[Feature Request]: CLS: add global constants/functions to completion suggestions

[ninivert]

Summary of Feature

When starting from an empty file, chpl-language-server should show the globally available symbols when prompted for suggestions, for instance:

• numLocales, Locales, here, ...
• writeln, write, warning, ...
• probably others that I'm not aware of

In the VSCode extension, some of these are made available through snippets: https://github.com/chapel-lang/chapel-vscode/blob/main/snippets/chapel.json

Code Sample

writeln(numLocales, " should equal ", Locales.size);
write("hello world", '--- \n');

Writing the above code would be much faster with this feature.

Currently Locales.<next LSP suggestion> yields nothing from CLS, where I would expect methods to be available on the array of locales.

[DanilaFe]

Hi, thanks for opening the issue!

My feeling is that this request is in two parts.

1. Make autocompletion aware of global symbols (e.g., numLocales, Locales, etc)
2. Make autocompletion aware of fields on those types (e.g., Locales.<next LSP suggestion>).

The former can be made to work today with relative ease. The latter is a bit more challenging. Today, CLS works by looking at the saved version of the file, largely because the parser isn't very good at recognizing partial programs. If you write:

var x = Locales.

It doesn't know what to do with that program, so it's difficult to provide intelligent suggestions. So, code completion based on context, such as 'what's on the left of the .?', is a bit further off in the future.

[ninivert]

Hi !

Indeed, this can be seen as two incremental parts. Just having the global symbols would be very useful to beginners in the language (such as me 😃).

I initially thought CLS was able to generate suggestions based on type information, for instance with the following program,

const D = {1..10};
var A: [D] real;
A.<next LSP suggestion>

CLS could propose rank, strides, size, etc. (from https://chapel-lang.org/docs/language/spec/arrays.html#predefined-routines-on-arrays), based on the fact it's an array (of reals). Unless I've messed up in setting up CLS, it seems this isn't yet available (so as you say, this would be the scope of another feature request)

[DanilaFe]

Oops, I didn't mean to auto-close this. @ninivert -- we just recently merged a PR that addresses the 'global symbols' part of your issue (Locales, numLocales, etc.). We haven't yet gotten support for Locale.size etc, since that's significantly more complicated, as we have discussed.

Since this original issue is largely about global symbols, I would be inclined to close it, and open another for methods / fields of types (i.e., Locales.size, and really anything.anythingelse). Does that sound reasonable to you?

[ninivert]

Thank you @DanilaFe ! I was eyeing that PR, thank you for your time ; I will check it out later today (edit : I can confirm it works ! 🎉 ).

Yes I think it's reasonable to open another issue for the methods / fields of types.
I can do this if it's helpful.

[DanilaFe]

I've opened #24836 to track the follow-up issue.

Thanks again for reporting the issue and validating that it works. And of course, thanks for trying out Chapel!