add compiler check for c++17

configure.ac

@@ -3,11 +3,13 @@ AC_INIT([patchelf], m4_esyscmd([printf $(cat ./version)]))
 AC_CONFIG_SRCDIR([src/patchelf.cc])
 AC_CONFIG_AUX_DIR([build-aux])
 AM_INIT_AUTOMAKE([1.11.1 -Wall -Werror dist-bzip2 foreign color-tests parallel-tests])
+AC_CONFIG_MACRO_DIR([m4])
 
 AC_CHECK_TOOL([STRIP], [strip])
 
 AM_PROG_CC_C_O
 AC_PROG_CXX
+AC_LANG([C++])
 AM_PROG_AS
 
 DEFAULT_PAGESIZE=auto
@@ -31,5 +33,12 @@ AC_ARG_WITH([ubsan],
 )
 AM_CONDITIONAL([WITH_UBSAN], [test x"$with_ubsan" = xyes])
 
+CPLUSPLUS=
+AX_CHECK_COMPILE_FLAG([-std=c++17], [CPLUSPLUS=17], [], [$WERROR])
+
+if test -z "$CPLUSPLUS"; then
+  AC_MSG_ERROR([Your compiler does not have the necessary C++17 support! Cannot proceed.])
+fi
+
 AC_CONFIG_FILES([Makefile src/Makefile tests/Makefile patchelf.spec])
 AC_OUTPUT

m4/ax_check_compile_flag.m4

@@ -0,0 +1,53 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# 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.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   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 <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 6
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+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_VAR_IF(CACHEVAR,yes,
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS