Manually sync ChannelDefs.pm from automake.

ChannelDefs.pm *ought* to be kept in sync between automake and autoconf,
because it defines the set of valid -W options, and autoreconf assumes
that it can pass arbitrary -W options to all of the tools it invokes.
However, it isn’t covered by either project’s ‘make fetch’ and it hasn’t
actually *been* in sync for more than 17 years.

This patch manually brings over all of the changes made on the
automake side.  Once the complementary patch is applied by the
automake team, both versions of the file will be the same, and then we
can add it to the list in fetch.pl and not have this problem any more
in the future.

There are some user-visible consequences to bringing this file back
into sync.  The only one worth mentioning in NEWS is that the ‘obsolete’
category of warnings is now on by default.  This had quite a bit of
fallout throughout the testsuite.  There are also some new warning
categories that get mentioned in --help output, but we don’t actually
generate any warnings in those categories, so people using ‘-Wall’
won’t see any change.  More diagnostics are automatically tagged with
‘warning:’ or ‘error:’, which also had some fallout in the testsuite.
Finally, ‘-Werror’ no longer causes complaints about unknown warning
categories to be treated as hard errors.

Internally, there are some small API changes: ‘parse_warnings’ is no
longer usable as a ‘getopt’ callback function, and we now have a stub
Autom4te/Config.pm to match the automake code’s expectations.  (This
file *should* also be synced from automake by ‘make fetch’, but we
can’t quite do that yet because it’s a generated file and our build
system is not prepared to handle adding *two* directories to @INC when
running a not-yet-installed Perl script.  I plan to fix that after 2.70.)

As a side-effect of adding a Config.pm, ‘prog_error’ now says to
report the bug to bug-autoconf, not bug-automake.  If this is why we
mostly haven’t been using prog_error for internal errors, we can stop
avoiding it.  (I did not change anything to use prog_error in this
patch.)

* lib/Autom4te/ChannelDefs.pm: Merge from automake.
* lib/Autom4te/Config.pm: New file.
* lib/local.mk (dist_perllib_DATA): Add Autom4te/Config.pm.

* bin/autoconf.as: Update list of warning categories to match
  Autom4te::ChannelDefs::usage.
* bin/autoheader.in (@warnings): New global.
  (parse_args): Don’t use parse_warnings as a getopt callback.
  (main): Add warnings options from our command line to $autoconf.
  No need to turn on 'obsolete' warnings explicitly.
  No need to include "warning: " in warning messages.
* bin/autom4te.in (parse_args): Don’t use parse_warnings as a getopt callback.
  (main): No need to include "warning: " in warning messages.
* bin/autoreconf.in (parse_args): parse_warnings now takes only one argument.
* bin/autoupdate.in: Set WARNINGS=none in environment for all child processes.

* tests/local.at
  (AT_CHECK_M4): Handle `autom4te: error: /usr/bin/m4 ...` like
  `autom4te: /usr/bin/m4 ...`.
  (_AT_CHECK_AC_MACRO): Add AUTOCONF-FLAGS argument, passed to both
  autoconf and autoheader.
  (AT_CHECK_MACRO): Default AUTOCONF-FLAGS argument to empty.
  Pass that argument to autoheader as well as autoconf.
  (AT_CHECK_AU_MACRO): Expect a “macro ‘NAME’ is obsolete’ diagnostic
  on the first run of autoconf.  Pass -Wno-obsolete to autoconf on the
  second run, and to autoheader on both runs.

* tests/base.at
* tests/c.at
* tests/compile.at
* tests/m4sh.at
* tests/m4sugar.at
* tests/semantics.at
* tests/tools.at
* tests/torture.at:
  No need to pass -Wobsolete to autoconf.
  Pass -Wno-obsolete to autoheader where needed to avoid handling
  the same warning twice.
  Update various expectations for diagnostics to match behavior
  changes.

* tests/tools.at (autoupdating AU_ALIAS): Add an AC_CONFIG_HEADERS
  line to the test configure.ac to eliminate an unrelated diagnostic.

18 files changed, 334 insertions, 120 deletions

diff --git a/NEWS b/NEWS
index 72761730..9ee7dbec 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,9 @@ GNU Autoconf NEWS - User visible changes.
    per-process temporary runtime files (such as pid files) into '/run'
    instead of '/var/run'.
 
+** Warnings about obsolete constructs are now on by default.
+   They can be turned off with '-Wno-obsolete'.
+
 ** The use of the long-deprecated name 'configure.in' for the autoconf
    input file now elicits a warning in the 'obsolete' category.
 
diff --git a/bin/autoconf.as b/bin/autoconf.as
index 1cfb5462..93563c97 100644
--- a/bin/autoconf.as
+++ b/bin/autoconf.as
@@ -37,16 +37,21 @@ Operation modes:
   -d, --debug               don't remove temporary files
   -f, --force               consider all files obsolete
   -o, --output=FILE         save output in FILE (stdout is the default)
-  -W, --warnings=CATEGORY   report the warnings falling in CATEGORY [syntax]
+  -W, --warnings=CATEGORY   report the warnings falling in CATEGORY
 
 Warning categories include:
-  'cross'         cross compilation issues
-  'obsolete'      obsolete constructs
-  'syntax'        dubious syntactic constructs
-  'all'           all the warnings
-  'no-CATEGORY'   turn off the warnings on CATEGORY
-  'none'          turn off all the warnings
-  'error'         warnings are error
+  cross                  cross compilation issues
+  gnu                    GNU coding standards (default in gnu and gnits modes)
+  obsolete               obsolete features or constructions (default)
+  override               user redefinitions of Automake rules or variables
+  portability            portability issues (default in gnu and gnits modes)
+  portability-recursive  nested Make variables (default with -Wportability)
+  extra-portability      extra portability issues related to obscure tools
+  syntax                 dubious syntactic constructs (default)
+  unsupported            unsupported or incomplete features (default)
+  all                    all the warnings
+  no-CATEGORY            turn off warnings in CATEGORY
+  none                   turn off all the warnings
 
 The environment variables 'M4' and 'WARNINGS' are honored.
 
