Remove build/ (#16600)

14 files changed, 0 insertions, 2312 deletions

diff --git a/build/m4/ax_c__generic.m4 b/build/m4/ax_c__generic.m4
deleted file mode 100644
index 0c4dd52c6a..0000000000
--- a/build/m4/ax_c__generic.m4
+++ /dev/null
@@ -1,28 +0,0 @@
-# https://lists.gnu.org/archive/html/autoconf-commit/2012-12/msg00004.html
-# AC_C__GENERIC
-# -------------
-# Define HAVE_C__GENERIC if _Generic works, a la C11.
-AN_IDENTIFIER([_Generic], [AC_C__GENERIC])
-AC_DEFUN([AC_C__GENERIC],
-[AC_CACHE_CHECK([for _Generic], ac_cv_c__Generic,
-[AC_COMPILE_IFELSE(
-   [AC_LANG_SOURCE(
-      [[int
-        main (int argc, char **argv)
-        {
-          int a = _Generic (argc, int: argc = 1);
-          int *b = &_Generic (argc, default: argc);
-          char ***c = _Generic (argv, int: argc, default: argv ? &argv : 0);
-          _Generic (1 ? 0 : b, int: a, default: b) = &argc;
-          _Generic (a = 1, default: a) = 3;
-          return a + !b + !c;
-        }
-      ]])],
-   [ac_cv_c__Generic=yes],
-   [ac_cv_c__Generic=no])])
-if test $ac_cv_c__Generic = yes; then
-  AC_DEFINE([HAVE_C__GENERIC], 1,
-           [Define to 1 if C11-style _Generic works.])
-fi
-])# AC_C__GENERIC
-
diff --git a/build/m4/ax_c_lto.m4 b/build/m4/ax_c_lto.m4
deleted file mode 100644
index 7e6bc0119f..0000000000
--- a/build/m4/ax_c_lto.m4
+++ /dev/null
@@ -1,21 +0,0 @@
-# AC_C_LTO
-# -------------
-# Define HAVE_LTO if -flto works.
-AN_IDENTIFIER([lto], [AC_C_LTO])
-AC_DEFUN([AC_C_LTO],
-[AC_CACHE_CHECK([if -flto builds executables], ac_cv_c_lto,
-[AC_RUN_IFELSE(
-   [AC_LANG_SOURCE(
-      [[#include <stdio.h>
-        int main(int argc, char **argv) {
-          return 0;
-        }
-      ]])],
-   [ac_cv_c_lto=yes],
-   [ac_cv_c_lto=no],
-   [ac_cv_c_lto=${ac_cv_c_lto_cross_compile}])])
-if test "${ac_cv_c_lto}" = "yes"; then
-  AC_DEFINE([HAVE_LTO], 1,
-           [Define to 1 if -flto works.])
-fi
-])# AC_C_LTO
diff --git a/build/m4/ax_c_mallinfo.m4 b/build/m4/ax_c_mallinfo.m4
deleted file mode 100644
index af8d0481e5..0000000000
--- a/build/m4/ax_c_mallinfo.m4
+++ /dev/null
@@ -1,24 +0,0 @@
-# AC_C_MALLINFO
-# -------------
-# Define HAVE_C_MALLINFO if mallinfo() works.
-AN_IDENTIFIER([mallinfo], [AC_C_MALLINFO])
-AC_DEFUN([AC_C_MALLINFO],
-[AC_CACHE_CHECK([for mallinfo], ac_cv_c_mallinfo,
-[AC_LINK_IFELSE(
-  [AC_LANG_PROGRAM(
-    [[#include <malloc.h>]],
-    [[
-      struct mallinfo mi = mallinfo();
-      /* make sure that fields exists */
-      mi.uordblks = 0;
-      mi.hblkhd = 0;
-      mi.arena = 0;
-    ]]
-  )],
-  [ac_cv_c_mallinfo=yes],
-  [ac_cv_c_mallinfo=no])])
-if test $ac_cv_c_mallinfo = yes; then
-  AC_DEFINE([HAVE_C_MALLINFO], 1,
-           [Define to 1 if glibc mallinfo exists.])
