build: Use ASAN and GCC warnings from Gnulib

9 files changed, 823 insertions, 0 deletions

diff --git a/m4/ax_append_flag.m4 b/m4/ax_append_flag.m4
new file mode 100644
index 0000000..dd6d8b6
--- /dev/null
+++ b/m4/ax_append_flag.m4
@@ -0,0 +1,50 @@
+# ===========================================================================
+#      https://www.gnu.org/software/autoconf-archive/ax_append_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_APPEND_FLAG(FLAG, [FLAGS-VARIABLE])
+#
+# DESCRIPTION
+#
+#   FLAG is appended to the FLAGS-VARIABLE shell variable, with a space
+#   added in between.
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  FLAGS-VARIABLE is not changed if it already contains
+#   FLAG.  If FLAGS-VARIABLE is unset in the shell, it is set to exactly
+#   FLAG.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION.
+#
+# 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 8
+
+AC_DEFUN([AX_APPEND_FLAG],
+[dnl
+AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_SET_IF
+AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])])
+AS_VAR_SET_IF(FLAGS,[
+  AS_CASE([" AS_VAR_GET(FLAGS) "],
+    [*" $1 "*], [AC_RUN_LOG([: FLAGS already contains $1])],
+    [
+     AS_VAR_APPEND(FLAGS,[" $1"])
+     AC_RUN_LOG([: FLAGS="$FLAGS"])
+    ])
+  ],
+  [
+  AS_VAR_SET(FLAGS,[$1])
+  AC_RUN_LOG([: FLAGS="$FLAGS"])
+  ])
+AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_APPEND_FLAG
diff --git a/m4/ax_cflags_warn_all.m4 b/m4/ax_cflags_warn_all.m4
new file mode 100644
index 0000000..9235a18
--- /dev/null
+++ b/m4/ax_cflags_warn_all.m4
@@ -0,0 +1,158 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_cflags_warn_all.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CFLAGS_WARN_ALL   [(shellvar[, default[, action-if-found[, action-if-not-found]]])]
+#   AX_CXXFLAGS_WARN_ALL [(shellvar[, default[, action-if-found[, action-if-not-found]]])]
+#   AX_FCFLAGS_WARN_ALL  [(shellvar[, default[, action-if-found[, action-if-not-found]]])]
+#
+# DESCRIPTION
+#
+#   Specify compiler options that enable most reasonable warnings.  For the
+#   GNU Compiler Collection (GCC), for example, it will be "-Wall".  The
+#   result is added to shellvar, one of CFLAGS, CXXFLAGS or FCFLAGS if the
+#   first parameter is not specified.
+#
+#   Each of these macros accepts the following optional arguments:
+#
+#     - $1 - shellvar
+#         shell variable to use (CFLAGS, CXXFLAGS or FCFLAGS if not
+#         specified, depending on macro)
+#
+#     - $2 - default
+#         value to use for flags if compiler vendor cannot be determined (by
+#         default, "")
+#
+#     - $3 - action-if-found
+#         action to take if the compiler vendor has been successfully
+#         determined (by default, add the appropriate compiler flags to
+#         shellvar)
+#
+#     - $4 - action-if-not-found
+#         action to take if the compiler vendor has not been determined or
+#         is unknown (by default, add the default flags, or "" if not
+#         specified, to shellvar)
+#
+#   These macros use AX_COMPILER_VENDOR to determine which flags should be
+#   returned for a given compiler.  Not all compilers currently have flags
+#   defined for them; patches are welcome.  If need be, compiler flags may
+#   be made language-dependent: use a construct like the following:
+#
+#     [vendor_name], [m4_if(_AC_LANG_PREFIX,[C],   VAR="--relevant-c-flags",dnl
+#                     m4_if(_AC_LANG_PREFIX,[CXX], VAR="--relevant-c++-flags",dnl
+#                     m4_if(_AC_LANG_PREFIX,[FC],  VAR="--relevant-fortran-flags",dnl
+#                     VAR="$2"; FOUND="no")))],
+#
