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      return make<SpecialName>("template parameter object for ", Arg);
+    }
+    // TV <type>    # virtual table
+    case 'V': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("vtable for ", Ty);
+    }
+    // TT <type>    # VTT structure (construction vtable index)
+    case 'T': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("VTT for ", Ty);
+    }
+    // TI <type>    # typeinfo structure
+    case 'I': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("typeinfo for ", Ty);
+    }
+    // TS <type>    # typeinfo name (null-terminated byte string)
+    case 'S': {
+      First += 2;
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
+        return nullptr;
+      return make<SpecialName>("typeinfo name for ", Ty);
+    }
+    // Tc <call-offset> <call-offset> <base encoding>
+    case 'c': {
+      First += 2;
+      if (parseCallOffset() || parseCallOffset())
+        return nullptr;
+      Node *Encoding = getDerived().parseEncoding();
+      if (Encoding == nullptr)
+        return nullptr;
+      return make<SpecialName>("covariant return thunk to ", Encoding);
+    }
+    // extension ::= TC <first type> <number> _ <second type>
+    //               # construction vtable for second-in-first
+    case 'C': {
+      First += 2;
+      Node *FirstType = getDerived().parseType();
+      if (FirstType == nullptr)
+        return nullptr;
+      if (parseNumber(true).empty() || !consumeIf('_'))
+        return nullptr;
+      Node *SecondType = getDerived().parseType();
+      if (SecondType == nullptr)
+        return nullptr;
+      return make<CtorVtableSpecialName>(SecondType, FirstType);
+    }
+    // TW <object name> # Thread-local wrapper
+    case 'W': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      return make<SpecialName>("thread-local wrapper routine for ", Name);
+    }
+    // TH <object name> # Thread-local initialization
+    case 'H': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      return make<SpecialName>("thread-local initialization routine for ", Name);
+    }
+    // T <call-offset> <base encoding>
+    default: {
+      ++First;
+      bool IsVirt = look() == 'v';
+      if (parseCallOffset())
+        return nullptr;
+      Node *BaseEncoding = getDerived().parseEncoding();
+      if (BaseEncoding == nullptr)
+        return nullptr;
+      if (IsVirt)
+        return make<SpecialName>("virtual thunk to ", BaseEncoding);
+      else
+        return make<SpecialName>("non-virtual thunk to ", BaseEncoding);
+    }
+    }
+  case 'G':
+    switch (look(1)) {
+    // GV <object name> # Guard variable for one-time initialization
+    case 'V': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      return make<SpecialName>("guard variable for ", Name);
+    }
+    // GR <object name> # reference temporary for object
+    // GR <object name> _             # First temporary
+    // GR <object name> <seq-id> _    # Subsequent temporaries
+    case 'R': {
+      First += 2;
+      Node *Name = getDerived().parseName();
+      if (Name == nullptr)
+        return nullptr;
+      size_t Count;
+      bool ParsedSeqId = !parseSeqId(&Count);
+      if (!consumeIf('_') && ParsedSeqId)
+        return nullptr;
+      return make<SpecialName>("reference temporary for ", Name);
+    }
+    // GI <module-name> v
+    case 'I': {
+      First += 2;
+      ModuleName *Module = nullptr;
+      if (getDerived().parseModuleNameOpt(Module))
+        return nullptr;
+      if (Module == nullptr)
+        return nullptr;
+      return make<SpecialName>("initializer for module ", Module);
+    }
+    }
+  }
+  return nullptr;
+}
+
+// <encoding> ::= <function name> <bare-function-type>
+//            ::= <data name>
+//            ::= <special-name>
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseEncoding() {
+  // The template parameters of an encoding are unrelated to those of the
+  // enclosing context.
+  class SaveTemplateParams {
+    AbstractManglingParser *Parser;
+    decltype(TemplateParams) OldParams;
+    decltype(OuterTemplateParams) OldOuterParams;
+
+  public:
+    SaveTemplateParams(AbstractManglingParser *TheParser) : Parser(TheParser) {
+      OldParams = std::move(Parser->TemplateParams);
+      OldOuterParams = std::move(Parser->OuterTemplateParams);
+      Parser->TemplateParams.clear();
+      Parser->OuterTemplateParams.clear();
+    }
+    ~SaveTemplateParams() {
+      Parser->TemplateParams = std::move(OldParams);
+      Parser->OuterTemplateParams = std::move(OldOuterParams);
+    }
+  } SaveTemplateParams(this);
+
+  if (look() == 'G' || look() == 'T')
+    return getDerived().parseSpecialName();
+
+  auto IsEndOfEncoding = [&] {
+    // The set of chars that can potentially follow an <encoding> (none of which
+    // can start a <type>). Enumerating these allows us to avoid speculative
+    // parsing.
+    return numLeft() == 0 || look() == 'E' || look() == '.' || look() == '_';
+  };
+
+  NameState NameInfo(this);
+  Node *Name = getDerived().parseName(&NameInfo);
+  if (Name == nullptr)
+    return nullptr;
+
+  if (resolveForwardTemplateRefs(NameInfo))
+    return nullptr;
+
+  if (IsEndOfEncoding())
+    return Name;
+
+  Node *Attrs = nullptr;
+  if (consumeIf("Ua9enable_ifI")) {
+    size_t BeforeArgs = Names.size();
+    while (!consumeIf('E')) {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+    Attrs = make<EnableIfAttr>(popTrailingNodeArray(BeforeArgs));
+    if (!Attrs)
+      return nullptr;
+  }
+
+  Node *ReturnType = nullptr;
+  if (!NameInfo.CtorDtorConversion && NameInfo.EndsWithTemplateArgs) {
+    ReturnType = getDerived().parseType();
+    if (ReturnType == nullptr)
+      return nullptr;
+  }
+
+  if (consumeIf('v'))
+    return make<FunctionEncoding>(ReturnType, Name, NodeArray(),
+                                  Attrs, NameInfo.CVQualifiers,
+                                  NameInfo.ReferenceQualifier);
+
+  size_t ParamsBegin = Names.size();
+  do {
+    Node *Ty = getDerived().parseType();
+    if (Ty == nullptr)
+      return nullptr;
+    Names.push_back(Ty);
+  } while (!IsEndOfEncoding());
+
+  return make<FunctionEncoding>(ReturnType, Name,
+                                popTrailingNodeArray(ParamsBegin),
+                                Attrs, NameInfo.CVQualifiers,
+                                NameInfo.ReferenceQualifier);
+}
+
+template <class Float>
+struct FloatData;
+
+template <>
+struct FloatData<float>
+{
+    static const size_t mangled_size = 8;
+    static const size_t max_demangled_size = 24;
+    static constexpr const char* spec = "%af";
+};
+
+template <>
+struct FloatData<double>
+{
+    static const size_t mangled_size = 16;
+    static const size_t max_demangled_size = 32;
+    static constexpr const char* spec = "%a";
+};
+
+template <>
+struct FloatData<long double>
+{
+#if defined(__mips__) && defined(__mips_n64) || defined(__aarch64__) || \
+    defined(__wasm__) || defined(__riscv)
+    static const size_t mangled_size = 32;
+#elif defined(__arm__) || defined(__mips__) || defined(__hexagon__)
+    static const size_t mangled_size = 16;
+#else
+    static const size_t mangled_size = 20;  // May need to be adjusted to 16 or 24 on other platforms
+#endif
+    // `-0x1.ffffffffffffffffffffffffffffp+16383` + 'L' + '\0' == 42 bytes.
+    // 28 'f's * 4 bits == 112 bits, which is the number of mantissa bits.
+    // Negatives are one character longer than positives.
+    // `0x1.` and `p` are constant, and exponents `+16383` and `-16382` are the
+    // same length. 1 sign bit, 112 mantissa bits, and 15 exponent bits == 128.
