Should filterText trim prefixes?

[stamblerre]

For example, if I have a variable abc in scope, and I have typed a, should the filter text be bc? I would guess yes, based on the behavior of VSCode, but it seems that other language servers behave differently.

For context, this question was first brought up in golang/go#31552 and tigersoldier/company-lsp#103.

[rcjsuen]

Personally, I don't trim filterText in my language server but I can't speak for anyone else. I don't recall any past discussions about this field either.

[stamblerre]

It seems that most other language servers don't either, and I didn't expect that I had to - however, without doing trimming, VSCode doesn't behave as I would expect it to. Perhaps this is a VSCode bug? Would be happy to file it there, but it would also be helpful to clarify this in the spec.

[muirdm]

The Rust server does not set filterPrefix but works correctly in VSCode (using the example in golang/go#31552 (comment)). This is starting to look like a VSCode go extension bug. Do language extensions have custom handling of completion candidates?

[stamblerre]

The only handling would be in the language client, which is in https://github.com/Microsoft/vscode-languageserver-node. I'll open an issue there, but for now, I'll leave the filter text as is in gopls. Maybe I can add a temporary config to not trim it.

[dbaeumer]

@stamblerre I commented in microsoft/vscode-languageserver-node#488

Lets close this issue for now until I have a better understanding why your case is failing. I was not able to reproduce it.