+#   Note: These macros also depend on AX_PREPEND_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2010 Rhys Ulerich <rhys.ulerich@gmail.com>
+#   Copyright (c) 2018 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 25
+
+AC_DEFUN([AX_FLAGS_WARN_ALL], [
+    AX_REQUIRE_DEFINED([AX_PREPEND_FLAG])dnl
+    AC_REQUIRE([AX_COMPILER_VENDOR])dnl
+
+    AS_VAR_PUSHDEF([FLAGS], [m4_default($1,_AC_LANG_PREFIX[]FLAGS)])dnl
+    AS_VAR_PUSHDEF([VAR],   [ac_cv_[]_AC_LANG_ABBREV[]flags_warn_all])dnl
+    AS_VAR_PUSHDEF([FOUND], [ac_save_[]_AC_LANG_ABBREV[]flags_warn_all_found])dnl
+
+    AC_CACHE_CHECK([FLAGS for most reasonable warnings], VAR, [
+	VAR=""
+	FOUND="yes"
+	dnl  Cases are listed in the order found in ax_compiler_vendor.m4
+	AS_CASE("$ax_cv_[]_AC_LANG_ABBREV[]_compiler_vendor",
+	    [intel],		[VAR="-w2"],
+	    [ibm],		[VAR="-qsrcmsg -qinfo=all:noppt:noppc:noobs:nocnd"],
+	    [pathscale],	[],
+	    [clang],		[VAR="-Wall"],
+	    [cray],		[VAR="-h msglevel 2"],
+	    [fujitsu],		[],
+	    [sdcc],		[],
+	    [sx],		[VAR="-pvctl[,]fullmsg"],
+	    [portland],		[],
+	    [gnu],		[VAR="-Wall"],
+	    [sun],		[VAR="-v"],
+	    [hp],		[VAR="+w1"],
+	    [dec],		[VAR="-verbose -w0 -warnprotos"],
+	    [borland],		[],
+	    [comeau],		[],
+	    [kai],		[],
+	    [lcc],		[],
+	    [sgi],		[VAR="-fullwarn"],
+	    [microsoft],	[],
+	    [metrowerks],	[],
+	    [watcom],		[],
+	    [tcc],		[],
+	    [unknown],		[
+				    VAR="$2"
+				    FOUND="no"
+				],
+				[
+				    AC_MSG_WARN([Unknown compiler vendor returned by [AX_COMPILER_VENDOR]])
+				    VAR="$2"
+				    FOUND="no"
+				]
+	)
+
+	AS_IF([test "x$FOUND" = "xyes"], [dnl
+	    m4_default($3, [AS_IF([test "x$VAR" != "x"], [AX_PREPEND_FLAG([$VAR], [FLAGS])])])
+	], [dnl
+	    m4_default($4, [m4_ifval($2, [AX_PREPEND_FLAG([$VAR], [FLAGS])], [true])])
+	])dnl
+    ])dnl
+
+    AS_VAR_POPDEF([FOUND])dnl
+    AS_VAR_POPDEF([VAR])dnl
+    AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_FLAGS_WARN_ALL
+
+AC_DEFUN([AX_CFLAGS_WARN_ALL], [dnl
+    AC_LANG_PUSH([C])
+    AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
+    AC_LANG_POP([C])
+])dnl
+
+AC_DEFUN([AX_CXXFLAGS_WARN_ALL], [dnl
+    AC_LANG_PUSH([C++])
+    AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
+    AC_LANG_POP([C++])
+])dnl
+
+AC_DEFUN([AX_FCFLAGS_WARN_ALL], [dnl
+    AC_LANG_PUSH([Fortran])
+    AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
+    AC_LANG_POP([Fortran])
+])dnl
diff --git a/m4/ax_check_compile_flag.m4 b/m4/ax_check_compile_flag.m4
new file mode 100644
index 0000000..bd753b3
--- /dev/null
+++ b/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
diff --git a/m4/ax_compiler_vendor.m4 b/m4/ax_compiler_vendor.m4
new file mode 100644
index 0000000..f06e865
--- /dev/null
+++ b/m4/ax_compiler_vendor.m4
@@ -0,0 +1,117 @@
+# ===========================================================================
+#    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", "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 30
+
+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
+		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/m4/ax_prepend_flag.m4 b/m4/ax_prepend_flag.m4
new file mode 100644
index 0000000..adac8c5
--- /dev/null
+++ b/m4/ax_prepend_flag.m4
@@ -0,0 +1,51 @@
+# ===========================================================================
+#     https://www.gnu.org/software/autoconf-archive/ax_prepend_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_PREPEND_FLAG(FLAG, [FLAGS-VARIABLE])
+#
+# DESCRIPTION
+#
+#   FLAG is added to the front of the FLAGS-VARIABLE shell variable, with a
+#   space added in between.
