30 files changed, 885 insertions, 519 deletions

diff --git a/.gitignore b/.gitignore
index cd341c2..3c7427f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,7 +4,8 @@
 *~
 *.orig
 
-# Files generated by aclocal, autoconf, and automake
+# Files generated by gettextize, aclocal, autoconf, and automake
+/ABOUT-NLS
 /aclocal.m4
 /autom4te.cache/
 /configure
@@ -28,7 +29,7 @@ Makefile
 .dirstamp
 *.o
 /version.c
-/@
+/atsign
 /test-suite.log
 /atsign-*.tar*
 /atsign-*/
diff --git a/Makefile.am b/Makefile.am
index 0048520..b53c109 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,6 +1,6 @@
 # Process this file with automake to produce an input makefile.
 #
-# Copyright (C) 2013, 2014, 2017, 2018, 2021  P. J. McDermott
+# Copyright (C) 2013, 2014, 2017, 2018, 2021, 2022  P. J. McDermott
 #
 # This file is part of @
 #
@@ -40,33 +40,39 @@ endif
 #   * Our release target
 PACKAGE_STRING = $(PACKAGE_NAME) $(PACKAGE_VERSION)$(PACKAGE_VERSION_GIT)
 
-bin_PROGRAMS = @
+# Automake lib/am/check.am since version 1.16.3 defines this with single quotes,
+# which breaks PACKAGE_VERSION_GIT above.
+AM_TESTSUITE_SUMMARY_HEADER = " for $(PACKAGE_STRING)"
 
-@_SOURCES =
-@_CFLAGS = \
+bin_PROGRAMS = atsign
+
+atsign_SOURCES =
+atsign_CFLAGS = \
 	$(WARN_CFLAGS) \
 	$(ASAN_CFLAGS)
-@_CPPFLAGS = \
+atsign_CPPFLAGS = \
 	$(SDL_CFLAGS) \
 	$(SDL_TTF_CFLAGS) \
 	-DABS_BUILDDIR=\"$(abs_builddir)\" \
-	-DFONTSDIR=\"$(fontsdir)\"
-@_LDADD = \
+	-DLOCALEDIR=\"$(localedir)\"
+atsign_LDADD = \
 	$(ASAN_CFLAGS) \
 	$(SDL_LIBS) \
 	$(SDL_TTF_LIBS)
-@_LINK = $(LINK) version.c
-EXTRA_@_DEPENDENCIES = version.c
+atsign_LINK = $(LINK) version.c
+EXTRA_atsign_DEPENDENCIES = version.c
 CLEANFILES = version.c
 CONFIG_CLEAN_FILES =
-EXTRA_DIST = autogen.sh FORMATS
+EXTRA_DIST = build-aux/config.rpath autogen.sh
 
 V_REDIR = $(V_REDIR_$(V))
 V_REDIR_ = $(V_REDIR_$(AM_DEFAULT_VERBOSITY))
 V_REDIR_0 = 1>/dev/null 2>&1
 V_REDIR_1 =
 
-version.c: $(@_OBJECTS) $(@_DEPENDENCIES)
+SUFFIXES =
+
+version.c: $(atsign_OBJECTS) $(atsign_DEPENDENCIES)
 	$(AM_V_GEN)printf 'const char *PACKAGE_VERSION_GIT = "%s";\n' \
 		"$(PACKAGE_VERSION_GIT)" >version.c
 
@@ -77,7 +83,37 @@ really-clean: distclean
 		$(srcdir)/build-aux/ $(srcdir)/INSTALL $(srcdir)/Makefile.in \
 		$(srcdir)/ChangeLog
 
+if ENABLE_SYMLINK
+install-exec-hook:
+	@set -e; \
+		dir="$(DESTDIR)$(bindir)"; \
+		dst="$$(printf 'atsign' | \
+			sed '$(transform); s/$$/$(EXEEXT)/')"; \
+		src='@$(EXEEXT)'; \
+		echo " (cd '$${dir}' && $(LN_S) '$${dst}' '$${src}')"; \
+		(cd "$${dir}" && $(LN_S) "$${dst}" "$${src}")
+install-data-hook:
+	@set -e; \
+		dir="$(DESTDIR)$(man1dir)"; \
+		dst="$$(printf 'atsign' | \
+			sed '$(transform); s/$$/$(EXEEXT)/').1"; \
+		src='@$(EXEEXT).1'; \
+		echo " (cd '$${dir}' && $(LN_S) '$${dst}' '$${src}')"; \
+		(cd "$${dir}" && $(LN_S) "$${dst}" "$${src}")
+uninstall-hook:
+	echo " rm -f '$(DESTDIR)$(bindir)/@$(EXEEXT)'"
+	rm -f "$(DESTDIR)$(bindir)/@$(EXEEXT)"
+endif
+
+if ENABLE_TESTS
+if CROSS_COMPILING
 dist-hook:
+else !CROSS_COMPILING
+dist-hook: atsign$(EXEEXT)
+endif !CROSS_COMPILING
+else !ENABLE_TESTS
+dist-hook:
+endif !ENABLE_TESTS
 if IN_GIT
 	printf 'Generated file.  Do not edit.\n\n' 1>'$(distdir)/ChangeLog~'
 	GIT_DIR='$(srcdir)/.git' git log --stat --color=never \
@@ -86,16 +122,21 @@ if IN_GIT
 endif
 if ENABLE_TESTS
 if CROSS_COMPILING
-	if ! [ -f 'FORMATS' ]; then \
+	if [ -f 'FORMATS' ]; then \
+		cp -p 'FORMATS' '$(distdir)/FORMATS'; \
+	else \
 		printf 'Error: "FORMATS" file cannot be generated when %s' \
 			'cross compiling' 1>&2; \
 		exit 1; \
 	fi
 else !CROSS_COMPILING
-	$(srcdir)/@ -d '1969-12-31 19:00:01' -F 1>FORMATS
+	$(builddir)/atsign$(EXEEXT) -d '1969-12-31 19:00:01' -F \
+		1>'$(distdir)/FORMATS'
 endif !CROSS_COMPILING
 else !ENABLE_TESTS
-	if ! [ -f 'FORMATS' ]; then \
+	if [ -f 'FORMATS' ]; then \
+		cp -p 'FORMATS' '$(distdir)/FORMATS'; \
+	else \
 		printf 'Error: "FORMATS" file cannot be generated without %s' \
 			'test suite support' 1>&2; \
 		exit 1; \
@@ -127,4 +168,7 @@ release:
 		files@files.pehjota.net:files/pub/$(PACKAGE)/$(VERSION)/
 
 include $(top_srcdir)/src/local.mk
+include $(top_srcdir)/man/local.mk
 include $(top_srcdir)/tests/local.mk
+
+SUBDIRS = . po
diff --git a/TODO b/TODO
index b8f4d77..6396ebe 100644
--- a/TODO
+++ b/TODO
@@ -1,6 +1,4 @@
+try to fix dst bug
 test with other libc's (newlib? musl? fbsd? obsd?)
 `./@ 7:00 PM` doesn't work with musl strptime()
 test other times
-update copyright years
-distcheck
-gettext?
diff --git a/autogen.sh b/autogen.sh
index c80fde1..d11efe6 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -2,7 +2,7 @@
 #
 # Script to generate the build system.
 #
-# Copyright (C) 2013  P. J. McDermott
+# Copyright (C) 2013, 2019  P. J. McDermott
 #
 # Copying and distribution of this file, with or without modification,
 # are permitted in any medium without royalty provided the copyright
@@ -19,6 +19,12 @@ srcdir="${0%/*}"
 	cat >ChangeLog <<-EOF
 This file is generated upon release.  Run \`git log\` for a list of changes.
 EOF
+	# Force gettextize to be non-interactive.  Stupid but necessary.
+	LC_ALL=C expect -f - <<-EOF
+		spawn gettextize --force --no-changelog
+		expect "Press Return to acknowledge the previous * paragraphs."
+		send "\n"
+		EOF
 	aclocal
 	autoconf
 	autoheader
diff --git a/configure.ac b/configure.ac
index cb1f0ce..5b527de 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,6 +1,6 @@
 # Process this file with autoconf to produce a configure script.
 #
-# Copyright (C) 2013, 2017, 2019, 2021  P. J. McDermott
+# Copyright (C) 2013, 2017, 2019, 2021, 2022  P. J. McDermott
 #
 # This file is part of @
 #
@@ -32,6 +32,12 @@ AM_CONDITIONAL([OUT_OF_TREE], [test x"${srcdir}" != x'.' ])
 
 AM_CONDITIONAL([CROSS_COMPILING], [! test x"${build_alias}" = x"${host_alias}"])
 
