Prevent `lsp` + `company` from losing completion after dot + symbol

Question

In many languages . is specially treated, so e.g. after typing a foo. a user expects a completion for methods available from foo.

That works with company as well, however after foo. triggered a completion, typing an additional letter (expecting for the list to get reduced), makes completion disappear completely. And it won't appear again till I type letters ≥ company-minimum-prefix-length.

Any way to prevent that from happening? Besides reducing company-minimum-prefix-length to 1, that is.

Steps to reproduce

1. Create /tmp/.emacs as follows:

   (package-initialize)
   (use-package company)
   (use-package lsp)
   

2. Start emacs as emacs -Q -l /tmp/.emacs test.py

3. Execute M-x lsp

4. Type "".

   A completion should appear

5. Type c to reduce completions to ones starting with that letter

Expected

Completions get reduced to ones starting with c, i.e. capitalize(), casefold(), etc.

Actual

The completions popup disappears.

Answer 1

It was an lsp-mode bug, fixed in the latest code by this merged pull request.

Commit e379ae5 "lsp-completion-at-point: looking back a few more chars for trigger-char"