Re: [PATCH] Support AC_CONFIG_LIBOBJ_DIR (fixes PR/401)

[Gary V. Vaughan]

Salut Alexandre,

Thanks for the feedback:

Alexandre Duret-Lutz wrote:
> * LIBOBJDIR seems worthy to document from the Autoconf user perspective.
>   Non-automake might also benefit from this; and we should avoid using
>   undocumented interfaces in Automake.

Okay, I've added that to the attached revision of this patch.

> * The comment in _AC_LIBOBJS_NORMALIZE seems misleading to me,
>   because LIBOBJDIR is unrelated to the macro
>   AC_CONFIG_LIBOBJ_DIR as far as Autoconf is concerned.
>   AC_CONFIG_LIBOBJ_DIR specifies where the *sources* files are.
>   LIBOBJDIR is a prefix variable the user cano use to relocate
>   the *object* files.  This is not necessary the same place.

True enough also.  I've changed the comments to describe the situation more
accurately.

> * Autoconf needs to be adjusted to reflect the fact that
>   Automake scans a new macro. See the comment above the %traced
>   variable you modified in scan_autoconf_trace.

AC_CONFIG_LIBOBJ_DIR is already there in autoconf-2.59 and HEAD.

> * Better write ${LIBOBJDIR} instead of $(LIBOBJDIR) in @LIBOBJS@
>   (for the same reason we use ${prefix}, etc.)

I disagree, LIBOBJDIR is a make macro not a shell variable, so it is more akin
to $(srcdir) than ${prefix}.  If I'm missing something, feel free to change it
before committing.

> * The Automake manual should be updated at least in two places: 
>     - the place where it documents all the macros that can
>       affect its behavior (your patch causes
>       AC_CONFIG_LIBOBJ_DIR to have a stronger semantic when used
>       with Automake than when used with only Autoconf).
>     - the section about how LIBOBJS is used.
> * Use $PERL, not perl.

Both done.  Thanks for the pointers.

> * AFAICT your patch assumes that users use option `subdir-objects' when 
>   using @LIBOBJS@ remotely. I think we should also support the other case.
> 
> I suggest you don't bother with the last point unless it looks
> easy to you.  I'll probably find some time this week-end or next
> week.

Agreed on all counts.  My perl-fu is as always insufficient to the task,
thanks for offering to do the rest.

ChangeLog entries for automake:

2005-04-25  Gary V. Vaughan  <address@hidden>

        Fixes PR/401
        * automake.in (config_libobj_dir): Either `.' or whatever directory is
        given to AC_CONFIG_LIBOBJ_DIR in configure.ac.
        (scan_autoconf_traces): Set config_libobj_dir.
        (sub_read_am_file): Define LIBOBJDIR according to relative path from
        each Makefile to AC_CONFIG_LIBOBJ_DIR directory.
        (require_libobj_with_macro): Use $config_libobj_dir when looking for
        LIBOBJs.
        (handle_LIBOBJS, handle_ALLOCA): Use it.
        * tests/Makefile.am (TESTS): Declare pr401.test.
        * tests/pr401.test: New test.
        * doc/automake.texi (LIBOBJS): Document changes in behaviour of
        LIBOBJS, ALLOCA, LTLIBOBJS & LTALLOCA in the presence of
        subdir-objects and an invocation of AC_CONFIG_LIBOBJ_DIR.

And autoconf:

2004-04-20  Gary V. Vaughan  <address@hidden>

        * lib/autoconf/general.m4 (_AC_LIBOBJS_NORMALIZE): Prepend each object
        named in LIBOBJS and LTLIBOBJS with the $(LIBOBJDIR), as set by latest
        automake.

Cheers,
        Gary.
-- 
Gary V. Vaughan      ())_.  address@hidden,gnu.org}
Research Scientist   ( '/   http://tkd.kicks-ass.net
GNU Hacker           / )=   http://www.gnu.org/software/libtool
Technical Author   `(_~)_   http://sources.redhat.com/autobook

--- automake.in.orig    2005-02-12 10:06:56.000000000 +0000
+++ automake.in 2005-04-20 14:08:05.000000000 +0100
@@ -142,6 +142,7 @@
 use Automake::RuleDef;
 use Automake::Wrap 'makefile_wrap';
 use File::Basename;
+use File::Spec;
 use Carp;
 
