Antlr4: Confusing error message (concatenates correct and incorrect lines) for Java grammar

1
votes

I am trying to build my own parser based on the existing Java grammar.

Even if I use the Java7 grammar from the source repo, generate the parser and use the TestRig from antlr-4.9.3-complete.jar given the code:

1  public class Test {
2    public static void main() {
3      test
4      int b = 1;
5    }
6  }

I get the following error:

line 4:8 no viable alternative at input 'test\n int'

So for some reason it concatenates the incorrect "test" line with correct "int" line. Also it says "line 4:8" pointing at the "int" line when it should be pointing to "test" (line 3).

(In a regular Java editor I would see a correct error highlighting for the "test" word which would sound like):

"Syntax error, insert "VariableDeclarators" to complete LocalVariableDeclaration"

What do I do to arrive at a similar error with ANTLR so it only picks on the wrong "test" line? Most likely it's just my misunderstanding how antlr interprets the errors, then how would I get the listener to at least report correctly the starting line?

javaantlr4grammar