Re: aclocal --diff on Tru64

[Ralf Wildenhues]

* Alexandre Duret-Lutz wrote on Tue, Jun 06, 2006 at 09:41:55PM CEST:
> >>> "RW" == Ralf Wildenhues <address@hidden> writes:
> 
>  RW> `diff /dev/null file' fails on Tru64, as noted in autoconf.texi.
>  RW> `aclocal --diff' invokes this.  acloca18.test exposes this failure.

>  RW> Before I venture into either one of those options, I'd appreciate a
>  RW> reality check that this isn't over-engineering, esp. since the user may
>  RW> override the diff command anyway.  What do you think?  (Since we don't
>  RW> show the file name in the output, we could easily use a more obscure or
>  RW> "unique" one, say, including `$$', if that is the only concern.)
> 
> The empty file sounds simple enough.  How about installing this
> empty file during automake's "make install"?  This way we don't
> need to worry about naming and cleaning in aclocal.

Like this?  (A diff for `lib/empty-file' is not shown, because, well,
it's an empty file.  I first thought about substituting the file-to-
compare-against from config.status/Makefile, but that causes ugly
quotation issues again (don't want ${libdir} expanded at substitution
time, and such), so the yes/no helper seemed easiest).

Cheers,
Ralf

        * configure.ac (am_cv_prog_diff_dev_null): New variable: whether
        `diff' works on `/dev/null'; substitute it.  Test from Autotest.
        * Makefile.am (do_subst): Substitute it here as well.
        * aclocal.in (diff_dev_null): New global.
        (install_file): If `diff' loses, use `$libdir/empty-file' instead
        to compare against.  For this, we need...
        (parse_arguments): New option `--libdir'.
        (usage): Document it.
        * doc/automake.texi (aclocal options): Likewise.
        * tests/aclocal.in: Point to build tree with `--libdir'.
        * lib/empty-file: New file, empty (as the name indicates :-).

? lib/empty-file
Index: Makefile.am
===================================================================
RCS file: /cvs/automake/automake/Makefile.am,v
retrieving revision 1.243
diff -u -r1.243 Makefile.am
--- Makefile.am 11 May 2006 17:33:31 -0000      1.243
+++ Makefile.am 7 Jun 2006 18:34:29 -0000
@@ -73,7 +73,8 @@
   -e 's,address@hidden@],$(SHELL),g' \
   -e 's,address@hidden@],$(VERSION),g' \
   -e 's,address@hidden@],Generated from address@hidden; do not edit by 
hand.,g' \
-  -e 's,address@hidden@],$(datadir),g'
+  -e 's,address@hidden@],$(datadir),g' \
+  -e 's,address@hidden@],$(am_cv_prog_diff_dev_null),g'
 
 ## These files depend on Makefile so they are rebuilt if $(VERSION),
 ## $(datadir) or other do_subst'ituted variables change.
Index: aclocal.in
===================================================================
RCS file: /cvs/automake/automake/aclocal.in,v
retrieving revision 1.138
diff -u -r1.138 aclocal.in
--- aclocal.in  21 Apr 2006 19:02:29 -0000      1.138
+++ aclocal.in  7 Jun 2006 18:34:29 -0000
@@ -65,6 +65,9 @@
 # --diff
 my @diff_command;
 
+# whether diff works on /dev/null
+my $diff_dev_null = ('@am_cv_prog_diff_dev_null@');
+
 # --dry-run
 my $dry_run = 0;
 
