1# warn-on-use.m4 serial 6
2dnl Copyright (C) 2010-2020 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7# gl_WARN_ON_USE_PREPARE(INCLUDES, NAMES)
8# ---------------------------------------
9# If the module 'posixcheck' is in use:
10#
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.
14#
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
21# should do likewise.
22#
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.
26AC_DEFUN([gl_WARN_ON_USE_PREPARE],
27[
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
33dnl FIXME: gl_Symbol must be used unquoted until we can assume
34dnl autoconf 2.64 or newer.
35     for gl_func in m4_flatten([$2]); do
36       AS_VAR_PUSHDEF([gl_Symbol], [gl_cv_have_raw_decl_$gl_func])dnl
37       AC_CACHE_CHECK([whether $gl_func is declared without a macro],
38         gl_Symbol,
39         [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$1],
40[@%:@undef $gl_func
41  (void) $gl_func;])],
42           [AS_VAR_SET(gl_Symbol, [yes])], [AS_VAR_SET(gl_Symbol, [no])])])
43       AS_VAR_IF(gl_Symbol, [yes],
44         [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_RAW_DECL_$gl_func]), [1])
45          dnl shortcut - if the raw declaration exists, then set a cache
46          dnl variable to allow skipping any later AC_CHECK_DECL efforts
47          eval ac_cv_have_decl_$gl_func=yes])
48       AS_VAR_POPDEF([gl_Symbol])dnl
49     done
50    ])
51])
52