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/strings.in.h b/lib/strings.in.h
index 7a8601da18..093189921d 100644
--- a/lib/strings.in.h
+++ b/lib/strings.in.h
@@ -29,10 +29,9 @@
 #define _GL_STRINGS_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" {
@@ -52,14 +51,14 @@ extern int strcasecmp (char const *s1, char const *s2)
    POSIX says that it operates on "strings", and "string" in POSIX is defined
    as a sequence of bytes, not of characters.   */
 # undef strcasecmp
-# define strcasecmp(a,b) \
-    (GL_LINK_WARNING ("strcasecmp cannot work correctly on character strings " \
-                      "in multibyte locales - " \
-                      "use mbscasecmp if you care about " \
-                      "internationalization, or use c_strcasecmp (from " \
-                      "gnulib module c-strcase) if you want a locale " \
-                      "independent function"), \
-     strcasecmp (a, b))
+# if HAVE_RAW_DECL_STRCASECMP
+_GL_WARN_ON_USE (strcasecmp, "strcasecmp cannot work correctly on character "
+                 "strings in multibyte locales - "
+                 "use mbscasecmp if you care about "
+                 "internationalization, or use c_strcasecmp , "
+                 "gnulib module c-strcase) if you want a locale "
+                 "independent function");
+# endif
 #endif
 
 /* Compare no more than N bytes of strings S1 and S2, ignoring case,
@@ -75,14 +74,14 @@ extern int strncasecmp (char const *s1, char const *s2, size_t n)
    POSIX says that it operates on "strings", and "string" in POSIX is defined
    as a sequence of bytes, not of characters.  */
 # undef strncasecmp
-# define strncasecmp(a,b,n) \
-    (GL_LINK_WARNING ("strncasecmp cannot work correctly on character " \
-                      "strings in multibyte locales - " \
-                      "use mbsncasecmp or mbspcasecmp if you care about " \
-                      "internationalization, or use c_strncasecmp (from " \
-                      "gnulib module c-strcase) if you want a locale " \
-                      "independent function"), \
-     strncasecmp (a, b, n))
+# if HAVE_RAW_DECL_STRNCASECMP
+_GL_WARN_ON_USE (strncasecmp, "strncasecmp cannot work correctly on character "
+                 "strings in multibyte locales - "
+                 "use mbsncasecmp or mbspcasecmp if you care about "
+                 "internationalization, or use c_strncasecmp , "
+                 "gnulib module c-strcase) if you want a locale "
+                 "independent function");
+# endif
 #endif