-fi
-])# AC_C_MALLINFO
diff --git a/build/m4/ax_c_mallopt.m4 b/build/m4/ax_c_mallopt.m4
deleted file mode 100644
index 31c4fdc36a..0000000000
--- a/build/m4/ax_c_mallopt.m4
+++ /dev/null
@@ -1,20 +0,0 @@
-# AC_C_MALLOPT
-# -------------
-# Define HAVE_C_MALLOPT if mallopt() works.
-AN_IDENTIFIER([mallopt], [AC_C_MALLOPT])
-AC_DEFUN([AC_C_MALLOPT],
-[AC_CACHE_CHECK([for mallopt], ac_cv_c_mallopt,
-[AC_LINK_IFELSE(
-   [AC_LANG_SOURCE(
-      [[#include <malloc.h>
-        int main(int argc, char **argv) {
-          mallopt(M_ARENA_MAX, 1);
-        }
-      ]])],
-   [ac_cv_c_mallopt=yes],
-   [ac_cv_c_mallopt=no])])
-if test $ac_cv_c_mallopt = yes; then
-  AC_DEFINE([HAVE_C_MALLOPT], 1,
-           [Define to 1 if glibc mallopt exists.])
-fi
-])# AC_C_MALLOPT
diff --git a/build/m4/ax_c_statement_expressions.m4 b/build/m4/ax_c_statement_expressions.m4
deleted file mode 100644
index fb259e7275..0000000000
--- a/build/m4/ax_c_statement_expressions.m4
+++ /dev/null
@@ -1,23 +0,0 @@
-# AC_C_STMT_EXPR
-# -------------
-# Define HAVE_STMT_EXPR if compiler has statement expressions.
-AN_IDENTIFIER([_Generic], [AC_C_STMT_EXPR])
-AC_DEFUN([AC_C_STMT_EXPR],
-[AC_CACHE_CHECK([for statement expressions], ac_cv_c_stmt_expr,
-[AC_COMPILE_IFELSE(
-   [AC_LANG_SOURCE(
-      [[int
-        main (int argc, char **argv)
-        {
-          int x = ({ int y = 1; y; });
-          return x;
-        }
-      ]])],
-   [ac_cv_c_stmt_expr=yes],
-   [ac_cv_c_stmt_expr=no])])
-if test $ac_cv_c_stmt_expr = yes; then
-  AC_DEFINE([HAVE_STMT_EXPR], 1,
-           [Define to 1 if compiler supports statement expressions.])
-fi
-])# AC_C_STMT_EXPR
-
diff --git a/build/m4/ax_check_compile_flag.m4 b/build/m4/ax_check_compile_flag.m4
deleted file mode 100644
index c515602f00..0000000000
--- a/build/m4/ax_check_compile_flag.m4
+++ /dev/null
@@ -1,50 +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], [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>
-#
-#   SPDX-License-Identifier: GPL-3.0
-
-#serial 3
-
-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],
-  [m4_default([$2], :)],
-  [m4_default([$3], :)])
-AS_VAR_POPDEF([CACHEVAR])dnl
-])dnl AX_CHECK_COMPILE_FLAGS
diff --git a/build/m4/ax_check_enable_debug.m4 b/build/m4/ax_check_enable_debug.m4
deleted file mode 100644
index db5bab2f40..0000000000
--- a/build/m4/ax_check_enable_debug.m4
+++ /dev/null
@@ -1,122 +0,0 @@
-# ===========================================================================
-#   http://www.gnu.org/software/autoconf-archive/ax_check_enable_debug.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CHECK_ENABLE_DEBUG([enable by default=yes/info/profile/no], [ENABLE DEBUG VARIABLES ...], [DISABLE DEBUG VARIABLES NDEBUG ...], [IS-RELEASE])
-#
-# DESCRIPTION
-#
-#   Check for the presence of an --enable-debug option to configure, with
-#   the specified default value used when the option is not present.  Return
-#   the value in the variable $ax_enable_debug.
