Enabling autocomplete for a custom language using Rust grammar

[selimsandal]

I am trying to add support for DSLX, the language uses mostly Rust syntax so I used Rust grammar for highlighting and added dslx_ls as the language server. Language server features work but autocomplete does not. Is there a way I can make autocomplete work using dslx_ls or reuse Rust autocomplete?

Here is my config:

languages.toml

[[language]]
name = "dslx"
scope = "source.dslx"
file-types = ["x"]
injection-regex = "dslx"
language-servers = [ "dslx_ls" ]
grammar = "rust"
indent = { tab-width = 2, unit = "  " }

[language-server.dslx_ls]
command = "dslx_ls"

runtime/queries/dslx/highlights.scm

; inherits: rust

[seifertm]

It looks like dslx_ls does not support autocompletion.

Looking at the linked repository I found the language server implementation. It doesn't seem to implement a handler for textDocument/completion, which is used to retrieve a list of possible completions from a language server.