+GETTEXT_PACKAGE="${PACKAGE}"
+AC_SUBST([GETTEXT_PACKAGE])
+AC_DEFINE_UNQUOTED([GETTEXT_PACKAGE], ["${GETTEXT_PACKAGE}"],
+	[Define the gettext package to be used.])
+AM_GNU_GETTEXT([external])
+
 save_CFLAGS="${CFLAGS-}"
 AC_PROG_CC()
 AM_PROG_CC_C_O()
@@ -42,7 +48,7 @@ AC_CHECK_FUNCS(
 	[\
 		calloc difftime fprintf fputs free isspace localtime mktime \
 		printf realloc setvbuf sleep strerror strlen strftime strptime \
-		time timegm
+		time
 	],
 	[],
 	[funcs_missing=true])
@@ -56,17 +62,26 @@ if ${funcs_missing}; then
 	AC_MSG_ERROR([required functions are missing])
 fi
 
+AC_PROG_LN_S()
+AC_ARG_ENABLE([symlink],
+	[AS_HELP_STRING([--disable-symlink],
+		[don't install \`@' symbolic link])],
+	[case "${enableval}" in yes|no) symlink=${enableval};;
+		*) AC_MSG_ERROR(
+			[bad value ${enableval} for symlink option]);;
+	esac],
+	[symlink=yes]
+)
+AM_CONDITIONAL([ENABLE_SYMLINK], [test x"${symlink}" = x'yes'])
+
 AC_ARG_ENABLE([tests],
-	[AS_HELP_STRING([--enable-tests],
-		[include test suite support in executable])],
+	[AS_HELP_STRING([--disable-tests],
+		[exclude test suite support from executable])],
 	[case "${enableval}" in yes|no) tests=${enableval};;
 		*) AC_MSG_ERROR(
 			[bad value ${enableval} for tests option]);;
 	esac],
-	[
-		tests=no
-		test -d "${srcdir}/.git" && tests=yes
-	]
+	[tests=yes]
 )
 if test x"${tests}" = x'yes'; then
 	AC_DEFINE([ENABLE_TESTS], [1],
@@ -142,6 +157,6 @@ for flag in -Os -fno-unwind-tables -fno-asynchronous-unwind-tables \
 	AX_CHECK_COMPILE_FLAG([${flag}], [AX_APPEND_FLAG([${flag}])])
 done
 
-AC_CONFIG_FILES([Makefile])
+AC_CONFIG_FILES([Makefile po/Makefile.in])
 AC_CONFIG_HEADERS([config.h])
 AC_OUTPUT()
diff --git a/m4/.gitignore b/m4/.gitignore
new file mode 100644
index 0000000..a9c97ca
--- /dev/null
+++ b/m4/.gitignore
@@ -0,0 +1,10 @@
+/*.m4
+!/ax_append_flag.m4
+!/ax_cflags_warn_all.m4
+!/ax_check_compile_flag.m4
+!/ax_compiler_vendor.m4
+!/ax_prepend_flag.m4
+!/ax_require_defined.m4
+!/gcc_version.m4
+!/gl_manywarnings.m4
+!/gl_warnings.m4
diff --git a/m4/ax_append_flag.m4 b/m4/ax_append_flag.m4
index e8c5312..dd6d8b6 100644
--- a/m4/ax_append_flag.m4
+++ b/m4/ax_append_flag.m4
@@ -23,33 +23,12 @@
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
+#   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 7
+#serial 8
 
 AC_DEFUN([AX_APPEND_FLAG],
 [dnl
diff --git a/m4/ax_cflags_warn_all.m4 b/m4/ax_cflags_warn_all.m4
index 094577e..9235a18 100644
--- a/m4/ax_cflags_warn_all.m4
+++ b/m4/ax_cflags_warn_all.m4
@@ -4,33 +4,54 @@
 #
 # SYNOPSIS
 #
-#   AX_CFLAGS_WARN_ALL   [(shellvar [,default, [A/NA]])]
-#   AX_CXXFLAGS_WARN_ALL [(shellvar [,default, [A/NA]])]
-#   AX_FCFLAGS_WARN_ALL  [(shellvar [,default, [A/NA]])]
+#   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
 #
-#   Try to find a compiler option that enables most reasonable warnings.
+#   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.
 #
-#   For the GNU compiler it will be -Wall (and -ansi -pedantic) The result
-#   is added to the shellvar being CFLAGS, CXXFLAGS, or FCFLAGS by default.
+#   Each of these macros accepts the following optional arguments:
 #
-#   Currently this macro knows about the GCC, Solaris, Digital Unix, AIX,
-#   HP-UX, IRIX, NEC SX-5 (Super-UX 10), Cray J90 (Unicos 10.0.0.8), and
-#   Intel compilers.  For a given compiler, the Fortran flags are much more
-#   experimental than their C equivalents.
+#     - $1 - shellvar
+#         shell variable to use (CFLAGS, CXXFLAGS or FCFLAGS if not
+#         specified, depending on macro)
 #
-#    - $1 shell-variable-to-add-to : CFLAGS, CXXFLAGS, or FCFLAGS
-#    - $2 add-value-if-not-found : nothing
-#    - $3 action-if-found : add value to shellvariable
-#    - $4 action-if-not-found : nothing
+#     - $2 - default
+#         value to use for flags if compiler vendor cannot be determined (by
+#         default, "")
 #
-#   NOTE: These macros depend on AX_APPEND_FLAG.
+#     - $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
@@ -58,65 +79,80 @@
 #   modified version of the Autoconf Macro, you may extend this special
 #   exception to the GPL to apply to your modified version as well.
 
-#serial 16
+#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
 
-AC_DEFUN([AX_FLAGS_WARN_ALL],[dnl
-AS_VAR_PUSHDEF([FLAGS],[_AC_LANG_PREFIX[]FLAGS])dnl
-AS_VAR_PUSHDEF([VAR],[ac_cv_[]_AC_LANG_ABBREV[]flags_warn_all])dnl
-AC_CACHE_CHECK([m4_ifval($1,$1,FLAGS) for maximum warnings],
-VAR,[VAR="no, unknown"
-ac_save_[]FLAGS="$[]FLAGS"
-for ac_arg dnl
-in "-warn all  % -warn all"   dnl Intel
-   "-pedantic  % -Wall"       dnl GCC
-   "-xstrconst % -v"          dnl Solaris C
-   "-std1      % -verbose -w0 -warnprotos" dnl Digital Unix
-   "-qlanglvl=ansi % -qsrcmsg -qinfo=all:noppt:noppc:noobs:nocnd" dnl AIX
-   "-ansi -ansiE % -fullwarn" dnl IRIX
-   "+ESlit     % +w1"         dnl HP-UX C
-   "-Xc        % -pvctl[,]fullmsg" dnl NEC SX-5 (Super-UX 10)
-   "-h conform % -h msglevel 2" dnl Cray C (Unicos)
-   #
-do FLAGS="$ac_save_[]FLAGS "`echo $ac_arg | sed -e 's,%%.*,,' -e 's,%,,'`
-   AC_COMPILE_IFELSE([AC_LANG_PROGRAM],
-                     [VAR=`echo $ac_arg | sed -e 's,.*% *,,'` ; break])
-done
-FLAGS="$ac_save_[]FLAGS"
-])
-AS_VAR_POPDEF([FLAGS])dnl
-AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
-case ".$VAR" in
-     .ok|.ok,*) m4_ifvaln($3,$3) ;;
-   .|.no|.no,*) m4_default($4,[m4_ifval($2,[AX_APPEND_FLAG([$2], [$1])])]) ;;
-   *) m4_default($3,[AX_APPEND_FLAG([$VAR], [$1])]) ;;
-esac
-AS_VAR_POPDEF([VAR])dnl
+    AS_VAR_POPDEF([FOUND])dnl
+    AS_VAR_POPDEF([VAR])dnl
+    AS_VAR_POPDEF([FLAGS])dnl
 ])dnl AX_FLAGS_WARN_ALL
-dnl  implementation tactics:
-dnl   the for-argument contains a list of options. The first part of
-dnl   these does only exist to detect the compiler - usually it is
-dnl   a global option to enable -ansi or -extrawarnings. All other
-dnl   compilers will fail about it. That was needed since a lot of
-dnl   compilers will give false positives for some option-syntax
-dnl   like -Woption or -Xoption as they think of it is a pass-through
-dnl   to later compile stages or something. The "%" is used as a
-dnl   delimiter. A non-option comment can be given after "%%" marks
-dnl   which will be shown but not added to the respective C/CXXFLAGS.
 
