build: try to avoid the case of a broken libc++

[Akim Demaille]

commit f157583c2d6f48efcabd5d9fa316bd659158bd28
Author: Akim Demaille <address@hidden>
Date:   Tue Sep 18 07:05:01 2018 +0200

    build: try to avoid the case of a broken libc++
    
    Use AC_LINK_IFELSE to check the compiler (and its std lib) rather than
    just AC_COMPILE_IFELSE.
    
    * m4/ax_check_compile_flag.m4 (AX_CHECK_COMPILE_FLAG): Rewrite as...
    * m4/bison-check-compile-flag.m4 (BISON_CHECK_COMPILE_FLAG): this.

diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
deleted file mode 100644
index 71d4f365..00000000
--- a/m4/ax_check_compile_flag.m4
+++ /dev/null
@@ -1,70 +0,0 @@
-# ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], 
[EXTRA-FLAGS])
-#
-# DESCRIPTION
-#
-#   Check whether the given FLAG works with the current language's compiler
-#   or gives an error.  (Warnings, however, are ignored)
-#
-#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
-#   success/failure.
-#
-#   If EXTRA-FLAGS is defined, it is added to the current language's default
-#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
-#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
-#   force the compiler to issue an error when a bad flag is given.
-#
-#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
-#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Guido U. Draheim <address@hidden>
-#   Copyright (c) 2011 Maarten Bosmans <address@hidden>
-#
-#   This program is free software: you can redistribute it and/or modify it
-#   under the terms of the GNU General Public License as published by the
-#   Free Software Foundation, either version 3 of the License, or (at your
-#   option) any later version.
-#
-#   This program is distributed in the hope that it will be useful, but
-#   WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
-#   Public License for more details.
-#
-#   You should have received a copy of the GNU General Public License along
-#   with this program. If not, see <http://www.gnu.org/licenses/>.
-#
-#   As a special exception, the respective Autoconf Macro's copyright owner
-#   gives unlimited permission to copy, distribute and modify the configure
-#   scripts that are the output of Autoconf when processing the Macro. You
-#   need not follow the terms of the GNU General Public License when using
-#   or distributing such scripts, even though portions of the text of the
-#   Macro appear in them. The GNU General Public License (GPL) does govern
-#   all other use of the material that constitutes the Autoconf Macro.
-#
-#   This special exception to the GPL applies to versions of the Autoconf
-#   Macro released by the Autoconf Archive. When you make and distribute a
-#   modified version of the Autoconf Macro, you may extend this special
-#   exception to the GPL to apply to your modified version as well.
-
-#serial 2
-
-AC_DEFUN([AX_CHECK_COMPILE_FLAG],
-[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
-AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
-AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
-  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
-  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
-  AC_COMPILE_IFELSE([m4_default([$5], [AC_LANG_PROGRAM()])],
-    [AS_VAR_SET(CACHEVAR,[yes])],
-    [AS_VAR_SET(CACHEVAR,[no])])
-  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
-AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes], [$2], [$3])
-AS_VAR_POPDEF([CACHEVAR])dnl
-])dnl AX_CHECK_COMPILE_FLAGS
diff --git a/m4/bison-check-compile-flag.m4 b/m4/bison-check-compile-flag.m4
new file mode 100644
index 00000000..fc80d45b
--- /dev/null
+++ b/m4/bison-check-compile-flag.m4
@@ -0,0 +1,39 @@
+# bison-check-compile-flag.m4
+
+# serial 1
+
+# Copyright (C) 2018 Free Software Foundation, # Inc.
+
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+
+
+# BISON_CHECK_COMPILE_FLAG(FLAG,
+#                          [ACTION-SUCCESS], [ACTION-FAILURE],
+#                          [EXTRA-FLAGS])
+# ------------------------------------------------------------
+
+# Based on Autoconf Macro Archive's AX_CHECK_COMPILE_FLAG, but using
+# AC_LINK_IFELSE, not just AC_COMPILE_IFELSE to capture failures such
+# as:
+#
+#  ./c++.at:401:  $PREPARSER ./list
+#  stderr:
+#  ./list: error while loading shared libraries: libc++.so.1: cannot open 
shared object file: No such file or directory
+#
+# because we thought '-stdlib=c++' works, as it passes with AC_COMPILE_IFELSE.
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.59)dnl for _AC_LANG_PREFIX
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_LINK_IFELSE([m4_default([$5], [AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_IF([test x"AS_VAR_GET(CACHEVAR)" = xyes], [$2], [$3])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS