From 793cea587159a0ba01fec6af28e899697ef4da79 Mon Sep 17 00:00:00 2001
From: Stanislaw Halik <sthalik@misaki.pl>
Date: Mon, 9 Jul 2018 05:33:58 +0200
Subject: cleanup only
---
compat/macros.hpp | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
(limited to 'compat')
diff --git a/compat/macros.hpp b/compat/macros.hpp
index 0807df4c..a6f3d0e9 100644
--- a/compat/macros.hpp
+++ b/compat/macros.hpp
@@ -40,17 +40,26 @@
# define PP_CAT2(x,y) x ## y
#endif
+#ifndef PP_EXPAND
+# define PP_EXPAND(x) PP_EXPAND__2(x)
+# define PP_EXPAND__2(x) PP_EXPAND__3(x) x
+# define PP_EXPAND__3(x) x
+#endif
+
#if defined __cplusplus
// from now only C++
#include <utility>
-//#define once_only(...) do { static bool once__ = false; if (!once__) { once__ = true; __VA_ARGS__; } } while(false)
-//#define once_only(expr) ([&] { static decltype(auto) ret___1132 = (expr); return (decltype(ret___1132) const&) ret___1132; }())
+// causes ICE in Visual Studio 2017 Preview. the ICE was reported and they handle them seriously in due time.
+// the ICE is caused by decltype(auto) and const& return value
+//#define eval_once(expr) ([&]() -> decltype(auto) { static decltype(auto) ret___1132 = (expr); return (decltype(ret___1132) const&) ret___1132; }())
-#define eval_once__2(expr, ident) (([&] { static bool ident = ((expr), true); (void)(ident); }))
-#define eval_once(expr) eval_once__2(expr, PP_CAT(eval_once_init__, __COUNTER__))
+#define eval_once(expr) eval_once__2(expr, PP_CAT(_EVAL_ONCE__, __COUNTER__))
+#define eval_once__2(expr, ident) eval_once__3(expr, ident)
+#define eval_once__3(expr, ident) \
+ ([&]() -> std::decay_t<decltype(expr)> const& { static const std::decay_t<decltype(expr)> INIT##ident = (expr); return INIT##ident; }())
#include <type_traits>
@@ -68,6 +77,7 @@ constexpr cc_forceinline void static_warn<true>() {}
#define static_warning(cond) \
static_warn<(cond)>(); \
+#define typed_progn(type, ...) (([&] () -> type { __VA_ARGS__ })())
#define progn(...) (([&] { __VA_ARGS__ })())
#define prog1(x, ...) (([&] { decltype(auto) ret1324 = (x); __VA_ARGS__; return ret1324; })())
--
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