warn-on-use: use instead of link-warning

Each *.in.h file serves two purposes - provide enough self-contained
content to serve as a replacement for the system header regardless of
the user's compiler, and offer the developer the ability to detect any
gnulib modules that might have been inadvertantly excluded.  The
former requires independence from config.h, and routes everything
through a Makefile.am snippet that uses @@ substitution specific to
the modules that were in use, with details learned at configure time.

The latter works by poisoning anything that gnulib did not replace,
but which the developer had natively available, explaining why their
tests passed during development.  Poisoning relies on gcc features,
and requires manual triggering by adding -DGNULIB_POSIXCHECK to
CFLAGS; it assumes that <config.h> is properly included.  In fact, we
do not want to use @@ substitution for HAVE_DECL_* during poisoning,
because the warning is only relevant for the gnulib modules which were
not included, and thus where the m4 macros to set proper @@ values
have not been run.  Furthermore, we only need to poison interfaces
that already have a declaration; if something is not declared, then
the developer wouldn't have been able to link, so their code won't be
using the problematic interface in the first place.

* modules/stdio (Depends-on, Makefile.am): Drop link-warning.
* modules/unistd (Depends-on, Makefile.am): Likewise.
* modules/arpa_inet (Depends-on): Replace link-warning with
warn-on-use.
(Makefile.am): Update rules accordingly.
* modules/ctype (Depends-on, Makefile.am): Likewise.
* modules/dirent (Depends-on, Makefile.am): Likewise.
* modules/fcntl-h (Depends-on, Makefile.am): Likewise.
* modules/inttypes (Depends-on, Makefile.am): Likewise.
* modules/langinfo (Depends-on, Makefile.am): Likewise.
* modules/locale (Depends-on, Makefile.am): Likewise.
* modules/math (Depends-on, Makefile.am): Likewise.
* modules/search (Depends-on, Makefile.am): Likewise.
* modules/signal (Depends-on, Makefile.am): Likewise.
* modules/spawn (Depends-on, Makefile.am): Likewise.
* modules/stdlib (Depends-on, Makefile.am): Likewise.
* modules/string (Depends-on, Makefile.am): Likewise.
* modules/strings (Depends-on, Makefile.am): Likewise.
* modules/sys_file (Depends-on, Makefile.am): Likewise.
* modules/sys_ioctl (Depends-on, Makefile.am): Likewise.
* modules/sys_select (Depends-on, Makefile.am): Likewise.
* modules/sys_socket (Depends-on, Makefile.am): Likewise.
* modules/sys_stat (Depends-on, Makefile.am): Likewise.
* modules/sys_times (Depends-on, Makefile.am): Likewise.
* modules/sys_utsname (Depends-on, Makefile.am): Likewise.
* modules/wchar (Depends-on, Makefile.am): Likewise.
* m4/arpa_inet_h.m4 (gl_HEADER_ARPA_INET): Check which functions
should be poisoned.
* m4/ctype.m4 (gl_CTYPE_H): Likewise.
* m4/dirent_h.m4 (gl_DIRENT_H): Likewise.
* m4/fcntl_h.m4 (gl_FCNTL_H): Likewise.
* m4/inttypes.m4 (gl_INTTYPES_H): Likewise.
* m4/langinfo_h.m4 (gl_LANGINFO_H): Likewise.
* m4/locale_h.m4 (gl_LOCALE_H): Likewise.
* m4/math_h.m4 (gl_MATH_H): Likewise.
* m4/search_h.m4 (gl_SEARCH_H): Likewise.
* m4/signal_h.m4 (gl_SIGNAL_H): Likewise.
* m4/spawn_h.m4 (gl_SPAWN_H): Likewise.
* m4/stdio_h.m4 (gl_STDIO_H): Likewise.
* m4/stdlib_h.m4 (gl_STDLIB_H): Likewise.
* m4/string_h.m4 (gl_HEADER_STRING_H_BODY): Likewise.
* m4/strings_h.m4 (gl_HEADER_STRINGS_H_BODY): Likewise.
* m4/sys_file_h.m4 (gl_HEADER_SYS_FILE_H_DEFAULTS): Likewise.
* m4/sys_ioctl_h.m4 (gl_SYS_IOCTL_H): Likewise.
* m4/sys_select_h.m4 (gl_HEADER_SYS_SELECT): Likewise.
* m4/sys_socket_h.m4 (gl_HEADER_SYS_SOCKET): Likewise.
* m4/sys_stat_h.m4 (gl_HEADER_SYS_STAT_H): Likewise.
* m4/sys_times_h.m4 (gl_SYS_TIMES_H): Likewise.
* m4/sys_utsname_h.m4 (gl_SYS_UTSNAME_H): Likewise.
* m4/unistd_h.m4 (gl_UNISTD_H): Likewise.
* m4/wchar.m4 (gl_WCHAR_H): Likewise.
* lib/arpa_inet.in.h: Use _GL_WARN_ON_USE instead of
GL_LINK_WARNING.
* lib/ctype.in.h: Likewise.
* lib/dirent.in.h: Likewise.
* lib/fcntl.in.h: Likewise.
* lib/inttypes.in.h: Likewise.
* lib/langinfo.in.h: Likewise.
* lib/locale.in.h: Likewise.
* lib/math.in.h: Likewise.
* lib/search.in.h: Likewise.
* lib/signal.in.h: Likewise.
* lib/spawn.in.h: Likewise.
* lib/stdio.in.h: Likewise.
* lib/stdlib.in.h: Likewise.
* lib/string.in.h: Likewise.
* lib/strings.in.h: Likewise.
* lib/sys_file.in.h: Likewise.
* lib/sys_ioctl.in.h: Likewise.
* lib/sys_select.in.h: Likewise.
* lib/sys_socket.in.h: Likewise.
* lib/sys_stat.in.h: Likewise.
* lib/sys_times.in.h: Likewise.
* lib/sys_utsname.in.h: Likewise.
* lib/unistd.in.h: Likewise.
* lib/wchar.in.h: Likewise.