-#
-#   Specifying 'yes' adds '-g -O0' to the compilation flags for all
-#   languages. Specifying 'info' adds '-g' to the compilation flags.
-#   Specifying 'profile' adds '-g -pg' to the compilation flags and '-pg' to
-#   the linking flags. Otherwise, nothing is added.
-#
-#   Define the variables listed in the second argument if debug is enabled,
-#   defaulting to no variables.  Defines the variables listed in the third
-#   argument if debug is disabled, defaulting to NDEBUG.  All lists of
-#   variables should be space-separated.
-#
-#   If debug is not enabled, ensure AC_PROG_* will not add debugging flags.
-#   Should be invoked prior to any AC_PROG_* compiler checks.
-#
-#   IS-RELEASE can be used to change the default to 'no' when making a
-#   release.  Set IS-RELEASE to 'yes' or 'no' as appropriate. By default, it
-#   uses the value of $ax_is_release, so if you are using the AX_IS_RELEASE
-#   macro, there is no need to pass this parameter.
-#
-#     AX_IS_RELEASE([git-directory])
-#     AX_CHECK_ENABLE_DEBUG()
-#
-# LICENSE
-#
-#   Copyright (c) 2011 Rhys Ulerich <rhys.ulerich@gmail.com>
-#   Copyright (c) 2014, 2015 Philip Withnall <philip@tecnocode.co.uk>
-#
-#   SPDX-License-Identifier: FSFAP
-
-#serial 5
-
-AC_DEFUN([AX_CHECK_ENABLE_DEBUG],[
-    AC_BEFORE([$0],[AC_PROG_CC])dnl
-    AC_BEFORE([$0],[AC_PROG_CXX])dnl
-    AC_BEFORE([$0],[AC_PROG_F77])dnl
-    AC_BEFORE([$0],[AC_PROG_FC])dnl
-
-    AC_MSG_CHECKING(whether to enable debugging)
-
-    ax_enable_debug_default=m4_tolower(m4_normalize(ifelse([$1],,[no],[$1])))
-    ax_enable_debug_is_release=m4_tolower(m4_normalize(ifelse([$4],,
-                                                              [$ax_is_release],
-                                                              [$4])))
-
-    # If this is a release, override the default.
-    AS_IF([test "$ax_enable_debug_is_release" = "yes"],
-      [ax_enable_debug_default="no"])
-
-    m4_define(ax_enable_debug_vars,[m4_normalize(ifelse([$2],,,[$2]))])
-    m4_define(ax_disable_debug_vars,[m4_normalize(ifelse([$3],,[NDEBUG],[$3]))])
-
-    AC_ARG_ENABLE(debug,
-	[AS_HELP_STRING([--enable-debug=]@<:@yes/info/profile/no@:>@,[compile with debugging])],
-	[],enable_debug=$ax_enable_debug_default)
-
-    # empty mean debug yes
-    AS_IF([test "x$enable_debug" = "x"],
-      [enable_debug="yes"])
-
-    # case of debug
-    AS_CASE([$enable_debug],
-      [yes],[
-	AC_MSG_RESULT(yes)
-	CFLAGS="${CFLAGS} -g -O0"
-	CXXFLAGS="${CXXFLAGS} -g -O0"
-	FFLAGS="${FFLAGS} -g -O0"
-	FCFLAGS="${FCFLAGS} -g -O0"
-	OBJCFLAGS="${OBJCFLAGS} -g -O0"
-      ],
-      [info],[
-	AC_MSG_RESULT(info)
-	CFLAGS="${CFLAGS} -g"
-	CXXFLAGS="${CXXFLAGS} -g"
-	FFLAGS="${FFLAGS} -g"
-	FCFLAGS="${FCFLAGS} -g"
-	OBJCFLAGS="${OBJCFLAGS} -g"
-      ],
-      [profile],[
-	AC_MSG_RESULT(profile)
-	CFLAGS="${CFLAGS} -g -pg"
-	CXXFLAGS="${CXXFLAGS} -g -pg"
