2001-05-21  Alexandre Duret-Lutz  <address@hidden>

	* automake.in (handle_languages, handle_single_transform_list): Use
	language '' for unknown extensions.
	(derive_suffix): Check whether $extension_map{$source_ext}
	is undefined, not empty.

--- automake.in~	Sat May 19 23:40:55 2001
+++ automake.in	Mon May 21 20:40:33 2001
@@ -1498,7 +1498,7 @@ sub handle_languages
     my $needs_c = 0;
     foreach my $ext (sort keys %extension_seen)
       {
-	my $lang = $languages{$extension_map{$ext}};
+	my $lang = $languages{$extension_map{$ext} || ''};
 
 	# Get information on $LANG.
 	my $pfx = $lang->autodep;
@@ -1748,7 +1748,7 @@ sub handle_single_transform_list ($$$@)
         my ($linker, $object);
 
         $extension = &derive_suffix ($extension);
-        my $lang = $languages{$extension_map{$extension}};
+        my $lang = $languages{$extension_map{$extension} || ''};
         if ($lang)
         {
             &saw_extension ($extension);
@@ -5189,7 +5189,7 @@ sub derive_suffix
 
     # FIXME: hard-coding `o' is a mistake.  Doing something
     # intelligent is harder.
-    while ($extension_map{$source_ext} eq ''
+    while (!defined $extension_map{$source_ext}
 	   && $source_ext ne 'o'
 	   && defined $suffix_rules{$source_ext})
     {