 ## ----------- ##
@@ -333,6 +334,10 @@
 # in Makefiles.
 my $am_config_aux_dir = '';
 
+# Directory to search for AC_LIBSOURCE file, as set by AC_CONFIG_LIBOBJ_DIR
+# in configure.ac.
+my $config_libobj_dir = '';
+
 # Whether AM_GNU_GETTEXT has been seen in configure.ac.
 my $seen_gettext = 0;
 # Whether AM_GNU_GETTEXT([external]) is used.
@@ -2067,7 +2072,7 @@
 
       if ($iter =~ /\.h$/)
        {
-         require_file_with_macro ($cond, $var, FOREIGN, $iter);
+         require_libobj_with_macro ($cond, $var, FOREIGN, $iter);
        }
       elsif ($iter ne 'alloca.c')
        {
@@ -2079,7 +2084,7 @@
          my $bs = var ('BUILT_SOURCES');
          if (! $bs || ! grep (/$rewrite/, $bs->value_as_list_recursive))
            {
-             require_file_with_macro ($cond, $var, FOREIGN, $iter);
+             require_libobj_with_macro ($cond, $var, FOREIGN, $iter);
            }
        }
     }
@@ -2092,7 +2097,7 @@
   $lt ||= '';
   $var->requires_variables ("address@hidden@ used", $lt . 'ALLOCA');
   $dep_files{'$(DEPDIR)/alloca.P' . $myobjext} = 1;
-  require_file_with_macro ($cond, $var, FOREIGN, 'alloca.c');
+  require_libobj_with_macro ($cond, $var, FOREIGN, 'alloca.c');
   &saw_extension ('c');
 }
 
@@ -4636,6 +4641,7 @@
                AC_CONFIG_AUX_DIR => 1,
                AC_CONFIG_FILES => 1,
                AC_CONFIG_HEADERS => 1,
+               AC_CONFIG_LIBOBJ_DIR => 1,
                AC_CONFIG_LINKS => 1,
                AC_INIT => 0,
                AC_LIBSOURCE => 1,
@@ -4731,6 +4737,12 @@
              push @config_headers, $spec;
            }
        }
+      elsif ($macro eq 'AC_CONFIG_LIBOBJ_DIR')
+       {
+         $config_libobj_dir = $args[1];
+         $relative_dir = '.';
+         check_directory ($config_libobj_dir, $where);
+       }
       elsif ($macro eq 'AC_CONFIG_LINKS')
        {
          foreach my $spec (split (' ', $args[1]))
@@ -5761,6 +5773,15 @@
     use constant IN_COMMENT => 2;
     my $prev_state = IN_RULE_DEF;
 
+    # Calculate the relative path from this Makefile to LIBOBJDIR.
+    my $am_libobj_dir = '';
+    unless ($config_libobj_dir eq '')
+      {
+       my $dir = File::Spec->abs2rel ($config_libobj_dir, $relative_dir);
+       $am_libobj_dir = "$dir/" unless $dir eq '';
+      }
+    &define_variable ('LIBOBJDIR', "$am_libobj_dir", INTERNAL);
+
     while ($_ = $am_file->getline)
     {
         $where->set ("$amfile:$.");
@@ -6975,6 +6996,22 @@
     require_file ($macro->rdef ($cond)->location, $mystrict, @files);
 }
 
+# &require_libobj_with_macro ($COND, $MACRO, $MYSTRICT, @FILES)
+# -------------------------------------------------------------
+sub require_libobj_with_macro ($$$@)
+{
+    my ($cond, $macro, $mystrict, @files) = @_;
+    $macro = rvar ($macro) unless ref $macro;
+    if ($config_libobj_dir eq '')
+      {
+       require_file ($macro->rdef ($cond)->location, $mystrict, @files);
+      }
+    else
+      {
+       require_file_internal ($macro->rdef ($cond)->location, $mystrict,
+                              $config_libobj_dir, @files);
+      }
+}
 
