wchar: Fix compilation errors in C++ mode on Solaris 11.3

[Bruno Haible]

On Solaris 11.3, a testdir produces these compilation errors:

* With Sun C/C++:

source='../../gltests/test-wchar-c++.cc' object='test-wchar-c++.o' libtool=no \
DEPDIR=.deps depmode=none /bin/sh ../../build-aux/depcomp \
CC -m64 -O -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I../../gltests -I..  
-DGNULIB_STRICT_CHECKING=1 -DIN_GNULIB_TESTS=1 -I. -I../../gltests -I.. 
-I../../gltests/.. -I../gllib -I../../gltests/../gllib 
-I/export/home/haible/prefix-sparc64/include -D_REENTRANT  -g -c -o 
test-wchar-c++.o ../../gltests/test-wchar-c++.cc
"../gllib/wchar.h", line 1259: Error: wcsnlen is not defined.
"../gllib/wchar.h", line 1297: Error: wcpcpy is not defined.
"../gllib/wchar.h", line 1340: Error: wcpncpy is not defined.
"../gllib/wchar.h", line 1439: Error: wcscasecmp is not defined.
"../gllib/wchar.h", line 1458: Error: wcsncasecmp is not defined.
"../gllib/wchar.h", line 1524: Error: wcsdup is not defined.
6 Error(s) and 135 Warning(s) detected.
gmake[4]: *** [Makefile:23350: test-wchar-c++.o] Error 2

* With gcc/g++:

