Extra lens are displayed when buffer is narrowed

[andreyorst]

Thank you for the bug report

• I am using the latest version of lsp-mode related packages.
• I checked FAQ and Troubleshooting sections
• You may also try reproduce the issue using clean environment using the following command

emacs -q -l lsp-start-plain.el

where lsp-start-plain.el can be downloaded here.

Bug description

If the buffer is narrowed all lenses below the narrowed region are displayed at the last line.

Steps to reproduce

Open a buffer, and create some variables, so the server could return the lens, for them. Here's an example in Clojure:

(ns foo)
(def a nil)
(def b nil)
(def c nil)
(def d nil)

Here are the lenses:

Then narrow to defun on (def a nil) line:

Expected behavior

Only one lens is displayed.

Which Language Server did you use?

clojure-lsp

OS

Linux

Error callstack

No response

Anything else?

No response

[ericdallo]

Hum, we should probably change lsp-mode to hide lens when narrowing c/c @yyoncho

[yyoncho]

does it fix itself after changing the text?

[yyoncho]

I was able to test it - it fixes itself after narrowing and changing the buffer content. So we should refresh the lenses after narowing.

[ericdallo]

@yyoncho do you know what narrow hook we can watch it?

[andreyorst]

I'm afraid there's no such hook. However all narrowing commands should use narrow-to-region, and it is a C function, so it seems to fix the issue it can just be advised:

(define-advice narrow-to-region (:after (&rest _))
  (lsp-lens-refresh t))
(define-advice widen (:after (&rest _))
  (lsp-lens-refresh t))

[andreyorst]

This, however, raises another issue, when using indirect narrowing. When I first narrow to an indirect buffer with the advice from above, I get the correct lens in the indirect buffer and no lens in the original buffer:

However, when I focus the original buffer I get this:

I'm not sure how this should be handled

[andreyorst]

I'm afraid there's no such hook. However all narrowing commands should use narrow-to-region, and it is a C function, so it seems to fix the issue it can just be advised:

(define-advice narrow-to-region (:after (&rest _))
  (lsp-lens-refresh t))
(define-advice widen (:after (&rest _))
  (lsp-lens-refresh t))

I've tried this for a day and noticed an extreme CPU usage in the clojure-lsp process (about 500%). I've not tried other servers, but removing the advices resolved the CPU usage issue, so I think this method is not very good.

[yyoncho]

it should be (lsp-lens-refresh nil) and also it should check if the buffer has lens mode enabled.