fix AC_CONFIG_LINKS([X:X]) (was: New module gnu-make)

[Ralf Wildenhues]

hmm, this was long ago:

* Ralf Wildenhues wrote on Fri, Nov 16, 2007 at 05:52:54PM CET:
> 
> Current Autoconf allows you to do this:
>   AC_CONFIG_LINKS([GNUmakefile:GNUmakefile])
> 
> the only bit that's missing is that automake shouldn't remove
> the original file upon
>   make distclean
> 
> in a non-VPATH build.  Will fix.

Here's a patch for automake, review appreciated.  I'll probably apply in
a couple of days, still wondering whether also to branch-1-10.

Does anybody know a better name for CONFIG_CLEAN_VPATH_FILES (files
which are to be removed from the build tree, but only if the build tree
does not coincide with the source tree)?

Thanks,
Ralf

        For AC_CONFIG_LINKS, if source and destination are equal, do not
        remove the file in a non-VPATH build.
        
        * automake.in (rewrite_inputs_into_dependencies): Do distribute
        inputs where input and output name are equal.  This relies on
        the assumption that it only happens with AC_CONFIG_LINKS.
        (handle_configure) <CONFIG_CLEAN_VPATH_FILES>: New variable, for
        links where source and dest are equal.
        * lib/am/clean.am (distclean-generic): Remove, if build tree not
        equal source tree.
        * tests/conflnk4.test: New test.
        * tests/Makefile.am: Adjust.

diff --git a/automake.in b/automake.in
index 9612204..b939e95 100755
--- a/automake.in
+++ b/automake.in
@@ -3863,7 +3863,7 @@ sub prepend_srcdir (@)
 # Compute a list of dependencies appropriate for the rebuild
 # rule of
 #   AC_CONFIG_FILES($OUTPUT:$INPUT[0]:$INPUTS[1]:...)
-# Also distribute $INPUTs which are not build by another AC_CONFIG_FILES.
+# Also distribute $INPUTs which are not built by another AC_CONFIG_FOOS.
 sub rewrite_inputs_into_dependencies ($@)
 {
   my ($file, @inputs) = @_;
@@ -3874,7 +3874,7 @@ sub rewrite_inputs_into_dependencies ($@)
       # We cannot create dependencies on shell variables.
       next if (substitute_ac_subst_variables $i) =~ /\$/;
 
-      if (exists $ac_config_files_location{$i})
+      if (exists $ac_config_files_location{$i} && $i ne $file)
        {
          my $di = dirname $i;
          if ($di eq $relative_dir)
@@ -4079,6 +4079,8 @@ sub handle_configure ($$$@)
   # Now look for other files in this directory which must be remade
   # by config.status, and generate rules for them.
   my @actual_other_files = ();
+  # These get cleaned only in a VPATH build.
+  my @actual_other_vpath_files = ();
   foreach my $lfile (@other_input_files)
     {
       my $file;
@@ -4166,7 +4168,14 @@ sub handle_configure ($$$@)
                  $local = undef;
                }
            }
-         push @actual_other_files, $local if $local;
+         if ($file ne $link)
+           {
+             push @actual_other_files, $local if $local;
+           }
+         else
+           {
+             push @actual_other_vpath_files, $local if $local;
+           }
        }
 
       # Do not process sources that contain shell variables.
@@ -4191,6 +4200,8 @@ sub handle_configure ($$$@)
   # These files get removed by "make distclean".
   define_pretty_variable ('CONFIG_CLEAN_FILES', TRUE, INTERNAL,
                          @actual_other_files);
+  define_pretty_variable ('CONFIG_CLEAN_VPATH_FILES', TRUE, INTERNAL,
+                         @actual_other_vpath_files);
 }
 
 # Handle C headers.
diff --git a/lib/am/clean.am b/lib/am/clean.am
index f3dd2c6..90b1175 100644
--- a/lib/am/clean.am
+++ b/lib/am/clean.am
@@ -29,6 +29,8 @@ clean-generic:
 distclean-am: distclean-generic clean-am
 distclean-generic:
        -test -z "$(CONFIG_CLEAN_FILES)" || rm -f $(CONFIG_CLEAN_FILES)
+       -test -z "$(CONFIG_CLEAN_VPATH_FILES)" || \
+       test "`pwd`" = "`cd $(srcdir) && pwd`" || rm -f 
$(CONFIG_CLEAN_VPATH_FILES)
 %DISTCLEAN_RMS%
 
 ## Makefiles and their dependencies cannot be cleaned by
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 42a330f..31153dd 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -176,6 +176,7 @@ confincl.test \
 conflnk.test \
 conflnk2.test \
 conflnk3.test \
+conflnk4.test \
 confsub.test \
 confvar.test \
 confvar2.test \
--- /dev/null   2007-10-18 18:26:07.000000000 +0200
+++ tests/conflnk4.test 2008-03-11 11:24:58.000000000 +0100
@@ -0,0 +1,85 @@
+#! /bin/sh
+# Copyright (C) 2003, 2008 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 3, 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., 51 Franklin Street, Fifth Floor,
+# Boston, MA 02110-1301, USA.
+
+# Test to make sure links to _identical files_ created by AC_CONFIG_LINKS get
+# removed with `make distclean' only if doing a VPATH build.
+
+. ./defs || exit 1
+
+set -e
+
+: > src
+mkdir sdir
+: > sdir/Makefile.am
+: > sdir/src2
+
+
+cat >> Makefile.am <<'EOF'
+SUBDIRS = sdir
+test: distdir
+       test -f $(distdir)/src
+       test -f $(distdir)/sdir/src2
+EOF
+
+cat >>configure.in << 'EOF'
+AC_CONFIG_FILES(sdir/Makefile)
+AC_CONFIG_LINKS(src:src)
+AC_CONFIG_LINKS(sdir/src2:sdir/src2)
+AC_OUTPUT
+EOF
+
+$ACLOCAL
+$AUTOMAKE
+$AUTOCONF
+
+mkdir build
+cd build
+../configure
+
+# TODO: Make sure links are distributed
+$MAKE test
+
+# Make sure nothing is deleted by `make clean'
+$MAKE clean
+
+test -f ../src
+test -f ../sdir/src2
+
+# Make sure the links are deleted by `make distclean' and the original files
+# are not.
+$MAKE distclean
+
+test -f ../src
+test -f ../sdir/src2
+
+test -r src && exit 1
+test -r sdir/src2 && exit 1
+
+cd ..
+./configure
+
+# TODO: Make sure links are distributed
+$MAKE test
+
+# Make sure nothing is deleted by `make distclean'
+$MAKE distclean
+
+test -f src
+test -f sdir/src2