-AC_DEFUN([AX_CFLAGS_WARN_ALL],[dnl
-AC_LANG_PUSH([C])
-AX_FLAGS_WARN_ALL([$1], [$2], [$3], [$4])
-AC_LANG_POP([C])
-])
+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++])
-])
+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])
-])
+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
index dcabb92..bd753b3 100644
--- a/m4/ax_check_compile_flag.m4
+++ b/m4/ax_check_compile_flag.m4
@@ -29,33 +29,12 @@
 #   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
 #   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
 #
-#   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.
+#   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 5
+#serial 6
 
 AC_DEFUN([AX_CHECK_COMPILE_FLAG],
 [AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
diff --git a/m4/ax_compiler_vendor.m4 b/m4/ax_compiler_vendor.m4
new file mode 100644
index 0000000..039f99d
--- /dev/null
+++ b/m4/ax_compiler_vendor.m4
@@ -0,0 +1,119 @@
+# ===========================================================================
+#    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/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/gcc_version.m4 b/m4/gcc_version.m4
index 9e16450..703973c 100644
--- a/m4/gcc_version.m4
+++ b/m4/gcc_version.m4
@@ -1,22 +1,18 @@
-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
+# Copyright (C) 1991-2023 Free Software Foundation, Inc.
+
+# 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/>.
+
 dnl Written by Jim Meyering.
 
 # gl_GCC_VERSION_IFELSE([major], [minor], [run-if-found], [run-if-not-found])
diff --git a/m4/gl_manywarnings.m4 b/m4/gl_manywarnings.m4
index d10bcd0..a06f26f 100644
--- a/m4/gl_manywarnings.m4
+++ b/m4/gl_manywarnings.m4
@@ -1,11 +1,13 @@
-# manywarnings.m4 serial 13
-dnl Copyright (C) 2008-2017 Free Software Foundation, Inc.
+# manywarnings.m4 serial 24
+dnl Copyright (C) 2008-2023 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
 
+AC_PREREQ([2.64])
+
 # gl_MANYWARN_COMPLEMENT(OUTVAR, LISTVAR, REMOVEVAR)
 # --------------------------------------------------
 # Copy LISTVAR to OUTVAR except for the entries in REMOVEVAR.
@@ -21,7 +23,7 @@ AC_DEFUN([gl_MANYWARN_COMPLEMENT],
       *" $gl_warn_item "*)
         ;;
       *)
-        gl_warn_set="$gl_warn_set $gl_warn_item"
+        AS_VAR_APPEND([gl_warn_set], [" $gl_warn_item"])
         ;;
     esac
   done
@@ -39,291 +41,166 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
 [_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
 
 # Specialization for _AC_LANG = C.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_MANYWARN_ALL_GCC(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 -W -Werror -Wno-missing-field-initializers is supported
-    dnl with the current $CC $CFLAGS $CPPFLAGS.
-    AC_MSG_CHECKING([whether -Wno-missing-field-initializers is supported])
-    AC_CACHE_VAL([gl_cv_cc_nomfi_supported], [
-      gl_save_CFLAGS="$CFLAGS"
-      CFLAGS="$CFLAGS -W -Werror -Wno-missing-field-initializers"
-      AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM([[]], [[]])],
-        [gl_cv_cc_nomfi_supported=yes],
-        [gl_cv_cc_nomfi_supported=no])
-      CFLAGS="$gl_save_CFLAGS"])
-    AC_MSG_RESULT([$gl_cv_cc_nomfi_supported])
-
-    if test "$gl_cv_cc_nomfi_supported" = yes; then
-      dnl Now check whether -Wno-missing-field-initializers is needed
-      dnl for the { 0, } construct.
-      AC_MSG_CHECKING([whether -Wno-missing-field-initializers is needed])
-      AC_CACHE_VAL([gl_cv_cc_nomfi_needed], [
-        gl_save_CFLAGS="$CFLAGS"
-        CFLAGS="$CFLAGS -W -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="$gl_save_CFLAGS"
-      ])
-      AC_MSG_RESULT([$gl_cv_cc_nomfi_needed])
-    fi
+  AS_IF([test -n "$GCC"], [
+    AC_CACHE_CHECK([whether -Wno-missing-field-initializers is needed],
+      [gl_cv_cc_nomfi_needed],
+      [gl_cv_cc_nomfi_needed=no
+       gl_save_CFLAGS="$CFLAGS"
+       CFLAGS="$CFLAGS -Wextra -Werror"
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[struct file_data { int desc, name; };
+              struct cmp { struct file_data file[1]; };
+              void f (struct cmp *r)
+              {
+                typedef struct { int a; int b; } s_t;
+                s_t s1 = { 0, };
+                struct cmp cmp = { .file[0].desc = r->file[0].desc + s1.a };
+                *r = cmp;
+              }
+            ]],
+            [[]])],
+         [],
+         [CFLAGS="$CFLAGS -Wno-missing-field-initializers"
+          AC_COMPILE_IFELSE([],
+            [gl_cv_cc_nomfi_needed=yes])])
+       CFLAGS="$gl_save_CFLAGS"
+    ])
 
     dnl Next, check if -Werror -Wuninitialized is useful with the
     dnl user's choice of $CFLAGS; some versions of gcc warn that it
     dnl has no effect if -O is not also used
-    AC_MSG_CHECKING([whether -Wuninitialized is supported])
-    AC_CACHE_VAL([gl_cv_cc_uninitialized_supported], [
-      gl_save_CFLAGS="$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"])
-    AC_MSG_RESULT([$gl_cv_cc_uninitialized_supported])
-
-  fi
+    AC_CACHE_CHECK([whether -Wuninitialized is supported],
+      [gl_cv_cc_uninitialized_supported],
+      [gl_save_CFLAGS="$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"
+      ])
+  ])
 
   # List all gcc warning categories.
   # To compare this list to your installed GCC's, run this Bash command:
   #
   # comm -3 \
-  #  <(sed -n 's/^  *\(-[^ ]*\) .*/\1/p' manywarnings.m4 | sort) \
-  #  <(gcc --help=warnings | sed -n 's/^  \(-[^ ]*\) .*/\1/p' | sort |
-  #      grep -v -x -F -f <(
-  #         awk '/^[^#]/ {print $1}' ../build-aux/gcc-warning.spec))
+  #  <((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)
 