+    static const size_t max_demangled_size = 42;
+    static constexpr const char *spec = "%LaL";
+};
+
+template <typename Alloc, typename Derived>
+template <class Float>
+Node *AbstractManglingParser<Alloc, Derived>::parseFloatingLiteral() {
+  const size_t N = FloatData<Float>::mangled_size;
+  if (numLeft() <= N)
+    return nullptr;
+  StringView Data(First, First + N);
+  for (char C : Data)
+    if (!std::isxdigit(C))
+      return nullptr;
+  First += N;
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<FloatLiteralImpl<Float>>(Data);
+}
+
+// <seq-id> ::= <0-9A-Z>+
+template <typename Alloc, typename Derived>
+bool AbstractManglingParser<Alloc, Derived>::parseSeqId(size_t *Out) {
+  if (!(look() >= '0' && look() <= '9') &&
+      !(look() >= 'A' && look() <= 'Z'))
+    return true;
+
+  size_t Id = 0;
+  while (true) {
+    if (look() >= '0' && look() <= '9') {
+      Id *= 36;
+      Id += static_cast<size_t>(look() - '0');
+    } else if (look() >= 'A' && look() <= 'Z') {
+      Id *= 36;
+      Id += static_cast<size_t>(look() - 'A') + 10;
+    } else {
+      *Out = Id;
+      return false;
+    }
+    ++First;
+  }
+}
+
+// <substitution> ::= S <seq-id> _
+//                ::= S_
+// <substitution> ::= Sa # ::std::allocator
+// <substitution> ::= Sb # ::std::basic_string
+// <substitution> ::= Ss # ::std::basic_string < char,
+//                                               ::std::char_traits<char>,
+//                                               ::std::allocator<char> >
+// <substitution> ::= Si # ::std::basic_istream<char,  std::char_traits<char> >
+// <substitution> ::= So # ::std::basic_ostream<char,  std::char_traits<char> >
+// <substitution> ::= Sd # ::std::basic_iostream<char, std::char_traits<char> >
+// The St case is handled specially in parseNestedName.
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSubstitution() {
+  if (!consumeIf('S'))
+    return nullptr;
+
+  if (look() >= 'a' && look() <= 'z') {
+    SpecialSubKind Kind;
+    switch (look()) {
+    case 'a':
+      Kind = SpecialSubKind::allocator;
+      break;
+    case 'b':
+      Kind = SpecialSubKind::basic_string;
+      break;
+    case 'd':
+      Kind = SpecialSubKind::iostream;
+      break;
+    case 'i':
+      Kind = SpecialSubKind::istream;
+      break;
+    case 'o':
+      Kind = SpecialSubKind::ostream;
+      break;
+    case 's':
+      Kind = SpecialSubKind::string;
+      break;
+    default:
+      return nullptr;
+    }
+    ++First;
+    auto *SpecialSub = make<SpecialSubstitution>(Kind);
+    if (!SpecialSub)
+      return nullptr;
+
+    // Itanium C++ ABI 5.1.2: If a name that would use a built-in <substitution>
+    // has ABI tags, the tags are appended to the substitution; the result is a
+    // substitutable component.
+    Node *WithTags = getDerived().parseAbiTags(SpecialSub);
+    if (WithTags != SpecialSub) {
+      Subs.push_back(WithTags);
+      SpecialSub = WithTags;
+    }
+    return SpecialSub;
+  }
+
+  //                ::= S_
+  if (consumeIf('_')) {
+    if (Subs.empty())
+      return nullptr;
+    return Subs[0];
+  }
+
+  //                ::= S <seq-id> _
+  size_t Index = 0;
+  if (parseSeqId(&Index))
+    return nullptr;
+  ++Index;
+  if (!consumeIf('_') || Index >= Subs.size())
+    return nullptr;
+  return Subs[Index];
+}
+
+// <template-param> ::= T_    # first template parameter
+//                  ::= T <parameter-2 non-negative number> _
+//                  ::= TL <level-1> __
+//                  ::= TL <level-1> _ <parameter-2 non-negative number> _
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseTemplateParam() {
+  if (!consumeIf('T'))
+    return nullptr;
+
+  size_t Level = 0;
+  if (consumeIf('L')) {
+    if (parsePositiveInteger(&Level))
+      return nullptr;
+    ++Level;
+    if (!consumeIf('_'))
+      return nullptr;
+  }
+
+  size_t Index = 0;
+  if (!consumeIf('_')) {
+    if (parsePositiveInteger(&Index))
+      return nullptr;
+    ++Index;
+    if (!consumeIf('_'))
+      return nullptr;
+  }
+
+  // If we're in a context where this <template-param> refers to a
+  // <template-arg> further ahead in the mangled name (currently just conversion
+  // operator types), then we should only look it up in the right context.
+  // This can only happen at the outermost level.
+  if (PermitForwardTemplateReferences && Level == 0) {
+    Node *ForwardRef = make<ForwardTemplateReference>(Index);
+    if (!ForwardRef)
+      return nullptr;
+    assert(ForwardRef->getKind() == Node::KForwardTemplateReference);
+    ForwardTemplateRefs.push_back(
+        static_cast<ForwardTemplateReference *>(ForwardRef));
+    return ForwardRef;
+  }
+
+  if (Level >= TemplateParams.size() || !TemplateParams[Level] ||
+      Index >= TemplateParams[Level]->size()) {
+    // Itanium ABI 5.1.8: In a generic lambda, uses of auto in the parameter
+    // list are mangled as the corresponding artificial template type parameter.
+    if (ParsingLambdaParamsAtLevel == Level && Level <= TemplateParams.size()) {
+      // This will be popped by the ScopedTemplateParamList in
+      // parseUnnamedTypeName.
+      if (Level == TemplateParams.size())
+        TemplateParams.push_back(nullptr);
+      return make<NameType>("auto");
+    }
+
+    return nullptr;
+  }
+
+  return (*TemplateParams[Level])[Index];
+}
+
+// <template-param-decl> ::= Ty                          # type parameter
+//                       ::= Tn <type>                   # non-type parameter
+//                       ::= Tt <template-param-decl>* E # template parameter
+//                       ::= Tp <template-param-decl>    # parameter pack
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseTemplateParamDecl() {
+  auto InventTemplateParamName = [&](TemplateParamKind Kind) {
+    unsigned Index = NumSyntheticTemplateParameters[(int)Kind]++;
+    Node *N = make<SyntheticTemplateParamName>(Kind, Index);
+    if (N) TemplateParams.back()->push_back(N);
+    return N;
+  };
+
+  if (consumeIf("Ty")) {
+    Node *Name = InventTemplateParamName(TemplateParamKind::Type);
+    if (!Name)
+      return nullptr;
+    return make<TypeTemplateParamDecl>(Name);
+  }
+
+  if (consumeIf("Tn")) {
+    Node *Name = InventTemplateParamName(TemplateParamKind::NonType);
+    if (!Name)
+      return nullptr;
+    Node *Type = parseType();
+    if (!Type)
+      return nullptr;
+    return make<NonTypeTemplateParamDecl>(Name, Type);
+  }
+
+  if (consumeIf("Tt")) {
+    Node *Name = InventTemplateParamName(TemplateParamKind::Template);
+    if (!Name)
+      return nullptr;
+    size_t ParamsBegin = Names.size();
+    ScopedTemplateParamList TemplateTemplateParamParams(this);
+    while (!consumeIf("E")) {
+      Node *P = parseTemplateParamDecl();
+      if (!P)
+        return nullptr;
+      Names.push_back(P);
+    }
+    NodeArray Params = popTrailingNodeArray(ParamsBegin);
+    return make<TemplateTemplateParamDecl>(Name, Params);
+  }
+
+  if (consumeIf("Tp")) {
+    Node *P = parseTemplateParamDecl();
+    if (!P)
+      return nullptr;
+    return make<TemplateParamPackDecl>(P);
+  }
+
+  return nullptr;
+}
+
+// <template-arg> ::= <type>                    # type or template
+//                ::= X <expression> E          # expression
+//                ::= <expr-primary>            # simple expressions
+//                ::= J <template-arg>* E       # argument pack
+//                ::= LZ <encoding> E           # extension
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseTemplateArg() {
+  switch (look()) {
+  case 'X': {
+    ++First;
+    Node *Arg = getDerived().parseExpr();
+    if (Arg == nullptr || !consumeIf('E'))
+      return nullptr;
+    return Arg;
+  }
+  case 'J': {
+    ++First;
+    size_t ArgsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+    NodeArray Args = popTrailingNodeArray(ArgsBegin);
+    return make<TemplateArgumentPack>(Args);
+  }
+  case 'L': {
+    //                ::= LZ <encoding> E           # extension
+    if (look(1) == 'Z') {
+      First += 2;
+      Node *Arg = getDerived().parseEncoding();
+      if (Arg == nullptr || !consumeIf('E'))
+        return nullptr;
+      return Arg;
+    }
+    //                ::= <expr-primary>            # simple expressions
+    return getDerived().parseExprPrimary();
+  }
+  default:
+    return getDerived().parseType();
+  }
+}
+
+// <template-args> ::= I <template-arg>* E
+//     extension, the abi says <template-arg>+
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parseTemplateArgs(bool TagTemplates) {
+  if (!consumeIf('I'))
+    return nullptr;
+
+  // <template-params> refer to the innermost <template-args>. Clear out any
+  // outer args that we may have inserted into TemplateParams.