@@ -193,7 +196,14 @@
       else
        {
          msg 'note', "installing `$dest' from `$src'";
-         $diff_dest = '/dev/null';
+         if ($diff_dev_null eq 'yes')
+           {
+             $diff_dest = '/dev/null';
+           }
+         else
+           {
+             $diff_dest = "$libdir/empty-file";
+           }
        }
 
       if (@diff_command)
@@ -819,6 +831,7 @@
       --help                print this help, then exit
   -I DIR                    add directory to search list for .m4 files
       --install             copy third-party files to the first -I directory
+      --libdir              directory storing library files
       --output=FILE         put output in FILE (default aclocal.m4)
       --print-ac-dir        print name of directory holding m4 files, then exit
       --verbose             don't be silent
@@ -872,6 +885,7 @@
      'force'           => \$force_output,
      'I=s'             => address@hidden,
      'install'          => \$install,
+     'libdir=s'         => \$libdir,
      'output=s'                => \$output_file,
      'print-ac-dir'     => \$print_and_exit,
      'verbose'         => sub { setup_channel 'verb', silent => 0; },
Index: configure.ac
===================================================================
RCS file: /cvs/automake/automake/configure.ac,v
retrieving revision 1.28
diff -u -r1.28 configure.ac
--- configure.ac        6 Jun 2006 20:54:18 -0000       1.28
+++ configure.ac        7 Jun 2006 18:34:29 -0000
@@ -130,6 +130,16 @@
 test "x$am_cv_prog_ln" = xln && result=yes
 AC_MSG_RESULT([$result])
 
+AC_MSG_CHECKING([whether diff likes /dev/null])
+AC_CACHE_VAL([am_cv_prog_diff_dev_null],
+[if diff /dev/null /dev/null >/dev/null 2>&1; then
+  am_cv_prog_diff_dev_null=yes
+else
+  am_cv_prog_diff_dev_null=no
+fi])
+AC_SUBST([am_cv_prog_diff_dev_null])
+AC_MSG_RESULT([$am_cv_prog_diff_dev_null])
+
 # The amount we should wait after modifying files depends on the platform.
 # On Windows '95, '98 and ME, files modifications have 2-seconds
 # granularity and can be up to 3 seconds in the future w.r.t. the
--- doc/automake.texi 2006-06-07 19:49:54.000000000 +0200
+++ doc/automake.texi   2006-06-07 18:39:55.000000000 +0200
@@ -1747,6 +1747,11 @@
 absolutely no influence on files that may need to be installed by
 @option{--install}.

address@hidden address@hidden
address@hidden --libdir
+Look for Automake data files in directory @var{dir} instead of in the
+installation directory.  This is typically used for debugging.
+
 @item address@hidden
 @opindex --output
 Cause the output to be put into @var{file} instead of @file{aclocal.m4}.
Index: lib/Makefile.am
===================================================================
RCS file: /cvs/automake/automake/lib/Makefile.am,v
retrieving revision 1.9
diff -u -r1.9 Makefile.am
--- lib/Makefile.am     14 May 2005 20:28:50 -0000      1.9
+++ lib/Makefile.am     7 Jun 2006 18:34:30 -0000
@@ -22,7 +22,7 @@
 SUBDIRS = Automake am
 
 dist_pkgvdata_DATA = COPYING INSTALL texinfo.tex ansi2knr.c ansi2knr.1 \
-  config-ml.in
+  config-ml.in empty-file
 
 ## These must all be executable when installed.  However, if we use
 ## _SCRIPTS, then the program transform will be applied, which is not
Index: tests/aclocal.in
===================================================================
RCS file: /cvs/automake/automake/tests/aclocal.in,v
retrieving revision 1.4
diff -u -r1.4 aclocal.in
--- tests/aclocal.in    30 Jan 2005 17:47:39 -0000      1.4
+++ tests/aclocal.in    7 Jun 2006 18:34:30 -0000
@@ -15,4 +15,5 @@
 # Most of the files are in $srcdir/../m4.  However amversion.m4 is
 # generated in ../m4, so we include that directory in the search path too.
 exec @abs_top_builddir@/aclocal $ACLOCAL_TESTSUITE_FLAGS \
-     -I @abs_top_builddir@/m4 address@hidden@/m4 ${1+"$@"}
+     -I @abs_top_builddir@/m4 address@hidden@/m4 \
+     address@hidden@/lib ${1+"$@"}