debugging antlr4 mojo help needed

[chris-miner]

I noticed that the problem list in vscode for my grammar doesn't update. So if there is an error in the .g4 file as reported by antlr4-maven-plugin and I change the file, I'll get new errors, but none of the old ones will go away.

Suppose, I have a spelling mistake in my Calc.g4 file:

import CommonLexerRulez;

This can't be found because the actual file is CommonLexerRules.g4

Errors show up in the problems view of VSCode:

can't find or load grammar CommonLexerRulez (org.antlr:antlr4-maven-plugin:4.9.3:antlr4:antlr:generate-sources)

If I fix that error — replacing the 'z' with 's' — the problem is still listed in the problem view. Reloading the window doesn't remedy the problem. The same list of errors are shown. Quitting and restarting VSCode doesn't fix the problem. Re-saving the project pom does clear the errors.

I'm pretty sure that is not how it is supposed to work. There's closed issue on the vscode project that mentions:

In your case, it means the corresponding extension is not updating. So please file issue against the extension.

So I attempted to debug this issue with the mojo — problems ensued. I found this basic guide to debugging a mojo in eclipse. The first step of building and installing the mojo failed in the tests with:

Prohibited package name: java.org.antlr.mojo.antlr4

So I skipped tests

cd antlr4-maven-plugin;
mvn install -DskipTests=true

this got me a 4.11.2-SNAPSHOT version installed which happens to have the same problem (I was using 4.9.3). When I opened Antlr4Mojo.java in my Calc project, I was able to set break points in the mojo and debug it. Well, I was able to step through the code and look for issues.

Another oddity about the reporting is they are shown as related to the project pom, not the actual grammar file. For example:

"resource": "/Users/chris/Dev/learn-antlr/calc/pom.xml",
"owner": "generated_diagnostic_collection_name#2",
"code": "0",
"severity": 8,
"message": "can't find or load grammar CommonLexerRulez (org.antlr:antlr4-maven-plugin:4.11.2-SNAPSHOT:antlr4:antlr:generate-sources)",

Any idea where to look for issues?