+  if (TagTemplates) {
+    TemplateParams.clear();
+    TemplateParams.push_back(&OuterTemplateParams);
+    OuterTemplateParams.clear();
+  }
+
+  size_t ArgsBegin = Names.size();
+  while (!consumeIf('E')) {
+    if (TagTemplates) {
+      auto OldParams = std::move(TemplateParams);
+      Node *Arg = getDerived().parseTemplateArg();
+      TemplateParams = std::move(OldParams);
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+      Node *TableEntry = Arg;
+      if (Arg->getKind() == Node::KTemplateArgumentPack) {
+        TableEntry = make<ParameterPack>(
+            static_cast<TemplateArgumentPack*>(TableEntry)->getElements());
+        if (!TableEntry)
+          return nullptr;
+      }
+      TemplateParams.back()->push_back(TableEntry);
+    } else {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
+    }
+  }
+  return make<TemplateArgs>(popTrailingNodeArray(ArgsBegin));
+}
+
+// <mangled-name> ::= _Z <encoding>
+//                ::= <type>
+// extension      ::= ___Z <encoding> _block_invoke
+// extension      ::= ___Z <encoding> _block_invoke<decimal-digit>+
+// extension      ::= ___Z <encoding> _block_invoke_<decimal-digit>+
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parse() {
+  if (consumeIf("_Z") || consumeIf("__Z")) {
+    Node *Encoding = getDerived().parseEncoding();
+    if (Encoding == nullptr)
+      return nullptr;
+    if (look() == '.') {
+      Encoding = make<DotSuffix>(Encoding, StringView(First, Last));
+      First = Last;
+    }
+    if (numLeft() != 0)
+      return nullptr;
+    return Encoding;
+  }
+
+  if (consumeIf("___Z") || consumeIf("____Z")) {
+    Node *Encoding = getDerived().parseEncoding();
+    if (Encoding == nullptr || !consumeIf("_block_invoke"))
+      return nullptr;
+    bool RequireNumber = consumeIf('_');
+    if (parseNumber().empty() && RequireNumber)
+      return nullptr;
+    if (look() == '.')
+      First = Last;
+    if (numLeft() != 0)
+      return nullptr;
+    return make<SpecialName>("invocation function for block in ", Encoding);
+  }
+
+  Node *Ty = getDerived().parseType();
+  if (numLeft() != 0)
+    return nullptr;
+  return Ty;
+}
+
+template <typename Alloc>
+struct ManglingParser : AbstractManglingParser<ManglingParser<Alloc>, Alloc> {
+  using AbstractManglingParser<ManglingParser<Alloc>,
+                               Alloc>::AbstractManglingParser;
+};
+
+DEMANGLE_NAMESPACE_END
+
+#endif // DEMANGLE_ITANIUMDEMANGLE_H
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/ItaniumNodes.def b/demangle/third_party/llvm/include/llvm/Demangle/ItaniumNodes.def
new file mode 100644
index 00000000..c0e277d5
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/ItaniumNodes.def
@@ -0,0 +1,95 @@
+//===--- ItaniumNodes.def ------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Define the demangler's node names
+
+#ifndef NODE
+#error Define NODE to handle nodes
+#endif
+
+NODE(NodeArrayNode)
+NODE(DotSuffix)
+NODE(VendorExtQualType)
+NODE(QualType)
+NODE(ConversionOperatorType)
+NODE(PostfixQualifiedType)
+NODE(ElaboratedTypeSpefType)
+NODE(NameType)
+NODE(AbiTagAttr)
+NODE(EnableIfAttr)
+NODE(ObjCProtoName)
+NODE(PointerType)
+NODE(ReferenceType)
+NODE(PointerToMemberType)
+NODE(ArrayType)
+NODE(FunctionType)
+NODE(NoexceptSpec)
+NODE(DynamicExceptionSpec)
+NODE(FunctionEncoding)
+NODE(LiteralOperator)
+NODE(SpecialName)
+NODE(CtorVtableSpecialName)
+NODE(QualifiedName)
+NODE(NestedName)
+NODE(LocalName)
+NODE(ModuleName)
+NODE(ModuleEntity)
+NODE(VectorType)
+NODE(PixelVectorType)
+NODE(BinaryFPType)
+NODE(BitIntType)
+NODE(SyntheticTemplateParamName)
+NODE(TypeTemplateParamDecl)
+NODE(NonTypeTemplateParamDecl)
+NODE(TemplateTemplateParamDecl)
+NODE(TemplateParamPackDecl)
+NODE(ParameterPack)
+NODE(TemplateArgumentPack)
+NODE(ParameterPackExpansion)
+NODE(TemplateArgs)
+NODE(ForwardTemplateReference)
+NODE(NameWithTemplateArgs)
+NODE(GlobalQualifiedName)
+NODE(ExpandedSpecialSubstitution)
+NODE(SpecialSubstitution)
+NODE(CtorDtorName)
+NODE(DtorName)
+NODE(UnnamedTypeName)
+NODE(ClosureTypeName)
+NODE(StructuredBindingName)
+NODE(BinaryExpr)
+NODE(ArraySubscriptExpr)
+NODE(PostfixExpr)
+NODE(ConditionalExpr)
+NODE(MemberExpr)
+NODE(SubobjectExpr)
+NODE(EnclosingExpr)
+NODE(CastExpr)
+NODE(SizeofParamPackExpr)
+NODE(CallExpr)
+NODE(NewExpr)
+NODE(DeleteExpr)
+NODE(PrefixExpr)
+NODE(FunctionParam)
+NODE(ConversionExpr)
+NODE(PointerToMemberConversionExpr)
+NODE(InitListExpr)
+NODE(FoldExpr)
+NODE(ThrowExpr)
+NODE(BoolExpr)
+NODE(StringLiteral)
+NODE(LambdaExpr)
+NODE(EnumLiteral)
+NODE(IntegerLiteral)
+NODE(FloatLiteral)
+NODE(DoubleLiteral)
+NODE(LongDoubleLiteral)
+NODE(BracedExpr)
+NODE(BracedRangeExpr)
+
+#undef NODE
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/MicrosoftDemangle.h b/demangle/third_party/llvm/include/llvm/Demangle/MicrosoftDemangle.h
new file mode 100644
index 00000000..f1a5e1b6
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/MicrosoftDemangle.h
@@ -0,0 +1,276 @@
+//===------------------------- MicrosoftDemangle.h --------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_MICROSOFTDEMANGLE_H
+#define LLVM_DEMANGLE_MICROSOFTDEMANGLE_H
+
+#include "llvm/Demangle/MicrosoftDemangleNodes.h"
+#include "llvm/Demangle/StringView.h"
+
+#include <utility>
+
+namespace llvm {
+namespace ms_demangle {
+// This memory allocator is extremely fast, but it doesn't call dtors
+// for allocated objects. That means you can't use STL containers
+// (such as std::vector) with this allocator. But it pays off --
+// the demangler is 3x faster with this allocator compared to one with
+// STL containers.
+constexpr size_t AllocUnit = 4096;
+
+class ArenaAllocator {
+  struct AllocatorNode {
+    uint8_t *Buf = nullptr;
+    size_t Used = 0;
+    size_t Capacity = 0;
+    AllocatorNode *Next = nullptr;
+  };
+
+  void addNode(size_t Capacity) {
+    AllocatorNode *NewHead = new AllocatorNode;
+    NewHead->Buf = new uint8_t[Capacity];
+    NewHead->Next = Head;
+    NewHead->Capacity = Capacity;
+    Head = NewHead;
+    NewHead->Used = 0;
+  }
+
+public:
+  ArenaAllocator() { addNode(AllocUnit); }
+
+  ~ArenaAllocator() {
+    while (Head) {
+      assert(Head->Buf);
+      delete[] Head->Buf;
+      AllocatorNode *Next = Head->Next;
+      delete Head;
+      Head = Next;
+    }
+  }
+
+  char *allocUnalignedBuffer(size_t Size) {
+    assert(Head && Head->Buf);
+
+    uint8_t *P = Head->Buf + Head->Used;
+
+    Head->Used += Size;
+    if (Head->Used <= Head->Capacity)
+      return reinterpret_cast<char *>(P);
+
+    addNode(std::max(AllocUnit, Size));
+    Head->Used = Size;
+    return reinterpret_cast<char *>(Head->Buf);
+  }
+
+  template <typename T, typename... Args> T *allocArray(size_t Count) {
+    size_t Size = Count * sizeof(T);
+    assert(Head && Head->Buf);
+
+    size_t P = (size_t)Head->Buf + Head->Used;
+    uintptr_t AlignedP =
+        (((size_t)P + alignof(T) - 1) & ~(size_t)(alignof(T) - 1));
+    uint8_t *PP = (uint8_t *)AlignedP;
+    size_t Adjustment = AlignedP - P;
+
+    Head->Used += Size + Adjustment;
+    if (Head->Used <= Head->Capacity)
+      return new (PP) T[Count]();
+
+    addNode(std::max(AllocUnit, Size));
+    Head->Used = Size;
+    return new (Head->Buf) T[Count]();
+  }
+
+  template <typename T, typename... Args> T *alloc(Args &&... ConstructorArgs) {
+    constexpr size_t Size = sizeof(T);
+    assert(Head && Head->Buf);
+
+    size_t P = (size_t)Head->Buf + Head->Used;
+    uintptr_t AlignedP =
+        (((size_t)P + alignof(T) - 1) & ~(size_t)(alignof(T) - 1));
+    uint8_t *PP = (uint8_t *)AlignedP;
+    size_t Adjustment = AlignedP - P;
+
+    Head->Used += Size + Adjustment;
+    if (Head->Used <= Head->Capacity)
+      return new (PP) T(std::forward<Args>(ConstructorArgs)...);
+
+    static_assert(Size < AllocUnit);
+    addNode(AllocUnit);
+    Head->Used = Size;
+    return new (Head->Buf) T(std::forward<Args>(ConstructorArgs)...);
+  }
+
+private:
+  AllocatorNode *Head = nullptr;
+};
+
+struct BackrefContext {
+  static constexpr size_t Max = 10;
+
+  TypeNode *FunctionParams[Max];
+  size_t FunctionParamCount = 0;
+
+  // The first 10 BackReferences in a mangled name can be back-referenced by
+  // special name @[0-9]. This is a storage for the first 10 BackReferences.
+  NamedIdentifierNode *Names[Max];
+  size_t NamesCount = 0;
+};
+
+enum class QualifierMangleMode { Drop, Mangle, Result };
+
+enum NameBackrefBehavior : uint8_t {
+  NBB_None = 0,          // don't save any names as backrefs.
+  NBB_Template = 1 << 0, // save template instanations.
+  NBB_Simple = 1 << 1,   // save simple names.
+};
+
+enum class FunctionIdentifierCodeGroup { Basic, Under, DoubleUnder };
+
+// Demangler class takes the main role in demangling symbols.
+// It has a set of functions to parse mangled symbols into Type instances.
+// It also has a set of functions to convert Type instances to strings.
+class Demangler {
+public:
+  Demangler() = default;
+  virtual ~Demangler() = default;
+
+  // You are supposed to call parse() first and then check if error is true.  If
+  // it is false, call output() to write the formatted name to the given stream.
+  SymbolNode *parse(StringView &MangledName);
+
+  TagTypeNode *parseTagUniqueName(StringView &MangledName);
+
+  // True if an error occurred.
+  bool Error = false;
+
+  void dumpBackReferences();
+
+private:
+  SymbolNode *demangleEncodedSymbol(StringView &MangledName,
+                                    QualifiedNameNode *QN);
+  SymbolNode *demangleDeclarator(StringView &MangledName);
+  SymbolNode *demangleMD5Name(StringView &MangledName);
+  SymbolNode *demangleTypeinfoName(StringView &MangledName);
+
+  VariableSymbolNode *demangleVariableEncoding(StringView &MangledName,
+                                               StorageClass SC);
+  FunctionSymbolNode *demangleFunctionEncoding(StringView &MangledName);
+
+  Qualifiers demanglePointerExtQualifiers(StringView &MangledName);
+
+  // Parser functions. This is a recursive-descent parser.
+  TypeNode *demangleType(StringView &MangledName, QualifierMangleMode QMM);
+  PrimitiveTypeNode *demanglePrimitiveType(StringView &MangledName);
+  CustomTypeNode *demangleCustomType(StringView &MangledName);
+  TagTypeNode *demangleClassType(StringView &MangledName);
+  PointerTypeNode *demanglePointerType(StringView &MangledName);
+  PointerTypeNode *demangleMemberPointerType(StringView &MangledName);
+  FunctionSignatureNode *demangleFunctionType(StringView &MangledName,
+                                              bool HasThisQuals);
+
+  ArrayTypeNode *demangleArrayType(StringView &MangledName);
+
+  NodeArrayNode *demangleFunctionParameterList(StringView &MangledName,
+                                               bool &IsVariadic);
+  NodeArrayNode *demangleTemplateParameterList(StringView &MangledName);
+
+  std::pair<uint64_t, bool> demangleNumber(StringView &MangledName);
+  uint64_t demangleUnsigned(StringView &MangledName);
+  int64_t demangleSigned(StringView &MangledName);
+
+  void memorizeString(StringView s);
+  void memorizeIdentifier(IdentifierNode *Identifier);
+
+  /// Allocate a copy of \p Borrowed into memory that we own.
+  StringView copyString(StringView Borrowed);
+
+  QualifiedNameNode *demangleFullyQualifiedTypeName(StringView &MangledName);
+  QualifiedNameNode *demangleFullyQualifiedSymbolName(StringView &MangledName);
+
+  IdentifierNode *demangleUnqualifiedTypeName(StringView &MangledName,
+                                              bool Memorize);
+  IdentifierNode *demangleUnqualifiedSymbolName(StringView &MangledName,
+                                                NameBackrefBehavior NBB);
+
+  QualifiedNameNode *demangleNameScopeChain(StringView &MangledName,
+                                            IdentifierNode *UnqualifiedName);
+  IdentifierNode *demangleNameScopePiece(StringView &MangledName);
+
+  NamedIdentifierNode *demangleBackRefName(StringView &MangledName);
+  IdentifierNode *demangleTemplateInstantiationName(StringView &MangledName,
+                                                    NameBackrefBehavior NBB);
+  IntrinsicFunctionKind
+  translateIntrinsicFunctionCode(char CH, FunctionIdentifierCodeGroup Group);
+  IdentifierNode *demangleFunctionIdentifierCode(StringView &MangledName);
+  IdentifierNode *
+  demangleFunctionIdentifierCode(StringView &MangledName,
+                                 FunctionIdentifierCodeGroup Group);
+  StructorIdentifierNode *demangleStructorIdentifier(StringView &MangledName,
+                                                     bool IsDestructor);
+  ConversionOperatorIdentifierNode *
+  demangleConversionOperatorIdentifier(StringView &MangledName);
+  LiteralOperatorIdentifierNode *
+  demangleLiteralOperatorIdentifier(StringView &MangledName);
+
+  SymbolNode *demangleSpecialIntrinsic(StringView &MangledName);
+  SpecialTableSymbolNode *
+  demangleSpecialTableSymbolNode(StringView &MangledName,
+                                 SpecialIntrinsicKind SIK);
+  LocalStaticGuardVariableNode *
+  demangleLocalStaticGuard(StringView &MangledName, bool IsThread);
+  VariableSymbolNode *demangleUntypedVariable(ArenaAllocator &Arena,
+                                              StringView &MangledName,
+                                              StringView VariableName);
+  VariableSymbolNode *
+  demangleRttiBaseClassDescriptorNode(ArenaAllocator &Arena,
+                                      StringView &MangledName);
+  FunctionSymbolNode *demangleInitFiniStub(StringView &MangledName,
+                                           bool IsDestructor);
+
+  NamedIdentifierNode *demangleSimpleName(StringView &MangledName,
+                                          bool Memorize);
+  NamedIdentifierNode *demangleAnonymousNamespaceName(StringView &MangledName);
+  NamedIdentifierNode *demangleLocallyScopedNamePiece(StringView &MangledName);
+  EncodedStringLiteralNode *demangleStringLiteral(StringView &MangledName);
+  FunctionSymbolNode *demangleVcallThunkNode(StringView &MangledName);
+
+  StringView demangleSimpleString(StringView &MangledName, bool Memorize);
+
+  FuncClass demangleFunctionClass(StringView &MangledName);
+  CallingConv demangleCallingConvention(StringView &MangledName);
+  StorageClass demangleVariableStorageClass(StringView &MangledName);
+  bool demangleThrowSpecification(StringView &MangledName);
+  wchar_t demangleWcharLiteral(StringView &MangledName);
+  uint8_t demangleCharLiteral(StringView &MangledName);
+
+  std::pair<Qualifiers, bool> demangleQualifiers(StringView &MangledName);
+
+  // Memory allocator.
