fix: Prevent use of labels such as start= from generating code that c…

…lashes with builtin funcs (#4161)

Signed-off-by: Jim.Idle <jimi@idle.ws>

tool/src/org/antlr/v4/codegen/target/GoTarget.java

@@ -44,7 +44,13 @@ public class GoTarget extends Target {
 		"SetInvokingState", "SetParent", "String",
 
 		// misc
-		"rule", "parserRule", "action"
+		"rule", "parserRule", "action",
+
+		// the use of start or stop abd others as a label name will cause the generation of a GetStart() or GetStop() method, which
+		// then clashes with the GetStart() or GetStop() method that is generated by the code gen for the rule. So, we need to
+		// convert it. This is not ideal as it will still probably confuse authors of parse listeners etc. but the code will
+		// compile. This is a proof of Hyrum's law.
+		"start", "stop", "exception"
 	));
 
 	private static final boolean DO_GOFMT = !Boolean.parseBoolean(System.getenv("ANTLR_GO_DISABLE_GOFMT"))