 # &require_conf_file ($WHERE, $MYSTRICT, @FILES)
 # ----------------------------------------------
--- tests/Makefile.am.orig      2005-04-20 13:09:37.000000000 +0100
+++ tests/Makefile.am   2005-04-20 13:39:05.000000000 +0100
@@ -405,6 +405,7 @@
 pr300-ltlib.test \
 pr300-prog.test \
 pr307.test \
+pr401.test \
 prefix.test \
 primary.test \
 primary2.test \
--- /dev/null   2005-04-25 18:07:47.000000000 +0100
+++ tests/pr401.test    2005-04-25 18:24:31.000000000 +0100
@@ -0,0 +1,155 @@
+#! /bin/sh
+# Copyright (C) 2005  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.
+
+# Check support for AC_CONFIG_LIBOBJ_DIR vs LIBOBJS.
+
+required=gcc
+. ./defs || exit 1
+
+set -e
+
+mkdir lib src
+
+cat >lib/feep.c <<'EOF'
+char *
+feep ()
+{
+  return "feep";
+}
+EOF
+
+cat >src/feep.c <<'EOF'
+#include <stdio.h>
+
+extern char *feep ();
+
+int
+main (int argc, char **argv)
+{
+  printf ("%s\n", feep ());
+  return 0;
+}
+EOF
+
+cat >>configure.in << 'EOF'
+## These lines are activated for later tests
+#: AC_CONFIG_LIBOBJ_DIR([lib])
+AC_PROG_CC
+#: AM_PROG_CC_C_O
+AC_LIBOBJ([feep])
+AC_LIBSOURCE([feep.c])
+AC_PROG_RANLIB
+AC_CONFIG_FILES([lib/Makefile src/Makefile])
+AC_OUTPUT
+EOF
+
+## ------------------------------------------ ##
+## First a test of traditional LIBOBJS usage. ##
+## ------------------------------------------ ##
+
+cat >Makefile.am <<'EOF'
+SUBDIRS = lib src
+EOF
+
+cat >lib/Makefile.am <<'EOF'
+noinst_LIBRARIES = libfeep.a
+libfeep_a_SOURCES =
+libfeep_a_LIBADD = $(LIBOBJS)
+EOF
+
+cat >src/Makefile.am <<'EOF'
+check_PROGRAMS = feep
+feep_LDADD = $(top_builddir)/lib/libfeep.a
+
+TESTS = feep
+EOF
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE
+./configure
+$MAKE
+$MAKE check
+
+rm -f configure Makefile* lib/Makefile* src/Makefile* */feep.o */libfeep.a
+
+
+## -------------------------------------------- ##
+## Test using LIBOBJS from a sibling directory. ##
+## -------------------------------------------- ##
+
+$PERL -pi -e 's/#: //' configure.in
+$PERL -pi -e 's/lib\/Makefile //' configure.in
+
+cat >Makefile.am <<'EOF'
+SUBDIRS = src
+EOF
+
+cat > src/Makefile.am <<'EOF'
+AUTOMAKE_OPTIONS = subdir-objects
+
+noinst_LIBRARIES = libfeep.a
+libfeep_a_SOURCES =
+libfeep_a_LIBADD = $(LIBOBJS)
+
+check_PROGRAMS = feep
+feep_LDADD = ./libfeep.a
+
+TESTS = feep
+EOF
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE --add-missing
+./configure
+$MAKE
+$MAKE check
+
+rm -f configure Makefile* src/Makefile* */feep.o */libfeep.a
+
+
+## ----------------------------------------- ##
+## Test using LIBOBJS from parent directory. ##
+## ----------------------------------------- ##
+
+$PERL -pi -e 's/^.*src\/Makefile.*$//' configure.in
+
+cat >Makefile.am <<'EOF'
+AUTOMAKE_OPTIONS = subdir-objects
+
+noinst_LIBRARIES = lib/libfeep.a
+lib_libfeep_a_SOURCES =
+lib_libfeep_a_LIBADD = $(LIBOBJS)
+
+check_PROGRAMS = src/feep
+src_feep_SOURCES = src/feep.c
+src_feep_LDADD = ./lib/libfeep.a
+
+TESTS = src/feep
+EOF
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE
+./configure
+$MAKE
+$MAKE check
+
+rm -f configure Makefile* */feep.o */libfeep.a
--- doc/automake.texi.orig      2005-04-25 18:27:36.000000000 +0100
+++ doc/automake.texi   2005-04-25 19:31:09.000000000 +0100
@@ -3785,7 +3785,10 @@
 
 The @code{AC_CONFIG_LIBOBJ_DIR} tells Autoconf that the source files
 of these object files are to be found in the @file{lib/} directory.
-Automake does not yet use this information; it knows the source files
+
+In conjunction with @code{subdir-objects}, Automake uses this
+information to deduce that the object files will be in the same
+subdirectory relative to @code{$top_builddir}; it knows the source files
 are expected to be in the directory where the @code{$(LIBOBJS)} and
 @code{$(ALLOCA)} variables are used.
 
@@ -3831,13 +3834,9 @@
 tool2_SOURCES = @dots{}
 @end example
 
-Please note it would be wrong to use the @code{$(LIBOBJS)} or
address@hidden(ALLOCA)} in @file{src/Makefile.am}, because these variables
-contains unprefixed object names, and for instance
address@hidden(OBJEXT)} is not buildable in the @file{src/} directory.
-(Actually if you try using @code{$(LIBOBJS)} in @file{src/}, Automake
-will require a copy of @file{malloc.c}, @file{memcmp.c},
address@hidden, @file{alloca.c} in @file{src/} too.)
+Please note @code{$(LIBOBJS)} or @code{$(ALLOCA)} can only be used in
address@hidden/Makefile.am} in @code{subdir-objects} mode, because these
+variables contain object names prefixed with @code{$(LIBOBJDIR)}.
 
 Because @code{$(LIBOBJS)} and @code{$(ALLOCA)} contain object
 filenames that end with @code{.$(OBJEXT)}, they are not suitable for

--- lib/autoconf/general.m4.orig        2003-10-27 11:10:56.000000000 +0000
+++ lib/autoconf/general.m4     2005-04-25 17:56:48.000000000 +0100
@@ -1,7 +1,7 @@
 # This file is part of Autoconf.                       -*- Autoconf -*-
 # Parameterized macros.
 # Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
-# 2002, 2003, Free Software Foundation, Inc.
+# 2002, 2003, 2005, 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
@@ -2435,7 +2435,7 @@
 
 # _AC_LIBOBJS_NORMALIZE
 # ---------------------
-# Clean up LIBOBJS abd LTLIBOBJS so that they work with 1. ac_objext,
+# Clean up LIBOBJS and LTLIBOBJS so that they work with 1. ac_objext,
 # 2. Automake's ANSI2KNR, 3. Libtool, 4. combination of the three.
 # Used with AC_CONFIG_COMMANDS_PRE.
 AC_DEFUN([_AC_LIBOBJS_NORMALIZE],
@@ -2445,9 +2445,10 @@
   # 1. Remove the extension, and $U if already installed.
   ac_i=`echo "$ac_i" |
         sed 's/\$U\././;s/\.o$//;s/\.obj$//'`
-  # 2. Add them.
-  ac_libobjs="$ac_libobjs $ac_i\$U.$ac_objext"
-  ac_ltlibobjs="$ac_ltlibobjs $ac_i"'$U.lo'
+  # 2. Prepend LIBOBJDIR.  When used with automake>1.9.5 LIBOBJDIR
+  #    will be set to the directory where LIBOBJS objects are built.
+  ac_libobjs="$ac_libobjs \$(LIBOBJDIR)$ac_i\$U.$ac_objext"
+  ac_ltlibobjs="$ac_ltlibobjs \$(LIBOBJDIR)$ac_i"'$U.lo'
 done
 AC_SUBST([LIB@&address@hidden, [$ac_libobjs])
 AC_SUBST([LTLIBOBJS], [$ac_ltlibobjs])
--- doc/autoconf.texi.orig      2005-04-25 18:04:28.000000000 +0100
+++ doc/autoconf.texi   2005-04-25 18:18:15.000000000 +0100
@@ -4330,7 +4330,10 @@
 @command{configure} might need to know the replacement directory for the
 following reasons: (i) some checks use the replacement files, (ii) some
 macros bypass broken system headers by installing links to the
-replacement headers, etc.
+replacement headers, etc. (iii) when used in conjunction with Automake,
+within each @file{Makefile}, @var{directory} is used as a relative path
+from @code{$(top_srcdir)} to each object named in @code(LIBOBJS) and
address@hidden(LTLIBOBJS).
 @end defmac
 
 @sp 1
@@ -14447,6 +14450,13 @@
 
 Note that @code{U} must not be used in your Makefiles.
 
address@hidden LIBOBJDIR
+When used with Automake 1.9.6 or newer, a suitable value for
address@hidden is set so that the @code{LIBOBJS} and @code{LTLIBOBJS}
+can be referenced from any @file{Makefile.am}.  Even without Automake,
+arranging for @code{LIBOBJDIR} to be set correctly will enable
+referencing @code{LIBOBJS} and @code{LTLIBOBJS} in another directory.
+
 
 @node AC_FOO_IFELSE vs AC_TRY_FOO
 @subsection @code{AC_FOO_IFELSE} vs.@: @code{AC_TRY_FOO}

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