+  ArenaAllocator Arena;
+
+  // A single type uses one global back-ref table for all function params.
+  // This means back-refs can even go "into" other types.  Examples:
+  //
+  //  // Second int* is a back-ref to first.
+  //  void foo(int *, int*);
+  //
+  //  // Second int* is not a back-ref to first (first is not a function param).
+  //  int* foo(int*);
+  //
+  //  // Second int* is a back-ref to first (ALL function types share the same
+  //  // back-ref map.
+  //  using F = void(*)(int*);
+  //  F G(int *);
+  BackrefContext Backrefs;
+};
+
+} // namespace ms_demangle
+} // namespace llvm
+
+#endif // LLVM_DEMANGLE_MICROSOFTDEMANGLE_H
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/MicrosoftDemangleNodes.h b/demangle/third_party/llvm/include/llvm/Demangle/MicrosoftDemangleNodes.h
new file mode 100644
index 00000000..8ad24723
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/MicrosoftDemangleNodes.h
@@ -0,0 +1,629 @@
+//===- MicrosoftDemangleNodes.h ---------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the AST nodes used in the MSVC demangler.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_MICROSOFTDEMANGLENODES_H
+#define LLVM_DEMANGLE_MICROSOFTDEMANGLENODES_H
+
+#include "llvm/Demangle/StringView.h"
+#include <array>
+#include <cstdint>
+#include <string>
+
+namespace llvm {
+namespace itanium_demangle {
+class OutputBuffer;
+}
+}
+
+using llvm::itanium_demangle::OutputBuffer;
+using llvm::itanium_demangle::StringView;
+
+namespace llvm {
+namespace ms_demangle {
+
+// Storage classes
+enum Qualifiers : uint8_t {
+  Q_None = 0,
+  Q_Const = 1 << 0,
+  Q_Volatile = 1 << 1,
+  Q_Far = 1 << 2,
+  Q_Huge = 1 << 3,
+  Q_Unaligned = 1 << 4,
+  Q_Restrict = 1 << 5,
+  Q_Pointer64 = 1 << 6
+};
+
+enum class StorageClass : uint8_t {
+  None,
+  PrivateStatic,
+  ProtectedStatic,
+  PublicStatic,
+  Global,
+  FunctionLocalStatic,
+};
+
+enum class PointerAffinity { None, Pointer, Reference, RValueReference };
+enum class FunctionRefQualifier { None, Reference, RValueReference };
+
+// Calling conventions
+enum class CallingConv : uint8_t {
+  None,
+  Cdecl,
+  Pascal,
+  Thiscall,
+  Stdcall,
+  Fastcall,
+  Clrcall,
+  Eabi,
+  Vectorcall,
+  Regcall,
+  Swift,      // Clang-only
+  SwiftAsync, // Clang-only
+};
+
+enum class ReferenceKind : uint8_t { None, LValueRef, RValueRef };
+
+enum OutputFlags {
+  OF_Default = 0,
+  OF_NoCallingConvention = 1,
+  OF_NoTagSpecifier = 2,
+  OF_NoAccessSpecifier = 4,
+  OF_NoMemberType = 8,
+  OF_NoReturnType = 16,
+  OF_NoVariableType = 32,
+};
+
+// Types
+enum class PrimitiveKind {
+  Void,
+  Bool,
+  Char,
+  Schar,
+  Uchar,
+  Char8,
+  Char16,
+  Char32,
+  Short,
+  Ushort,
+  Int,
+  Uint,
+  Long,
+  Ulong,
+  Int64,
+  Uint64,
+  Wchar,
+  Float,
+  Double,
+  Ldouble,
+  Nullptr,
+};
+
+enum class CharKind {
+  Char,
+  Char16,
+  Char32,
+  Wchar,
+};
+
+enum class IntrinsicFunctionKind : uint8_t {
+  None,
+  New,                        // ?2 # operator new
+  Delete,                     // ?3 # operator delete
+  Assign,                     // ?4 # operator=
+  RightShift,                 // ?5 # operator>>
+  LeftShift,                  // ?6 # operator<<
+  LogicalNot,                 // ?7 # operator!
+  Equals,                     // ?8 # operator==
+  NotEquals,                  // ?9 # operator!=
+  ArraySubscript,             // ?A # operator[]
+  Pointer,                    // ?C # operator->
+  Dereference,                // ?D # operator*
+  Increment,                  // ?E # operator++
+  Decrement,                  // ?F # operator--
+  Minus,                      // ?G # operator-
+  Plus,                       // ?H # operator+
+  BitwiseAnd,                 // ?I # operator&
+  MemberPointer,              // ?J # operator->*
+  Divide,                     // ?K # operator/
+  Modulus,                    // ?L # operator%
+  LessThan,                   // ?M operator<
+  LessThanEqual,              // ?N operator<=
+  GreaterThan,                // ?O operator>
+  GreaterThanEqual,           // ?P operator>=
+  Comma,                      // ?Q operator,
+  Parens,                     // ?R operator()
+  BitwiseNot,                 // ?S operator~
+  BitwiseXor,                 // ?T operator^
+  BitwiseOr,                  // ?U operator|
+  LogicalAnd,                 // ?V operator&&
+  LogicalOr,                  // ?W operator||
+  TimesEqual,                 // ?X operator*=
+  PlusEqual,                  // ?Y operator+=
+  MinusEqual,                 // ?Z operator-=
+  DivEqual,                   // ?_0 operator/=
+  ModEqual,                   // ?_1 operator%=
+  RshEqual,                   // ?_2 operator>>=
+  LshEqual,                   // ?_3 operator<<=
+  BitwiseAndEqual,            // ?_4 operator&=
+  BitwiseOrEqual,             // ?_5 operator|=
+  BitwiseXorEqual,            // ?_6 operator^=
+  VbaseDtor,                  // ?_D # vbase destructor
+  VecDelDtor,                 // ?_E # vector deleting destructor
+  DefaultCtorClosure,         // ?_F # default constructor closure
+  ScalarDelDtor,              // ?_G # scalar deleting destructor
+  VecCtorIter,                // ?_H # vector constructor iterator
+  VecDtorIter,                // ?_I # vector destructor iterator
+  VecVbaseCtorIter,           // ?_J # vector vbase constructor iterator
+  VdispMap,                   // ?_K # virtual displacement map
+  EHVecCtorIter,              // ?_L # eh vector constructor iterator
+  EHVecDtorIter,              // ?_M # eh vector destructor iterator
+  EHVecVbaseCtorIter,         // ?_N # eh vector vbase constructor iterator
+  CopyCtorClosure,            // ?_O # copy constructor closure
+  LocalVftableCtorClosure,    // ?_T # local vftable constructor closure
+  ArrayNew,                   // ?_U operator new[]
+  ArrayDelete,                // ?_V operator delete[]
+  ManVectorCtorIter,          // ?__A managed vector ctor iterator
+  ManVectorDtorIter,          // ?__B managed vector dtor iterator
+  EHVectorCopyCtorIter,       // ?__C EH vector copy ctor iterator
+  EHVectorVbaseCopyCtorIter,  // ?__D EH vector vbase copy ctor iterator
+  VectorCopyCtorIter,         // ?__G vector copy constructor iterator
+  VectorVbaseCopyCtorIter,    // ?__H vector vbase copy constructor iterator
+  ManVectorVbaseCopyCtorIter, // ?__I managed vector vbase copy constructor