depbase=`echo test-wchar-c++.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\
g++ -m64 -O2 -DHAVE_CONFIG_H -DEXEEXT=\"\" -I. -I../../gltests -I..  
-DGNULIB_STRICT_CHECKING=1 -DIN_GNULIB_TESTS=1 -I. -I../../gltests -I.. 
-I../../gltests/.. -I../gllib -I../../gltests/../gllib 
-I/export/home/haible/prefix-sparc64/include -Wall -D_REENTRANT 
-I/opt/csw/include  -Wno-error -g -O2 -MT test-wchar-c++.o -MD -MP -MF 
$depbase.Tpo -c -o test-wchar-c++.o ../../gltests/test-wchar-c++.cc &&\
mv -f $depbase.Tpo $depbase.Po
In file included from /usr/include/sys/time.h:480:0,
                 from ../gllib/sys/time.h:39,
                 from /usr/include/sys/select.h:28,
                 from ../gllib/sys/select.h:36,
                 from /usr/include/sys/types.h:664,
                 from ../gllib/sys/types.h:39,
                 from ../gllib/stdio.h:58,
                 from /usr/include/iso/wchar_iso.h:28,
                 from 
/opt/csw/lib/gcc/sparc-sun-solaris2.10/5.5.0/include-fixed/wchar.h:22,
                 from ../gllib/wchar.h:80,
                 from ../../gltests/test-wchar-c++.cc:22:
../gllib/wchar.h: In member function 'gnulib::_gl_wcsnlen_wrapper::operator 
gnulib::_gl_wcsnlen_wrapper::type() const':
../gllib/wchar.h:1259:1: error: '::wcsnlen' has not been declared
 _GL_CXXALIAS_SYS (wcsnlen, size_t, (const wchar_t *s, size_t maxlen));
 ^
../gllib/wchar.h: At global scope:
../gllib/wchar.h:1260:1: error: 'wcsnlen' was not declared in this scope
 _GL_CXXALIASWARN (wcsnlen);
 ^
../gllib/wchar.h:1260:1: note: suggested alternative:
../gllib/wchar.h:1259:1: note:   'gnulib::wcsnlen'
 _GL_CXXALIAS_SYS (wcsnlen, size_t, (const wchar_t *s, size_t maxlen));
 ^
../gllib/wchar.h: In member function 'gnulib::_gl_wcpcpy_wrapper::operator 
gnulib::_gl_wcpcpy_wrapper::type() const':
../gllib/wchar.h:1296:1: error: '::wcpcpy' has not been declared
 _GL_CXXALIAS_SYS (wcpcpy, wchar_t *,
 ^
../gllib/wchar.h: At global scope:
../gllib/wchar.h:1298:1: error: 'wcpcpy' was not declared in this scope
 _GL_CXXALIASWARN (wcpcpy);
 ^
../gllib/wchar.h:1298:1: note: suggested alternative:
../gllib/wchar.h:1296:1: note:   'gnulib::wcpcpy'
 _GL_CXXALIAS_SYS (wcpcpy, wchar_t *,
 ^
../gllib/wchar.h: In member function 'gnulib::_gl_wcpncpy_wrapper::operator 
gnulib::_gl_wcpncpy_wrapper::type() const':
../gllib/wchar.h:1338:1: error: '::wcpncpy' has not been declared
 _GL_CXXALIAS_SYS (wcpncpy, wchar_t *,
 ^
../gllib/wchar.h: At global scope:
../gllib/wchar.h:1341:1: error: 'wcpncpy' was not declared in this scope
 _GL_CXXALIASWARN (wcpncpy);
 ^
../gllib/wchar.h:1341:1: note: suggested alternative:
../gllib/wchar.h:1338:1: note:   'gnulib::wcpncpy'
 _GL_CXXALIAS_SYS (wcpncpy, wchar_t *,
 ^
../gllib/wchar.h: In member function 'gnulib::_gl_wcscasecmp_wrapper::operator 
gnulib::_gl_wcscasecmp_wrapper::type() const':
../gllib/wchar.h:1439:1: error: '::wcscasecmp' has not been declared
 _GL_CXXALIAS_SYS (wcscasecmp, int, (const wchar_t *s1, const wchar_t *s2));
 ^
../gllib/wchar.h: At global scope:
../gllib/wchar.h:1440:1: error: 'wcscasecmp' was not declared in this scope
 _GL_CXXALIASWARN (wcscasecmp);
 ^
../gllib/wchar.h:1440:1: note: suggested alternative:
../gllib/wchar.h:1439:1: note:   'gnulib::wcscasecmp'
 _GL_CXXALIAS_SYS (wcscasecmp, int, (const wchar_t *s1, const wchar_t *s2));
 ^
../gllib/wchar.h: In member function 'gnulib::_gl_wcsncasecmp_wrapper::operator 
gnulib::_gl_wcsncasecmp_wrapper::type() const':
../gllib/wchar.h:1457:1: error: '::wcsncasecmp' has not been declared
 _GL_CXXALIAS_SYS (wcsncasecmp, int,
 ^
../gllib/wchar.h: At global scope:
../gllib/wchar.h:1459:1: error: 'wcsncasecmp' was not declared in this scope
 _GL_CXXALIASWARN (wcsncasecmp);
 ^
../gllib/wchar.h:1459:1: note: suggested alternative:
../gllib/wchar.h:1457:1: note:   'gnulib::wcsncasecmp'
 _GL_CXXALIAS_SYS (wcsncasecmp, int,
 ^
../gllib/wchar.h: In member function 'gnulib::_gl_wcsdup_wrapper::operator 
gnulib::_gl_wcsdup_wrapper::type() const':
../gllib/wchar.h:1524:1: error: '::wcsdup' has not been declared
 _GL_CXXALIAS_SYS (wcsdup, wchar_t *, (const wchar_t *s));
 ^
../gllib/wchar.h: At global scope:
../gllib/wchar.h:1526:1: error: 'wcsdup' was not declared in this scope
 _GL_CXXALIASWARN (wcsdup);
 ^
../gllib/wchar.h:1526:1: note: suggested alternative:
../gllib/wchar.h:1524:1: note:   'gnulib::wcsdup'
 _GL_CXXALIAS_SYS (wcsdup, wchar_t *, (const wchar_t *s));
 ^
gmake[4]: *** [Makefile:23347: test-wchar-c++.o] Error 1


The cause is that on this platform, the functions wcsnlen, wcpcpy, etc.
are declared inside
  namespace std { ... }
But to make our _GL_CXXALIAS_SYS macros work, we need the declaration in
the global namespace. There are two ways to achieve this:
  (a) through a 'using std::wcsnlen;' declaration,
  (b) by providing a declaration in the global namespace ourselves.

I think (b) will lead to fewer problems than (a), regarding different
Solaris versions. Therefore that's the solution I choose.