-	FFLAGS="${FFLAGS} -g -pg"
-	FCFLAGS="${FCFLAGS} -g -pg"
-	OBJCFLAGS="${OBJCFLAGS} -g -pg"
-	LDFLAGS="${LDFLAGS} -pg"
-      ],
-      [
-	AC_MSG_RESULT(no)
-	dnl Ensure AC_PROG_CC/CXX/F77/FC/OBJC will not enable debug flags
-	dnl by setting any unset environment flag variables
-	AS_IF([test "x${CFLAGS+set}" != "xset"],
-	  [CFLAGS=""])
-	AS_IF([test "x${CXXFLAGS+set}" != "xset"],
-	  [CXXFLAGS=""])
-	AS_IF([test "x${FFLAGS+set}" != "xset"],
-	  [FFLAGS=""])
-	AS_IF([test "x${FCFLAGS+set}" != "xset"],
-	  [FCFLAGS=""])
-	AS_IF([test "x${OBJCFLAGS+set}" != "xset"],
-	  [OBJCFLAGS=""])
-      ])
-
-    dnl Define various variables if debugging is disabled.
-    dnl assert.h is a NOP if NDEBUG is defined, so define it by default.
-    AS_IF([test "x$enable_debug" = "xyes"],
-      [m4_map_args_w(ax_enable_debug_vars, [AC_DEFINE(], [,,[Define if debugging is enabled])])],
-      [m4_map_args_w(ax_disable_debug_vars, [AC_DEFINE(], [,,[Define if debugging is disabled])])])
-    ax_enable_debug=$enable_debug
-])
diff --git a/build/m4/ax_compiler_vendor.m4 b/build/m4/ax_compiler_vendor.m4
deleted file mode 100644
index 039f99d2bd..0000000000
--- a/build/m4/ax_compiler_vendor.m4
+++ /dev/null
@@ -1,119 +0,0 @@
-# ===========================================================================
-#    https://www.gnu.org/software/autoconf-archive/ax_compiler_vendor.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_COMPILER_VENDOR
-#
-# DESCRIPTION
-#
-#   Determine the vendor of the C, C++ or Fortran compiler.  The vendor is
-#   returned in the cache variable $ax_cv_c_compiler_vendor for C,
-#   $ax_cv_cxx_compiler_vendor for C++ or $ax_cv_fc_compiler_vendor for
-#   (modern) Fortran.  The value is one of "intel", "ibm", "pathscale",
-#   "clang" (LLVM), "cray", "fujitsu", "sdcc", "sx", "nvhpc" (NVIDIA HPC
-#   Compiler), "portland" (PGI), "gnu" (GCC), "sun" (Oracle Developer
-#   Studio), "hp", "dec", "borland", "comeau", "kai", "lcc", "sgi",
-#   "microsoft", "metrowerks", "watcom", "tcc" (Tiny CC) or "unknown" (if
-#   the compiler cannot be determined).
-#
-#   To check for a Fortran compiler, you must first call AC_FC_PP_SRCEXT
-#   with an appropriate preprocessor-enabled extension.  For example:
-#
-#     AC_LANG_PUSH([Fortran])
-#     AC_PROG_FC
-#     AC_FC_PP_SRCEXT([F])
-#     AX_COMPILER_VENDOR
-#     AC_LANG_POP([Fortran])
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>
-#   Copyright (c) 2008 Matteo Frigo
-#   Copyright (c) 2018-19 John Zaitseff <J.Zaitseff@zap.org.au>
-#
-#   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 <https://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 32
-
-AC_DEFUN([AX_COMPILER_VENDOR], [dnl
-    AC_CACHE_CHECK([for _AC_LANG compiler vendor], ax_cv_[]_AC_LANG_ABBREV[]_compiler_vendor, [dnl
-	dnl  If you modify this list of vendors, please add similar support
-	dnl  to ax_compiler_version.m4 if at all possible.