-  gl_manywarn_set=
-  for gl_manywarn_item in -fno-common \
-    -W \
-    -Wabi \
-    -Waddress \
-    -Waggressive-loop-optimizations \
+  $1=
+  for gl_manywarn_item in -fanalyzer -fstrict-flex-arrays \
     -Wall \
-    -Wattributes \
+    -Warith-conversion \
     -Wbad-function-cast \
-    -Wbool-compare \
-    -Wbool-operation \
-    -Wbuiltin-declaration-mismatch \
-    -Wbuiltin-macro-redefined \
-    -Wcast-align \
-    -Wchar-subscripts \
-    -Wchkp \
-    -Wclobbered \
-    -Wcomment \
-    -Wcomments \
-    -Wcoverage-mismatch \
-    -Wcpp \
-    -Wdangling-else \
+    -Wcast-align=strict \
     -Wdate-time \
-    -Wdeprecated \
-    -Wdeprecated-declarations \
-    -Wdesignated-init \
     -Wdisabled-optimization \
-    -Wdiscarded-array-qualifiers \
-    -Wdiscarded-qualifiers \
-    -Wdiv-by-zero \
     -Wdouble-promotion \
     -Wduplicated-branches \
     -Wduplicated-cond \
-    -Wduplicate-decl-specifier \
-    -Wempty-body \
-    -Wendif-labels \
-    -Wenum-compare \
-    -Wexpansion-to-defined \
     -Wextra \
-    -Wformat-contains-nul \
-    -Wformat-extra-args \
-    -Wformat-nonliteral \
-    -Wformat-security \
     -Wformat-signedness \
-    -Wformat-y2k \
-    -Wformat-zero-length \
-    -Wframe-address \
-    -Wfree-nonheap-object \
-    -Whsa \
-    -Wignored-attributes \
-    -Wignored-qualifiers \
-    -Wimplicit \
-    -Wimplicit-function-declaration \
-    -Wimplicit-int \
-    -Wincompatible-pointer-types \
     -Winit-self \
     -Winline \
-    -Wint-conversion \
-    -Wint-in-bool-context \
-    -Wint-to-pointer-cast \
-    -Winvalid-memory-model \
     -Winvalid-pch \
-    -Wjump-misses-init \
-    -Wlogical-not-parentheses \
     -Wlogical-op \
-    -Wmain \
-    -Wmaybe-uninitialized \
-    -Wmemset-elt-size \
-    -Wmemset-transposed-args \
-    -Wmisleading-indentation \
-    -Wmissing-braces \
     -Wmissing-declarations \
-    -Wmissing-field-initializers \
     -Wmissing-include-dirs \
-    -Wmissing-parameter-type \
     -Wmissing-prototypes \
-    -Wmultichar \
-    -Wnarrowing \
     -Wnested-externs \
-    -Wnonnull \
-    -Wnonnull-compare \
     -Wnull-dereference \
-    -Wodr \
-    -Wold-style-declaration \
     -Wold-style-definition \
     -Wopenmp-simd \
-    -Woverflow \
     -Woverlength-strings \
-    -Woverride-init \
     -Wpacked \
-    -Wpacked-bitfield-compat \
-    -Wparentheses \
     -Wpointer-arith \
-    -Wpointer-compare \
-    -Wpointer-sign \
-    -Wpointer-to-int-cast \
-    -Wpragmas \
-    -Wpsabi \
-    -Wrestrict \
-    -Wreturn-local-addr \
-    -Wreturn-type \
-    -Wscalar-storage-order \
-    -Wsequence-point \
     -Wshadow \
-    -Wshift-count-negative \
-    -Wshift-count-overflow \
-    -Wshift-negative-value \
-    -Wsizeof-array-argument \
-    -Wsizeof-pointer-memaccess \
     -Wstack-protector \
-    -Wstrict-aliasing \
+    -Wstrict-flex-arrays \
     -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 \
-    -Wswitch \
-    -Wswitch-bool \
-    -Wswitch-default \
-    -Wswitch-unreachable \
     -Wsync-nand \
     -Wsystem-headers \
-    -Wtautological-compare \
     -Wtrampolines \
-    -Wtrigraphs \
-    -Wtype-limits \
     -Wuninitialized \
     -Wunknown-pragmas \
     -Wunsafe-loop-optimizations \
-    -Wunused \
-    -Wunused-but-set-parameter \
-    -Wunused-but-set-variable \
-    -Wunused-function \
-    -Wunused-label \
-    -Wunused-local-typedefs \
     -Wunused-macros \
-    -Wunused-parameter \
-    -Wunused-result \
-    -Wunused-value \
-    -Wunused-variable \
-    -Wvarargs \
     -Wvariadic-macros \
     -Wvector-operation-performance \
     -Wvla \
-    -Wvolatile-register-var \
     -Wwrite-strings \
     \
     ; do
-    gl_manywarn_set="$gl_manywarn_set $gl_manywarn_item"
+    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.
-  # Would prefer "min (PTRDIFF_MAX, SIZE_MAX)", but it must be a literal.
-  # Also, AC_COMPUTE_INT requires it to fit in a long; it is 2**63 on
-  # the only platforms where it does not fit in a long, so make that
-  # a special case.
-  AC_MSG_CHECKING([max safe object size])
-  AC_COMPUTE_INT([gl_alloc_max],
-    [LONG_MAX < (PTRDIFF_MAX < (size_t) -1 ? PTRDIFF_MAX : (size_t) -1)
-     ? -1
-     : PTRDIFF_MAX < (size_t) -1 ? (long) PTRDIFF_MAX : (long) (size_t) -1],
-    [[#include <limits.h>
-      #include <stddef.h>
-      #include <stdint.h>
-    ]],
-    [gl_alloc_max=2147483647])
-  case $gl_alloc_max in
-    -1) gl_alloc_max=9223372036854775807;;
-  esac
-  AC_MSG_RESULT([$gl_alloc_max])
-  gl_manywarn_set="$gl_manywarn_set -Walloc-size-larger-than=$gl_alloc_max"
-  gl_manywarn_set="$gl_manywarn_set -Warray-bounds=2"
-  gl_manywarn_set="$gl_manywarn_set -Wformat-overflow=2"
-  gl_manywarn_set="$gl_manywarn_set -Wformat-truncation=2"
-  gl_manywarn_set="$gl_manywarn_set -Wimplicit-fallthrough=5"
-  gl_manywarn_set="$gl_manywarn_set -Wnormalized=nfc"
-  gl_manywarn_set="$gl_manywarn_set -Wshift-overflow=2"
-  gl_manywarn_set="$gl_manywarn_set -Wstringop-overflow=2"
-  gl_manywarn_set="$gl_manywarn_set -Wunused-const-variable=2"
-  gl_manywarn_set="$gl_manywarn_set -Wvla-larger-than=4031"
+  AS_VAR_APPEND([$1], [' -Warray-bounds=2'])
+  AS_VAR_APPEND([$1], [' -Wattribute-alias=2'])
+  AS_VAR_APPEND([$1], [' -Wbidi-chars=any,ucn'])
+  AS_VAR_APPEND([$1], [' -Wformat-overflow=2'])
+  AS_VAR_APPEND([$1], [' -Wformat=2'])
+  AS_VAR_APPEND([$1], [' -Wformat-truncation=2'])
+  AS_VAR_APPEND([$1], [' -Wimplicit-fallthrough=5'])
+  AS_VAR_APPEND([$1], [' -Wshift-overflow=2'])
+  AS_VAR_APPEND([$1], [' -Wuse-after-free=3'])
+  AS_VAR_APPEND([$1], [' -Wunused-const-variable=2'])
+  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
+  if test -n "$GCC" && gl_gcc_version=`($CC --version) 2>/dev/null`; then
+    case $gl_gcc_version in
       'gcc (GCC) '[[0-3]].* | \
       'gcc (GCC) '4.[[0-7]].*)
-        gl_manywarn_set="$gl_manywarn_set -fdiagnostics-show-option"
-        gl_manywarn_set="$gl_manywarn_set -funit-at-a-time"
+        AS_VAR_APPEND([$1], [' -fdiagnostics-show-option'])
+        AS_VAR_APPEND([$1], [' -funit-at-a-time'])
+          ;;
+    esac
+    case $gl_gcc_version in
+      'gcc (GCC) '[[0-9]].*)
+        AS_VAR_APPEND([$1], [' -fno-common'])
           ;;
     esac
   fi
 
   # Disable specific options as needed.
   if test "$gl_cv_cc_nomfi_needed" = yes; then
-    gl_manywarn_set="$gl_manywarn_set -Wno-missing-field-initializers"
+    AS_VAR_APPEND([$1], [' -Wno-missing-field-initializers'])
   fi
 
   if test "$gl_cv_cc_uninitialized_supported" = no; then
-    gl_manywarn_set="$gl_manywarn_set -Wno-uninitialized"
+    AS_VAR_APPEND([$1], [' -Wno-uninitialized'])
   fi
 
-  $1=$gl_manywarn_set
+  # This warning have too many false alarms in GCC 11.2.1.
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101713
+  AS_VAR_APPEND([$1], [' -Wno-analyzer-malloc-leak'])
 
   AC_LANG_POP([C])
 ])
 
 # Specialization for _AC_LANG = C++.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_MANYWARN_ALL_GCC(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
index 870472b..9433cb5 100644
--- a/m4/gl_warnings.m4
+++ b/m4/gl_warnings.m4
@@ -1,19 +1,12 @@
-# warnings.m4 serial 13
-dnl Copyright (C) 2008-2017 Free Software Foundation, Inc.
+# warnings.m4 serial 19
+dnl Copyright (C) 2008-2023 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])])])
-
+AC_PREREQ([2.64])
 
 # gl_COMPILER_OPTION_IF(OPTION, [IF-SUPPORTED], [IF-NOT-SUPPORTED],
 #                       [PROGRAM = AC_LANG_PROGRAM()])
@@ -23,8 +16,6 @@ m4_ifdef([AS_VAR_APPEND],
 # The effects of this macro depend on the current language (_AC_LANG).
 AC_DEFUN([gl_COMPILER_OPTION_IF],
 [
-dnl FIXME: gl_Warn must be used unquoted until we can assume Autoconf
-dnl 2.64 or newer.
 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],
@@ -34,13 +25,13 @@ 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], m4_defn([gl_Warn]), [
+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]),
+  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])])
+  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])
@@ -59,8 +50,7 @@ AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],
 [_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
 
 # Specialization for _AC_LANG = C. This macro can be AC_REQUIREd.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
 [
   AC_LANG_PUSH([C])
   gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL
@@ -68,14 +58,21 @@ m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C)],
 ])
 
 # Specialization for _AC_LANG = C++. This macro can be AC_REQUIREd.
-# Use of m4_defun rather than AC_DEFUN works around a bug in autoconf < 2.63b.
-m4_defun([gl_UNKNOWN_WARNINGS_ARE_ERRORS(C++)],
+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'],
@@ -84,16 +81,18 @@ AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS_IMPL],
 # 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]).
+# Adds OPTION to VARIABLE (which defaults to WARN_CFLAGS or WARN_CXXFLAGS)
+# if the compiler supports it when compiling PROGRAM.
 #
 # If VARIABLE is a variable name, AC_SUBST it.
 #
 # The effects of this macro depend on the current language (_AC_LANG).
+#
+# Example: gl_WARN_ADD([-Wparentheses]).
 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"])],
+  [AS_VAR_APPEND(m4_if([$2], [], [[WARN_]_AC_LANG_PREFIX[FLAGS]], [[$2]]), [" $1"])],
   [],
   [$3])
 m4_ifval([$2],
@@ -101,6 +100,77 @@ m4_ifval([$2],
          [AC_SUBST([WARN_]_AC_LANG_PREFIX[FLAGS])])dnl
 ])
 
