| 1 | # warn-on-use.m4 serial 10
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| 2 | dnl Copyright (C) 2010-2022 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | # gl_WARN_ON_USE_PREPARE(INCLUDES, NAMES)
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| 8 | # ---------------------------------------
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| 9 | # If the module 'posixcheck' is in use:
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| 10 | #
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| 11 | # For each whitespace-separated element in the list of NAMES, define
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| 12 | # HAVE_RAW_DECL_name if the function has a declaration among INCLUDES
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| 13 | # even after being undefined as a macro.
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| 14 | #
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| 15 | # See warn-on-use.h for some hints on how to poison function names, as
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| 16 | # well as ideas on poisoning global variables and macros. NAMES may
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| 17 | # include global variables, but remember that only functions work with
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| 18 | # _GL_WARN_ON_USE. Typically, INCLUDES only needs to list a single
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| 19 | # header, but if the replacement header pulls in other headers because
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| 20 | # some systems declare functions in the wrong header, then INCLUDES
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| 21 | # should do likewise.
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| 22 | #
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| 23 | # It is generally safe to assume declarations for functions declared
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| 24 | # in the intersection of C89 and C11 (such as printf) without
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| 25 | # needing gl_WARN_ON_USE_PREPARE.
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| 26 | AC_DEFUN([gl_WARN_ON_USE_PREPARE],
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| 27 | [
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| 28 | m4_ifdef([gl_POSIXCHECK],
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| 29 | [m4_foreach_w([gl_decl], [$2],
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| 30 | [AH_TEMPLATE([HAVE_RAW_DECL_]AS_TR_CPP(m4_defn([gl_decl])),
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| 31 | [Define to 1 if ]m4_defn([gl_decl])[ is declared even after
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| 32 | undefining macros.])])dnl
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| 33 | for gl_func in m4_flatten([$2]); do
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| 34 | AS_VAR_PUSHDEF([gl_Symbol], [gl_cv_have_raw_decl_$gl_func])dnl
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| 35 | dnl As a workaround to implicit built-in function declarations in
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| 36 | dnl clang (e.g. strndup), reference ac_compile_for_check_decl instead
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| 37 | dnl of ac_compile. If, for whatever reason, the override of AC_PROG_CC
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| 38 | dnl in zzgnulib.m4 is inactive, use the original ac_compile.
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| 39 | ac_save_ac_compile="$ac_compile"
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| 40 | if test -n "$ac_compile_for_check_decl"; then
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| 41 | ac_compile="$ac_compile_for_check_decl"
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| 42 | fi
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| 43 | AC_CACHE_CHECK([whether $gl_func is declared without a macro],
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| 44 | [gl_Symbol],
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| 45 | [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([$1],
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| 46 | [[#undef $gl_func
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| 47 | (void) $gl_func;]])],
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| 48 | [AS_VAR_SET([gl_Symbol], [yes])], [AS_VAR_SET([gl_Symbol], [no])])])
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| 49 | ac_compile="$ac_save_ac_compile"
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| 50 | AS_VAR_IF([gl_Symbol], [yes],
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| 51 | [AC_DEFINE_UNQUOTED(AS_TR_CPP([HAVE_RAW_DECL_$gl_func]), [1])
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| 52 | dnl Shortcut for an AC_CHECK_DECL invocation that may come later:
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| 53 | dnl If the raw declaration exists with the given includes, then
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| 54 | dnl AC_CHECK_DECL with its many includes would see it as well.
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| 55 | dnl So, set a cache variable to allow skipping any later
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| 56 | dnl AC_CHECK_DECL invocation for $gl_func.
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| 57 | eval "ac_cv_have_decl_$gl_func=yes"
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| 58 | ])
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| 59 | AS_VAR_POPDEF([gl_Symbol])dnl
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| 60 | done
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| 61 | ])
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| 62 | ])
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