-	dnl
-	dnl  Note: Do NOT check for GCC first since some other compilers
-	dnl  define __GNUC__ to remain compatible with it.  Compilers that
-	dnl  are very slow to start (such as Intel) are listed first.
-
-	vendors="
-		intel:		__ICC,__ECC,__INTEL_COMPILER
-		ibm:		__xlc__,__xlC__,__IBMC__,__IBMCPP__,__ibmxl__
-		pathscale:	__PATHCC__,__PATHSCALE__
-		clang:		__clang__
-		cray:		_CRAYC
-		fujitsu:	__FUJITSU
-		sdcc:		SDCC,__SDCC
-		sx:		_SX
-		nvhpc:		__NVCOMPILER
-		portland:	__PGI
-		gnu:		__GNUC__
-		sun:		__SUNPRO_C,__SUNPRO_CC,__SUNPRO_F90,__SUNPRO_F95
-		hp:		__HP_cc,__HP_aCC
-		dec:		__DECC,__DECCXX,__DECC_VER,__DECCXX_VER
-		borland:	__BORLANDC__,__CODEGEARC__,__TURBOC__
-		comeau:		__COMO__
-		kai:		__KCC
-		lcc:		__LCC__
-		sgi:		__sgi,sgi
-		microsoft:	_MSC_VER
-		metrowerks:	__MWERKS__
-		watcom:		__WATCOMC__
-		tcc:		__TINYC__
-		unknown:	UNKNOWN
-	"
-	for ventest in $vendors; do
-	    case $ventest in
-		*:)
-		    vendor=$ventest
-		    continue
-		    ;;
-		*)
-		    vencpp="defined("`echo $ventest | sed 's/,/) || defined(/g'`")"
-		    ;;
-	    esac
-
-	    AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [[
-#if !($vencpp)
-      thisisanerror;
-#endif
-	    ]])], [break])
-	done
-
-	ax_cv_[]_AC_LANG_ABBREV[]_compiler_vendor=`echo $vendor | cut -d: -f1`
-    ])
-])dnl
diff --git a/build/m4/ax_cxx_compile_stdcxx.m4 b/build/m4/ax_cxx_compile_stdcxx.m4
deleted file mode 100644
index 8edf5152ec..0000000000
--- a/build/m4/ax_cxx_compile_stdcxx.m4
+++ /dev/null
@@ -1,1018 +0,0 @@
-# ===========================================================================
-#  https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html
-# ===========================================================================
-#
-# SYNOPSIS
-#
-#   AX_CXX_COMPILE_STDCXX(VERSION, [ext|noext], [mandatory|optional])
-#
-# DESCRIPTION
-#
-#   Check for baseline language coverage in the compiler for the specified
-#   version of the C++ standard.  If necessary, add switches to CXX and
-#   CXXCPP to enable support.  VERSION may be '11', '14', '17', or '20' for
-#   the respective C++ standard version.
-#
-#   The second argument, if specified, indicates whether you insist on an
-#   extended mode (e.g. -std=gnu++11) or a strict conformance mode (e.g.
-#   -std=c++11).  If neither is specified, you get whatever works, with
-#   preference for no added switch, and then for an extended mode.
-#
-#   The third argument, if specified 'mandatory' or if left unspecified,
-#   indicates that baseline support for the specified C++ standard is
-#   required and that the macro should error out if no mode with that
-#   support is found.  If specified 'optional', then configuration proceeds
-#   regardless, after defining HAVE_CXX${VERSION} if and only if a
-#   supporting mode is found.
