From 8f62c3329948f3bd1aa5dc208ab5efac42543a57 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Tue, 16 Jul 2024 15:08:07 +0200
Subject: wa

---
 compat/borrowed-ptr.hpp | 36 ++++++++++++++++--------------------
 compat/borrowed-ptr.inl |  5 ++++-
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/compat/borrowed-ptr.hpp b/compat/borrowed-ptr.hpp
index 7ab42ebb..c4cc7975 100644
--- a/compat/borrowed-ptr.hpp
+++ b/compat/borrowed-ptr.hpp
@@ -12,7 +12,17 @@
 #define fm_bptr_assert(...) void()
 #endif
 
-namespace floormat { struct bptr_base; }
+namespace floormat {
+struct bptr_base
+{
+    virtual ~bptr_base() noexcept;
+    bptr_base() noexcept;
+    bptr_base(const bptr_base&) noexcept;
+    bptr_base(bptr_base&&) noexcept;
+    bptr_base& operator=(const bptr_base&) noexcept;
+    bptr_base& operator=(bptr_base&&) noexcept;
+};
+} // namespace floormat
 
 namespace floormat::detail_bptr {
 
@@ -24,7 +34,6 @@ struct control_block final
     static void weak_decrement(control_block*& blk) noexcept;
 };
 
-#if 0
 template<typename From, typename To>
 concept StaticCastable = requires(From* from, To* to) {
     static_cast<To*>(from);
@@ -34,29 +43,13 @@ concept StaticCastable = requires(From* from, To* to) {
 
 template<typename From, typename To>
 concept DerivedFrom = requires(From* from, To* to) {
-    static_cast<const bptr_base*>(from);
-    static_cast<const bptr_base*>(to);
-    requires std::is_convertible_v<From*, To*>;
+    requires std::is_convertible_v<From&, To&>;
 };
-#else
-template<typename From, typename To> concept DerivedFrom = true;
-template<typename From, typename To> concept StaticCastable = true;
-#endif
 
 } // namespace floormat::detail_bptr
 
 namespace floormat {
 
-struct bptr_base
-{
-    virtual ~bptr_base() noexcept;
-    bptr_base() noexcept;
-    bptr_base(const bptr_base&) noexcept;
-    bptr_base(bptr_base&&) noexcept;
-    bptr_base& operator=(const bptr_base&) noexcept;
-    bptr_base& operator=(bptr_base&&) noexcept;
-};
-
 template<typename T>
 class bptr final // NOLINT(*-special-member-functions)
 {
@@ -69,7 +62,7 @@ class bptr final // NOLINT(*-special-member-functions)
 
 public:
     template<typename... Ts>
-    //requires std::is_constructible_v<std::remove_const_t<T>, Ts&&...>
+    requires std::is_constructible_v<std::remove_const_t<T>, Ts&&...>
     explicit bptr(InPlaceInitT, Ts&&... args) noexcept;
 
     template<detail_bptr::DerivedFrom<T> Y> explicit bptr(Y* ptr) noexcept;
@@ -79,6 +72,9 @@ public:
     bptr(std::nullptr_t) noexcept; // NOLINT(*-explicit-conversions)
     bptr& operator=(std::nullptr_t) noexcept;
 
+    bptr(const bptr<std::remove_const_t<T>>& ptr) noexcept requires std::is_const_v<T>;
+    bptr(bptr<std::remove_const_t<T>>&& ptr) noexcept requires std::is_const_v<T>;
+
     bptr(const bptr&) noexcept;
     bptr& operator=(const bptr&) noexcept;
     template<detail_bptr::DerivedFrom<T> Y> bptr(const bptr<Y>&) noexcept;
diff --git a/compat/borrowed-ptr.inl b/compat/borrowed-ptr.inl
index 327bd7cd..dfc112c7 100644
--- a/compat/borrowed-ptr.inl
+++ b/compat/borrowed-ptr.inl
@@ -11,7 +11,7 @@ namespace floormat {
 
 template<typename T>
 template<typename... Ts>
-//requires std::is_constructible_v<std::remove_const_t<T>, Ts&&...>
+requires std::is_constructible_v<std::remove_const_t<T>, Ts&&...>
 bptr<T>::bptr(InPlaceInitT, Ts&&... args) noexcept:
     bptr{ new std::remove_const_t<T>{ forward<Ts>(args)... } }
 {}
@@ -26,6 +26,9 @@ bptr<T>::bptr(Y* ptr) noexcept:
 
 template<typename T> bptr<T>::~bptr() noexcept { if (blk) detail_bptr::control_block::decrement(blk); }
 
+template<typename T> bptr<T>::bptr(const bptr<std::remove_const_t<T>>& ptr) noexcept requires std::is_const_v<T>: bptr{ptr, nullptr} {}
+template<typename T> bptr<T>::bptr(bptr<std::remove_const_t<T>>&& ptr) noexcept requires std::is_const_v<T>: bptr{move(ptr), nullptr} {}
+
 template<typename T> bptr<T>::bptr(const bptr& other) noexcept: bptr{other, nullptr} {}
 template<typename T> bptr<T>::bptr(bptr&& other) noexcept: bptr{move(other), nullptr} {}
 template<typename T> bptr<T>& bptr<T>::operator=(const bptr& other) noexcept { return _copy_assign(other); }
-- 
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