+  CoAwait,                    // ?__L operator co_await
+  Spaceship,                  // ?__M operator<=>
+  MaxIntrinsic
+};
+
+enum class SpecialIntrinsicKind {
+  None,
+  Vftable,
+  Vbtable,
+  Typeof,
+  VcallThunk,
+  LocalStaticGuard,
+  StringLiteralSymbol,
+  UdtReturning,
+  Unknown,
+  DynamicInitializer,
+  DynamicAtexitDestructor,
+  RttiTypeDescriptor,
+  RttiBaseClassDescriptor,
+  RttiBaseClassArray,
+  RttiClassHierarchyDescriptor,
+  RttiCompleteObjLocator,
+  LocalVftable,
+  LocalStaticThreadGuard,
+};
+
+// Function classes
+enum FuncClass : uint16_t {
+  FC_None = 0,
+  FC_Public = 1 << 0,
+  FC_Protected = 1 << 1,
+  FC_Private = 1 << 2,
+  FC_Global = 1 << 3,
+  FC_Static = 1 << 4,
+  FC_Virtual = 1 << 5,
+  FC_Far = 1 << 6,
+  FC_ExternC = 1 << 7,
+  FC_NoParameterList = 1 << 8,
+  FC_VirtualThisAdjust = 1 << 9,
+  FC_VirtualThisAdjustEx = 1 << 10,
+  FC_StaticThisAdjust = 1 << 11,
+};
+
+enum class TagKind { Class, Struct, Union, Enum };
+
+enum class NodeKind {
+  Unknown,
+  Md5Symbol,
+  PrimitiveType,
+  FunctionSignature,
+  Identifier,
+  NamedIdentifier,
+  VcallThunkIdentifier,
+  LocalStaticGuardIdentifier,
+  IntrinsicFunctionIdentifier,
+  ConversionOperatorIdentifier,
+  DynamicStructorIdentifier,
+  StructorIdentifier,
+  LiteralOperatorIdentifier,
+  ThunkSignature,
+  PointerType,
+  TagType,
+  ArrayType,
+  Custom,
+  IntrinsicType,
+  NodeArray,
+  QualifiedName,
+  TemplateParameterReference,
+  EncodedStringLiteral,
+  IntegerLiteral,
+  RttiBaseClassDescriptor,
+  LocalStaticGuardVariable,
+  FunctionSymbol,
+  VariableSymbol,
+  SpecialTableSymbol
+};
+
+struct Node {
+  explicit Node(NodeKind K) : Kind(K) {}
+  virtual ~Node() = default;
+
+  NodeKind kind() const { return Kind; }
+
+  virtual void output(OutputBuffer &OB, OutputFlags Flags) const = 0;
+
+  std::string toString(OutputFlags Flags = OF_Default) const;
+
+private:
+  NodeKind Kind;
+};
+
+struct TypeNode;
+struct PrimitiveTypeNode;
+struct FunctionSignatureNode;
+struct IdentifierNode;
+struct NamedIdentifierNode;
+struct VcallThunkIdentifierNode;
+struct IntrinsicFunctionIdentifierNode;
+struct LiteralOperatorIdentifierNode;
+struct ConversionOperatorIdentifierNode;
+struct StructorIdentifierNode;
+struct ThunkSignatureNode;
+struct PointerTypeNode;
+struct ArrayTypeNode;
+struct TagTypeNode;
+struct NodeArrayNode;
+struct QualifiedNameNode;
+struct TemplateParameterReferenceNode;
+struct EncodedStringLiteralNode;
+struct IntegerLiteralNode;
+struct RttiBaseClassDescriptorNode;
+struct LocalStaticGuardVariableNode;
+struct SymbolNode;
+struct FunctionSymbolNode;
+struct VariableSymbolNode;
+struct SpecialTableSymbolNode;
+
+struct TypeNode : public Node {
+  explicit TypeNode(NodeKind K) : Node(K) {}
+
+  virtual void outputPre(OutputBuffer &OB, OutputFlags Flags) const = 0;
+  virtual void outputPost(OutputBuffer &OB, OutputFlags Flags) const = 0;
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override {
+    outputPre(OB, Flags);
+    outputPost(OB, Flags);
+  }
+
+  Qualifiers Quals = Q_None;
+};
+
+struct PrimitiveTypeNode : public TypeNode {
+  explicit PrimitiveTypeNode(PrimitiveKind K)
+      : TypeNode(NodeKind::PrimitiveType), PrimKind(K) {}
+
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override {}
+
+  PrimitiveKind PrimKind;
+};
+
+struct FunctionSignatureNode : public TypeNode {
+  explicit FunctionSignatureNode(NodeKind K) : TypeNode(K) {}
+  FunctionSignatureNode() : TypeNode(NodeKind::FunctionSignature) {}
+
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  // Valid if this FunctionTypeNode is the Pointee of a PointerType or
+  // MemberPointerType.
+  PointerAffinity Affinity = PointerAffinity::None;
+
+  // The function's calling convention.
+  CallingConv CallConvention = CallingConv::None;
+
+  // Function flags (gloabl, public, etc)
+  FuncClass FunctionClass = FC_Global;
+
+  FunctionRefQualifier RefQualifier = FunctionRefQualifier::None;
+
+  // The return type of the function.
+  TypeNode *ReturnType = nullptr;
+
+  // True if this is a C-style ... varargs function.
+  bool IsVariadic = false;
+
+  // Function parameters
+  NodeArrayNode *Params = nullptr;
+
+  // True if the function type is noexcept.
+  bool IsNoexcept = false;
+};
+
+struct IdentifierNode : public Node {
+  explicit IdentifierNode(NodeKind K) : Node(K) {}
+
+  NodeArrayNode *TemplateParams = nullptr;
+
+protected:
+  void outputTemplateParameters(OutputBuffer &OB, OutputFlags Flags) const;
+};
+
+struct VcallThunkIdentifierNode : public IdentifierNode {
+  VcallThunkIdentifierNode() : IdentifierNode(NodeKind::VcallThunkIdentifier) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  uint64_t OffsetInVTable = 0;
+};
+
+struct DynamicStructorIdentifierNode : public IdentifierNode {
+  DynamicStructorIdentifierNode()
+      : IdentifierNode(NodeKind::DynamicStructorIdentifier) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  VariableSymbolNode *Variable = nullptr;
+  QualifiedNameNode *Name = nullptr;
+  bool IsDestructor = false;
+};
+
+struct NamedIdentifierNode : public IdentifierNode {
+  NamedIdentifierNode() : IdentifierNode(NodeKind::NamedIdentifier) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  StringView Name;
+};
+
+struct IntrinsicFunctionIdentifierNode : public IdentifierNode {
+  explicit IntrinsicFunctionIdentifierNode(IntrinsicFunctionKind Operator)
+      : IdentifierNode(NodeKind::IntrinsicFunctionIdentifier),
+        Operator(Operator) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  IntrinsicFunctionKind Operator;
+};
+
+struct LiteralOperatorIdentifierNode : public IdentifierNode {
+  LiteralOperatorIdentifierNode()
+      : IdentifierNode(NodeKind::LiteralOperatorIdentifier) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  StringView Name;
+};
+
+struct LocalStaticGuardIdentifierNode : public IdentifierNode {
+  LocalStaticGuardIdentifierNode()
+      : IdentifierNode(NodeKind::LocalStaticGuardIdentifier) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  bool IsThread = false;
+  uint32_t ScopeIndex = 0;
+};
+
+struct ConversionOperatorIdentifierNode : public IdentifierNode {
+  ConversionOperatorIdentifierNode()
+      : IdentifierNode(NodeKind::ConversionOperatorIdentifier) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  // The type that this operator converts too.