2022-09-17  Bruno Haible  <bruno@clisp.org>

        wchar: Fix compilation errors in C++ mode on Solaris 11.3.
        * lib/wchar.in.h (wcsnlen, wcpcpy, wcpncpy, wcscasecmp, wcsncasecmp,
        wcsdup): Force declaration in C++ mode on Solaris (which does not
        declare these functions in the global namespace).

diff --git a/lib/wchar.in.h b/lib/wchar.in.h
index 835ddbe659..3558adfb9d 100644
--- a/lib/wchar.in.h
+++ b/lib/wchar.in.h
@@ -745,7 +745,10 @@ _GL_WARN_ON_USE (wcslen, "wcslen is unportable - "
 
 /* Return the number of wide characters in S, but at most MAXLEN.  */
 #if @GNULIB_WCSNLEN@
-# if !@HAVE_WCSNLEN@
+/* On Solaris 11.3, the header files declare the function in the std::
+   namespace, not in the global namespace.  So, force a declaration in
+   the global namespace.  */
+# if !@HAVE_WCSNLEN@ || (defined __sun && defined __cplusplus)
 _GL_FUNCDECL_SYS (wcsnlen, size_t, (const wchar_t *s, size_t maxlen)
                                    _GL_ATTRIBUTE_PURE);
 # endif
@@ -782,7 +785,10 @@ _GL_WARN_ON_USE (wcscpy, "wcscpy is unportable - "
 
 /* Copy SRC to DEST, returning the address of the terminating L'\0' in DEST.  
*/
 #if @GNULIB_WCPCPY@
-# if !@HAVE_WCPCPY@
+/* On Solaris 11.3, the header files declare the function in the std::
+   namespace, not in the global namespace.  So, force a declaration in
+   the global namespace.  */
+# if !@HAVE_WCPCPY@ || (defined __sun && defined __cplusplus)
 _GL_FUNCDECL_SYS (wcpcpy, wchar_t *,
                   (wchar_t *restrict dest, const wchar_t *restrict src));
 # endif
@@ -823,7 +829,10 @@ _GL_WARN_ON_USE (wcsncpy, "wcsncpy is unportable - "
 /* Copy no more than N characters of SRC to DEST, returning the address of
    the last character written into DEST.  */
 #if @GNULIB_WCPNCPY@
-# if !@HAVE_WCPNCPY@
+/* On Solaris 11.3, the header files declare the function in the std::
+   namespace, not in the global namespace.  So, force a declaration in
+   the global namespace.  */
+# if !@HAVE_WCPNCPY@ || (defined __sun && defined __cplusplus)
 _GL_FUNCDECL_SYS (wcpncpy, wchar_t *,
                   (wchar_t *restrict dest,
                    const wchar_t *restrict src, size_t n));
@@ -925,7 +934,10 @@ _GL_WARN_ON_USE (wcsncmp, "wcsncmp is unportable - "
 
 /* Compare S1 and S2, ignoring case.  */
 #if @GNULIB_WCSCASECMP@
-# if !@HAVE_WCSCASECMP@
+/* On Solaris 11.3, the header files declare the function in the std::
+   namespace, not in the global namespace.  So, force a declaration in
+   the global namespace.  */
+# if !@HAVE_WCSCASECMP@ || (defined __sun && defined __cplusplus)
 _GL_FUNCDECL_SYS (wcscasecmp, int, (const wchar_t *s1, const wchar_t *s2)
                                    _GL_ATTRIBUTE_PURE);
 # endif
@@ -942,7 +954,10 @@ _GL_WARN_ON_USE (wcscasecmp, "wcscasecmp is unportable - "
 
 /* Compare no more than N chars of S1 and S2, ignoring case.  */
 #if @GNULIB_WCSNCASECMP@
-# if !@HAVE_WCSNCASECMP@
+/* On Solaris 11.3, the header files declare the function in the std::
+   namespace, not in the global namespace.  So, force a declaration in
+   the global namespace.  */
+# if !@HAVE_WCSNCASECMP@ || (defined __sun && defined __cplusplus)
 _GL_FUNCDECL_SYS (wcsncasecmp, int,
                   (const wchar_t *s1, const wchar_t *s2, size_t n)
                   _GL_ATTRIBUTE_PURE);
@@ -1009,7 +1024,10 @@ _GL_WARN_ON_USE (wcsxfrm, "wcsxfrm is unportable - "
 #  endif
 _GL_CXXALIAS_MDA (wcsdup, wchar_t *, (const wchar_t *s));
 # else
-#  if !@HAVE_WCSDUP@ || __GNUC__ >= 11
+/* On Solaris 11.3, the header files declare the function in the std::
+   namespace, not in the global namespace.  So, force a declaration in
+   the global namespace.  */
+#  if !@HAVE_WCSDUP@ || (defined __sun && defined __cplusplus) || __GNUC__ >= 
11
 _GL_FUNCDECL_SYS (wcsdup, wchar_t *,
                   (const wchar_t *s)
                   _GL_ATTRIBUTE_MALLOC _GL_ATTRIBUTE_DEALLOC_FREE);