Signed-off-by: Eric Blake <ebb9@byu.net>

1 files changed, 17 insertions, 18 deletions

diff --git a/lib/dirent.in.h b/lib/dirent.in.h
index 4b02cfbcf6..ccd0a1064c 100644
--- a/lib/dirent.in.h
+++ b/lib/dirent.in.h
@@ -29,10 +29,9 @@
 /* Get ino_t.  Needed on some systems, including glibc 2.8.  */
 #include <sys/types.h>
 
-/* The definition of GL_LINK_WARNING is copied here.  */
-
 /* The definition of _GL_ARG_NONNULL is copied here.  */
 
+/* The definition of _GL_WARN_ON_USE is copied here.  */
 
 #ifdef __cplusplus
 extern "C" {
@@ -53,10 +52,10 @@ extern int dirfd (DIR *dir) _GL_ARG_NONNULL ((1));
 # endif
 #elif defined GNULIB_POSIXCHECK
 # undef dirfd
-# define dirfd(d) \
-    (GL_LINK_WARNING ("dirfd is unportable - " \
-                      "use gnulib module dirfd for portability"), \
-     dirfd (d))
+# if HAVE_RAW_DECL_DIRFD
+_GL_WARN_ON_USE (dirfd, "dirfd is unportable - "
+                 "use gnulib module dirfd for portability");
+# endif
 #endif
 
 #if @GNULIB_FDOPENDIR@
@@ -74,10 +73,10 @@ extern DIR *fdopendir (int fd);
 # endif
 #elif defined GNULIB_POSIXCHECK
 # undef fdopendir
-# define fdopendir(f) \
-    (GL_LINK_WARNING ("fdopendir is unportable - " \
-                      "use gnulib module fdopendir for portability"), \
-     fdopendir (f))
+# if HAVE_RAW_DECL_FDOPENDIR
+_GL_WARN_ON_USE (fdopendir, "fdopendir is unportable - "
+                 "use gnulib module fdopendir for portability");
+# endif
 #endif
 
 #if @REPLACE_OPENDIR@
@@ -98,10 +97,10 @@ extern int scandir (const char *dir, struct dirent ***namelist,
 # endif
 #elif defined GNULIB_POSIXCHECK
 # undef scandir
-# define scandir(d,n,f,c) \
-    (GL_LINK_WARNING ("scandir is unportable - " \
-                      "use gnulib module scandir for portability"), \
-     scandir (d, n, f, c))
+# if HAVE_RAW_DECL_SCANDIR
+_GL_WARN_ON_USE (scandir, "scandir is unportable - "
+                 "use gnulib module scandir for portability");
+# endif
 #endif
 
 #if @GNULIB_ALPHASORT@
@@ -112,10 +111,10 @@ extern int alphasort (const struct dirent **, const struct dirent **)
 # endif
 #elif defined GNULIB_POSIXCHECK
 # undef alphasort
-# define alphasort(a,b) \
-    (GL_LINK_WARNING ("alphasort is unportable - " \
-                      "use gnulib module alphasort for portability"), \
-     alphasort (a, b))
+# if HAVE_RAW_DECL_ALPHASORT
+_GL_WARN_ON_USE (alphasort, "alphasort is unportable - "
+                 "use gnulib module alphasort for portability");
+# endif
 #endif
 
 #ifdef __cplusplus