diff --git a/bin/autoheader.in b/bin/autoheader.in
index 29d0fe52..6b02cbb8 100644
--- a/bin/autoheader.in
+++ b/bin/autoheader.in
@@ -58,7 +58,7 @@ my $autom4te = $ENV{'AUTOM4TE'} || '@bindir@/@autom4te-name@';
 my $config_h_in;
 my @prepend_include;
 my @include;
-
+my @warnings;
 
 # $HELP
 # -----
@@ -112,10 +112,12 @@ sub parse_args ()
 {
   my $srcdir;
 
-  parse_WARNINGS;
   getopt ('I|include=s'         => \@include,
 	  'B|prepend-include=s' => \@prepend_include,
-	  'W|warnings=s'        => \&parse_warnings);
+	  'W|warnings=s'        => \@warnings);
+
+  parse_WARNINGS;
+  parse_warnings @warnings;
 
   if (! @ARGV)
     {
@@ -130,7 +132,6 @@ sub parse_args ()
 ## -------------- ##
 
 mktmpdir ('ah');
-switch_warning 'obsolete';
 parse_args;
 
 # Preach.
@@ -165,6 +166,7 @@ END
 my $autoconf = "'$autom4te' --language=autoconf ";
 $autoconf .= join (' --include=', '', map { shell_quote ($_) } @include);
 $autoconf .= join (' --prepend-include=', '', map { shell_quote ($_) } @prepend_include);
+$autoconf .= join (' --warnings=', '', map { shell_quote ($_) } @warnings);
 $autoconf .= ' --debug' if $debug;
 $autoconf .= ' --force' if $force;
 $autoconf .= ' --verbose' if $verbose;
@@ -278,7 +280,7 @@ $out->close;
     {
       if (! -r $template)
 	{
-	  msg 'syntax', "warning: cannot read $template: $!";
+	  msg 'syntax', "cannot read $template: $!";
 	}
       else
 	{
@@ -297,7 +299,7 @@ $out->close;
 
   foreach (sort keys %symbol)
     {
-      msg 'syntax', "warning: missing template: $_";
+      msg 'syntax', "missing template: $_";
       if ($suggest_ac_define)
 	{
 	  msg 'syntax',  "Use AC_DEFINE([$_], [], [Description])";
diff --git a/bin/autom4te.in b/bin/autom4te.in
index 78902f13..20ecca9e 100644
--- a/bin/autom4te.in
+++ b/bin/autom4te.in
@@ -336,12 +336,13 @@ sub parse_args ()
   # Process the arguments for real this time.
   my @trace;
   my @prepend_include;
-  parse_WARNINGS;
+  my @warnings;
+
   getopt
     (
      # Operation modes:
      "o|output=s"   => \$output,
-     "W|warnings=s" => \&parse_warnings,
+     "W|warnings=s" => \@warnings,
      "m|mode=s"     => \$mode,
      "M|melt"       => \$melt,
 
@@ -365,6 +366,9 @@ sub parse_args ()
      "no-cache"  => sub { $cache = undef; },
     );
 
+  parse_WARNINGS;
+  parse_warnings @warnings;
+
   fatal "too few arguments
 Try '$me --help' for more information."
     unless @ARGV;
@@ -1048,7 +1052,7 @@ for (split (/\n*$separator\n*/o, contents ("$tmp/warnings")))
   # In particular, m4_warn guarantees that either $stackdump is empty, or
   # it consists of lines where only the last line ends in "top level".
   my ($cat, $loc, $msg, $stacktrace) = split ('::', $_, 4);
-  msg $cat, $loc, "warning: $msg",
+  msg $cat, $loc, $msg,
     partial => ($stacktrace =~ /top level$/) + 0;
   for (split /\n/, $stacktrace)
     {
diff --git a/bin/autoreconf.in b/bin/autoreconf.in
index 73de08a7..80185ba9 100644
--- a/bin/autoreconf.in
+++ b/bin/autoreconf.in
@@ -167,7 +167,7 @@ sub parse_args ()
   # lists.
   @warning = map { split /,/ } @warning;
   parse_WARNINGS;
-  parse_warnings '--warnings', @warning;
+  parse_warnings @warning;
 
   # Even if the user specified a configure.ac, trim to get the
   # directory, and look for configure.ac again.  Because (i) the code
diff --git a/bin/autoupdate.in b/bin/autoupdate.in
index 3f13254b..047f8e0e 100644
--- a/bin/autoupdate.in
+++ b/bin/autoupdate.in
@@ -229,6 +229,11 @@ $autoconf .= " --verbose" if $verbose;
 $autoconf .= join (' --include=', '', map { shell_quote ($_) } @include);
 $autoconf .= join (' --prepend-include=', '', map { shell_quote ($_) } @prepend_include);
 
+# Disable all warnings from autoconf invocations.
+# In particular we do not want warnings about obsolete constructs,
+# which are on by default as of autoconf 2.70.
+$ENV{'WARNINGS'} = 'none';
+
 mktmpdir ('au');
 handle_autoconf_macros;
 
diff --git a/lib/Autom4te/ChannelDefs.pm b/lib/Autom4te/ChannelDefs.pm
index 84e634e8..21f444b9 100644
--- a/lib/Autom4te/ChannelDefs.pm
+++ b/lib/Autom4te/ChannelDefs.pm
@@ -1,10 +1,9 @@
-# Copyright (C) 2002-2003, 2006, 2008-2017, 2020 Free Software
-# Foundation, Inc.
+# Copyright (C) 2002-2020 Free Software Foundation, Inc.
 
-# This program is free software: you can redistribute it and/or modify
+# 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.
+# the Free Software Foundation; either version 2, 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
@@ -16,8 +15,6 @@
 
 package Autom4te::ChannelDefs;
 
-use Autom4te::Channels;
-
 =head1 NAME
 
 Autom4te::ChannelDefs - channel definitions for Automake and helper functions
@@ -53,6 +50,17 @@ use warnings FATAL => 'all';
 
 use Exporter;
 
+use Autom4te::Channels;
+use Autom4te::Config;
+BEGIN
+{
+  if ($perl_threads)
+    {
+      require threads;
+      import threads;
+    }
+}
+
 our @ISA = qw (Exporter);
 our @EXPORT = qw (&prog_error &error &fatal &verb
 		  &switch_warning &parse_WARNINGS &parse_warnings);
@@ -79,7 +87,7 @@ Errors related to GNU Standards.
 
