-# 00gnulib.m4 serial 3
-dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
+# 00gnulib.m4 serial 8
+dnl Copyright (C) 2009-2022 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
dnl This file must be named something that sorts before all other
-dnl gnulib-provided .m4 files. It is needed until such time as we can
-dnl assume Autoconf 2.64, with its improved AC_DEFUN_ONCE and
-dnl m4_divert semantics.
+dnl gnulib-provided .m4 files. It is needed until the clang fix has
+dnl been included in Autoconf.
-# Until autoconf 2.63, handling of the diversion stack required m4_init
-# to be called first; but this does not happen with aclocal. Wrapping
-# the entire execution in another layer of the diversion stack fixes this.
-# Worse, prior to autoconf 2.62, m4_wrap depended on the underlying m4
-# for whether it was FIFO or LIFO; in order to properly balance with
-# m4_init, we need to undo our push just before anything wrapped within
-# the m4_init body. The way to ensure this is to wrap both sides of
-# m4_init with a one-shot macro that does the pop at the right time.
-m4_ifndef([_m4_divert_diversion],
-[m4_divert_push([KILL])
-m4_define([gl_divert_fixup], [m4_divert_pop()m4_define([$0])])
-m4_define([m4_init],
- [gl_divert_fixup()]m4_defn([m4_init])[gl_divert_fixup()])])
-
-
-# AC_DEFUN_ONCE([NAME], VALUE)
-# ----------------------------
-# Define NAME to expand to VALUE on the first use (whether by direct
-# expansion, or by AC_REQUIRE), and to nothing on all subsequent uses.
-# Avoid bugs in AC_REQUIRE in Autoconf 2.63 and earlier. This
-# definition is slower than the version in Autoconf 2.64, because it
-# can only use interfaces that existed since 2.59; but it achieves the
-# same effect. Quoting is necessary to avoid confusing Automake.
-m4_version_prereq([2.63.263], [],
-[m4_define([AC][_DEFUN_ONCE],
- [AC][_DEFUN([$1],
- [AC_REQUIRE([_gl_DEFUN_ONCE([$1])],
- [m4_indir([_gl_DEFUN_ONCE([$1])])])])]dnl
-[AC][_DEFUN([_gl_DEFUN_ONCE([$1])], [$2])])])
+# The following definitions arrange to use a compiler option
+# -Werror=implicit-function-declaration in AC_CHECK_DECL, when the
+# compiler is clang. Without it, clang implicitly declares "known"
+# library functions in C mode, but not in C++ mode, which would cause
+# Gnulib to omit a declaration and thus later produce an error in C++
+# mode. As of clang 9.0, these "known" functions are identified through
+# LIBBUILTIN invocations in the LLVM source file
+# llvm/tools/clang/include/clang/Basic/Builtins.def.
+# It's not possible to AC_REQUIRE the extra tests from AC_CHECK_DECL,
+# because AC_CHECK_DECL, like other Autoconf built-ins, is not supposed
+# to AC_REQUIRE anything: some configure.ac files have their first
+# AC_CHECK_DECL executed conditionally. Therefore append the extra tests
+# to AC_PROG_CC.
+AC_DEFUN([gl_COMPILER_CLANG],
+[
+dnl AC_REQUIRE([AC_PROG_CC])
+ AC_CACHE_CHECK([whether the compiler is clang],
+ [gl_cv_compiler_clang],
+ [dnl Use _AC_COMPILE_IFELSE instead of AC_EGREP_CPP, to avoid error
+ dnl "circular dependency of AC_LANG_COMPILER(C)" if AC_PROG_CC has
+ dnl not yet been invoked.
+ _AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([[
+ #ifdef __clang__
+ barfbarf
+ #endif
+ ]],[[]])
+ ],
+ [gl_cv_compiler_clang=no],
+ [gl_cv_compiler_clang=yes])
+ ])
+])
+AC_DEFUN([gl_COMPILER_PREPARE_CHECK_DECL],
+[
+dnl AC_REQUIRE([AC_PROG_CC])
+dnl AC_REQUIRE([gl_COMPILER_CLANG])
+ AC_CACHE_CHECK([for compiler option needed when checking for declarations],
+ [gl_cv_compiler_check_decl_option],
+ [if test $gl_cv_compiler_clang = yes; then
+ dnl Test whether the compiler supports the option
+ dnl '-Werror=implicit-function-declaration'.
+ save_ac_compile="$ac_compile"
+ ac_compile="$ac_compile -Werror=implicit-function-declaration"
+ dnl Use _AC_COMPILE_IFELSE instead of AC_COMPILE_IFELSE, to avoid a
+ dnl warning "AC_COMPILE_IFELSE was called before AC_USE_SYSTEM_EXTENSIONS".
+ _AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]],[[]])],
+ [gl_cv_compiler_check_decl_option='-Werror=implicit-function-declaration'],
+ [gl_cv_compiler_check_decl_option=none])
+ ac_compile="$save_ac_compile"
+ else
+ gl_cv_compiler_check_decl_option=none
+ fi
+ ])
+ if test "x$gl_cv_compiler_check_decl_option" != xnone; then
+ ac_compile_for_check_decl="$ac_compile $gl_cv_compiler_check_decl_option"
+ else
+ ac_compile_for_check_decl="$ac_compile"
+ fi
+])
+dnl Redefine _AC_CHECK_DECL_BODY so that it references ac_compile_for_check_decl
+dnl instead of ac_compile. If, for whatever reason, the override of AC_PROG_CC
+dnl in zzgnulib.m4 is inactive, use the original ac_compile.
+m4_define([_AC_CHECK_DECL_BODY],
+[ ac_save_ac_compile="$ac_compile"
+ if test -n "$ac_compile_for_check_decl"; then
+ ac_compile="$ac_compile_for_check_decl"
+ fi]
+m4_defn([_AC_CHECK_DECL_BODY])[ ac_compile="$ac_save_ac_compile"
+])
# gl_00GNULIB
# -----------
projects / platform / upstream / make.git / blobdiff