+  TypeNode *TargetType = nullptr;
+};
+
+struct StructorIdentifierNode : public IdentifierNode {
+  StructorIdentifierNode() : IdentifierNode(NodeKind::StructorIdentifier) {}
+  explicit StructorIdentifierNode(bool IsDestructor)
+      : IdentifierNode(NodeKind::StructorIdentifier),
+        IsDestructor(IsDestructor) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  // The name of the class that this is a structor of.
+  IdentifierNode *Class = nullptr;
+  bool IsDestructor = false;
+};
+
+struct ThunkSignatureNode : public FunctionSignatureNode {
+  ThunkSignatureNode() : FunctionSignatureNode(NodeKind::ThunkSignature) {}
+
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  struct ThisAdjustor {
+    uint32_t StaticOffset = 0;
+    int32_t VBPtrOffset = 0;
+    int32_t VBOffsetOffset = 0;
+    int32_t VtordispOffset = 0;
+  };
+
+  ThisAdjustor ThisAdjust;
+};
+
+struct PointerTypeNode : public TypeNode {
+  PointerTypeNode() : TypeNode(NodeKind::PointerType) {}
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  // Is this a pointer, reference, or rvalue-reference?
+  PointerAffinity Affinity = PointerAffinity::None;
+
+  // If this is a member pointer, this is the class that the member is in.
+  QualifiedNameNode *ClassParent = nullptr;
+
+  // Represents a type X in "a pointer to X", "a reference to X", or
+  // "rvalue-reference to X"
+  TypeNode *Pointee = nullptr;
+};
+
+struct TagTypeNode : public TypeNode {
+  explicit TagTypeNode(TagKind Tag) : TypeNode(NodeKind::TagType), Tag(Tag) {}
+
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  QualifiedNameNode *QualifiedName = nullptr;
+  TagKind Tag;
+};
+
+struct ArrayTypeNode : public TypeNode {
+  ArrayTypeNode() : TypeNode(NodeKind::ArrayType) {}
+
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  void outputDimensionsImpl(OutputBuffer &OB, OutputFlags Flags) const;
+  void outputOneDimension(OutputBuffer &OB, OutputFlags Flags, Node *N) const;
+
+  // A list of array dimensions.  e.g. [3,4,5] in `int Foo[3][4][5]`
+  NodeArrayNode *Dimensions = nullptr;
+
+  // The type of array element.
+  TypeNode *ElementType = nullptr;
+};
+
+struct IntrinsicNode : public TypeNode {
+  IntrinsicNode() : TypeNode(NodeKind::IntrinsicType) {}
+  void output(OutputBuffer &OB, OutputFlags Flags) const override {}
+};
+
+struct CustomTypeNode : public TypeNode {
+  CustomTypeNode() : TypeNode(NodeKind::Custom) {}
+
+  void outputPre(OutputBuffer &OB, OutputFlags Flags) const override;
+  void outputPost(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  IdentifierNode *Identifier = nullptr;
+};
+
+struct NodeArrayNode : public Node {
+  NodeArrayNode() : Node(NodeKind::NodeArray) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  void output(OutputBuffer &OB, OutputFlags Flags, StringView Separator) const;
+
+  Node **Nodes = nullptr;
+  size_t Count = 0;
+};
+
+struct QualifiedNameNode : public Node {
+  QualifiedNameNode() : Node(NodeKind::QualifiedName) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  NodeArrayNode *Components = nullptr;
+
+  IdentifierNode *getUnqualifiedIdentifier() {
+    Node *LastComponent = Components->Nodes[Components->Count - 1];
+    return static_cast<IdentifierNode *>(LastComponent);
+  }
+};
+
+struct TemplateParameterReferenceNode : public Node {
+  TemplateParameterReferenceNode()
+      : Node(NodeKind::TemplateParameterReference) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  SymbolNode *Symbol = nullptr;
+
+  int ThunkOffsetCount = 0;
+  std::array<int64_t, 3> ThunkOffsets;
+  PointerAffinity Affinity = PointerAffinity::None;
+  bool IsMemberPointer = false;
+};
+
+struct IntegerLiteralNode : public Node {
+  IntegerLiteralNode() : Node(NodeKind::IntegerLiteral) {}
+  IntegerLiteralNode(uint64_t Value, bool IsNegative)
+      : Node(NodeKind::IntegerLiteral), Value(Value), IsNegative(IsNegative) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  uint64_t Value = 0;
+  bool IsNegative = false;
+};
+
+struct RttiBaseClassDescriptorNode : public IdentifierNode {
+  RttiBaseClassDescriptorNode()
+      : IdentifierNode(NodeKind::RttiBaseClassDescriptor) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  uint32_t NVOffset = 0;
+  int32_t VBPtrOffset = 0;
+  uint32_t VBTableOffset = 0;
+  uint32_t Flags = 0;
+};
+
+struct SymbolNode : public Node {
+  explicit SymbolNode(NodeKind K) : Node(K) {}
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+  QualifiedNameNode *Name = nullptr;
+};
+
+struct SpecialTableSymbolNode : public SymbolNode {
+  explicit SpecialTableSymbolNode()
+      : SymbolNode(NodeKind::SpecialTableSymbol) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+  QualifiedNameNode *TargetName = nullptr;
+  Qualifiers Quals = Qualifiers::Q_None;
+};
+
+struct LocalStaticGuardVariableNode : public SymbolNode {
+  LocalStaticGuardVariableNode()
+      : SymbolNode(NodeKind::LocalStaticGuardVariable) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  bool IsVisible = false;
+};
+
+struct EncodedStringLiteralNode : public SymbolNode {
+  EncodedStringLiteralNode() : SymbolNode(NodeKind::EncodedStringLiteral) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  StringView DecodedString;
+  bool IsTruncated = false;
+  CharKind Char = CharKind::Char;
+};
+
+struct VariableSymbolNode : public SymbolNode {
+  VariableSymbolNode() : SymbolNode(NodeKind::VariableSymbol) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  StorageClass SC = StorageClass::None;
+  TypeNode *Type = nullptr;
+};
+
+struct FunctionSymbolNode : public SymbolNode {
+  FunctionSymbolNode() : SymbolNode(NodeKind::FunctionSymbol) {}
+
+  void output(OutputBuffer &OB, OutputFlags Flags) const override;
+
+  FunctionSignatureNode *Signature = nullptr;
+};
+
+} // namespace ms_demangle
+} // namespace llvm
+
+#endif
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/StringView.h b/demangle/third_party/llvm/include/llvm/Demangle/StringView.h
new file mode 100644
index 00000000..6bbb8837
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/StringView.h
@@ -0,0 +1,122 @@
+//===--- StringView.h ----------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// FIXME: Use std::string_view instead when we support C++17.
+// There are two copies of this file in the source tree.  The one under
+// libcxxabi is the original and the one under llvm is the copy.  Use
+// cp-to-llvm.sh to update the copy.  See README.txt for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_STRINGVIEW_H
+#define DEMANGLE_STRINGVIEW_H
+
+#include "DemangleConfig.h"
+#include <cassert>
+#include <cstring>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+class StringView {
+  const char *First;
+  const char *Last;
+
+public:
+  static const size_t npos = ~size_t(0);
+
+  template <size_t N>
+  StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
+  StringView(const char *First_, const char *Last_)
+      : First(First_), Last(Last_) {}
+  StringView(const char *First_, size_t Len)
+      : First(First_), Last(First_ + Len) {}
+  StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
+  StringView() : First(nullptr), Last(nullptr) {}
+
+  StringView substr(size_t Pos, size_t Len = npos) const {
+    assert(Pos <= size());
+    if (Len > size() - Pos)
+      Len = size() - Pos;
+    return StringView(begin() + Pos, Len);
+  }
+
+  size_t find(char C, size_t From = 0) const {
+    // Avoid calling memchr with nullptr.
+    if (From < size()) {
+      // Just forward to memchr, which is faster than a hand-rolled loop.
