[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’
From: |
Bruno Haible |
Subject: |
Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’ |
Date: |
Wed, 14 Sep 2022 18:10:43 +0200 |
> > Where it’s easy, prefer ‘static_assert’ to ‘verify’,
>
> Compiling a current GNU gettext with MSVC 14, I get this compilation error:
I got this working, by using preprocessor tricks, inspired by
<https://github.com/Hirrolot/awesome-c-preprocessor>
<https://stackoverflow.com/questions/11761703/>
<https://groups.google.com/g/comp.std.c/c/d-6Mj5Lko_s?pli=1>
<https://stackoverflow.com/questions/5134523/>
2022-09-14 Bruno Haible <bruno@clisp.org>
verify: Avoid syntax error due to static_assert with MSVC 14 in C++.
* lib/verify.h (static_assert): For MSVC in C++ mode, use a definition
that supports both the two-arguments and the one-argument syntax.
diff --git a/lib/verify.h b/lib/verify.h
index a0d597f3d4..0f5f0edc86 100644
--- a/lib/verify.h
+++ b/lib/verify.h
@@ -229,7 +229,22 @@ template <int w>
# if (!defined static_assert \
&& __STDC_VERSION__ < 202311 \
&& __cpp_static_assert < 201411 && __GNUG__ < 6)
-# define static_assert _Static_assert /* C11 requires this #define. */
+# if defined __cplusplus && _MSC_VER >= 1900 && !defined __clang__
+/* MSVC 14 in C++ mode supports the two-arguments static_assert but not
+ the one-argument static_assert, and it does not support _Static_assert.
+ We have to play preprocessor tricks to distinguish the two cases.
+ Since the MSVC preprocessor is not ISO C compliant (cf.
+ <https://stackoverflow.com/questions/5134523/>), the solution is specific
+ to MSVC. */
+# define _GL_EXPAND(x) x
+# define _GL_SA1(a1) static_assert ((a1), "static assertion failed")
+# define _GL_SA2 static_assert
+# define _GL_SA3 static_assert
+# define _GL_SA_PICK(x1,x2,x3,x4,...) x4
+# define static_assert(...)
_GL_EXPAND(_GL_SA_PICK(__VA_ARGS__,_GL_SA3,_GL_SA2,_GL_SA1)) (__VA_ARGS__)
+# else
+# define static_assert _Static_assert /* C11 requires this #define. */
+# endif
# endif
#endif
- [PROPOSED 0/2] static_assert and C23, Paul Eggert, 2022/09/12
- [PROPOSED 1/2] assert-h: static_assert is a keyword in C23, Paul Eggert, 2022/09/12
- [PROPOSED 2/2] assert-h: prefer to ‘verify’, Paul Eggert, 2022/09/12
- Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’, Bruno Haible, 2022/09/14
- Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’, Bruno Haible, 2022/09/14
- Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’,
Bruno Haible <=
- Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’, Bruno Haible, 2022/09/14
- Re: [PROPOSED 0/2] static_assert and C23, Bruno Haible, 2022/09/13