+#
+#   If FLAGS-VARIABLE is not specified, the current language's flags (e.g.
+#   CFLAGS) is used.  FLAGS-VARIABLE is not changed if it already contains
+#   FLAG.  If FLAGS-VARIABLE is unset in the shell, it is set to exactly
+#   FLAG.
+#
+#   NOTE: Implementation based on AX_APPEND_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#   Copyright (c) 2018 John Zaitseff <J.Zaitseff@zap.org.au>
+#
+#   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 2
+
+AC_DEFUN([AX_PREPEND_FLAG],
+[dnl
+AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_SET_IF
+AS_VAR_PUSHDEF([FLAGS], [m4_default($2,_AC_LANG_PREFIX[FLAGS])])
+AS_VAR_SET_IF(FLAGS,[
+  AS_CASE([" AS_VAR_GET(FLAGS) "],
+    [*" $1 "*], [AC_RUN_LOG([: FLAGS already contains $1])],
+    [
+     FLAGS="$1 $FLAGS"
+     AC_RUN_LOG([: FLAGS="$FLAGS"])
+    ])
+  ],
+  [
+  AS_VAR_SET(FLAGS,[$1])
+  AC_RUN_LOG([: FLAGS="$FLAGS"])
+  ])
+AS_VAR_POPDEF([FLAGS])dnl
+])dnl AX_PREPEND_FLAG
diff --git a/m4/ax_require_defined.m4 b/m4/ax_require_defined.m4
new file mode 100644
index 0000000..17c3eab
--- /dev/null
+++ b/m4/ax_require_defined.m4
@@ -0,0 +1,37 @@
+# ===========================================================================
+#    https://www.gnu.org/software/autoconf-archive/ax_require_defined.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_REQUIRE_DEFINED(MACRO)
+#
+# DESCRIPTION
+#
+#   AX_REQUIRE_DEFINED is a simple helper for making sure other macros have
+#   been defined and thus are available for use.  This avoids random issues
+#   where a macro isn't expanded.  Instead the configure script emits a
+#   non-fatal:
+#
+#     ./configure: line 1673: AX_CFLAGS_WARN_ALL: command not found
+#
+#   It's like AC_REQUIRE except it doesn't expand the required macro.
+#
+#   Here's an example:
+#
+#     AX_REQUIRE_DEFINED([AX_CHECK_LINK_FLAG])
+#
+# LICENSE
+#
+#   Copyright (c) 2014 Mike Frysinger <vapier@gentoo.org>
+#
+#   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 2
+
+AC_DEFUN([AX_REQUIRE_DEFINED], [dnl
+  m4_ifndef([$1], [m4_fatal([macro ]$1[ is not defined; is a m4 file missing?])])
+])dnl AX_REQUIRE_DEFINED
diff --git a/m4/gcc_version.m4 b/m4/gcc_version.m4
new file mode 100644
index 0000000..9e16450
--- /dev/null
+++ b/m4/gcc_version.m4
@@ -0,0 +1,38 @@
+dnl Copied from GNU Coreutils configure.ac
+dnl
+dnl The 17 lines are probably too trivial to be copyrightable, but just in case:
+dnl
+dnl Copyright (C) 1991-2017 Free Software Foundation, Inc.
+dnl
+dnl This program is free software: you can redistribute it and/or modify
+dnl it under the terms of the GNU General Public License as published by
+dnl the Free Software Foundation, either version 3 of the License, or
+dnl (at your option) any later version.
+dnl
+dnl This program is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl GNU General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU General Public License
+dnl along with this program.  If not, see <https://www.gnu.org/licenses/>.
+dnl
+dnl Written by Jim Meyering.
+
+# gl_GCC_VERSION_IFELSE([major], [minor], [run-if-found], [run-if-not-found])
+# ------------------------------------------------
+# If $CPP is gcc-MAJOR.MINOR or newer, then run RUN-IF-FOUND.
+# Otherwise, run RUN-IF-NOT-FOUND.
