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      1 # warn-on-use.m4 serial 9
      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.
      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.
     26 AC_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
     33      for gl_func in m4_flatten([$2]); do
     34        AS_VAR_PUSHDEF([gl_Symbol], [gl_cv_have_raw_decl_$gl_func])dnl
     35        AC_CACHE_CHECK([whether $gl_func is declared without a macro],
     36          [gl_Symbol],
     37          [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$1],
     38 [[#undef $gl_func
     39   (void) $gl_func;]])],
     40            [AS_VAR_SET([gl_Symbol], [yes])], [AS_VAR_SET([gl_Symbol], [no])])])
     41        AS_VAR_IF([gl_Symbol], [yes],
     42          [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_RAW_DECL_$gl_func]), [1])
     43           dnl shortcut - if the raw declaration exists, then set a cache
     44           dnl variable to allow skipping any later AC_CHECK_DECL efforts
     45           eval ac_cv_have_decl_$gl_func=yes])
     46        AS_VAR_POPDEF([gl_Symbol])dnl
     47      done
     48     ])
     49 ])
     50