-#
-# LICENSE
-#
-#   Copyright (c) 2008 Benjamin Kosnik <bkoz@redhat.com>
-#   Copyright (c) 2012 Zack Weinberg <zackw@panix.com>
-#   Copyright (c) 2013 Roy Stogner <roystgnr@ices.utexas.edu>
-#   Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov <sokolov@google.com>
-#   Copyright (c) 2015 Paul Norman <penorman@mac.com>
-#   Copyright (c) 2015 Moritz Klammler <moritz@klammler.eu>
-#   Copyright (c) 2016, 2018 Krzesimir Nowak <qdlacz@gmail.com>
-#   Copyright (c) 2019 Enji Cooper <yaneurabeya@gmail.com>
-#   Copyright (c) 2020 Jason Merrill <jason@redhat.com>
-#   Copyright (c) 2021 Jörn Heusipp <osmanx@problemloesungsmaschine.de>
-#
-#   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 18
-
-dnl  This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro
-dnl  (serial version number 13).
-
-AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl
-  m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"],
-        [$1], [14], [ax_cxx_compile_alternatives="14 1y"],
-        [$1], [17], [ax_cxx_compile_alternatives="17 1z"],
-        [$1], [20], [ax_cxx_compile_alternatives="20"],
-        [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl
-  m4_if([$2], [], [],
-        [$2], [ext], [],
-        [$2], [noext], [],
-        [m4_fatal([invalid second argument `$2' to AX_CXX_COMPILE_STDCXX])])dnl
-  m4_if([$3], [], [ax_cxx_compile_cxx$1_required=true],
-        [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true],
-        [$3], [optional], [ax_cxx_compile_cxx$1_required=false],
-        [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])])
-  AC_LANG_PUSH([C++])dnl
-  ac_success=no
-
-  m4_if([$2], [], [dnl
-    AC_CACHE_CHECK(whether $CXX supports C++$1 features by default,
-		   ax_cv_cxx_compile_cxx$1,
-      [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
-        [ax_cv_cxx_compile_cxx$1=yes],
-        [ax_cv_cxx_compile_cxx$1=no])])
-    if test x$ax_cv_cxx_compile_cxx$1 = xyes; then
-      ac_success=yes
-    fi])
-
-  m4_if([$2], [noext], [], [dnl
-  if test x$ac_success = xno; then
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      switch="-std=gnu++${alternative}"
-      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
-      AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
-                     $cachevar,
-        [ac_save_CXX="$CXX"
-         CXX="$CXX $switch"
-         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
-          [eval $cachevar=yes],
-          [eval $cachevar=no])
-         CXX="$ac_save_CXX"])
-      if eval test x\$$cachevar = xyes; then
-        CXX="$CXX $switch"
-        if test -n "$CXXCPP" ; then
-          CXXCPP="$CXXCPP $switch"
-        fi
-        ac_success=yes
-        break
-      fi
-    done
-  fi])
-
-  m4_if([$2], [ext], [], [dnl
-  if test x$ac_success = xno; then
-    dnl HP's aCC needs +std=c++11 according to:
-    dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf
-    dnl Cray's crayCC needs "-h std=c++11"
-    dnl MSVC needs -std:c++NN for C++17 and later (default is C++14)
-    for alternative in ${ax_cxx_compile_alternatives}; do
-      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
-        if test x"$switch" = xMSVC; then
-          dnl AS_TR_SH maps both `:` and `=` to `_` so -std:c++17 would collide
-          dnl with -std=c++17.  We suffix the cache variable name with _MSVC to
-          dnl avoid this.
-          switch=-std:c++${alternative}
-          cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_${switch}_MSVC])
-        else
-          cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch])
-        fi
-        AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch,
-                       $cachevar,
-          [ac_save_CXX="$CXX"
-           CXX="$CXX $switch"
-           AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])],
-            [eval $cachevar=yes],
-            [eval $cachevar=no])
-           CXX="$ac_save_CXX"])
-        if eval test x\$$cachevar = xyes; then
-          CXX="$CXX $switch"
-          if test -n "$CXXCPP" ; then
-            CXXCPP="$CXXCPP $switch"
-          fi
-          ac_success=yes
-          break
-        fi
-      done
-      if test x$ac_success = xyes; then
-        break
-      fi
-    done
-  fi])
-  AC_LANG_POP([C++])
-  if test x$ax_cxx_compile_cxx$1_required = xtrue; then
-    if test x$ac_success = xno; then
-      AC_MSG_ERROR([*** A compiler with support for C++$1 language features is required.])