+AC_DEFUN([gl_GCC_VERSION_IFELSE],
+  [AC_PREPROC_IFELSE(
+    [AC_LANG_PROGRAM(
+      [[
+#if ($1) < __GNUC__ || (($1) == __GNUC__ && ($2) <= __GNUC_MINOR__)
+/* ok */
+#else
+# error "your version of gcc is older than $1.$2"
+#endif
+      ]]),
+    ], [$3], [$4])
+  ]
+)
diff --git a/m4/gl_manywarnings.m4 b/m4/gl_manywarnings.m4
new file mode 100644
index 0000000..872ea58
--- /dev/null
+++ b/m4/gl_manywarnings.m4
@@ -0,0 +1,209 @@
+# manywarnings.m4 serial 23
+dnl Copyright (C) 2008-2021 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 From Simon Josefsson
+
+# gl_MANYWARN_COMPLEMENT(OUTVAR, LISTVAR, REMOVEVAR)
+# --------------------------------------------------
+# Copy LISTVAR to OUTVAR except for the entries in REMOVEVAR.
+# Elements separated by whitespace.  In set logic terms, the function
+# does OUTVAR = LISTVAR \ REMOVEVAR.
+AC_DEFUN([gl_MANYWARN_COMPLEMENT],
+[
+  gl_warn_set=
+  set x $2; shift
+  for gl_warn_item
+  do
+    case " $3 " in
+      *" $gl_warn_item "*)
+        ;;
+      *)
+        gl_AS_VAR_APPEND([gl_warn_set], [" $gl_warn_item"])
+        ;;
+    esac
+  done
+  $1=$gl_warn_set
+])
+
+# gl_MANYWARN_ALL_GCC(VARIABLE)
+# -----------------------------
+# Add all documented GCC warning parameters to variable VARIABLE.
+# Note that you need to test them using gl_WARN_ADD if you want to
+# make sure your gcc understands it.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_MANYWARN_ALL_GCC],
+[_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
+
+# Specialization for _AC_LANG = C.
+AC_DEFUN([gl_MANYWARN_ALL_GCC(C)],
+[
+  AC_LANG_PUSH([C])
+
+  dnl First, check for some issues that only occur when combining multiple
+  dnl gcc warning categories.
+  AC_REQUIRE([AC_PROG_CC])
+  if test -n "$GCC"; then
+
+    dnl Check if -Wextra -Werror -Wno-missing-field-initializers is supported
+    dnl with the current $CC $CFLAGS $CPPFLAGS.
+    AC_CACHE_CHECK([whether -Wno-missing-field-initializers is supported],
+      [gl_cv_cc_nomfi_supported],
+      [gl_save_CFLAGS="$CFLAGS"
+       CFLAGS="$CFLAGS -Wextra -Werror -Wno-missing-field-initializers"
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM([[]], [[]])],
+         [gl_cv_cc_nomfi_supported=yes],
+         [gl_cv_cc_nomfi_supported=no])
+       CFLAGS="$gl_save_CFLAGS"
+      ])
+
+    if test "$gl_cv_cc_nomfi_supported" = yes; then
+      dnl Now check whether -Wno-missing-field-initializers is needed
+      dnl for the { 0, } construct.
+      AC_CACHE_CHECK([whether -Wno-missing-field-initializers is needed],
+        [gl_cv_cc_nomfi_needed],
+        [gl_save_CFLAGS="$CFLAGS"
+         CFLAGS="$CFLAGS -Wextra -Werror"
+         AC_COMPILE_IFELSE(
+           [AC_LANG_PROGRAM(
+              [[int f (void)
+                {
+                  typedef struct { int a; int b; } s_t;
+                  s_t s1 = { 0, };
+                  return s1.b;
+                }
+              ]],
+              [[]])],
+           [gl_cv_cc_nomfi_needed=no],
+           [gl_cv_cc_nomfi_needed=yes])
+         CFLAGS="$gl_save_CFLAGS"
+        ])
+    fi
+
+    dnl Next, check if -Werror -Wuninitialized is useful with the
+    dnl user's choice of $CFLAGS; some versions of gcc warn that it
+    dnl has no effect if -O is not also used
+    AC_CACHE_CHECK([whether -Wuninitialized is supported],
+      [gl_cv_cc_uninitialized_supported],
+      [gl_save_CFLAGS="$CFLAGS"
+       CFLAGS="$CFLAGS -Werror -Wuninitialized"
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM([[]], [[]])],
+         [gl_cv_cc_uninitialized_supported=yes],
+         [gl_cv_cc_uninitialized_supported=no])
+       CFLAGS="$gl_save_CFLAGS"
+      ])
+
+  fi
+
+  # List all gcc warning categories.
