-# gnulib-common.m4 serial 73.5
+# gnulib-common.m4 serial 73.6
dnl Copyright (C) 2007-2023 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
m4_popdef([gl_header_name])
])
+dnl Preparations for gl_CHECK_FUNCS_MACOS.
+AC_DEFUN([gl_PREPARE_CHECK_FUNCS_MACOS],
+[
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_REQUIRE([gl_COMPILER_CLANG])
+ AC_CACHE_CHECK([for compiler option needed when checking for future declarations],
+ [gl_cv_compiler_check_future_option],
+ [case "$host_os" in
+ dnl This is only needed on macOS.
+ darwin*)
+ if test $gl_cv_compiler_clang = yes; then
+ dnl Test whether the compiler supports the option
+ dnl '-Werror=unguarded-availability-new'.
+ save_ac_compile="$ac_compile"
+ ac_compile="$ac_compile -Werror=unguarded-availability-new"
+ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],
+ [gl_cv_compiler_check_future_option='-Werror=unguarded-availability-new'],
+ [gl_cv_compiler_check_future_option=none])
+ ac_compile="$save_ac_compile"
+ else
+ gl_cv_compiler_check_future_option=none
+ fi
+ ;;
+ *) gl_cv_compiler_check_future_option=none ;;
+ esac
+ ])
+])
+
+dnl gl_CHECK_FUNCS_MACOS([func], [[#include <foo.h>]])
+dnl is like AC_CHECK_FUNCS([func]), taking into account a portability problem
+dnl on macOS.
+dnl
+dnl When code is compiled on macOS, it is in the context of a certain minimum
+dnl macOS version, that can be set through the option '-mmacosx-version-min='.
+dnl In other words, you don't compile for a specific version of macOS. You
+dnl compile for all versions of macOS, onwards from the given version.
+dnl Thus, the question "does the OS have the function func" has three possible
+dnl answers:
+dnl - yes, in all versions starting from the given version,
+dnl - no, in no version,
+dnl - not in the given version, but in a later version of macOS.
+dnl
+dnl In detail, this works as follows:
+dnl If func was added to, say, macOS version 13, then the libc has the
+dnl symbol func always, whereas the header file <foo.h> declares func
+dnl conditionally with a special availability attribute:
+dnl ... func (...) __attribute__((availability(macos,introduced=13.0)));
+dnl Thus, when compiling with "clang mmacosx-version-min=13", there is no
+dnl warning about the use of func, and the resulting binary
+dnl - runs fine on macOS 13,
+dnl - aborts with a dyld "Symbol not found" message on macOS 12.
+dnl Whereas, when compiling with "clang mmacosx-version-min=12", there is a
+dnl warning: 'func' is only available on macOS 13.0 or newer
+dnl [-Wunguarded-availability-new],
+dnl and the resulting binary
+dnl - runs fine on macOS 13,
+dnl - crashes with a SIGSEGV (signal 11) on macOS 12.
+dnl
+dnl This macro sets two variables:
+dnl - gl_cv_onwards_func_<func> to yes / no / "future OS version"
+dnl - ac_cv_func_<func> to yes / no / no
+dnl The first variable allows to distinguish all three cases.
+dnl The second variable is set, so that an invocation
+dnl gl_CHECK_FUNCS_MACOS([func], [[#include <foo.h>]])
+dnl can be used as a drop-in replacement for
+dnl AC_CHECK_FUNCS([func]).
+AC_DEFUN([gl_CHECK_FUNCS_MACOS],
+[
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_REQUIRE([gl_PREPARE_CHECK_FUNCS_MACOS])
+ AC_CACHE_CHECK([for [$1]],
+ [[gl_cv_onwards_func_][$1]],
+ [gl_SILENT([
+ case "$host_os" in
+ darwin*)
+ if test "x$gl_cv_compiler_check_future_option" != "xnone"; then
+ dnl Use a compile test, not a link test.
+ save_ac_compile="$ac_compile"
+ ac_compile="$ac_compile $gl_cv_compiler_check_future_option"
+ save_ac_compile_for_check_decl="$ac_compile_for_check_decl"
+ ac_compile_for_check_decl="$ac_compile_for_check_decl $gl_cv_compiler_check_future_option"
+ unset [ac_cv_have_decl_][$1]
+ AC_CHECK_DECL([$1], , , [$2])
+ ac_compile="$save_ac_compile"
+ ac_compile_for_check_decl="$save_ac_compile_for_check_decl"
+ [ac_cv_func_][$1]="$[ac_cv_have_decl_][$1]"
+ if test $[ac_cv_func_][$1] = yes; then
+ [gl_cv_onwards_func_][$1]=yes
+ else
+ unset [ac_cv_have_decl_][$1]
+ AC_CHECK_DECL([$1], , , [$2])
+ if test $[ac_cv_have_decl_][$1] = yes; then
+ [gl_cv_onwards_func_][$1]='future OS version'
+ else
+ [gl_cv_onwards_func_][$1]=no
+ fi
+ fi
+ else
+ AC_CHECK_FUNC([$1])
+ [gl_cv_onwards_func_][$1]=$[ac_cv_func_][$1]
+ fi
+ ;;
+ *)
+ AC_CHECK_FUNC([$1])
+ [gl_cv_onwards_func_][$1]=$[ac_cv_func_][$1]
+ ;;
+ esac
+ ])
+ ])
+ case "$[gl_cv_onwards_func_][$1]" in
+ future*) [ac_cv_func_][$1]=no ;;
+ *) [ac_cv_func_][$1]=$[gl_cv_onwards_func_][$1] ;;
+ esac
+ if test $[ac_cv_func_][$1] = yes; then
+ AC_DEFINE([HAVE_]m4_translit([[$1]],
+ [abcdefghijklmnopqrstuvwxyz],
+ [ABCDEFGHIJKLMNOPQRSTUVWXYZ]),
+ [1], [Define to 1 if you have the `$1' function.])
+ fi
+])
+
dnl Expands to some code for use in .c programs that, on native Windows, defines
dnl the Microsoft deprecated alias function names to the underscore-prefixed
dnl actual function names. With this macro, these function names are available