-    fi
-  fi
-  if test x$ac_success = xno; then
-    HAVE_CXX$1=0
-    AC_MSG_NOTICE([No compiler with C++$1 support was found])
-  else
-    HAVE_CXX$1=1
-    AC_DEFINE(HAVE_CXX$1,1,
-              [define if the compiler supports basic C++$1 syntax])
-  fi
-  AC_SUBST(HAVE_CXX$1)
-])
-
-
-dnl  Test body for checking C++11 support
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_11],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-)
-
-dnl  Test body for checking C++14 support
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
-)
-
-dnl  Test body for checking C++17 support
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
-)
-
-dnl  Test body for checking C++20 support
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_20],
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_11
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_14
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_17
-  _AX_CXX_COMPILE_STDCXX_testbody_new_in_20
-)
-
-
-dnl  Tests for new features in C++11
-
-m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_11], [[
-
-// If the compiler admits that it is not ready for C++11, why torture it?
-// Hopefully, this will speed up the test.
-
-#ifndef __cplusplus
-
-#error "This is not a C++ compiler"
-
-// MSVC always sets __cplusplus to 199711L in older versions; newer versions
-// only set it correctly if /Zc:__cplusplus is specified as well as a
-// /std:c++NN switch:
-// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
-#elif __cplusplus < 201103L && !defined _MSC_VER
-
-#error "This is not a C++11 compiler"
-
-#else
-
-namespace cxx11
-{
-
-  namespace test_static_assert
-  {
-
-    template <typename T>
-    struct check
-    {
-      static_assert(sizeof(int) <= sizeof(T), "not big enough");
-    };
-
-  }
-
-  namespace test_final_override
-  {
-
-    struct Base
-    {
-      virtual ~Base() {}
-      virtual void f() {}
-    };
-
-    struct Derived : public Base
-    {
-      virtual ~Derived() override {}
-      virtual void f() override {}
-    };
-
-  }
-
-  namespace test_double_right_angle_brackets
-  {
-
-    template < typename T >
-    struct check {};
-
-    typedef check<void> single_type;
-    typedef check<check<void>> double_type;
-    typedef check<check<check<void>>> triple_type;
-    typedef check<check<check<check<void>>>> quadruple_type;
-
-  }
-
-  namespace test_decltype
-  {
-
-    int
-    f()
-    {
-      int a = 1;
-      decltype(a) b = 2;
-      return a + b;
-    }
-
-  }
-
-  namespace test_type_deduction
-  {
-
-    template < typename T1, typename T2 >
-    struct is_same
-    {
-      static const bool value = false;
-    };
-
-    template < typename T >
-    struct is_same<T, T>
-    {
-      static const bool value = true;
-    };
-
-    template < typename T1, typename T2 >
-    auto
-    add(T1 a1, T2 a2) -> decltype(a1 + a2)
-    {
-      return a1 + a2;
-    }
-
-    int
-    test(const int c, volatile int v)
-    {
-      static_assert(is_same<int, decltype(0)>::value == true, "");
-      static_assert(is_same<int, decltype(c)>::value == false, "");
-      static_assert(is_same<int, decltype(v)>::value == false, "");
-      auto ac = c;
-      auto av = v;
-      auto sumi = ac + av + 'x';
-      auto sumf = ac + av + 1.0;
-      static_assert(is_same<int, decltype(ac)>::value == true, "");
-      static_assert(is_same<int, decltype(av)>::value == true, "");
-      static_assert(is_same<int, decltype(sumi)>::value == true, "");
-      static_assert(is_same<int, decltype(sumf)>::value == false, "");
-      static_assert(is_same<int, decltype(add(c, v))>::value == true, "");
-      return (sumf > 0.0) ? sumi : add(c, v);
