JS: Tolerate trailing comma in JSON objects

Author: asgerf

javascript/extractor/src/com/semmle/js/parser/JSONParser.java

@@ -152,9 +152,6 @@ private JSONObject readObject(int startoff, Position start) throws ParseError {
         char c = next();
         switch (c) {
           case '}':
-            if (!needsComma) {
-              raise("Trailing commas are not allowed in JSON.");
-            }
             break out;
           case ',':
             if (!needsComma) {

javascript/extractor/tests/json/output/trap/object-trailing-comma.json.trap

@@ -7,9 +7,29 @@ containerparent(#10001,#10000)
 locations_default(#10002,#10000,0,0,0,0)
 hasLocation(#10000,#10002)
 #20000=*
-json_errors(#20000,"Error: Trailing commas are not allowed in JSON.")
-#20001=@"loc,{#10000},5,5,5,5"
-locations_default(#20001,#10000,5,5,5,5)
-hasLocation(#20000,#20001)
+json(#20000,5,#10000,0,"{\n    "" ...     }\n}")
+#20001=@"loc,{#10000},1,1,6,1"
+locations_default(#20001,#10000,1,1,6,1)
+json_locations(#20000,#20001)
+#20002=*
+json(#20002,5,#20000,0,"{\n      ... ,\n    }")
+#20003=@"loc,{#10000},2,15,5,5"
+locations_default(#20003,#10000,2,15,5,5)
+json_locations(#20002,#20003)
+#20004=*
+json(#20004,2,#20002,0,"1")
+#20005=@"loc,{#10000},3,16,3,16"
+locations_default(#20005,#10000,3,16,3,16)
+json_locations(#20004,#20005)
+json_literals("1","1",#20004)
+json_properties(#20002,"foo",#20004)
+#20006=*
+json(#20006,2,#20002,1,"2")
+#20007=@"loc,{#10000},4,16,4,16"
+locations_default(#20007,#10000,4,16,4,16)
+json_locations(#20006,#20007)
+json_literals("2","2",#20006)
+json_properties(#20002,"bar",#20006)
+json_properties(#20000,"object",#20002)
 numlines(#10000,6,0,0)
 filetype(#10000,"json")