+      if (const void *P = ::memchr(First + From, C, size() - From))
+        return size_t(static_cast<const char *>(P) - First);
+    }
+    return npos;
+  }
+
+  StringView dropFront(size_t N = 1) const {
+    if (N >= size())
+      N = size();
+    return StringView(First + N, Last);
+  }
+
+  StringView dropBack(size_t N = 1) const {
+    if (N >= size())
+      N = size();
+    return StringView(First, Last - N);
+  }
+
+  char front() const {
+    assert(!empty());
+    return *begin();
+  }
+
+  char back() const {
+    assert(!empty());
+    return *(end() - 1);
+  }
+
+  char popFront() {
+    assert(!empty());
+    return *First++;
+  }
+
+  bool consumeFront(char C) {
+    if (!startsWith(C))
+      return false;
+    *this = dropFront(1);
+    return true;
+  }
+
+  bool consumeFront(StringView S) {
+    if (!startsWith(S))
+      return false;
+    *this = dropFront(S.size());
+    return true;
+  }
+
+  bool startsWith(char C) const { return !empty() && *begin() == C; }
+
+  bool startsWith(StringView Str) const {
+    if (Str.size() > size())
+      return false;
+    return std::strncmp(Str.begin(), begin(), Str.size()) == 0;
+  }
+
+  const char &operator[](size_t Idx) const { return *(begin() + Idx); }
+
+  const char *begin() const { return First; }
+  const char *end() const { return Last; }
+  size_t size() const { return static_cast<size_t>(Last - First); }
+  bool empty() const { return First == Last; }
+};
+
+inline bool operator==(const StringView &LHS, const StringView &RHS) {
+  return LHS.size() == RHS.size() &&
+         std::strncmp(LHS.begin(), RHS.begin(), LHS.size()) == 0;
+}
+
+DEMANGLE_NAMESPACE_END
+
+#endif
diff --git a/demangle/third_party/llvm/include/llvm/Demangle/Utility.h b/demangle/third_party/llvm/include/llvm/Demangle/Utility.h
new file mode 100644
index 00000000..855c56e9
--- /dev/null
+++ b/demangle/third_party/llvm/include/llvm/Demangle/Utility.h
@@ -0,0 +1,199 @@
+//===--- Utility.h -------------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Provide some utility classes for use in the demangler.
+// There are two copies of this file in the source tree.  The one in libcxxabi
+// is the original and the one in llvm is the copy.  Use cp-to-llvm.sh to update
+// the copy.  See README.txt for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_UTILITY_H
+#define DEMANGLE_UTILITY_H
+
+#include "StringView.h"
+#include <array>
+#include <cstdint>
+#include <cstdlib>
+#include <cstring>
+#include <exception>
+#include <limits>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+// Stream that AST nodes write their string representation into after the AST
+// has been parsed.
+class OutputBuffer {
+  char *Buffer = nullptr;
+  size_t CurrentPosition = 0;
+  size_t BufferCapacity = 0;
+
+  // Ensure there are at least N more positions in the buffer.
+  void grow(size_t N) {
+    size_t Need = N + CurrentPosition;
+    if (Need > BufferCapacity) {
+      // Reduce the number of reallocations, with a bit of hysteresis. The
+      // number here is chosen so the first allocation will more-than-likely not
+      // allocate more than 1K.
+      Need += 1024 - 32;
+      BufferCapacity *= 2;
+      if (BufferCapacity < Need)
+        BufferCapacity = Need;
+      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
+      if (Buffer == nullptr)
+        std::terminate();
+    }
+  }
+
+  OutputBuffer &writeUnsigned(uint64_t N, bool isNeg = false) {
+    std::array<char, 21> Temp;
+    char *TempPtr = Temp.data() + Temp.size();
+
+    // Output at least one character.
+    do {
+      *--TempPtr = char('0' + N % 10);
+      N /= 10;
+    } while (N);
+
+    // Add negative sign.
+    if (isNeg)
+      *--TempPtr = '-';
+
+    return operator+=(StringView(TempPtr, Temp.data() + Temp.size()));
+  }
+
+public:
+  OutputBuffer(char *StartBuf, size_t Size)
+      : Buffer(StartBuf), BufferCapacity(Size) {}
+  OutputBuffer(char *StartBuf, size_t *SizePtr)
+      : OutputBuffer(StartBuf, StartBuf ? *SizePtr : 0) {}
+  OutputBuffer() = default;
+  // Non-copyable
+  OutputBuffer(const OutputBuffer &) = delete;
+  OutputBuffer &operator=(const OutputBuffer &) = delete;
+
+  operator StringView() const { return StringView(Buffer, CurrentPosition); }
+
+  /// If a ParameterPackExpansion (or similar type) is encountered, the offset
+  /// into the pack that we're currently printing.
+  unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max();
+  unsigned CurrentPackMax = std::numeric_limits<unsigned>::max();
+
+  /// When zero, we're printing template args and '>' needs to be parenthesized.
+  /// Use a counter so we can simply increment inside parentheses.
+  unsigned GtIsGt = 1;
+
+  bool isGtInsideTemplateArgs() const { return GtIsGt == 0; }
+
+  void printOpen(char Open = '(') {
+    GtIsGt++;
+    *this += Open;
+  }
+  void printClose(char Close = ')') {
+    GtIsGt--;
+    *this += Close;
+  }
+
+  OutputBuffer &operator+=(StringView R) {
+    if (size_t Size = R.size()) {
+      grow(Size);
+      std::memcpy(Buffer + CurrentPosition, R.begin(), Size);
+      CurrentPosition += Size;
+    }
+    return *this;
+  }
+
+  OutputBuffer &operator+=(char C) {
+    grow(1);
+    Buffer[CurrentPosition++] = C;
+    return *this;
+  }
+
+  OutputBuffer &prepend(StringView R) {
+    size_t Size = R.size();
+
+    grow(Size);
+    std::memmove(Buffer + Size, Buffer, CurrentPosition);
+    std::memcpy(Buffer, R.begin(), Size);
+    CurrentPosition += Size;
+
+    return *this;
+  }
+
+  OutputBuffer &operator<<(StringView R) { return (*this += R); }
+
+  OutputBuffer &operator<<(char C) { return (*this += C); }
+
+  OutputBuffer &operator<<(long long N) {
+    return writeUnsigned(static_cast<unsigned long long>(std::abs(N)), N < 0);
+  }
+
+  OutputBuffer &operator<<(unsigned long long N) {
+    return writeUnsigned(N, false);
+  }
+
+  OutputBuffer &operator<<(long N) {
+    return this->operator<<(static_cast<long long>(N));
+  }
+
+  OutputBuffer &operator<<(unsigned long N) {
+    return this->operator<<(static_cast<unsigned long long>(N));
+  }
+
+  OutputBuffer &operator<<(int N) {
+    return this->operator<<(static_cast<long long>(N));
+  }
+
+  OutputBuffer &operator<<(unsigned int N) {
+    return this->operator<<(static_cast<unsigned long long>(N));
+  }
+
+  void insert(size_t Pos, const char *S, size_t N) {
+    assert(Pos <= CurrentPosition);
+    if (N == 0)
+      return;
+    grow(N);
+    std::memmove(Buffer + Pos + N, Buffer + Pos, CurrentPosition - Pos);
+    std::memcpy(Buffer + Pos, S, N);
+    CurrentPosition += N;
+  }
+
+  size_t getCurrentPosition() const { return CurrentPosition; }
+  void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; }
+
+  char back() const {
+    assert(CurrentPosition);
+    return Buffer[CurrentPosition - 1];
+  }
+
+  bool empty() const { return CurrentPosition == 0; }
+
+  char *getBuffer() { return Buffer; }
+  char *getBufferEnd() { return Buffer + CurrentPosition - 1; }
+  size_t getBufferCapacity() const { return BufferCapacity; }
+};
+
+template <class T> class ScopedOverride {
+  T &Loc;
+  T Original;
+
+public:
+  ScopedOverride(T &Loc_) : ScopedOverride(Loc_, Loc_) {}
+
+  ScopedOverride(T &Loc_, T NewVal) : Loc(Loc_), Original(Loc_) {
+    Loc_ = std::move(NewVal);
+  }
+  ~ScopedOverride() { Loc = std::move(Original); }
+
+  ScopedOverride(const ScopedOverride &) = delete;
+  ScopedOverride &operator=(const ScopedOverride &) = delete;
+};
+
+DEMANGLE_NAMESPACE_END
+
+#endif