+
+# gl_CC_INHIBIT_WARNINGS
+# sets and substitutes a variable GL_CFLAG_INHIBIT_WARNINGS, to a $(CC) option
+# that reverts all preceding -W* options, if available.
+# This is expected to be '-w' at least on gcc, clang, AIX xlc, xlclang, Sun cc,
+# "compile cl" (MSVC), "compile clang-cl" (MSVC-compatible clang). Or it can be
+# empty.
+AC_DEFUN([gl_CC_INHIBIT_WARNINGS],
+[
+  AC_REQUIRE([AC_PROG_CC])
+  AC_CACHE_CHECK([for C compiler option to inhibit all warnings],
+    [gl_cv_cc_winhibit],
+    [rm -f conftest*
+     echo 'int dummy;' > conftest.c
+     AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c 2>conftest1.err]) >/dev/null
+     AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -w -c conftest.c 2>conftest2.err]) >/dev/null
+     if test $? = 0 && test `wc -l < conftest1.err` = `wc -l < conftest2.err`; then
+       gl_cv_cc_winhibit='-w'
+     else
+       gl_cv_cc_winhibit=none
+     fi
+     rm -f conftest*
+    ])
+  case "$gl_cv_cc_winhibit" in
+    none) GL_CFLAG_INHIBIT_WARNINGS='' ;;
+    *)
+      GL_CFLAG_INHIBIT_WARNINGS="$gl_cv_cc_winhibit"
+      dnl If all warnings are inhibited, there's no point in having the GCC
+      dnl analyzer enabled. This saves RAM requirements and CPU consumption.
+      gl_WARN_ADD([-fno-analyzer], [GL_CFLAG_INHIBIT_WARNINGS])
+      ;;
+  esac
+  AC_SUBST([GL_CFLAG_INHIBIT_WARNINGS])
+])
+
+# gl_CXX_INHIBIT_WARNINGS
+# sets and substitutes a variable GL_CXXFLAG_INHIBIT_WARNINGS, to a $(CC) option
+# that reverts all preceding -W* options, if available.
+AC_DEFUN([gl_CXX_INHIBIT_WARNINGS],
+[
+  dnl Requires AC_PROG_CXX or gl_PROG_ANSI_CXX.
+  if test -n "$CXX" && test "$CXX" != no; then
+    AC_CACHE_CHECK([for C++ compiler option to inhibit all warnings],
+      [gl_cv_cxx_winhibit],
+      [rm -f conftest*
+       echo 'int dummy;' > conftest.cc
+       AC_TRY_COMMAND([${CXX-c++} $CXXFLAGS $CPPFLAGS -c conftest.cc 2>conftest1.err]) >/dev/null
+       AC_TRY_COMMAND([${CXX-c++} $CXXFLAGS $CPPFLAGS -w -c conftest.cc 2>conftest2.err]) >/dev/null
+       if test $? = 0 && test `wc -l < conftest1.err` = `wc -l < conftest2.err`; then
+         gl_cv_cxx_winhibit='-w'
+       else
+         gl_cv_cxx_winhibit=none
+       fi
+       rm -f conftest*
+      ])
+    case "$gl_cv_cxx_winhibit" in
+      none) GL_CXXFLAG_INHIBIT_WARNINGS='' ;;
+      *)
+        GL_CXXFLAG_INHIBIT_WARNINGS="$gl_cv_cxx_winhibit"
+        dnl If all warnings are inhibited, there's no point in having the GCC
+        dnl analyzer enabled. This saves RAM requirements and CPU consumption.
+        gl_WARN_ADD([-fno-analyzer], [GL_CXXFLAG_INHIBIT_WARNINGS])
+        ;;
+    esac
+  else
+    GL_CXXFLAG_INHIBIT_WARNINGS=''
+  fi
+  AC_SUBST([GL_CXXFLAG_INHIBIT_WARNINGS])
+])
+
+
 # Local Variables:
 # mode: autoconf
 # End:
diff --git a/man/.gitignore b/man/.gitignore
new file mode 100644
index 0000000..ba0d22a
--- /dev/null
+++ b/man/.gitignore
@@ -0,0 +1 @@
+*.?
diff --git a/man/atsign.1in b/man/atsign.1in
new file mode 100644
index 0000000..6cc1123
--- /dev/null
+++ b/man/atsign.1in
@@ -0,0 +1,41 @@
+.TH ATSIGN "1" "2023-10-14" "@PACKAGE_STRING@"
+
+.SH NAME
+@ATSIGN@ \- delay until a specified time
+
+.SH SYNOPSIS
+.B @ATSIGN@
+[\fI\,date\/\fR]\fI\,time\/\fR
+
+.SH OPTIONS
+
+.TP
+\fB\-F\fR, \fB\-\-list\-formats\fR
+List all supported date and time formats
+
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Show this help information
+
+.TP
+\fB\-V\fR, \fB\-\-version\fR
+Show version information
+
+.SH "REPORTING BUGS"
+Report bugs to <@PACKAGE_BUGREPORT@>.
+
+.SH COPYRIGHT
+Copyright \(co 2023  P. J. McDermott
+.PP
+@ 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.
+.PP
+@ 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.
+.PP
+You should have received a copy of the GNU General Public License
+along with @.  If not, see <http://www.gnu.org/licenses/>.
diff --git a/man/local.mk b/man/local.mk
new file mode 100644
index 0000000..65814fe
--- /dev/null
+++ b/man/local.mk
@@ -0,0 +1,43 @@
+# Process this file with automake to produce an input makefile.
+#
+# Copyright (C) 2018, 2023  P. J. McDermott
+#
+# This file is part of @
+#
+# @ 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.
+#
+# @ 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 @.  If not, see <http://www.gnu.org/licenses/>.
+
+man1_sources = \
+	%reldir%/atsign.1in
+man1_MANS = $(man1_sources:.1in=.1)
+
+CLEANFILES += \
+	$(man1_MANS)
+EXTRA_DIST += \
+	$(man1_sources)
+
+if ENABLE_SYMLINK
+atsign = @$(EXEEXT)
+else !ENABLE_SYMLINK
+atsign = $$(printf 'atsign' | sed '$(transform); s/$$/$(EXEEXT)/')
+endif
+man_subst = sed \
+	-e "s|[@]PACKAGE_STRING[@]|$(PACKAGE_STRING)|g" \
+	-e "s|[@]PACKAGE_BUGREPORT[@]|$(PACKAGE_BUGREPORT)|g" \
+	-e "s|[@]ATSIGN[@]|$(atsign)|g"
+
+SUFFIXES += .1in .1
+
+.1in.1:
+	$(AM_V_GEN)$(MKDIR_P) "$$(dirname $@)"
+	$(AM_V_at)$(man_subst) $< >$@
diff --git a/po/.gitignore b/po/.gitignore
new file mode 100644
index 0000000..532f823
--- /dev/null
+++ b/po/.gitignore
@@ -0,0 +1,11 @@
+/Makefile.in.in
+/Makevars.template
+/Rules-quot
+/*.sed
+/POTFILES
+/*.pot
+/*.po
+/*.mo
+/*@boldquot.header
+/*@quot.header
+/stamp-po
diff --git a/po/Makevars b/po/Makevars
new file mode 100644
index 0000000..1753e43
--- /dev/null
+++ b/po/Makevars
@@ -0,0 +1,26 @@
+# Variables to be inserted into Makefile
+
+DOMAIN = $(PACKAGE)
+
+subdir = po
+top_builddir = ..
+
+XGETTEXT_OPTIONS = --add-comments=TRANSLATORS --keyword=_
+
+COPYRIGHT_HOLDER = P. J. McDermott
+
+PACKAGE_GNU = no
+
+MSGID_BUGS_ADDRESS = mailto:pj@pehjota.net
+
+EXTRA_LOCALE_CATEGORIES =
+
+USE_MSGCTXT = no
+
+MSGMERGE_OPTIONS =
+
+MSGINIT_OPTIONS =
+
+PO_DEPENDS_ON_POT = yes
+
+DIST_DEPENDS_ON_UPDATE_PO = yes
diff --git a/po/POTFILES.in b/po/POTFILES.in
new file mode 100644
index 0000000..5472064
--- /dev/null
+++ b/po/POTFILES.in
@@ -0,0 +1,2 @@
+src/datetime.c
+src/main.c
diff --git a/scripts/update-m4.sh b/scripts/update-m4.sh
new file mode 100755
index 0000000..e0d500d
--- /dev/null
+++ b/scripts/update-m4.sh
@@ -0,0 +1,30 @@
+#!/bin/sh
+#
+# Script to update M4 files from Gnulib, GNU Autoconf Archive, and GNU Coreutils
+#
+# Copyright (C) 2023  P. J. McDermott
+#
+# Copying and distribution of this file, with or without modification,
+# are permitted in any medium without royalty provided the copyright
+# notice and this notice are preserved.  This file is offered as-is,
+# without any warranty.
+
+set -eu
+
+SV_CGIT='https://git.savannah.gnu.org/cgit'
+
+for f in m4/gl_*.m4; do
+	wget -O "${f}" "${SV_CGIT}/gnulib.git/plain/m4/${f#m4/gl_}"
+done
+
+for f in m4/ax_*.m4; do
+	wget -O "${f}" "${SV_CGIT}/autoconf-archive.git/plain/${f}"
+done
+
+wget -O - "${SV_CGIT}/coreutils.git/plain/configure.ac" | sed -n '
+		/^# Copyright /,/^dnl Written /{
+			p;
+			s/^dnl Written .*$//p;
+		};
+		/^# gl_GCC_VERSION_IFELSE/,/^$/p;
+	' | sed '$d' 1>'m4/gcc_version.m4'
diff --git a/src/datetime.c b/src/datetime.c
index f7cdb89..72f0219 100644
--- a/src/datetime.c
+++ b/src/datetime.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2021  P. J. McDermott
+ * Copyright (C) 2021, 2022  P. J. McDermott
  *
  * This file is part of @
  *
@@ -18,6 +18,9 @@
  */
 
