Fix makedepend depmode to cope with VPATH builds

[Ralf Wildenhues]

Ugh, a looong-standing depmode=makedepend bug that silently breaks
rebuilds in VPATH trees.  It has now hit me in the wild.  :-(

Anyway, this is for maint, and I'd appreciate review, but will
otherwise push soonish.

(I'll probably have to defer any reviewing until the weekend ...)

Thanks,
Ralf

    Fix makedepend depmode for VPATH builds.
    
    * lib/depcomp [makedepend]: Remove any VPATH prefix from the
    object file name, so a rebuild doesn't attempt to update the
    .Po files in the source tree.
    * tests/depcomp9.test: New test.
    * tests/Makefile.am (TESTS): Update.
    * NEWS: Update.

diff --git a/NEWS b/NEWS
index d368eec..1fc539d 100644
--- a/NEWS
+++ b/NEWS
@@ -120,6 +120,8 @@ Bugs fixed in 1.11a:
 
   - The parallel-tests driver now does not produce erroneous results
     with Tru64/OSF 5.1 sh upon unreadable log files any more.
+
+  - The makedepend depmode now works better with VPATH builds.
 
 New in 1.11:
 
diff --git a/lib/depcomp b/lib/depcomp
index c3163be..3740d29 100755
--- a/lib/depcomp
+++ b/lib/depcomp
@@ -1,10 +1,10 @@
 #! /bin/sh
 # depcomp - compile a program generating dependencies as side-effects
 
-scriptversion=2010-10-07.20; # UTC
+scriptversion=2011-04-06.20; # UTC
 
-# Copyright (C) 1999, 2000, 2003, 2004, 2005, 2006, 2007, 2009, 2010
-# Free Software Foundation, Inc.
+# Copyright (C) 1999, 2000, 2003, 2004, 2005, 2006, 2007, 2009, 2010,
+# 2011 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
@@ -557,7 +557,9 @@ makedepend)
   touch "$tmpdepfile"
   ${MAKEDEPEND-makedepend} -o"$obj_suffix" -f"$tmpdepfile" "$@"
   rm -f "$depfile"
-  cat < "$tmpdepfile" > "$depfile"
+  # makedepend may prepend the VPATH from the source file name to the object.
+  sed_object_re=`echo $object | sed 's/[].[^$\\*|]/\\\\&/g'`
+  sed "s|^.*\($sed_object_re *:\)|\1|" "$tmpdepfile" > "$depfile"
   sed '1,2d' "$tmpdepfile" | tr ' ' '
 ' | \
 ## Some versions of the HPUX 10.20 sed can't process this invocation
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7f165ac..880206e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -371,6 +371,7 @@ depcomp6.test \
 depcomp7.test \
 depcomp8a.test \
 depcomp8b.test \
+depcomp9.test \
 depdist.test \
 depend.test \
 depend2.test \
diff --git a/tests/Makefile.in b/tests/Makefile.in
index d1e3a73..90f3d6b 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -632,6 +632,7 @@ depcomp6.test \
 depcomp7.test \
 depcomp8a.test \
 depcomp8b.test \
+depcomp9.test \
 depdist.test \
 depend.test \
 depend2.test \
diff --git a/tests/depcomp9.test b/tests/depcomp9.test
new file mode 100755
index 0000000..c4dd2ed
--- /dev/null
+++ b/tests/depcomp9.test
@@ -0,0 +1,84 @@
+#! /bin/sh
+# Copyright (C) 2011 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 <http://www.gnu.org/licenses/>.
+
+# makedepend should work in VPATH mode.
+
+# Here's the bug: makedepend will prefix VPATH to the object file name,
+# thus the second make will invoke depcomp with object='../../src/foo.o',
+# causing errors such as:
+# touch: cannot touch `../../src/.deps/foo.TPo': No such file or directory
+# makedepend: error:  cannot open "../../src/.deps/foo.TPo"
+# ../../depcomp: line 560: ../../src/.deps/foo.TPo: No such file or directory
+
+# We include subfoo only to be sure that we don't remove too much
+# from the object file name.
+
+required='makedepend'
+. ./defs || Exit 1
+
+mkdir src src/sub build
+
+cat >> configure.in << 'END'
+AC_PROG_CC
+AM_PROG_CC_C_O
+AC_CONFIG_FILES([src/Makefile])
+AC_OUTPUT
+END
+
+cat > Makefile.am << 'END'
+SUBDIRS = src
+END
+
+cat > src/Makefile.am << 'END'
+AUTOMAKE_OPTIONS = subdir-objects
+bin_PROGRAMS = foo
+foo_SOURCES = foo.c foo.h sub/subfoo.c
+END
+
+cat > src/foo.h <<EOF
+extern int subfoo (void);
+EOF
+
+cat >src/foo.c <<EOF
+#include "foo.h"
+int main (void)
+{
+  return subfoo ();
+}
+EOF
+
+cat >src/sub/subfoo.c <<EOF
+#include "foo.h"
+int subfoo (void)
+{
+  return 0;
+}
+EOF
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE -a
+
+cd build
+../configure am_cv_CC_dependencies_compiler_type=makedepend
+$MAKE || Exit 77
+$MAKE clean
+
+$MAKE >out 2>&1 || { cat out; Exit 1; }
+cat out
+$FGREP 'src/.deps' out && Exit 1
+
+: