[WIP] Improve elixir-ls compilation

[darwintantuco]

An attempt to improve elixir-ls compilation.
I notice elixir-ls uses asdf together with asdf-erlang and asdf-elixir. (checkout https://github.com/elixir-lsp/elixir-ls/blob/master/.tool-versions).
Maybe we can also use it by default for compilation.
I think this will reduce the need to compile elixir-ls manually (https://github.com/elixir-lsp/coc-elixir#server-fails-to-start)

Although this will require users to have asdf, asdf-erlang and asdf-elixir installed in their machine.
Not sure if this is ideal but seemed to work well on my testing.

[darwintantuco]

Tested it by pointing coc-elixir to my fork e.g. Plug 'darwintantuco/coc-elixir', {'do': 'yarn install && yarn prepack'}
Unable to test :CocInstall coc-elixir though

[darwintantuco]

not ideal I guess, maybe we will only call asdf install for asdf-elixir and asdf-erlang users?

[amiralies]

You're right,
two things should happen

• When publishing to npm , We've to compile els with minimum supported erl/elixir version
• For users who install using this repo with plugin managers (ie plug), we should create a script which uses asdf if available otherwise fall back to regular elixir installation

[darwintantuco]

ahh right 👍
I realize I should have created an issue first, oops, sorry
anyways, happy to check this out :D

[darwintantuco]

if the user have asdf-elixir and asdf-erlang installed, can we call asdf install?
I think the idea is to always use the correct/compatible version of elixir and erlang in compilation.
although this would take additional time in installation, as it will download elixir and erlang defined in .tool-versions (if not yet downloaded)

[amiralies]

I'm not sure about this, I think i've to ask @axelson to help

[darwintantuco]

looks like .tool-versions is removed on master (elixir-lsp/elixir-ls#351)
closing this PR

[darwintantuco]

still, it would be nice if we can figure out a way to improve current compilation to avoid the need to build/compile elixir-ls manually, as specified in https://github.com/elixir-lsp/coc-elixir#server-fails-to-start

will let you know if I come up with something :D

[axelson]

Would it be possible to add some code that checks if the server needs to be recompiled? And it could do that by checking if the current version of elixir and erlang is different the version used to compile ElixirLS? And if it is then coc-elixir could remove the existing release and recompile (or perhaps it could compile each elixir-erlang) pair into a new directory.

As a side-note it is generally better for elixir-ls to run on the same version of elixir (and to a lesser degree erlang) that it was compiled with (here's one specific annoying issue elixir-lsp/elixir-ls#193). So I'm likely to move ElixirLS in the direction of compiling before launching than the reverse, although ideally that would be something that is built into ElixirLS rather than having to run that for each extension.

[darwintantuco]

As I understand, the plugin will compile ElixirLS once during installation using elixir/erlang versions installed on the user's machine.
Checkout package.json.
Hmm I think that's possible, maybe we could create a script that checks for versions and compare it to recommended versions? or maybe we can improve the error message when installation failed due to ElixirLS compilation.
just thinking out loud :D

[axelson]

Does coc-elixir share one global installation of elixir-ls or is it one per project? Because if it's shared if you are using different versions of Elixir and Erlang you will run into problems.

[darwintantuco]

I think coc-elixir uses one global installation of elixir-ls.
I see, I wonder how vscode plugin compile elixir-ls.

[axelson]

VSCode is released with a precompiled version of ElixirLS that was built with minimal elixir and erlang versions: https://github.com/elixir-lsp/elixir-ls/blob/f61e81f1ca7f564741a386dc353510d92469a838/.release-tool-versions

[darwintantuco]

Interesting!
I wonder if we can also release coc-elixir with a precompiled version of ElixirLS.
So that users won’t need to compile it on installation.
Will investigate when I have the time.

[darwintantuco]

sorry just had the time

It seems coc-elixir is already released with a precompiled version of ElixirLS.
and it works well when you install it using :CocInstall coc-elixir.

Apologies, I think some of my statements before is wrong and only applicable if you install elixir-ls via
Plug 'elixir-lsp/coc-elixir', {'do': 'yarn install && yarn prepack'} - which will eventually compile elixir-ls on users end.
At the moment, the only thing I can think of is to commit compiled elixir-ls, which is not ideal.

[amiralies]

Maybe we can have a release branch with compiled elixir-ls artifacts, but for now I think it's fine to use :CocInstall or manually compile elixir-ls and use config option elixir.pathToElixirLS.