GDscript CLI checking tool

[rcorre]

From #20503:

Not for now. --check-only just means that the editor will close as soon as it has loaded the script. A proper script validation tool would need to be implemented differently.

I couln't find an existing issue for a "proper script validation tool", so I'm opening this as an official feature request.

Basic features would include:

• Runnable from the command line on a single script
• Consistent, machine-readable error format (compatible with e.g. vim's errorformat)
• Produces errors for invalid syntax
• Uses an existing godot instance rather than launching a new instance

"Nice to have" features include:

• Usable without any godot instance running
• Style warnings (e.g. nonstandard indentations)
• Linting (unused variables, mismatched string format, ect.)

I think --check-only currently satisfies the first 3 basic features, so the only thing missing is to not open a new instance of godot to lint every script (I'd like to check syntax automatically on saving a .gd file with neomake).

[Zylann]

If you want to be able to do that in neomake, you will need to connect it to the correct Godot instance (you could be running more than one) and communicate via signals or TCP.

[rcorre]

@Zylann I'm not sure why that should be necessary. All neomake would need is a CLI tool that takes a script path as input and produces machine-readable errors as output (and neomake is just one example). --check-only pretty much does that, but starts a new instance of godot.

Even if TCP communication with godot is required to check scripts, it would make sense to have a CLI in front of that to standardize the interface for editors.

[Zylann]

@rcorre you would need such communication if you want to re-use an instance (as in, an already-running one).

[rcorre]

@Zylann right, but it wouldn't make sense to have neomake do that communication (and have that work repeated in every other linter). I'm saying that godot --check-only -s myscript.gd should perform that communication.

Of course, it would be even better if the gdscript parser didn't require the full godot engine to be running. Does gdscript have a grammar specification somewhere?

[Zylann]

@rcorre it would make sense because you have to select the instance. People may not be running only one instance of Godot. Also how would you re-use a running Godot from a CLI if what you write in that CLI is godot <something>? (which actually runs another instance of godot). Or am I missing something?

[rcorre]

@Zylann ah, I see what you're saying. I guess the question is how important it is to actually reuse an instance. Do you actually need the godot engine running to parse a script?

I also haven't looked at the code much but I'm wondering if just not starting the GUI when --check-only is passed would be a low-hanging fruit here.

[vnen]

There's the --no-window option, but currently it works only on Windows.

[Zylann]

I was talking about re-use because you wrote this as a 4th point :p

[xsellier]

Sorry for the necro bump.
I've been working on a very rough linter for GDscript:
https://github.com/binogure-studio/gdlinter

It is really far from being perfect.

[rcorre]

@xsellier nice! Unfortunately I'm on 3.1, and it looks like your linter supports 2.X only.

[xsellier]

@rcorre There is one module, but you'll need to recompile Godot Engine to use it:
https://github.com/hedin-hiervard/gdlint