[gettext-u-en] empty output from msgmerge should not be interpreted as error

[Yaohan Chen]

Hello,

I noticed that if a ruby file has no translatable strings, and a pot file is 
created from it, then running update_pofiles again will cause an error with 
such output:

  po/file.pot
  . done.
  Failed to merge with po/file.pot
  New .pot was copied to tmp.pot~
  Check these po/pot-files. It may have syntax errors or something wrong.

The cause of this is that GNU gettext's msgmerge (0.17) seems to never output 
anything when the def.po and ref.pot files are identical. But if you supply a 
switch -o output.po, the output.po file will be untouched. Also msgmerge 
prints ". done." in stderr as usually, without any error message. I think 
this suggests that empty output from msgmerge does not indicate an error in 
the pot file, only that no change is needed.

Following is my proposed patch.


? msgmerge-empty-output.diff
Index: lib/gettext/utils.rb
===================================================================
RCS file: /var/cvs/gettext/gettext/lib/gettext/utils.rb,v
retrieving revision 1.7
diff -u -r1.7 utils.rb
--- lib/gettext/utils.rb	6 May 2008 17:36:43 -0000	1.7
+++ lib/gettext/utils.rb	5 Jun 2008 22:06:54 -0000
@@ -60,13 +60,14 @@
 	cont = io.read
       end
     end
-    if cont.empty?
+    unless $?.success?
       failed_filename = refpo + "~"
       FileUtils.cp(refpo, failed_filename)
       $stderr.puts _("Failed to merge with %{defpo}") % {:defpo => defpo}
       $stderr.puts _("New .pot was copied 
to %{failed_filename}") %{:failed_filename => failed_filename}
       raise _("Check these po/pot-files. It may have syntax errors or 
something wrong.")
     else
+      cont = File.read(defpo) if cont.empty?
       cont.sub!(/(Project-Id-Version\:).*$/, "\\1 #{app_version}\\n\"")
       File.open(defpo, "w") do |out|
         out.write(cont)