 #define _XOPEN_SOURCE
+/* glibc requires these for timegm(): */
+#define _DEFAULT_SOURCE
+#define _BSD_SOURCE
 
 #include <ctype.h>
 #include <errno.h>
@@ -29,18 +32,7 @@
 #include <time.h>
 #include "datetime.h"
 #include "formats.h"
-
-static struct tm DATETIME_EPOCH_ = {
-	.tm_sec   = 0,
-	.tm_min   = 0,
-	.tm_hour  = 0,
-	.tm_mday  = 1,
-	.tm_mon   = 0,
-	.tm_year  = 70,
-	.tm_wday  = 4,
-	.tm_yday  = 0,
-	.tm_isdst = -1,
-};
+#include "i18n.h"
 
 static void
 _datetime_buf_cpy_p(char *dst, const char *src)
@@ -83,7 +75,13 @@ _datetime_reset_tm(struct tm *tm)
 static void
 _datetime_normalize(struct tm *now_tm, struct tm *arg_tm, time_t *arg_sec)
 {
-	int wday;
+	int days_in_mon[12] = {31, 28, 31, 30, 31, 30,
+	                       31, 31, 30, 31, 30, 31};
+
+	if (now_tm->tm_year % 4 == 0 && (now_tm->tm_year % 100 != 0 ||
+				now_tm->tm_year % 400 == 0)) {
+		days_in_mon[1] = 29;
+	}
 
 	if (arg_tm->tm_sec == INT_MIN) {
 		arg_tm->tm_sec = 0;
@@ -95,36 +93,44 @@ _datetime_normalize(struct tm *now_tm, struct tm *arg_tm, time_t *arg_sec)
 		arg_tm->tm_mday = now_tm->tm_mday;
 		arg_tm->tm_wday = now_tm->tm_wday;
 		*arg_sec = mktime(arg_tm);
-		if (*arg_sec <= mktime(now_tm)) {
+		if (difftime(*arg_sec, mktime(now_tm)) <= 0) {
 			/* Specified time already happened today; use tomorrow.
-			 * Adding the number of seconds in a day is a shortcut
-			 * that ignores leap seconds.  One better method would
-			 * be to increment tm_mday % days in tm_mon, etc. */
-			*arg_sec += 60 * 60 * 24;
-			now_tm = localtime(arg_sec);
-			arg_tm->tm_year = now_tm->tm_year;
-			arg_tm->tm_mon  = now_tm->tm_mon;
-			arg_tm->tm_mday = now_tm->tm_mday;
+			 */
+			++arg_tm->tm_mday;
+			arg_tm->tm_wday = (arg_tm->tm_wday + 1) % 7;
+			if (arg_tm->tm_mday > days_in_mon[arg_tm->tm_mon]) {
+				arg_tm->tm_mday = 1;
+				++arg_tm->tm_mon;
+				if (arg_tm->tm_mon >= 12) {
+					arg_tm->tm_mon = 0;
+					++arg_tm->tm_year;
+				}
+			}
 			*arg_sec = mktime(arg_tm);
 		}
 	} else if (arg_tm->tm_mday == INT_MIN) {
-		/* Only a weekday specified; try tomorrow or next week.  Uses
-		 * same shortcut as above. */
-		wday = arg_tm->tm_wday;
+		/* Only a weekday specified; try tomorrow or next week. */
 		arg_tm->tm_year = now_tm->tm_year;
 		arg_tm->tm_mon  = now_tm->tm_mon;
 		arg_tm->tm_mday = now_tm->tm_mday;
-		arg_tm->tm_wday = now_tm->tm_wday;
-		if (wday <= now_tm->tm_wday) {
-			wday += 7;
+		if (arg_tm->tm_wday <= now_tm->tm_wday) {
+			arg_tm->tm_mday += 7;
+		}
+		arg_tm->tm_mday += arg_tm->tm_wday - now_tm->tm_wday;
+		if (arg_tm->tm_mday > days_in_mon[arg_tm->tm_mon]) {
+			arg_tm->tm_mday -= days_in_mon[arg_tm->tm_mon];
+			++arg_tm->tm_mon;
+			if (arg_tm->tm_mon >= 12) {
+				arg_tm->tm_mon = 0;
+				++arg_tm->tm_year;
+			}
 		}
 		*arg_sec = mktime(arg_tm);
-		*arg_sec += (60 * 60 * 24) * (wday - now_tm->tm_wday);
 	} else if (arg_tm->tm_year == INT_MIN) {
 		/* No year specified; try this year. */
 		arg_tm->tm_year = now_tm->tm_year;
 		*arg_sec = mktime(arg_tm);
-		if (*arg_sec <= mktime(now_tm)) {
+		if (difftime(*arg_sec, mktime(now_tm)) <= 0) {
 			/* Specified time already happened this year; use next
 			 * year. */
 			++arg_tm->tm_year;
@@ -136,7 +142,8 @@ _datetime_normalize(struct tm *now_tm, struct tm *arg_tm, time_t *arg_sec)
 }
 
 int
-datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
+datetime_parse(struct tm *now_tm, const char *input,
+		struct tm *arg_tm, time_t *arg_sec)
 {
 	int        date_fmt_len;
 	int        time_fmt_len;
@@ -146,7 +153,6 @@ datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
 	size_t     d;
 	size_t     t;
 	char      *end;
-	struct tm  arg_tm;
 	time_t     sec;
 	bool       got;
 
@@ -159,20 +165,20 @@ datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
 	}
 	fmt_buf = calloc(fmt_len + 1, sizeof(*fmt_buf));
 	if (fmt_buf == NULL) {
-		fprintf(stderr, "Failed to allocate buffer: %s\n",
+		fprintf(stderr, _("Failed to allocate buffer: %s\n"),
 				strerror(errno));
 		return -1;
 	}
 