+  # To compare this list to your installed GCC's, run this Bash command:
+  #
+  # comm -3 \
+  #  <((sed -n 's/^  *\(-[^ 0-9][^ ]*\).*/\1/p' manywarnings.m4; \
+  #     awk '/^[^#]/ {print $1}' ../build-aux/gcc-warning.spec) | sort) \
+  #  <(LC_ALL=C gcc --help=warnings | sed -n 's/^  \(-[^ ]*\) .*/\1/p' | sort)
+
+  $1=
+  for gl_manywarn_item in -fanalyzer -fno-common \
+    -Wall \
+    -Warith-conversion \
+    -Wbad-function-cast \
+    -Wcast-align=strict \
+    -Wdate-time \
+    -Wdisabled-optimization \
+    -Wdouble-promotion \
+    -Wduplicated-branches \
+    -Wduplicated-cond \
+    -Wextra \
+    -Wformat-signedness \
+    -Winit-self \
+    -Winline \
+    -Winvalid-pch \
+    -Wlogical-op \
+    -Wmissing-declarations \
+    -Wmissing-include-dirs \
+    -Wmissing-prototypes \
+    -Wnested-externs \
+    -Wnull-dereference \
+    -Wold-style-definition \
+    -Wopenmp-simd \
+    -Woverlength-strings \
+    -Wpacked \
+    -Wpointer-arith \
+    -Wshadow \
+    -Wstack-protector \
+    -Wstrict-overflow \
+    -Wstrict-prototypes \
+    -Wsuggest-attribute=cold \
+    -Wsuggest-attribute=const \
+    -Wsuggest-attribute=format \
+    -Wsuggest-attribute=malloc \
+    -Wsuggest-attribute=noreturn \
+    -Wsuggest-attribute=pure \
+    -Wsuggest-final-methods \
+    -Wsuggest-final-types \
+    -Wsync-nand \
+    -Wsystem-headers \
+    -Wtrampolines \
+    -Wuninitialized \
+    -Wunknown-pragmas \
+    -Wunsafe-loop-optimizations \
+    -Wunused-macros \
+    -Wvariadic-macros \
+    -Wvector-operation-performance \
+    -Wvla \
+    -Wwrite-strings \
+    \
+    ; do
+    gl_AS_VAR_APPEND([$1], [" $gl_manywarn_item"])
+  done
+
+  # gcc --help=warnings outputs an unusual form for these options; list
+  # them here so that the above 'comm' command doesn't report a false match.
+  gl_AS_VAR_APPEND([$1], [' -Warray-bounds=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wattribute-alias=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wformat-overflow=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wformat=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wformat-truncation=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wimplicit-fallthrough=5'])
+  gl_AS_VAR_APPEND([$1], [' -Wshift-overflow=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wunused-const-variable=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wvla-larger-than=4031'])
+
+  # These are needed for older GCC versions.
+  if test -n "$GCC"; then
+    case `($CC --version) 2>/dev/null` in
+      'gcc (GCC) '[[0-3]].* | \
+      'gcc (GCC) '4.[[0-7]].*)
+        gl_AS_VAR_APPEND([$1], [' -fdiagnostics-show-option'])
+        gl_AS_VAR_APPEND([$1], [' -funit-at-a-time'])
+          ;;
+    esac
+  fi
+
+  # Disable specific options as needed.
+  if test "$gl_cv_cc_nomfi_needed" = yes; then
+    gl_AS_VAR_APPEND([$1], [' -Wno-missing-field-initializers'])
+  fi
+
+  if test "$gl_cv_cc_uninitialized_supported" = no; then
+    gl_AS_VAR_APPEND([$1], [' -Wno-uninitialized'])
+  fi
+
+  # This warning have too many false alarms in GCC 11.2.1.
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101713
+  gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-malloc-leak'])
+
+  AC_LANG_POP([C])
+])
+
+# Specialization for _AC_LANG = C++.
+AC_DEFUN([gl_MANYWARN_ALL_GCC(C++)],
+[
+  gl_MANYWARN_ALL_GCC_CXX_IMPL([$1])
+])
diff --git a/m4/gl_warnings.m4 b/m4/gl_warnings.m4
new file mode 100644
index 0000000..9e24d89
--- /dev/null
+++ b/m4/gl_warnings.m4
@@ -0,0 +1,110 @@
+# warnings.m4 serial 16
+dnl Copyright (C) 2008-2021 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 From Simon Josefsson
+
+# gl_AS_VAR_APPEND(VAR, VALUE)
+# ----------------------------
+# Provide the functionality of AS_VAR_APPEND if Autoconf does not have it.
