1 # warn-on-use.m4 serial 10
2 dnl Copyright (C) 2010-2022 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 # gl_WARN_ON_USE_PREPARE(INCLUDES, NAMES)
8 # ---------------------------------------
9 # If the module 'posixcheck' is in use:
11 # For each whitespace-separated element in the list of NAMES, define
12 # HAVE_RAW_DECL_name if the function has a declaration among INCLUDES
13 # even after being undefined as a macro.
15 # See warn-on-use.h for some hints on how to poison function names, as
16 # well as ideas on poisoning global variables and macros. NAMES may
17 # include global variables, but remember that only functions work with
18 # _GL_WARN_ON_USE. Typically, INCLUDES only needs to list a single
19 # header, but if the replacement header pulls in other headers because
20 # some systems declare functions in the wrong header, then INCLUDES
23 # It is generally safe to assume declarations for functions declared
24 # in the intersection of C89 and C11 (such as printf) without
25 # needing gl_WARN_ON_USE_PREPARE.
26 AC_DEFUN([gl_WARN_ON_USE_PREPARE],
28 m4_ifdef([gl_POSIXCHECK],
29 [m4_foreach_w([gl_decl], [$2],
30 [AH_TEMPLATE([HAVE_RAW_DECL_]AS_TR_CPP(m4_defn([gl_decl])),
31 [Define to 1 if ]m4_defn([gl_decl])[ is declared even after
32 undefining macros.])])dnl
33 for gl_func in m4_flatten([$2]); do
34 AS_VAR_PUSHDEF([gl_Symbol], [gl_cv_have_raw_decl_$gl_func])dnl
35 dnl As a workaround to implicit built-in function declarations in
36 dnl clang (e.g. strndup), reference ac_compile_for_check_decl instead
37 dnl of ac_compile. If, for whatever reason, the override of AC_PROG_CC
38 dnl in zzgnulib.m4 is inactive, use the original ac_compile.
39 ac_save_ac_compile="$ac_compile"
40 if test -n "$ac_compile_for_check_decl"; then
41 ac_compile="$ac_compile_for_check_decl"
43 AC_CACHE_CHECK([whether $gl_func is declared without a macro],
45 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$1],
48 [AS_VAR_SET([gl_Symbol], [yes])], [AS_VAR_SET([gl_Symbol], [no])])])
49 ac_compile="$ac_save_ac_compile"
50 AS_VAR_IF([gl_Symbol], [yes],
51 [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_RAW_DECL_$gl_func]), [1])
52 dnl Shortcut for an AC_CHECK_DECL invocation that may come later:
53 dnl If the raw declaration exists with the given includes, then
54 dnl AC_CHECK_DECL with its many includes would see it as well.
55 dnl So, set a cache variable to allow skipping any later
56 dnl AC_CHECK_DECL invocation for $gl_func.
57 eval "ac_cv_have_decl_$gl_func=yes"
59 AS_VAR_POPDEF([gl_Symbol])dnl