 	sec = *arg_sec;  /* GCC is dumb. */
 	got = false;
-	for (t = 0; t < sizeof(FORMATS_TIME) / sizeof(FORMATS_TIME[0]) ; ++t) {
+	for (t = 0; t < sizeof(FORMATS_TIME) / sizeof(FORMATS_TIME[0]); ++t) {
 		_datetime_buf_cpy_p(fmt_buf, FORMATS_TIME[t]);
-		_datetime_reset_tm(&arg_tm);
-		end = strptime(input, fmt_buf, &arg_tm);
+		_datetime_reset_tm(arg_tm);
+		end = strptime(input, fmt_buf, arg_tm);
 		if (end != NULL && *end == '\0') {
-			_datetime_normalize(now_tm, &arg_tm, arg_sec);
-			if (datetime_diff_epoch(*arg_sec) >= 0) {
+			_datetime_normalize(now_tm, arg_tm, arg_sec);
+			if (arg_tm->tm_year >= 0) {
 				free(fmt_buf);
 				return 0;
 			}
@@ -189,11 +195,11 @@ datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
 				++t) {
 			_datetime_buf_cpy_p(fmt_buf + date_fmt_len,
 					FORMATS_TIME[t]);
-			_datetime_reset_tm(&arg_tm);
-			end = strptime(input, fmt_buf, &arg_tm);
+			_datetime_reset_tm(arg_tm);
+			end = strptime(input, fmt_buf, arg_tm);
 			if (end != NULL && *end == '\0') {
-				_datetime_normalize(now_tm, &arg_tm, arg_sec);
-				if (datetime_diff_epoch(*arg_sec) >= 0) {
+				_datetime_normalize(now_tm, arg_tm, arg_sec);
+				if (arg_tm->tm_year >= 0) {
 					free(fmt_buf);
 					return 0;
 				}
@@ -211,11 +217,11 @@ datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
 			}
 			_datetime_buf_cpy_p(fmt_buf + time_fmt_len,
 					FORMATS_DATE[d]);
-			_datetime_reset_tm(&arg_tm);
-			end = strptime(input, fmt_buf, &arg_tm);
+			_datetime_reset_tm(arg_tm);
+			end = strptime(input, fmt_buf, arg_tm);
 			if (end != NULL && *end == '\0') {
-				_datetime_normalize(now_tm, &arg_tm, arg_sec);
-				if (datetime_diff_epoch(*arg_sec) >= 0) {
+				_datetime_normalize(now_tm, arg_tm, arg_sec);
+				if (arg_tm->tm_year >= 0) {
 					free(fmt_buf);
 					return 0;
 				}
@@ -224,13 +230,13 @@ datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
 			}
 		}
 	}
-	for (d = 0; d < sizeof(FORMATS_MISC) / sizeof(FORMATS_MISC[0]) ; ++d) {
+	for (d = 0; d < sizeof(FORMATS_MISC) / sizeof(FORMATS_MISC[0]); ++d) {
 		_datetime_buf_cpy_p(fmt_buf, FORMATS_MISC[d]);
-		_datetime_reset_tm(&arg_tm);
-		end = strptime(input, fmt_buf, &arg_tm);
+		_datetime_reset_tm(arg_tm);
+		end = strptime(input, fmt_buf, arg_tm);
 		if (end != NULL && *end == '\0') {
-			_datetime_normalize(now_tm, &arg_tm, arg_sec);
-			if (datetime_diff_epoch(*arg_sec) >= 0) {
+			_datetime_normalize(now_tm, arg_tm, arg_sec);
+			if (arg_tm->tm_year >= 0) {
 				free(fmt_buf);
 				return 0;
 			}
@@ -244,7 +250,7 @@ datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec)
 		free(fmt_buf);
 		return 0;
 	} else {
-		fputs("Unknown date format\n", stderr);
+		fputs(_("Unknown date format\n"), stderr);
 		free(fmt_buf);
 		return -1;
 	}
@@ -289,13 +295,13 @@ _datetime_strftime(const char *fmts[], const struct tm *tm, char **out,
 		*buf_sz = strlen(fmts[0]) + 1;
 		*buf = calloc(*buf_sz, sizeof(**buf));
 		if (*buf == NULL) {
-			fprintf(stderr, "Failed to allocate buffer: %s\n",
+			fprintf(stderr, _("Failed to allocate buffer: %s\n"),
 					strerror(errno));
 			return -1;
 		}
 		*out = calloc(*buf_sz, sizeof(**out));
 		if (*out == NULL) {
-			fprintf(stderr, "Failed to allocate buffer: %s\n",
+			fprintf(stderr, _("Failed to allocate buffer: %s\n"),
 					strerror(errno));
 			return -1;
 		}
@@ -315,7 +321,7 @@ _datetime_strftime(const char *fmts[], const struct tm *tm, char **out,
 		++*buf_sz;
 		*buf = realloc(*buf, *buf_sz * sizeof(**buf));
 		if (*buf == NULL) {
-			fprintf(stderr, "Failed to allocate buffer: %s\n",
+			fprintf(stderr, _("Failed to allocate buffer: %s\n"),
 					strerror(errno));
 			return -1;
 		}
@@ -324,7 +330,7 @@ _datetime_strftime(const char *fmts[], const struct tm *tm, char **out,
 	if (resized > 0) {
 		*out = realloc(*out, *buf_sz * sizeof(**out));
 		if (*out == NULL) {
-			fprintf(stderr, "Failed to allocate buffer: %s\n",
+			fprintf(stderr, _("Failed to allocate buffer: %s\n"),
 					strerror(errno));
 			return -1;
 		}
@@ -386,13 +392,3 @@ datetime_strftime_misc(const struct tm *tm, char **out, size_t *buf_sz,
 
 	return _datetime_strftime(FORMATS_MISC, tm, out, buf_sz, buf, i);
 }
-
-double
-datetime_diff_epoch(time_t t)
-{
-	time_t epoch;
-
-	epoch = timegm(&DATETIME_EPOCH_);
-
-	return difftime(t, epoch);
-}
diff --git a/src/datetime.h b/src/datetime.h
index e225b52..1094cf8 100644
--- a/src/datetime.h
+++ b/src/datetime.h
@@ -23,7 +23,8 @@
 #include <time.h>
 
 int
-datetime_parse(struct tm *now_tm, const char *input, time_t *arg_sec);
+datetime_parse(struct tm *now_tm, const char *input,
+		struct tm *arg_tm, time_t *arg_sec);
 
 int
 datetime_strftime_date(const struct tm *tm, char **out, size_t *out_sz,
@@ -37,7 +38,4 @@ int
 datetime_strftime_misc(const struct tm *tm, char **out, size_t *out_sz,
 		char **buf, size_t *i);
 
-double
-datetime_diff_epoch(time_t t);
-
 #endif  /* DATETIME_H_ */
diff --git a/src/formats.h b/src/formats.h
index 262912e..c88f731 100644
--- a/src/formats.h
+++ b/src/formats.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2021-2022  P. J. McDermott
+ * Copyright (C) 2021, 2022  P. J. McDermott
  *
  * This file is part of @
  *
diff --git a/src/i18n.h b/src/i18n.h
new file mode 100644
index 0000000..4d8ee76
--- /dev/null
+++ b/src/i18n.h
@@ -0,0 +1,11 @@
+#ifdef ENABLE_NLS
+
+#include <libintl.h>
+
+#define _(msgid) gettext(msgid)
+
+#else
+
+#define _(msgid) (msgid)
+
+#endif
diff --git a/src/local.mk b/src/local.mk
index 9992269..1012945 100644
--- a/src/local.mk
+++ b/src/local.mk
@@ -1,5 +1,6 @@
-@_SOURCES += \
+atsign_SOURCES += \
 	%reldir%/datetime.c \
 	%reldir%/datetime.h \
 	%reldir%/formats.h \
+	%reldir%/i18n.h \
 	%reldir%/main.c
diff --git a/src/main.c b/src/main.c
index 01a0a4c..0ff76c9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -17,16 +17,21 @@
  * along with @.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "config.h"
+
+#ifdef ENABLE_NLS
+#include <locale.h>
+#endif
+
 #include <errno.h>
-#include <inttypes.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
-#include "config.h"
 #include "datetime.h"
+#include "i18n.h"
 
 #if defined(HAVE_GETOPT_LONG) && HAVE_GETOPT_LONG
 #include <getopt.h>
@@ -60,22 +65,23 @@ static const struct option LONGOPTS_[] = {
 static void
 _print_usage(FILE *stream, const char *program_name)
 {
-	fprintf(stream, "Usage: %s [date]time\n", program_name);
+	fprintf(stream, _("Usage: %s [date]time\n"), program_name);
 }
 
 static void
 _print_help(const char *program_name)
 {
 	_print_usage(stdout, program_name);
-	puts("Options:");
 #if defined(HAVE_GETOPT_LONG) && HAVE_GETOPT_LONG
-	puts("\t-F, --list-formats  List all supported date and time formats");
-	puts("\t-h, --help          Show this help information");
-	puts("\t-V, --version       Show version information");
+	puts(_("Options:\n"
+	"  -F, --list-formats  List all supported date and time formats\n"
+	"  -h, --help          Show this help information\n"
+	"  -V, --version       Show version information"));
 #else
-	puts("\t-F  List all supported date and time formats");
-	puts("\t-h  Show this help information");
-	puts("\t-V  Show version information");
+	puts(_("Options:\n"
+	"  -F  List all supported date and time formats\n"
+	"  -h  Show this help information\n"
+	"  -V  Show version information"));
 #endif
 }
 
@@ -111,31 +117,31 @@ _list_formats(const struct tm *tm)
 	char   *buf;
 	size_t  i;
 
-	puts("Time formats:");
+	puts(_("Time formats:"));
 	i = 0;
 	while (datetime_strftime_time(tm, &out, &buf_sz, &buf, &i) > 0) {
 		if (out[0] == '\0') {
 			continue;
 		}
-		printf("  * %s\n", out);
+		printf(_("  * %s\n"), out);
 	}
 