 =item C<error-gnu/warn>
 
-Errors related to GNU Standards that should be warnings in "foreign" mode.
+Errors related to GNU Standards that should be warnings in 'foreign' mode.
 
 =item C<error-gnits>
 
@@ -99,7 +107,7 @@ Warnings related to GNU Coding Standards.
 
 =item C<obsolete>
 
-Warnings about obsolete features (silent by default).
+Warnings about obsolete features.
 
 =item C<override>
 
@@ -110,9 +118,21 @@ variables (silent by default).
 
 Warnings about non-portable constructs.
 
+=item C<portability-recursive>
+
+Warnings about recursive variable expansions (C<$(foo$(x))>).
+These are not universally supported, but are more portable than
+the other non-portable constructs diagnosed by C<-Wportability>.
+These warnings are turned on by C<-Wportability> but can then be
+turned off separately by C<-Wno-portability-recursive>.
+
+=item C<extra-portability>
+
+Extra warnings about non-portable constructs covering obscure tools.
+
 =item C<syntax>
 
-Warnings about weird syntax, unused variables, typos ...
+Warnings about weird syntax, unused variables, typos...
 
 =item C<unsupported>
 
@@ -134,7 +154,7 @@ Informative messages.
 # Do not forget to update &usage and the manual
 # if you add or change a warning channel.
 
-register_channel 'fatal', type => 'fatal', ordered => 0;
+register_channel 'fatal', type => 'fatal', uniq_part => UP_NONE, ordered => 0;
 register_channel 'error', type => 'error';
 register_channel 'error-gnu', type => 'error';
 register_channel 'error-gnu/warn', type => 'error';
@@ -143,20 +163,27 @@ register_channel 'automake', type => 'fatal', backtrace => 1,
   header => ("####################\n" .
 	     "## Internal Error ##\n" .
 	     "####################\n"),
-  footer => "\nPlease contact <bug-automake\@gnu.org>.",
-  ordered => 0;
+  footer => "\nPlease contact <$PACKAGE_BUGREPORT>.",
+  uniq_part => UP_NONE, ordered => 0;
 
 register_channel 'cross', type => 'warning', silent => 1;
 register_channel 'gnu', type => 'warning';
-register_channel 'obsolete', type => 'warning', silent => 1;
+register_channel 'obsolete', type => 'warning';
 register_channel 'override', type => 'warning', silent => 1;
 register_channel 'portability', type => 'warning', silent => 1;
+register_channel 'extra-portability', type => 'warning', silent => 1;
+register_channel 'portability-recursive', type => 'warning', silent => 1;
 register_channel 'syntax', type => 'warning';
 register_channel 'unsupported', type => 'warning';
 
-register_channel 'verb', type => 'debug', silent => 1, ordered => 0;
+register_channel 'verb', type => 'debug', silent => 1, uniq_part => UP_NONE,
+  ordered => 0;
 register_channel 'note', type => 'debug', silent => 0;
 
+setup_channel_type 'warning', header => 'warning: ';
+setup_channel_type 'error', header => 'error: ';
+setup_channel_type 'fatal', header => 'error: ';
+
 =head2 FUNCTIONS
 
 =over 4
@@ -170,17 +197,19 @@ Return the warning category descriptions.
 sub usage ()
 {
   return "Warning categories include:
-  `cross'         cross compilation issues
-  `gnu'           GNU coding standards (default in gnu and gnits modes)
-  `obsolete'      obsolete features or constructions
-  `override'      user redefinitions of Automake rules or variables
-  `portability'   portability issues (default in gnu and gnits modes)
-  `syntax'        dubious syntactic constructs (default)
-  `unsupported'   unsupported or incomplete features (default)
-  `all'           all the warnings
-  `no-CATEGORY'   turn off warnings in CATEGORY
-  `none'          turn off all the warnings
-  `error'         treat warnings as errors";
+  cross                  cross compilation issues
+  gnu                    GNU coding standards (default in gnu and gnits modes)
+  obsolete               obsolete features or constructions (default)
+  override               user redefinitions of Automake rules or variables
+  portability            portability issues (default in gnu and gnits modes)
+  portability-recursive  nested Make variables (default with -Wportability)
+  extra-portability      extra portability issues related to obscure tools
+  syntax                 dubious syntactic constructs (default)
+  unsupported            unsupported or incomplete features (default)
+  all                    all the warnings
+  no-CATEGORY            turn off warnings in CATEGORY
+  none                   turn off all the warnings
+  error                  treat warnings as errors";
 }
 
 =item C<prog_error ($MESSAGE, [%OPTIONS])>
@@ -233,6 +262,8 @@ C<--verbose> messages.
 sub verb ($;%)
 {
   my ($msg, %opts) = @_;
+  $msg = "thread " . threads->tid . ": " . $msg
+    if $perl_threads;
   msg 'verb', '', $msg, %opts;
 }
 
@@ -274,6 +305,38 @@ sub switch_warning ($)
   elsif (channel_type ($cat) eq 'warning')
     {
       setup_channel $cat, silent => $has_no;
+      #
+      # Handling of portability warnings is trickier.  For relevant tests,
+      # see 'dollarvar2', 'extra-portability' and 'extra-portability3'.
+      #
+      # -Wportability-recursive and -Wno-portability-recursive should not
+      # have any effect on other 'portability' or 'extra-portability'
+      # warnings, so there's no need to handle them separately or ad-hoc.
+      #
+      if ($cat eq 'extra-portability' && ! $has_no) # -Wextra-portability
+        {
+          # -Wextra-portability must enable 'portability' and
+          # 'portability-recursive' warnings.
+          setup_channel 'portability', silent => 0;
+          setup_channel 'portability-recursive', silent => 0;
+        }
+      if ($cat eq 'portability') # -Wportability or -Wno-portability
+        {
+          if ($has_no) # -Wno-portability
+            {
+              # -Wno-portability must disable 'extra-portability' and
+              # 'portability-recursive' warnings.
+              setup_channel 'portability-recursive', silent => 1;
+              setup_channel 'extra-portability', silent => 1;
+            }
+          else # -Wportability
+            {
+              # -Wportability must enable 'portability-recursive'
+              # warnings.  But it should have no influence over the
+              # 'extra-portability' warnings.
+              setup_channel 'portability-recursive', silent => 0;
+            }
+        }
     }
   else
     {
@@ -288,36 +351,62 @@ Parse the WARNINGS environment variable.
 
