Re: [PROPOSED 2/2] assert-h: prefer to ‘verify’

[Bruno Haible]

Paul Eggert wrote:
> Where it’s easy, prefer ‘static_assert’ to ‘verify’,

Compiling a current GNU gettext with these patches on Cygwin and mingw
I get a compilation error:

/bin/sh ./libtool  --tag=CXX   --mode=compile x86_64-pc-cygwin-g++ 
-DIN_LIBASPRINTF -DHAVE_CONFIG_H -D__USE_MINGW_ANSI_STDIO=0 -I. 
-I../../../gettext-runtime/libasprintf  -Ignulib-lib 
-I../../../gettext-runtime/libasprintf/gnulib-lib -I/usr/local/cygwin64/include 
-Wall  -g -O2 -c -o autosprintf.lo 
../../../gettext-runtime/libasprintf/autosprintf.cc
libtool: compile:  x86_64-pc-cygwin-g++ -DIN_LIBASPRINTF -DHAVE_CONFIG_H 
-D__USE_MINGW_ANSI_STDIO=0 -I. -I../../../gettext-runtime/libasprintf 
-Ignulib-lib -I../../../gettext-runtime/libasprintf/gnulib-lib 
-I/usr/local/cygwin64/include -Wall -g -O2 -c 
../../../gettext-runtime/libasprintf/autosprintf.cc -o autosprintf.o
In file included from ./config.h:1097:0,
                 from ../../../gettext-runtime/libasprintf/autosprintf.cc:18:
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/type_traits:1105:7: error: 
expected identifier before 'sizeof'
       static_assert(sizeof...(_Args) > 1,
       ^
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/type_traits:1105:7: error: 
expected ',' or '...' before 'sizeof'
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/type_traits:2093:7: error: 
expected identifier before 'sizeof'
       static_assert(sizeof...(_Types) != 0, "At least one type is required");
       ^
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/type_traits:2093:7: error: 
expected ',' or '...' before 'sizeof'
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/bits/ptr_traits.h:114:7: error: 
expected identifier before '!' token
       static_assert(!is_same<element_type, __undefined>::value,
       ^
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/bits/ptr_traits.h:114:7: error: 
expected ',' or '...' before '!' token
In file included from /usr/include/features.h:12:0,
                 from gnulib-lib/wchar.h:66,
                 from /usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/cwchar:44,
                 from 
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/bits/postypes.h:40,
                 from 
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/bits/char_traits.h:40,
                 from /usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/string:40,
                 from ./autosprintf.h:35,
                 from ../../../gettext-runtime/libasprintf/autosprintf.cc:21:
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/utility:309:7: error: '_Num' is 
not a type
       static_assert( _Num >= 0,
       ^
/usr/lib/gcc/x86_64-pc-cygwin/6.4.0/include/c++/utility:309:7: error: expected 
',' or '...' before '>=' token
       static_assert( _Num >= 0,
       ^
make[6]: *** [Makefile:1412: autosprintf.lo] Error 1

This patch fixes it.


2022-09-13  Bruno Haible  <bruno@clisp.org>

        verify: Avoid syntax error due to static_assert with GNU C++ 6.x.
        * lib/verify.h (static_assert): Don't define in GNU C++ 6 or newer.

diff --git a/lib/verify.h b/lib/verify.h
index 0066d211b2..154a5b76bf 100644
--- a/lib/verify.h
+++ b/lib/verify.h
@@ -227,7 +227,8 @@ template <int w>
      _GL_VERIFY (__VA_ARGS__, "static assertion failed", -)
 # endif
 # if (!defined static_assert \
-      && __STDC_VERSION__ < 202311 && __cpp_static_assert < 201411)
+      && __STDC_VERSION__ < 202311 \
+      && __cpp_static_assert < 201411 && __GNUG__ < 6)
 #  define static_assert _Static_assert /* C11 requires this #define.  */
 # endif
 #endif