-	puts("Date formats:");
+	puts(_("Date formats:"));
 	i = 0;
 	while (datetime_strftime_date(tm, &out, &buf_sz, &buf, &i) > 0) {
 		if (out[0] == '\0') {
 			continue;
 		}
-		printf("  * %s\n", out);
+		printf(_("  * %s\n"), out);
 	}
 
-	puts("Additional formats:");
+	puts(_("Additional formats:"));
 	i = 0;
 	while (datetime_strftime_misc(tm, &out, &buf_sz, &buf, &i) > 0) {
 		if (out[0] == '\0') {
 			continue;
 		}
-		printf("  * %s\n", out);
+		printf(_("  * %s\n"), out);
 	}
 }
 
@@ -143,13 +149,12 @@ static void
 _print_version(void)
 {
 	printf("@ (atsign) %s%s\n", PACKAGE_VERSION, PACKAGE_VERSION_GIT);
-	puts("Copyright (C) 2021-2022  P. J. McDermott");
-	puts("License GPLv3+: GNU GPL version 3 or later "
-			"<http://gnu.org/licenses/gpl.html>.");
-	puts("This is free software: you are free to change and redistribute "
-			"it.");
-	puts("There is NO WARRANTY, to the extent permitted by law.\n");
-	printf("Please report bugs to <%s>.\n", PACKAGE_BUGREPORT);
+	puts(_("Copyright (C) 2021, 2022  P. J. McDermott\n"
+	"License GPLv3+: GNU GPL version 3 or later "
+		"<http://gnu.org/licenses/gpl.html>.\n"
+	"This is free software: you are free to change and redistribute it.\n"
+	"There is NO WARRANTY, to the extent permitted by law.\n"));
+	printf(_("Please report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 }
 
 static char *
@@ -168,7 +173,7 @@ _concat_args(int argc, char * const argv[])
 
 	buf = calloc(buf_l, sizeof(*buf));
 	if (buf == NULL) {
-		fprintf(stderr, "Failed to allocate buffer: %s\n",
+		fprintf(stderr, _("Failed to allocate buffer: %s\n"),
 				strerror(errno));
 		return NULL;
 	}
@@ -196,9 +201,19 @@ main(int argc, char * const argv[])
 	char      *buf;
 	time_t     now;
 	struct tm *now_tm;
+	struct tm  arg_tm;
 	time_t     arg;
 	double     dif;
 
+#ifdef ENABLE_NLS
+	bindtextdomain(GETTEXT_PACKAGE, LOCALEDIR);
+#ifdef HAVE_BIND_TEXTDOMAIN_CODESET
+	bind_textdomain_codeset(PACKAGE, "UTF-8");
+#endif
+	textdomain(PACKAGE);
+	setlocale(LC_ALL, "");
+#endif
+
 #if defined(ENABLE_TESTS) && ENABLE_TESTS
 	dbg = false;
 #endif
@@ -243,11 +258,11 @@ main(int argc, char * const argv[])
 			default:
 				_print_usage(stderr, argv[0]);
 #if defined(HAVE_GETOPT_LONG) && HAVE_GETOPT_LONG
-				fprintf(stderr, "Try '%s --help' for more "
-						"information.\n", argv[0]);
+				fprintf(stderr, _("Try '%s --help' for more "
+						"information.\n"), argv[0]);
 #else
-				fprintf(stderr, "Try '%s -h' for more "
-						"information.\n", argv[0]);
+				fprintf(stderr, _("Try '%s -h' for more "
+						"information.\n"), argv[0]);
 #endif
 				return EXIT_FAILURE;
 		}
@@ -265,7 +280,7 @@ main(int argc, char * const argv[])
 		return EXIT_FAILURE;
 	}
 
-	if (datetime_parse(now_tm, buf, &arg) < 0) {
+	if (datetime_parse(now_tm, buf, &arg_tm, &arg) < 0) {
 		free(buf);
 		return EXIT_FAILURE;
 	}
@@ -273,8 +288,13 @@ main(int argc, char * const argv[])
 
 #if defined(ENABLE_TESTS) && ENABLE_TESTS
 	if (dbg == true) {
-		dif = datetime_diff_epoch(arg);
-		printf("%" PRId64 "\n", (int64_t) dif);
+		printf("%04d-%02d-%02d %02d:%02d:%02d\n",
+				arg_tm.tm_year + 1900,
+				arg_tm.tm_mon  +    1,
+				arg_tm.tm_mday,
+				arg_tm.tm_hour,
+				arg_tm.tm_min,
+				arg_tm.tm_sec);
 		return EXIT_SUCCESS;
 	}
 #endif
@@ -282,7 +302,7 @@ main(int argc, char * const argv[])
 	now = time(NULL);
 	dif = difftime(arg, now);
 	if (dif >= 1000 * 24 * 60 * 60) {
-		fputs("Date too far in the future\n", stderr);
+		fputs(_("Date too far in the future\n"), stderr);
 		return EXIT_FAILURE;
 	}
 
diff --git a/tests/formats.sh b/tests/formats.sh
index a0c4188..576b96a 100755
--- a/tests/formats.sh
+++ b/tests/formats.sh
@@ -24,7 +24,7 @@ set -eu
 plan_ 1
 
 exp="$(cat "${0%.sh}.exp")"
-got="$("${TOP_BUILDDIR}/@" -d '1970-01-02 03:04:05' -F)"
+got="$("${TOP_BUILDDIR}/atsign" -d '1970-01-02 03:04:05' -F)"
 
 if [ x"${got}" = x"${exp}" ]; then
 	ok_ -- 'formats list'
diff --git a/tests/local.mk b/tests/local.mk
index 9124d94..84eb79e 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -16,5 +16,6 @@ SH_LOG_DRIVER = \
 EXTRA_DIST += \
 	$(tests) \
 	%reldir%/disabled.sh \
+	%reldir%/formats.exp \
 	$(top_srcdir)/build-aux/tap-driver.sh \
 	%reldir%/aux/tap-functions.sh
diff --git a/tests/parse.sh b/tests/parse.sh
index 1150f28..eadd2cf 100755
--- a/tests/parse.sh
+++ b/tests/parse.sh
@@ -21,7 +21,10 @@ set -eu
 
 . "${TOP_SRCDIR}/tests/aux/tap-functions.sh"
 
-fmts="$(TZ=UTC0 "${TOP_BUILDDIR}/@" -d '1970-01-01 00:00:00' -F)"
+now='1969-12-31 23:59:30'
+tgt='1970-01-01 00:00:00'
+
+fmts="$(TZ=UTC0 "${TOP_BUILDDIR}/atsign" -d "${tgt}" -F)"
 time_fmts="$(printf '%s\n' "${fmts}" | \
 	sed -n '/^Time formats:$/,/^Date formats:$/s/^  \* //p')"
 date_fmts="$(printf '%s\n' "${fmts}" | \
@@ -44,30 +47,31 @@ for fmt in $(printf '%s\n' "${fmts}"); do
 	diag_ "${fmt}"
 done
 
-run_test()
+test_fmt()
 {
-	datetime="${1}"
-	shift 1
+	now="${1}"
+	tgt="${2}"
+	fmt="${3}"
+	shift 3
 
-	got="$(TZ=UTC0 "${TOP_BUILDDIR}/@" -d '1969-12-31 23:59:30' \
-		"${datetime}" 2>&1)" || :
-	if [ x"${got}" = x'0' ]; then
-		ok_ -- "${datetime}"
+	got="$(TZ=UTC0 "${TOP_BUILDDIR}/atsign" -d "${now}" "${fmt}" 2>&1)" || :
+	if [ x"${got}" = x"${tgt}" ]; then
+		ok_ -- "${fmt}"
 	else
-		not_ok_ -- "${datetime}"
-		diag_ " Failed test '${datetime}'"
+		not_ok_ -- "${fmt}"
+		diag_ " Failed test '${fmt}'"
 		diag_ "         got: '${got}'"
-		diag_ "    expected: '0'"
+		diag_ "    expected: '${tgt}'"
 	fi
 }
 
 for time_fmt in ${time_fmts}; do
-	run_test "${time_fmt}"
+	test_fmt "${now}" "${tgt}" "${time_fmt}"
 	for date_fmt in ${date_fmts}; do
-		run_test "${date_fmt} ${time_fmt}"
-		run_test "${time_fmt} ${date_fmt}"
+		test_fmt "${now}" "${tgt}" "${date_fmt} ${time_fmt}"
+		test_fmt "${now}" "${tgt}" "${time_fmt} ${date_fmt}"
 	done
 done
 for misc_fmt in ${misc_fmts}; do
-	run_test "${misc_fmt}"
+	test_fmt "${now}" "${tgt}" "${misc_fmt}"
 done