company-minimum-prefix-length isn't taken into account when backspacing

[haoyuan80s]

I have (setq company-minimum-prefix-length 1). The company starts after I type one letter, but keep triggering after I delete the letter (it is slow to complete with zero length prefix). Any fix for that?

---

After typing one letter:

After deleting that letter:

[haoyuan80s]

Company without lsp-mode works well.

[haoyuan80s]

(use-package company-lsp
  :ensure t)
(push 'company-lsp company-backends)

Adding company-lsp fixed the issue but it is no longer supported. Any fix without using company-lsp?

[suzuki11109]

Seems to happen when I use csharp lsp-mode.
I have (setq company-minimum-prefix-length 2) but it triggers after one character and keep triggering after delete.

[kiennq]

What's your lsp-mode version? Can you take io trace when this happens?

[yyoncho]

@kiennq FYI it reproduces with lsp-start-plain.el

[kiennq]

Does it only happen with csharp language server?

[yyoncho]

@kiennq FYI it reproduces with lsp-start-plain.el

disregard that, I though that I am in another issue.

[suzuki11109]

@kiennq So far I see this problem only in csharp.
I tried again with lsp-start-plain.el and the behaviour is kind of improved. I think this happen when company-yasnippets is enabled.
After I disable yasnippets, the candidates are more relevant but company-minimum-prefix-length is still not working (company triggered after typing 1 character even though company-minimum-prefix-length is 2).

[kiennq]

I found out the problem, csharp language server is sending space as trigger character, that's why the automatic completion is triggered even if you type with 1 character (you or Emacs must have insert spaces before the current symbol).
Since space as trigger character is too invasive, I think we can help a new custom setting/defvar to specify the character that will be omitted from the trigger characters list.
@yyoncho WDYT?

[dsdshcym]

Same with https://github.com/merrickluo/lsp-tailwindcss/
Since tailwindcss language server is using space as trigger char as well, it would trigger completion even with 1 space
and with tons of tailwind css classes to complete, the typing becomes extremely slow

[kiennq]

Some thing like this might help

(advice-add #'lsp-completion--looking-back-trigger-characterp
            :filter-args
            (lambda (r) (seq-remove (lambda (it) (equal it " ")) r))
            '((name . --filter-spaces)))

[dmvianna]

I see that happening in both Scala and Haskell and the workaround does not help.