clang++ hard failure with GNULIB_NAMESPACE

[Alexandre Duret-Lutz]

Alexandre Duret-Lutz <adl@lrde.epita.fr> writes:

> Bruno Haible <bruno@clisp.org> writes:
>
>> in C++, it is easier and more robust to define GNULIB_NAMESPACE.
>
> OK, thanks, I'll progress this way.

Progress is not smooth.  This time it's unrelated to -Werror.

Using clang++ 11, compilation fails because of the overloads of memchr
and friends.  Note that clang++11 defines __GNUC__ and __GNU_MINOR__ as
4 and 2 (Yuck!) so the two _GL_CXXALIASWARN1 calls dealing with the two
overloads in lib/string.h are not performed.

In file included from bitvect.cc:28:
In file included from 
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/cstring:42:
../../lib/string.h:693:1: error: reference to overloaded function could not be 
resolved; did you mean to call it?
_GL_CXXALIASWARN (memchr);
^~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:382:4: note: expanded from macro '_GL_CXXALIASWARN'
   _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:384:4: note: expanded from macro '_GL_CXXALIASWARN_1'
   _GL_CXXALIASWARN_2 (func, namespace)
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:389:5: note: expanded from macro '_GL_CXXALIASWARN_2'
    _GL_WARN_ON_USE (func, \
    ^~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:552:19: note: expanded from macro '_GL_WARN_ON_USE'
extern __typeof__ (function) function \
                  ^~~~~~~~~~
/usr/include/string.h:84:1: note: possible target for call
memchr (const void *__s, int __c, size_t __n) __THROW
^
/usr/include/string.h:78:1: note: possible target for call
memchr (void *__s, int __c, size_t __n) __THROW
^
In file included from bitvect.cc:28:
In file included from 
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/cstring:42:
../../lib/string.h:807:1: error: reference to overloaded function could not be 
resolved; did you mean to call it?
_GL_CXXALIASWARN (rawmemchr);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:382:4: note: expanded from macro '_GL_CXXALIASWARN'
   _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:384:4: note: expanded from macro '_GL_CXXALIASWARN_1'
   _GL_CXXALIASWARN_2 (func, namespace)
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:389:5: note: expanded from macro '_GL_CXXALIASWARN_2'
    _GL_WARN_ON_USE (func, \
    ^~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:552:19: note: expanded from macro '_GL_WARN_ON_USE'
extern __typeof__ (function) function \
                  ^~~~~~~~~~
/usr/include/string.h:101:26: note: possible target for call
extern "C++" const void *rawmemchr (const void *__s, int __c)
                         ^
/usr/include/string.h:99:20: note: possible target for call
extern "C++" void *rawmemchr (void *__s, int __c)
                   ^
In file included from bitvect.cc:28:
In file included from 
/usr/bin/../lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/cstring:42:
../../lib/string.h:911:1: error: reference to overloaded function could not be 
resolved; did you mean to call it?
_GL_CXXALIASWARN (strchrnul);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:382:4: note: expanded from macro '_GL_CXXALIASWARN'
   _GL_CXXALIASWARN_1 (func, GNULIB_NAMESPACE)
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:384:4: note: expanded from macro '_GL_CXXALIASWARN_1'
   _GL_CXXALIASWARN_2 (func, namespace)
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:389:5: note: expanded from macro '_GL_CXXALIASWARN_2'
    _GL_WARN_ON_USE (func, \
    ^~~~~~~~~~~~~~~~~~~~~~~~
../../lib/wchar.h:552:19: note: expanded from macro '_GL_WARN_ON_USE'
extern __typeof__ (function) function \
                  ^~~~~~~~~~
/usr/include/string.h:263:26: note: possible target for call
extern "C++" const char *strchrnul (const char *__s, int __c)
                         ^
/usr/include/string.h:261:20: note: possible target for call
extern "C++" char *strchrnul (char *__s, int __c)
                   ^
3 errors generated.
make[3]: *** [Makefile:1445: bitvect.lo] Error 1
make[2]: *** [Makefile:1549: all-recursive] Error 1
make[1]: *** [Makefile:1424: all-recursive] Error 1
make: *** [Makefile:1344: all] Error 2

-- 
Alexandre Duret-Lutz