-    }
-
-  }
-
-  namespace test_noexcept
-  {
-
-    int f() { return 0; }
-    int g() noexcept { return 0; }
-
-    static_assert(noexcept(f()) == false, "");
-    static_assert(noexcept(g()) == true, "");
-
-  }
-
-  namespace test_constexpr
-  {
-
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c_r(const CharT *const s, const unsigned long acc) noexcept
-    {
-      return *s ? strlen_c_r(s + 1, acc + 1) : acc;
-    }
-
-    template < typename CharT >
-    unsigned long constexpr
-    strlen_c(const CharT *const s) noexcept
-    {
-      return strlen_c_r(s, 0UL);
-    }
-
-    static_assert(strlen_c("") == 0UL, "");
-    static_assert(strlen_c("1") == 1UL, "");
-    static_assert(strlen_c("example") == 7UL, "");
-    static_assert(strlen_c("another\0example") == 7UL, "");
-
-  }
-
-  namespace test_rvalue_references
-  {
-
-    template < int N >
-    struct answer
-    {
-      static constexpr int value = N;
-    };
-
-    answer<1> f(int&)       { return answer<1>(); }
-    answer<2> f(const int&) { return answer<2>(); }
-    answer<3> f(int&&)      { return answer<3>(); }
-
-    void
-    test()
-    {
-      int i = 0;
-      const int c = 0;
-      static_assert(decltype(f(i))::value == 1, "");
-      static_assert(decltype(f(c))::value == 2, "");
-      static_assert(decltype(f(0))::value == 3, "");
-    }
-
-  }
-
-  namespace test_uniform_initialization
-  {
-
-    struct test
-    {
-      static const int zero {};
-      static const int one {1};
-    };
-
-    static_assert(test::zero == 0, "");
-    static_assert(test::one == 1, "");
-
-  }
-
-  namespace test_lambdas
-  {
-
-    void
-    test1()
-    {
-      auto lambda1 = [](){};
-      auto lambda2 = lambda1;
-      lambda1();
-      lambda2();
-    }
-
-    int
-    test2()
-    {
-      auto a = [](int i, int j){ return i + j; }(1, 2);
-      auto b = []() -> int { return '0'; }();
-      auto c = [=](){ return a + b; }();
-      auto d = [&](){ return c; }();
-      auto e = [a, &b](int x) mutable {
-        const auto identity = [](int y){ return y; };
-        for (auto i = 0; i < a; ++i)
-          a += b--;
-        return x + identity(a + b);
-      }(0);
-      return a + b + c + d + e;
-    }
-
-    int
-    test3()
-    {
-      const auto nullary = [](){ return 0; };
-      const auto unary = [](int x){ return x; };
-      using nullary_t = decltype(nullary);
-      using unary_t = decltype(unary);
-      const auto higher1st = [](nullary_t f){ return f(); };
-      const auto higher2nd = [unary](nullary_t f1){
-        return [unary, f1](unary_t f2){ return f2(unary(f1())); };
-      };
-      return higher1st(nullary) + higher2nd(nullary)(unary);
-    }
-
-  }
-
-  namespace test_variadic_templates
-  {
-
-    template <int...>
-    struct sum;
-
-    template <int N0, int... N1toN>
-    struct sum<N0, N1toN...>
-    {
-      static constexpr auto value = N0 + sum<N1toN...>::value;
-    };
-
-    template <>
-    struct sum<>
-    {
-      static constexpr auto value = 0;
-    };
-
-    static_assert(sum<>::value == 0, "");
-    static_assert(sum<1>::value == 1, "");
-    static_assert(sum<23>::value == 23, "");
-    static_assert(sum<1, 2>::value == 3, "");
-    static_assert(sum<5, 5, 11>::value == 21, "");
-    static_assert(sum<2, 3, 5, 7, 11, 13>::value == 41, "");
-
-  }
-
-  // http://stackoverflow.com/questions/13728184/template-aliases-and-sfinae
-  // Clang 3.1 fails with headers of libstd++ 4.8.3 when using std::function
-  // because of this.
-  namespace test_template_alias_sfinae
-  {
-
-    struct foo {};
-
-    template<typename T>
-    using member = typename T::member_type;
-
-    template<typename T>