+m4_ifdef([AS_VAR_APPEND],
+[m4_copy([AS_VAR_APPEND], [gl_AS_VAR_APPEND])],
+[m4_define([gl_AS_VAR_APPEND],
+[AS_VAR_SET([$1], [AS_VAR_GET([$1])$2])])])
+
+
+# gl_COMPILER_OPTION_IF(OPTION, [IF-SUPPORTED], [IF-NOT-SUPPORTED],
+#                       [PROGRAM = AC_LANG_PROGRAM()])
+# -----------------------------------------------------------------
+# Check if the compiler supports OPTION when compiling PROGRAM.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_COMPILER_OPTION_IF],
+[
+AS_VAR_PUSHDEF([gl_Warn], [gl_cv_warn_[]_AC_LANG_ABBREV[]_$1])dnl
+AS_VAR_PUSHDEF([gl_Flags], [_AC_LANG_PREFIX[]FLAGS])dnl
+AS_LITERAL_IF([$1],
+  [m4_pushdef([gl_Positive], m4_bpatsubst([$1], [^-Wno-], [-W]))],
+  [gl_positive="$1"
+case $gl_positive in
+  -Wno-*) gl_positive=-W`expr "X$gl_positive" : 'X-Wno-\(.*\)'` ;;
+esac
+m4_pushdef([gl_Positive], [$gl_positive])])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], [gl_Warn], [
+  gl_save_compiler_FLAGS="$gl_Flags"
+  gl_AS_VAR_APPEND(m4_defn([gl_Flags]),
+    [" $gl_unknown_warnings_are_errors ]m4_defn([gl_Positive])["])
+  AC_LINK_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([[]])])],
+                 [AS_VAR_SET([gl_Warn], [yes])],
+                 [AS_VAR_SET([gl_Warn], [no])])
+  gl_Flags="$gl_save_compiler_FLAGS"
+])
+AS_VAR_IF(gl_Warn, [yes], [$2], [$3])
+m4_popdef([gl_Positive])dnl
+AS_VAR_POPDEF([gl_Flags])dnl
+AS_VAR_POPDEF([gl_Warn])dnl
+])
+
+# gl_UNKNOWN_WARNINGS_ARE_ERRORS
+# ------------------------------
+# Clang doesn't complain about unknown warning options unless one also
+# specifies -Wunknown-warning-option -Werror.  Detect this.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],
+[_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
+
+# Specialization for _AC_LANG = C. This macro can be AC_REQUIREd.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
+[
+  AC_LANG_PUSH([C])
+  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
+  AC_LANG_POP([C])
+])
+
+# Specialization for _AC_LANG = C++. This macro can be AC_REQUIREd.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
+[
+  AC_LANG_PUSH([C++])
+  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
+  AC_LANG_POP([C++])
+])
+
+# Specialization for _AC_LANG = Objective C. This macro can be AC_REQUIREd.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(Objective C)],
+[
+  AC_LANG_PUSH([Objective C])
+  gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
+  AC_LANG_POP([Objective C])
+])
+
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL],
+[gl_COMPILER_OPTION_IF([-Werror -Wunknown-warning-option],
+   [gl_unknown_warnings_are_errors='-Wunknown-warning-option -Werror'],
+   [gl_unknown_warnings_are_errors=])])
+
+# gl_WARN_ADD(OPTION, [VARIABLE = WARN_CFLAGS/WARN_CXXFLAGS],
+#             [PROGRAM = AC_LANG_PROGRAM()])
+# -----------------------------------------------------------
+# Adds parameter to WARN_CFLAGS/WARN_CXXFLAGS if the compiler supports it
+# when compiling PROGRAM.  For example, gl_WARN_ADD([-Wparentheses]).
+#
+# If VARIABLE is a variable name, AC_SUBST it.
+#
+# The effects of this macro depend on the current language (_AC_LANG).
+AC_DEFUN([gl_WARN_ADD],
+[AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS(]_AC_LANG[)])
+gl_COMPILER_OPTION_IF([$1],
+  [gl_AS_VAR_APPEND(m4_if([$2], [], [[WARN_]_AC_LANG_PREFIX[FLAGS]], [[$2]]), [" $1"])],
+  [],
+  [$3])
+m4_ifval([$2],
+         [AS_LITERAL_IF([$2], [AC_SUBST([$2])])],
+         [AC_SUBST([WARN_]_AC_LANG_PREFIX[FLAGS])])dnl
+])
+
+# Local Variables:
+# mode: autoconf
+# End: