[PATCH] {maint} Fix a bug in variable concatanation with `+='. (was: Re: bug#7333: bug concatenating CLEANFILES in automake 1.11)

[Stefano Lattarini]

On Friday 05 November 2010, Stefano Lattarini wrote: 
> I can confirm the bug with latest automake (from git master), with
> a much-reduced minimal testcase (see attachment).
> 
> I still haven't looked for an explanation or a fix, though.
I've manged to find a very simple fix for the bug (see attached patch).

OK to apply to maint?

Regards,
  Stefano

From b8de299295e081909c6d0a8a1cef957b337e3732 Mon Sep 17 00:00:00 2001
From: Stefano Lattarini <address@hidden>
Date: Sat, 6 Nov 2010 12:46:52 +0100
Subject: [PATCH] Fix a bug in variable concatanation with `+='.

* lib/Automake/VarDef.pm (append): Remove extra backslash-escaped
newlines from the end of the variable's content, before appending
to it.
* tests/pluseq11.test: New test, exposing the bug.
* tests/Makefile.am (TESTS): Update.

Reported by Andy Wingo.
---
 ChangeLog              |   10 ++++++++
 lib/Automake/VarDef.pm |   13 +---------
 tests/Makefile.am      |    1 +
 tests/Makefile.in      |    1 +
 tests/pluseq11.test    |   54 ++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 68 insertions(+), 11 deletions(-)
 create mode 100755 tests/pluseq11.test

diff --git a/ChangeLog b/ChangeLog
index 6c17cd3..a928363 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2010-11-06  Stefano Lattarini  <address@hidden>
+
+       Fix a bug in variable concatanation with `+='.
+       * lib/Automake/VarDef.pm (append): Remove extra backslash-escaped
+       newlines from the end of the variable's content, before appending
+       to it.
+       * tests/pluseq11.test: New test, exposing the bug.
+       * tests/Makefile.am (TESTS): Update.
+       Reported by Andy Wingo.
+
 2010-11-01  Ralf Wildenhues  <address@hidden>
 
        Fix and document rules to not touch the tree with `make -n'.
diff --git a/lib/Automake/VarDef.pm b/lib/Automake/VarDef.pm
index d7ba155..568c82a 100644
--- a/lib/Automake/VarDef.pm
+++ b/lib/Automake/VarDef.pm
@@ -185,17 +185,8 @@ sub append ($$$)
   # Furthermore keeping `#' would not be portable if the variable is
   # output on multiple lines.
   $val =~ s/ ?#.*//;
-
-  if (chomp $val)
-    {
-      # Insert a backslash before a trailing newline.
-      $val .= "\\\n";
-    }
-  elsif ($val)
-    {
-      # Insert a separator.
-      $val .= ' ';
-    }
+  # Insert a separator, if required.
+  $val .= ' ' if $val;
   $self->{'value'} = $val . $value;
   # Turn ASIS appended variables into PRETTY variables.  This is to
   # cope with `make' implementation that cannot read very long lines.
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 9c81564..da81c49 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -570,6 +570,7 @@ pluseq7.test \
 pluseq8.test \
 pluseq9.test \
 pluseq10.test \
+pluseq11.test \
 postproc.test \
 ppf77.test \
 pr2.test \
diff --git a/tests/Makefile.in b/tests/Makefile.in
index b568a09..eb461a9 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -837,6 +837,7 @@ pluseq7.test \
 pluseq8.test \
 pluseq9.test \
 pluseq10.test \
+pluseq11.test \
 postproc.test \
 ppf77.test \
 pr2.test \
diff --git a/tests/pluseq11.test b/tests/pluseq11.test
new file mode 100755
index 0000000..293270f
--- /dev/null
+++ b/tests/pluseq11.test
@@ -0,0 +1,54 @@
+#!/bin/sh
+# Copyright (C) 2010 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/>.
+
+# Check for bug in variable concatenation with `+=': an extra backslash
+# is erroneously retained in the final value.
+# See also sister test pluseq11b.test.
+
+. ./defs || Exit 1
+
+set -e
+
+cat >>configure.in <<'END'
+AC_OUTPUT
+END
+
+cat > Makefile.am <<'END'
+## Use more line continuation to ensure we are robust and can (hopefully)
+## cope any number of them, and not just one
+FOO = \
+\
+\
+bar
+## Both this two variable additions are required to trigger the bug.
+FOO +=
+FOO += baz
+
+.PHONY: test
+test:
+       case '$(FOO)' in *\\*) exit 1;; *) exit 0;; esac
+END
+
+$ACLOCAL
+$AUTOMAKE
+
+grep '^ *FOO *=.*\\.' Makefile.in && Exit 1
+
+$AUTOCONF
+./configure
+$MAKE test
+
+:
-- 
1.7.1