 =cut
 
+# Used to communicate from parse_WARNINGS to parse_warnings.
+our $_werror = 0;
+
 sub parse_WARNINGS ()
 {
   if (exists $ENV{'WARNINGS'})
     {
       # Ignore unknown categories.  This is required because WARNINGS
       # should be honored by many tools.
-      switch_warning $_ foreach (split (',', $ENV{'WARNINGS'}));
+      # For the same reason, do not turn on -Werror at this point, just
+      # record that we saw it; parse_warnings will turn on -Werror after
+      # the command line has been processed.
+      foreach (split (',', $ENV{'WARNINGS'}))
+        {
+          if (/^(no-)?error$/)
+            {
+              $_werror = !defined $1;
+            }
+          else
+            {
+              switch_warning $_;
+            }
+        }
     }
 }
 
-=item C<parse_warnings ($OPTION, @ARGUMENT)>
+=item C<parse_warnings (@CATEGORIES)>
 
 Parse the argument of C<--warning=CATEGORY> or C<-WCATEGORY>.
+C<@CATEGORIES> is the accumulated set of warnings categories.
+Use like this:
 
-C<$OPTIONS> is C<"--warning"> or C<"-W">, C<@ARGUMENT> is a list of
-C<CATEGORY>.
-
-This can be used as an argument to C<Getopt>.
+    Autom4te::GetOpt::parse_options (
+        # ...
+        'W|warnings=s' => \@warnings,
+    )
+    # possibly call set_strictness here
+    parse_warnings @warnings;
 
 =cut
 
-sub parse_warnings ($@)
+sub parse_warnings (@)
 {
-  my ($opt, @categories) = @_;
-
-  foreach my $cat (map { split ',' } @categories)
+  foreach my $cat (map { split ',' } @_)
     {
-      msg 'unsupported', "unknown warning category `$cat'"
-	if switch_warning $cat;
+      if ($cat =~ /^(no-)?error$/)
+        {
+          $_werror = !defined $1;
+        }
+      elsif (switch_warning $cat)
+        {
+          msg 'unsupported', "unknown warning category '$cat'";
+        }
     }
+
+  switch_warning ($_werror ? 'error' : 'no-error');
 }
 
 =item C<set_strictness ($STRICTNESS_NAME)>
@@ -336,6 +425,7 @@ sub set_strictness ($)
       setup_channel 'error-gnu/warn', silent => 0, type => 'error';
       setup_channel 'error-gnits', silent => 1;
       setup_channel 'portability', silent => 0;
+      setup_channel 'extra-portability', silent => 1;
       setup_channel 'gnu', silent => 0;
     }
   elsif ($name eq 'gnits')
@@ -344,6 +434,7 @@ sub set_strictness ($)
       setup_channel 'error-gnu/warn', silent => 0, type => 'error';
       setup_channel 'error-gnits', silent => 0;
       setup_channel 'portability', silent => 0;
+      setup_channel 'extra-portability', silent => 1;
       setup_channel 'gnu', silent => 0;
     }
   elsif ($name eq 'foreign')
@@ -352,11 +443,12 @@ sub set_strictness ($)
       setup_channel 'error-gnu/warn', silent => 0, type => 'warning';
       setup_channel 'error-gnits', silent => 1;
       setup_channel 'portability', silent => 1;
+      setup_channel 'extra-portability', silent => 1;
       setup_channel 'gnu', silent => 1;
     }
   else
     {
-      prog_error "level `$name' not recognized\n";
+      prog_error "level '$name' not recognized";
     }
 }
 
@@ -372,6 +464,8 @@ Written by Alexandre Duret-Lutz E<lt>F<adl@gnu.org>E<gt>.
 
 =cut
 
+1;
+
 ### Setup "GNU" style for perl-mode and cperl-mode.
 ## Local Variables:
 ## perl-indent-level: 2
diff --git a/lib/Autom4te/Config.pm b/lib/Autom4te/Config.pm
new file mode 100644
index 00000000..23c5ac14
--- /dev/null
+++ b/lib/Autom4te/Config.pm
@@ -0,0 +1,43 @@
+#  -*- Perl -*-
+# Copyright (C) 2003-2020 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 2, 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/>.
+
+package Autom4te::Config;
+
+# This is a stub version of Automake/Config.pm.
+# It defines only the variables that are necessary in order to fetch
+# Autom4te/ChannelDefs.pm from Automake/ChannelDefs.pm
+# (see build-aux/fetch.pl).
+# We would like to fetch Automake/Config.pm as well,
+# but that file is generated when automake is built,
+# and autoconf's build machinery is not prepared to do that.
+# Revisit after 2.70.
+
+use 5.006;
+use strict;
+use warnings FATAL => 'all';
+
+use Exporter;
+
+our @ISA = qw (Exporter);
+our @EXPORT = qw ($PACKAGE_BUGREPORT $perl_threads);
+
+# this must be kept in sync with configure.ac
+our $PACKAGE_BUGREPORT = 'bug-autoconf@gnu.org';
+
+# autom4te currently has no use for threads
+our $perl_threads = 0;
+
+1;
diff --git a/lib/local.mk b/lib/local.mk
index 5cc9d44a..4e2e5b65 100644
--- a/lib/local.mk
+++ b/lib/local.mk
@@ -34,6 +34,7 @@ dist_perllib_DATA = \
   lib/Autom4te/C4che.pm \
   lib/Autom4te/ChannelDefs.pm \
   lib/Autom4te/Channels.pm \
+  lib/Autom4te/Config.pm \
   lib/Autom4te/Configure_ac.pm \
   lib/Autom4te/FileUtils.pm \
   lib/Autom4te/General.pm \
diff --git a/tests/base.at b/tests/base.at
index 6894990a..6a1d9742 100644
--- a/tests/base.at
+++ b/tests/base.at
@@ -81,7 +81,7 @@ AT_DATA([configure.ac],
 AT_CHECK_AUTOCONF([], [1], [],
 [[configure.ac:1: error: AC_REQUIRE(AC_PROG_CC): cannot be used outside of an AC_DEFUN'd macro
 configure.ac:1: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 AT_CLEANUP
 
diff --git a/tests/c.at b/tests/c.at
index d13b321e..1ae678d1 100644
--- a/tests/c.at
+++ b/tests/c.at
@@ -262,7 +262,7 @@ AT_SETUP([AC_USE_SYSTEM_EXTENSIONS])
 _AT_CHECK_AC_MACRO(
 [[AC_AIX
 AC_DEFINE([__EXTENSIONS__], [1], [Manually defined for Solaris])
-]])
+]], [], [-Wno-obsolete])
 
