Do the Windows oldnames workaround through the C++ GNULIB_NAMESPACE.

Reported by Daniel R. Hurtmans <Daniel.Hurtmans@ulb.ac.be> in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-12/msg00029.html>.

* lib/c++defs.h (_GL_CXXALIAS_MDA_CAST): New macro.
* lib/fcntl.in.h (creat, open):  In C++ mode, when GNULIB_NAMESPACE is
defined: 1. Define a symbol in this namespace. 2. Don't redirect using
a preprocessor #define.
* lib/math.in.h (j0, j1, jn, y0, y1, yn): Likewise.
* lib/search.in.h (lfind, lsearch): Likewise.
* lib/stdio.in.h (fcloseall, fdopen, fileno, getw, putw, tempnam):
Likewise.
* lib/stdlib.in.h (ecvt, fcvt, gcvt, mktemp, putenv): Likewise.
* lib/string.in.h (memccpy, strdup): Likewise.
* lib/sys_stat.in.h (chmod, umask): Likewise.
* lib/time.in.h (tzset): Likewise.
* lib/unistd.in.h (access, chdir, close, dup, dup2, execl, execle,
execlp, execv, execve, execvp, execvpe, getcwd, getpid, isatty, lseek,
read, rmdir, swab, unlink, write): Likewise.
* lib/utime.in.h (utime): Likewise.
* lib/wchar.in.h (wcsdup): Likewise.
* m4/stdio_h.m4 (gl_STDIO_H_DEFAULTS): Initialize HAVE_DECL_FCLOSEALL.
(gl_STDIO_H): Set HAVE_DECL_FCLOSEALL.
* modules/stdio (Makefile.am): Substitute HAVE_DECL_FCLOSEALL.
* m4/stdlib_h.m4 (gl_STDLIB_H_DEFAULTS): Initialize HAVE_DECL_ECVT,
HAVE_DECL_FCVT, HAVE_DECL_GCVT.
(gl_STDLIB_H): Set HAVE_DECL_ECVT, HAVE_DECL_FCVT, HAVE_DECL_GCVT.
* modules/stdlib (Makefile.am): Substitute HAVE_DECL_ECVT,
HAVE_DECL_FCVT, HAVE_DECL_GCVT.
* m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Initialize HAVE_DECL_EXECVPE.
(gl_UNISTD_H): Set HAVE_DECL_EXECVPE.
* modules/unistd (Makefile.am): Substitute HAVE_DECL_EXECVPE.
* m4/wchar_h.m4 (gl_WCHAR_H_DEFAULTS): Initialize HAVE_DECL_WCSDUP.
(gl_WCHAR_H): Set HAVE_DECL_WCSDUP.
* modules/wchar (Makefile.am): Substitute HAVE_DECL_WCSDUP.

1 files changed, 31 insertions, 6 deletions

diff --git a/lib/fcntl.in.h b/lib/fcntl.in.h
index 6f16bc6692..11c9aae9bc 100644
--- a/lib/fcntl.in.h
+++ b/lib/fcntl.in.h
@@ -112,9 +112,21 @@ _GL_CXXALIASWARN (creat);
 /* Assume creat is always declared.  */
 _GL_WARN_ON_USE (creat, "creat is not always POSIX compliant - "
                  "use gnulib module creat for portability");
-#elif defined _WIN32 && !defined __CYGWIN__
-# undef creat
-# define creat _creat
+#else
+/* On native Windows, map 'creat' to '_creat', so that -loldnames is not
+   required.  In C++ with GNULIB_NAMESPACE, avoid differences between
+   platforms by defining GNULIB_NAMESPACE::creat always.  */
+# if defined _WIN32 && !defined __CYGWIN__
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef creat
+#   define creat _creat
+#  endif
+/* Need to cast, because in mingw the last argument is 'int mode'.  */
+_GL_CXXALIAS_MDA_CAST (creat, int, (const char *filename, mode_t mode));
+# else
+_GL_CXXALIAS_SYS (creat, int, (const char *filename, mode_t mode));
+# endif
+_GL_CXXALIASWARN (creat);
 #endif
 
 #if @GNULIB_FCNTL@
@@ -174,9 +186,22 @@ _GL_CXXALIASWARN (open);
 /* Assume open is always declared.  */
 _GL_WARN_ON_USE (open, "open is not always POSIX compliant - "
                  "use gnulib module open for portability");
-#elif defined _WIN32 && !defined __CYGWIN__
-# undef open
-# define open _open
+#else
+/* On native Windows, map 'open' to '_open', so that -loldnames is not
+   required.  In C++ with GNULIB_NAMESPACE, avoid differences between
+   platforms by defining GNULIB_NAMESPACE::open always.  */
+# if defined _WIN32 && !defined __CYGWIN__
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef open
+#   define open _open
+#  endif
+_GL_CXXALIAS_MDA (open, int, (const char *filename, int flags, ...));
+# else
+_GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...));
+# endif
+# if !defined __hpux
+_GL_CXXALIASWARN (open);
+# endif
 #endif
 
 #if @GNULIB_OPENAT@