Re: tracing from aclocal

[Alexandre Duret-Lutz]

I'm finally installing this patch as follows.

2003-08-24  Alexandre Duret-Lutz  <address@hidden>

        * aclocal.in (write_aclocal): Take an output file and list of
        used macros in arguments and make up the file contents here.
        (trace_used_macros): New function.
        (add_file): Do not update $output.
        ($output): Delete.
        (MAIN): Call trace_used_macros.  Then rewrite aclocal.m4 only
        for these traced macros.  This should shorten aclocal.m4 by
        stripping out unused macros.
        * automake.texi (Invoking aclocal): Document ${AUTOM4TE}.
        * tests/aclibobj.test: Make sure configure.in exists by the time
        aclocal runs.
        * tests/aclocal8.test: New file.
        * tests/Makefile.am (TESTS): Add aclocal8.test.
        Suggested by Bruno Haible and Akim Demaille.

Index: NEWS
===================================================================
RCS file: /cvs/automake/automake/NEWS,v
retrieving revision 1.222
diff -u -r1.222 NEWS
--- NEWS        17 Aug 2003 18:09:10 -0000      1.222
+++ NEWS        24 Aug 2003 01:54:42 -0000
@@ -71,6 +71,11 @@
     Autom4te's cache isn't needlessly invalidated.  This behavior can
     be switched off with the new `--force' option.
 
+  - aclocal now uses Autoconf's --trace to detect macros which are actually
+    used and will no longer include unused macros simply because they
+    where mentioned.  This was often the case for macros called
+    conditionally.
+
   - New option no-dist-gzip.
 
   - install-sh now understands --version and --help.
Index: aclocal.in
===================================================================
RCS file: /cvs/automake/automake/aclocal.in,v
retrieving revision 1.85
diff -u -r1.85 aclocal.in
--- aclocal.in  21 Aug 2003 08:49:24 -0000      1.85
+++ aclocal.in  24 Aug 2003 01:54:42 -0000
@@ -58,9 +58,6 @@
 # Exit status.
 $exit_status = 0;
 
-# Text to output.
-$output = '';
-
 # Output file name.
 $output_file = 'aclocal.m4';
 
@@ -103,9 +100,10 @@
 &scan_m4_files (@dirlist);
 &scan_configure;
 if (! $exit_status)
-{
-    &write_aclocal;
-}
+  {
+    my %macro_traced = &trace_used_macros;
+    &write_aclocal ($output_file, keys %macro_traced);
+  }
 &check_acinclude;
 
 exit $exit_status;
@@ -457,22 +455,75 @@
     return $contents;
 }
 
+sub trace_used_macros ($)
+{
+  my ($filename) = @_;
+
+  my %files = map { $map{$_} => 1 } keys %macro_seen;
+
+  my $traces = ($ENV{AUTOM4TE} || 'autom4te');
+  $traces .= " --language Autoconf-without-aclocal-m4 $filename ";
+  # All candidate files.
+  $traces .= join (' ', sort keys %files) . " ";
+  # All candidate macros.
+  $traces .= join (' ', map { "--trace='$_:\$n'" } (keys %macro_seen));
+
+  print STDERR "aclocal: running $traces $configure_ac\n" if $verbose;
+
+  my $tracefh = new Automake::XFile ("$traces $configure_ac |");
+
+  my %traced = ();
+
+  while ($_ = $tracefh->getline)
+    {
+      chomp;
+      $traced{$_} = 1 if $macro_seen{$_};
+    }
+  return %traced;
+}
+
 ################################################################
 
 # Write output.
-sub write_aclocal ()
+sub write_aclocal ($@)
 {
-    # Nothing to output?!
-    # FIXME: Shouldn't we diagnose this?
-    return if ! length ($output);
-
-# We used to print `# $output_file generated automatically etc.'  But
-# this creates spurious differences when using autoreconf.  Autoreconf
-# creates aclocal.m4t and then rename it to aclocal.m4, but the
-# rebuild rules generated by Automake create aclocal.m4 directly --
-# this would gives two ways to get the same file, with a different
-# name in the header.
-    $output = "# generated automatically by aclocal $VERSION -*- Autoconf -*-
+  my ($output_file, @macros) = @_;
+  my $output = '';
+
+  my %files = map { $map{$_} => 1 } @macros;
+  $files{'acinclude.m4'} = 1 if -f 'acinclude.m4';
+
+  for $file (sort keys %files)
+    {
+      my $mtime = mtime $file;
+      $greatest_mtime = $mtime if $greatest_mtime < $mtime;
+
+      # If the file to add looks like path outside the project,
+      # copy it to the output.
+      # The regex catches filenames starting with things like
+      #   / \ c:\ ../ ./../ etc.
+      if ($file =~ m,^(?:(?:\w:)?[\\/]|(?:\.[\\/]+)*\.\.[\\/]),)
+       {
+         $output .= $file_contents{$file} . "\n";
+       }
+      else
+       {
+         # Otherwise, simply include the file.
+         $output .= "m4_include([$file])\n";
+       }
+    }
+
+  # Nothing to output?!
+  # FIXME: Shouldn't we diagnose this?
+  return if ! length ($output);
+
+  # We used to print `# $output_file generated automatically etc.'  But
+  # this creates spurious differences when using autoreconf.  Autoreconf
+  # creates aclocal.m4t and then rename it to aclocal.m4, but the
+  # rebuild rules generated by Automake create aclocal.m4 directly --
+  # this would gives two ways to get the same file, with a different
+  # name in the header.
+  $output = "# generated automatically by aclocal $VERSION -*- Autoconf -*-
 
 # Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
 # Free Software Foundation, Inc.
@@ -487,29 +538,30 @@
 
 $output";
 
-    # We try not to update $output_file unless necessary, because
-    # doing so invalidate Autom4te's cache and therefore slows down
-    # tools called after aclocal.
-    #
-    # We need to overwrite $output_file in the following situations.
-    #   * The --force option is in use.
-    #   * One of the dependencies is younger.
-    #     (Not updating $output_file in this situation would cause
-    #     make to call aclocal in loop.)
-    #   * The contents of the current file are different from what
-    #     we have computed.
-    if (!$force_output
-       && $greatest_mtime < mtime ($output_file)
-       && $output eq contents ($output_file))
-      {
-       print STDERR "aclocal: $output_file unchanged\n" if $verbose;
-       return;
-      }
-
-    print STDERR "aclocal: writing $output_file\n" if $verbose;
-
-    my $out = new Automake::XFile "> $output_file";
-    print $out $output;
+  # We try not to update $output_file unless necessary, because
+  # doing so invalidate Autom4te's cache and therefore slows down
+  # tools called after aclocal.
+  #
+  # We need to overwrite $output_file in the following situations.
+  #   * The --force option is in use.
+  #   * One of the dependencies is younger.
+  #     (Not updating $output_file in this situation would cause
+  #     make to call aclocal in loop.)
+  #   * The contents of the current file are different from what
+  #     we have computed.
+  if (!$force_output
+      && $greatest_mtime < mtime ($output_file)
+      && $output eq contents ($output_file))
+    {
+      print STDERR "aclocal: $output_file unchanged\n" if $verbose;
+      return;
+    }
+
+  print STDERR "aclocal: writing $output_file\n" if $verbose;
+
+  my $out = new Automake::XFile "> $output_file";
+  print $out $output;
+  return;
 }
 
 ### Setup "GNU" style for perl-mode and cperl-mode.
Index: automake.texi
===================================================================
RCS file: /cvs/automake/automake/automake.texi,v
retrieving revision 1.349
diff -u -r1.349 automake.texi
--- automake.texi       17 Aug 2003 18:09:10 -0000      1.349
+++ automake.texi       24 Aug 2003 01:54:47 -0000
@@ -1350,6 +1350,16 @@
 automatically included in @file{aclocal.m4}.  We recommend against
 using @file{acinclude.m4} in new packages (@pxref{Local Macros}).
 
address@hidden AUTOM4TE
+While computing @file{aclocal.m4}, @code{aclocal} runs @code{autom4te}
+(@pxref{Using autom4te, , Using @code{Autom4te}, autoconf, The
+Autoconf Manual}) in order to trace the macros which are really used,
+and omit from @file{aclocal.m4} all macros which are mentioned but
+otherwise unexpanded (this can happen when a macro is called
+conditionally).  @code{autom4te} is expected to be in the @code{PATH},
+just as @code{autoconf}.  Its location can be overridden using the
address@hidden environment variable.
+
 @menu
 * aclocal options::             Options supported by aclocal
 * Macro search path::           How aclocal finds .m4 files
Index: tests/aclibobj.test
===================================================================
RCS file: /cvs/automake/automake/tests/aclibobj.test,v
retrieving revision 1.3
diff -u -r1.3 aclibobj.test
--- tests/aclibobj.test 8 Sep 2002 13:07:54 -0000       1.3
+++ tests/aclibobj.test 24 Aug 2003 01:54:49 -0000
@@ -1,5 +1,5 @@
 #! /bin/sh
-# Copyright (C) 2001, 2002  Free Software Foundation, Inc.
+# Copyright (C) 2001, 2002, 2003  Free Software Foundation, Inc.
 #
 # This file is part of GNU Automake.
 #
@@ -22,12 +22,10 @@
 
 . ./defs || exit 1
 
-cat > X << 'END'
-AC_INIT
-AM_INIT_AUTOMAKE(nonesuch, nonesuch)
+cat >> configure.in << 'END'
 AC_PROG_CC
 AC_PROG_RANLIB
-AC_OUTPUT(Makefile)
+AC_OUTPUT
 END
 
 cat > Makefile.am << 'END'
@@ -43,7 +41,7 @@
 
 set -e
 
-cp X configure.in
+cp configure.in X
 echo 'AC_LIBSOURCE(maude.c)' >> configure.in
 $AUTOMAKE
 
Index: tests/aclocal8.test
===================================================================
RCS file: tests/aclocal8.test
diff -N tests/aclocal8.test
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ tests/aclocal8.test 24 Aug 2003 01:54:49 -0000
@@ -0,0 +1,44 @@
+#! /bin/sh
+# Copyright (C) 2003  Free Software Foundation, Inc.
+#
+# This file is part of GNU Automake.
+#
+# GNU Automake 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.
+#
+# GNU Automake 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 Automake; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+# Make sure aclocal does not require unused macros.
+
+. ./defs || exit 1
+
+set -e
+
+cat >> configure.in << 'END'
+SOME_DEFS
+END
+
+mkdir m4
+cat >m4/somedefs.m4 <<EOF
+AC_DEFUN([SOME_DEFS], [
+  m4_if([a], [a], [MACRO1], [MACRO2])
+])
+EOF
+
+echo 'AC_DEFUN([MACRO1],)' >m4/macro1.m4
+echo 'AC_DEFUN([MACRO2],)' >m4/macro2.m4
+
+$ACLOCAL -I m4
+grep macro1.m4 aclocal.m4
+grep macro2.m4 aclocal.m4 && exit 1
+:

-- 
Alexandre Duret-Lutz