 _AT_CHECK_AC_MACRO(
 [[AC_USE_SYSTEM_EXTENSIONS
diff --git a/tests/compile.at b/tests/compile.at
index fbba8e63..c93722b9 100644
--- a/tests/compile.at
+++ b/tests/compile.at
@@ -344,7 +344,12 @@ test $estatus != 3 &&
 AC_OUTPUT
 ]])
 
-AT_CHECK_AUTOCONF
+AT_CHECK_AUTOCONF([], 0, [],
+[[configure.ac:14: warning: The macro `AC_TRY_RUN' is obsolete.
+configure.ac:14: You should run autoupdate.
+general.m4: AC_TRY_RUN is expanded from...
+configure.ac:14: the top level
+]])
 AT_CHECK_CONFIGURE([-q])
 
 AT_CLEANUP
diff --git a/tests/local.at b/tests/local.at
index a875b5e0..3424bd6a 100644
--- a/tests/local.at
+++ b/tests/local.at
@@ -137,6 +137,7 @@ m4_case([$4], [], [], [ignore], [],
 	s/: C\(annot open \)\([^`:]*\):/: c\1`\2'\'':/
 	s/: include:\( cannot open\)/:\1/
 	s/^autom4te: [^ ]*m4[.ex]* /autom4te: m4 /
+	s/^autom4te: error: [^ ]*m4[.ex]* /autom4te: error: m4 /
         s!^.*/\([^/][^/]*\)\.m4: *[0-9][0-9]*: *!\1.m4: !
         s!^.*/\([^/][^/]*\)\.m4: *[0-9][0-9]*: *[0-9][0-9]*: *!\1.m4: !
 	s/ (E[A-Z]*)$//
@@ -508,39 +509,37 @@ dnl pacify editors that don't understand sh case: ((
 ])
 
 
-# _AT_CHECK_AC_MACRO(AC-BODY, PRE-TESTS)
+# _AT_CHECK_AC_MACRO(AC-BODY, PRE-TESTS, [AUTOCONF-FLAGS])
 # --------------------------------------
 # Create a minimalist configure.ac running the macro named
 # NAME-OF-THE-MACRO, check that autoconf runs on that script,
-# and that the shell runs correctly the configure.
+# and that the generated configure script runs without error.
 m4_define([_AT_CHECK_AC_MACRO],
 [AT_CONFIGURE_AC([$1])
 $2
-AT_CHECK_AUTOCONF
-AT_CHECK_AUTOHEADER([], [ignore])
+AT_CHECK_AUTOCONF([$3])
+AT_CHECK_AUTOHEADER([$3], [ignore])
 AT_CHECK_CONFIGURE
 AT_CHECK_ENV
 ])# _AT_CHECK_AC_MACRO
 
 
 # AT_CHECK_MACRO(MACRO, [MACRO-USE], [ADDITIONAL-CMDS],
-#                [AUTOCONF-FLAGS = -W obsolete])
+#                [AUTOCONF-FLAGS])
 # -----------------------------------------------------
 # Create a minimalist configure.ac running the macro named
 # NAME-OF-THE-MACRO, check that autoconf runs on that script,
-# and that the shell runs correctly the configure.
+# and that the generated configure script runs without error.
 #
 # We run `configure' twice, both times with a cache, and compare
 # the environment after each run to detect inconsistencies.
-#
-# New macros are not expected to depend upon obsolete macros.
 m4_define([AT_CHECK_MACRO],
 [AT_SETUP([$1])
 
 AT_CONFIGURE_AC([m4_default([$2], [$1])])
 
-AT_CHECK_AUTOCONF([m4_default([$4], [-W obsolete])])
-AT_CHECK_AUTOHEADER([], [ignore])
+AT_CHECK_AUTOCONF([$4])
+AT_CHECK_AUTOHEADER([$4], [ignore])
 
 for at_run in r1 r2
 do
@@ -562,7 +561,7 @@ AT_CLEANUP[]dnl
 
 
 # AT_CHECK_MACRO_CROSS(MACRO, [MACRO-USE], [ADDITIONAL-CMDS],
-#                      [AUTOCONF-FLAGS = -W obsolete])
+#                      [AUTOCONF-FLAGS])
 # -----------------------------------------------------------
 # Like the previous one, but creates two checks: for native
 # compile and for cross-compile.
@@ -581,22 +580,29 @@ AT_CHECK_MACRO([$1 (cross compile)],
 # AT_CHECK_AU_MACRO(MACRO)
 # ------------------------
 # Create a minimalist configure.ac running the macro named
-# NAME-OF-THE-MACRO, autoupdate this script, check that autoconf runs
-# on that script, and that the shell runs correctly the configure.
-#
-# Updated configure.ac shall not depend upon obsolete macros, which votes
-# in favor of `-W obsolete', but since many of these macros leave a message
-# to be removed by the user once her code is adjusted, let's not check.
-#
-# Remove config.hin to avoid `autoheader: config.hin is unchanged'.
+# NAME-OF-THE-MACRO, check that autoconf runs on that script,
+# and that the generated configure script runs without error.
+#
+# Then run autoupdate on that script, and check that NAME-OF-THE-MACRO
+# no longer appears in configure.ac, autoconf runs on the updated
+# script, the configure script still runs without error, and the
+# result is unchanged.
+#
+# On the first pass, check for a -Wobsolete warning naming
+# NAME-OF-THE-MACRO.  On the second pass, *don't* check for the
+# absence of -Wobsolete warnings, because many of autoupdate's edits
+# leave the configure.ac author with some manual work to do, and
+# indicate this by inserting an AC_DIAGNOSE message to be removed
+# after the manual work is complete.
 m4_define([AT_CHECK_AU_MACRO],
 [AT_SETUP([$1])
 AT_KEYWORDS([autoupdate])
 
