widl: Allow trailing commas in attribute lists, take 2

[Dan Hipschman]

MIDL allows extraneous commas in attribute lists such as:

[][,][,,version(1.0),][,,][uuid(...)]
coclass Foo {...}

presumably to ease the job of code generators.  In particular, the file
attached to this posting
<http://www.winehq.org/pipermail/wine-devel/2006-June/048307.html>
contains an attribute list with a trailing comma which currently trips
up widl.  With this patch the file will compile.  (Although another bug
prevents widl from generating a typelib from it, it can at least now
generate a header.)

ChangeLog:
* Allow extraneous commas in attribute lists (MIDL feature)
---
 tools/widl/parser.y |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/tools/widl/parser.y b/tools/widl/parser.y
index a7b1269..1790985 100644
--- a/tools/widl/parser.y
+++ b/tools/widl/parser.y
@@ -343,16 +343,23 @@ m_attributes:					{ $$ = NULL; }
 	;
 
 attributes:
-	  '[' attrib_list ']'			{ $$ = $2; }
+	  '[' attrib_list ']'			{ $$ = $2;
+						  if (!$$)
+						    yyerror("empty attribute lists unsupported");
+						}
 	;
 
 attrib_list: attribute
-	| attrib_list ',' attribute		{ LINK($3, $1); $$ = $3; }
-	| attrib_list ']' '[' attribute		{ LINK($4, $1); $$ = $4; }
+	| attrib_list ',' attribute		{ if ($3) { LINK($3, $1); $$ = $3; }
+						  else { $$ = $1; }
+						}
+	| attrib_list ']' '[' attribute		{ if ($4) { LINK($4, $1); $$ = $4; }
+						  else { $$ = $1; }
+						}
 	;
 
-attribute:
-	  tAGGREGATABLE				{ $$ = make_attr(ATTR_AGGREGATABLE); }
+attribute:					{ $$ = NULL; }
+	| tAGGREGATABLE				{ $$ = make_attr(ATTR_AGGREGATABLE); }
 	| tAPPOBJECT				{ $$ = make_attr(ATTR_APPOBJECT); }
 	| tASYNC				{ $$ = make_attr(ATTR_ASYNC); }
 	| tAUTOHANDLE				{ $$ = make_attr(ATTR_AUTO_HANDLE); }