 AT_CONFIGURE_AC([$1])
 
-AT_CHECK_AUTOCONF
-AT_CHECK_AUTOHEADER([], [ignore])
+AT_CHECK_AUTOCONF([], 0, [], [stderr])
+AT_CHECK([grep 'macro .$1. is obsolete' stderr], 0, [ignore], [ignore])
+AT_CHECK_AUTOHEADER([-Wno-obsolete], [ignore])
 AT_CHECK_CONFIGURE
 AT_CHECK_ENV
 
@@ -604,8 +610,8 @@ rm config.hin
 AT_CHECK_AUTOUPDATE([], 0, [], ignore)
 AT_CHECK([grep '^$1$' configure.ac], 1)
 
-AT_CHECK_AUTOCONF
-AT_CHECK_AUTOHEADER([], [ignore])
+AT_CHECK_AUTOCONF([-Wno-obsolete])
+AT_CHECK_AUTOHEADER([-Wno-obsolete], [ignore])
 AT_CHECK_CONFIGURE
 AT_CHECK_ENV
 
diff --git a/tests/m4sh.at b/tests/m4sh.at
index b352704d..30e3fa58 100644
--- a/tests/m4sh.at
+++ b/tests/m4sh.at
@@ -599,7 +599,7 @@ ECHO_TEST([
 AS_EXIT(0)
 ]])
 
-AT_CHECK_M4SH([-Wobsolete], 0, [],
+AT_CHECK_M4SH([], 0, [],
 [[script.as:13: warning: $as@&t@_echo is obsolete; use AS@&t@_ECHO(["message"]) instead
 script.as:13: warning: $as@&t@_echo_n is obsolete; use AS@&t@_ECHO_N(["message"]) instead
 script.as:14: warning: $as@&t@_echo is obsolete; use AS@&t@_ECHO(["message"]) instead
diff --git a/tests/m4sugar.at b/tests/m4sugar.at
index 3b861d55..aff83cfa 100644
--- a/tests/m4sugar.at
+++ b/tests/m4sugar.at
@@ -259,6 +259,7 @@ m4_warn([syntax], [syntax])dnl
 
 AT_CHECK_M4SUGAR([-o-], 0, [],
 [script.4s:4: warning: prefer named diversions
+script.4s:5: warning: obsolete
 script.4s:7: warning: syntax
 script.4s:9: warning: syntax
 ])
@@ -354,7 +355,7 @@ AT_DATA_M4SUGAR([script.4s],
 AT_CHECK_M4SUGAR([-o-], [1], [],
 [[script.4s:1: error: too many m4@&t@_divert_pop
 script.4s:1: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_DATA_M4SUGAR([script.4s],
@@ -367,7 +368,7 @@ AT_CHECK_M4SUGAR([-o-], [1], [],
 script.4s:2: m4@&t@_divert_push: 1
 script.4s:1: m4@&t@_divert: KILL
 script.4s:3: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_DATA_M4SUGAR([script.4s],
@@ -380,7 +381,7 @@ AT_CHECK_M4SUGAR([-o-], [1], [],
 script.4s:3: m4@&t@_divert_push: 2
 script.4s:2: m4@&t@_divert: KILL
 script.4s:2: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_CLEANUP
@@ -425,7 +426,7 @@ m4_require([foo])
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:2: error: m4@&t@_require(foo): cannot be used outside of an m4_defun'd macro
 script.4s:2: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 AT_CLEANUP
 
@@ -506,7 +507,7 @@ script.4s:3: bar is expanded from...
 script.4s:1: foo is expanded from...
 script.4s:5: baz is expanded from...
 script.4s:9: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 AT_CLEANUP
 
@@ -923,7 +924,7 @@ m4_argn([0], [a], [b], [c])
 AT_CHECK_M4SUGAR([-o-], [1], [],
 [[script.4s:2: error: assert failed: 0 < 0
 script.4s:2: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_CLEANUP
@@ -1605,7 +1606,7 @@ m4_for([myvar], 1, 3,-1, [ myvar])
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:3: error: assert failed: -1 > 0
 script.4s:3: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_DATA_M4SUGAR([script.4s],
@@ -1616,7 +1617,7 @@ m4_for([myvar], 1, 2, 0, [ myvar])
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:3: error: assert failed: 0 > 0
 script.4s:3: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_DATA_M4SUGAR([script.4s],
@@ -1627,7 +1628,7 @@ m4_for([myvar], 2, 1, 0, [ myvar])
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:3: error: assert failed: 0 < 0
 script.4s:3: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 dnl m4_shiftn also does bounds checking
@@ -1639,7 +1640,7 @@ m4_shiftn(3,1,2)
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:3: error: assert failed: 0 < 3 && 3 < 3
 script.4s:3: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_CLEANUP
@@ -1832,7 +1833,7 @@ AT_DATA_M4SUGAR([script.4s],
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:1: error: too few arguments to m4@&t@_max
 script.4s:1: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_DATA_M4SUGAR([script.4s],
@@ -1842,7 +1843,7 @@ AT_DATA_M4SUGAR([script.4s],
 AT_CHECK_M4SUGAR([], 1, [],
 [[script.4s:1: error: too few arguments to m4@&t@_min
 script.4s:1: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 AT_CHECK_M4SUGAR_TEXT([[dnl
diff --git a/tests/semantics.at b/tests/semantics.at
index 32811f6d..e7dd7c5a 100644
--- a/tests/semantics.at
+++ b/tests/semantics.at
@@ -251,7 +251,7 @@ AT_DATA([autoconf_io.h],
 ])
 
 AT_CONFIGURE_AC([AC_CHECK_HEADERS(stdio.h autoconf_io.h)])
-AT_CHECK_AUTOCONF([-W obsolete])
+AT_CHECK_AUTOCONF
 AT_CHECK_AUTOHEADER([], [
   HAVE_AUTOCONF_IO_H
   HAVE_INTTYPES_H
@@ -291,7 +291,7 @@ AT_DATA([header2.h],
 
 AT_CONFIGURE_AC([[AC_CHECK_HEADERS([header2.h], [], [], [-])]])
 
-AT_CHECK_AUTOCONF([-W obsolete], [], [],
+AT_CHECK_AUTOCONF([], 0, [],
 [[configure.ac:4: warning: Checking for headers with the preprocessor is
 configure.ac:4: deprecated. Specify prerequisite code to AC_CHECK_HEADER
 configure.ac:4: instead of using fourth argument `-'. (Many headers need
@@ -303,7 +303,7 @@ headers.m4: AC_CHECK_HEADER is expanded from...
 headers.m4: AC_CHECK_HEADERS is expanded from...
 configure.ac:4: the top level
 ]])
-AT_CHECK_AUTOHEADER([], [HAVE_HEADER2_H])
+AT_CHECK_AUTOHEADER([-W no-obsolete], [HAVE_HEADER2_H])
 AT_CHECK_CONFIGURE([CPPFLAGS=-I.])
 AT_CHECK_ENV
 AT_CHECK_DEFINES(
@@ -334,7 +334,7 @@ AT_DATA([header3.h],
 AT_CONFIGURE_AC(
 [AC_CHECK_HEADERS(header2.h header3.h, [], [], [[@%:@include "header1.h"]])])
 
-AT_CHECK_AUTOCONF([-W obsolete])
+AT_CHECK_AUTOCONF
 AT_CHECK_AUTOHEADER([], [
   HAVE_HEADER2_H
   HAVE_HEADER3_H
@@ -829,14 +829,14 @@ $1([dn@&t@l
     fn_blurf dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete], [0], [],
+AT_CHECK_AUTOCONF([], [0], [],
 [configure.ac:6: warning: whitespace-separated list contains macros;
 configure.ac:6: in a future version of Autoconf they will not be expanded
 configure.ac:6: note: `dn@&t@l' is a macro
 functions.m4: $1 is expanded from...
 configure.ac:6: the top level
 ])
-AT_CHECK_AUTOHEADER([], [
+AT_CHECK_AUTOHEADER([-W no-obsolete], [
   HAVE_FN_BLURF
   HAVE_FN_FOO
   HAVE_FN_NOCOMMENT
@@ -858,7 +858,7 @@ $1([dn@&t@l
     fn_blurf dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete], [0], [],
+AT_CHECK_AUTOCONF([], [0], [],
 [configure.ac:8: warning: whitespace-separated list contains macros;
 configure.ac:8: in a future version of Autoconf they will not be expanded
 configure.ac:8: note: `dn@&t@l' is a macro
@@ -868,7 +868,7 @@ configure.ac:8: warning: $1($fns): you should use literals
 functions.m4: $1 is expanded from...
 configure.ac:8: the top level
 ])
-AT_CHECK_AUTOHEADER([], [
+AT_CHECK_AUTOHEADER([-W no-obsolete], [
   HAVE_FN_BLURF
   HAVE_FN_FOO
   HAVE_FN_NOCOMMENT
@@ -894,14 +894,14 @@ $1([dn@&t@l
     blurf.h dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete], [0], [],
+AT_CHECK_AUTOCONF([], [0], [],
 [configure.ac:6: warning: whitespace-separated list contains macros;
 configure.ac:6: in a future version of Autoconf they will not be expanded
 configure.ac:6: note: `dn@&t@l' is a macro
 headers.m4: $1 is expanded from...
 configure.ac:6: the top level
 ])
-AT_CHECK_AUTOHEADER([], [
+AT_CHECK_AUTOHEADER([-W no-obsolete], [
   HAVE_BLURF_H
   HAVE_FOO_H
   HAVE_INTTYPES_H
@@ -932,7 +932,7 @@ $1([dn@&t@l
     blurf.h dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete], [0], [],
+AT_CHECK_AUTOCONF([], [0], [],
 [configure.ac:8: warning: whitespace-separated list contains macros;
 configure.ac:8: in a future version of Autoconf they will not be expanded
 configure.ac:8: note: `dn@&t@l' is a macro
@@ -942,7 +942,7 @@ configure.ac:8: warning: $1($hs): you should use literals
 headers.m4: $1 is expanded from...
 configure.ac:8: the top level
 ])
-AT_CHECK_AUTOHEADER([], [
+AT_CHECK_AUTOHEADER([-W no-obsolete], [
   HAVE_BLURF_H
   HAVE_FOO_H
   HAVE_INTTYPES_H
@@ -982,14 +982,14 @@ AC_CHECK_FILES([dn@&t@l
   /nonex/f_blurf dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete], [0], [],
+AT_CHECK_AUTOCONF([], [0], [],
 [configure.ac:6: warning: whitespace-separated list contains macros;
 configure.ac:6: in a future version of Autoconf they will not be expanded
 configure.ac:6: note: `dn@&t@l' is a macro
 general.m4: AC_CHECK_FILES is expanded from...
 configure.ac:6: the top level
 ])
-AT_CHECK_AUTOHEADER([], [
+AT_CHECK_AUTOHEADER([-W no-obsolete], [
   HAVE__NONEX_F_BLURF
   HAVE__NONEX_F_FOO
   HAVE__NONEX_F_QUUX
@@ -1008,7 +1008,7 @@ AC_CONFIG_MACRO_DIRS([dn@&t@l
   d_blurf dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete -t AC_CONFIG_MACRO_DIR_TRACE], [0],
+AT_CHECK_AUTOCONF([-t AC_CONFIG_MACRO_DIR_TRACE], [0],
 [configure.ac:6:AC_CONFIG_MACRO_DIR_TRACE:d_foo
 configure.ac:6:AC_CONFIG_MACRO_DIR_TRACE:d_quux
 configure.ac:6:AC_CONFIG_MACRO_DIR_TRACE:d_blurf
@@ -1040,14 +1040,14 @@ AC_CONFIG_SUBDIRS([dn@&t@l
   d_blurf dn@&t@l Apos'trophed comment
 ])
 ]])
-AT_CHECK_AUTOCONF([-W obsolete], [0], [],
+AT_CHECK_AUTOCONF([], [0], [],
 [configure.ac:6: warning: whitespace-separated list contains macros;
 configure.ac:6: in a future version of Autoconf they will not be expanded
 configure.ac:6: note: `dn@&t@l' is a macro
 status.m4: AC_CONFIG_SUBDIRS is expanded from...
 configure.ac:6: the top level
 ])
-AT_CHECK_AUTOHEADER
+AT_CHECK_AUTOHEADER([-W no-obsolete])
 AT_CHECK_CONFIGURE([], [0], [stdout])
 AT_CHECK([grep '^entered' stdout], [0],
 [[entered d_foo/configure
diff --git a/tests/tools.at b/tests/tools.at
index 3093225c..1bb670fa 100644
--- a/tests/tools.at
+++ b/tests/tools.at
@@ -100,7 +100,7 @@ mkdir sub
 mv foo sub
 AT_CHECK_M4SUGAR([], [1], [],
 [m4:script.4s:1: cannot open `foo': No such file or directory
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ])
 
 # But if we change the main file, then we should no longer complain of
@@ -414,7 +414,7 @@ AC_CONFIG_MACRO_DIR_TRACE([dir1])
 AT_CHECK_AUTOCONF([], [1], [],
 [[configure.ac:2: error: Do not invoke AC_CONFIG_MACRO_DIR_TRACE directly
 configure.ac:2: the top level
-autom4te: m4 failed with exit status: 1
+autom4te: error: m4 failed with exit status: 1
 ]])
 
 # Legacy macro use is not required, but still gets traced
@@ -952,7 +952,17 @@ AT_DATA([dst2], dst2
 
 # Checking `autoupdate'.
 AT_CHECK_AUTOUPDATE([], 0, [], ignore)
-AT_CHECK_AUTOCONF
+
+# The replacement for AC_LINK_FILES includes a forced -Wobsolete
+# warning, becuause it needs to be manually adjusted afterward.
+# Look for it in the autoconf output.
+AT_CHECK_AUTOCONF([], 0, [], stderr)
+AT_CHECK([grep 'AC_LINK_FILES' stderr], 0, ignore, ignore)
+AT_CHECK([grep 'AC_CONFIG_LINKS' stderr], 0, ignore, ignore)
+AT_CHECK([grep 'warning: It is technically impossible' stderr],
+         0, ignore, ignore)
+AT_CHECK([grep 'tune the result yourself' stderr], 0, ignore, ignore)
+
 AT_CHECK_CONFIGURE
 AT_CHECK([cat src1], 0, [dst1
 ])
@@ -994,12 +1004,37 @@ AU_ALIAS([BAZ],[FOO])
 test "FOO:FOO():FOO(x) BAZ:BAZ():BAZ(x)" = "0:1:1 0:1:1" || exit 1
 AC_PROG_CC
 AC_WORDS_BIGENDIAN
+AC_CONFIG_HEADERS([config.h])
 AC_OUTPUT
 ]])
 
 # Checking `autoupdate'.
 AT_CHECK_AUTOUPDATE
-AT_CHECK_AUTOCONF
+
+# autoupdate does not replace AU_DEFUNs/AU_ALIASes defined by
+# configure.ac itself, nor by aclocal.m4, so BAZ will still be present
+# in the updated configure.ac.  This is actually desirable for this
+# test: the point of that part of the above configure.ac is to to
+# verify that the expansion of an AU_ALIAS definition handles $#
+# correctly.  If BAZ got turned into FOO by the above call to
+# autoupdate, we would need to run autoconf and configure twice in
+# this test.  However, it does also mean that by default we get a
+# -Wobsolete warning because of BAZ, so turn that off so it doesn't
+# cause a spurious failure.
+AT_CHECK_AUTOCONF([-Wno-obsolete])
+AT_CHECK_AUTOHEADER([-Wno-obsolete], [
+  AC_APPLE_UNIVERSAL_BUILD
+  HAVE_INTTYPES_H
+  HAVE_STDINT_H
+  HAVE_STDLIB_H
+  HAVE_STRINGS_H
+  HAVE_STRING_H
+  HAVE_SYS_STAT_H
+  HAVE_SYS_TYPES_H
+  HAVE_UNISTD_H
+  STDC_HEADERS
+  WORDS_BIGENDIAN
+])
 AT_CHECK_CONFIGURE
 AT_CHECK([grep 'AC_C_BIGENDIAN[(]' configure.ac], 1, [ignore], [ignore])
 AT_CHECK([grep 'AC_C_BIGENDIAN' configure.ac], 0, [ignore], [ignore])
@@ -1208,9 +1243,16 @@ AC_OUTPUT
 ]])
 
 # Checking `autoupdate'.
+
+# Both the autoupdate and autoconf invocations will complain about
+# AC_LANG_SAVE being obsolete, because autoupdate cannot replace
+# two-macro sequences (e.g. AC_LANG_SAVE \n AC_LANG([C]) ideally would
+# become AC_LANG_PUSH([C]) but we can't do that) so an AC_DIAGNOSE
+# is left in place to remind people they need to do some hand edits.
+# Ignore these diagnostics.
 AT_CHECK_AUTOUPDATE([], [], [], [ignore])
-AT_CHECK_AUTOCONF
-AT_CHECK_CONFIGURE([], [], [], [ignore])
+AT_CHECK_AUTOCONF([], [], [], [ignore])
+AT_CHECK_CONFIGURE
 
 AT_CLEANUP
 
diff --git a/tests/torture.at b/tests/torture.at
index 53859f6b..5c61027c 100644
--- a/tests/torture.at
+++ b/tests/torture.at
@@ -149,7 +149,10 @@ AT_DATA([file.in],
 [[`@precious@'
 ]])
 
-AT_CHECK_AUTOCONF
+AT_CHECK_AUTOCONF([], 0, [],
+[[configure.ac:4: warning: AC_OUTPUT should be used without arguments.
+configure.ac:4: You should run autoupdate.
+]])
 
 # Set a precious variable
 AT_CHECK_AC_ARG_VAR([], [apple of my eye])