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Eglot: fix jit-lock inlay hint bugs

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One of the bugs was straightforward.  The timer function of
eglot--update-hints must set the correct buffer.

The other is much more odd.  When using Eglot on Emacs's own
src/coding.c, the jit-lock code starts calling its jit-functions over
and over again with the same sequence of arguments, like so:

======================================================================
1 -> (eglot--update-hints 63551 65051)
1 <- eglot--update-hints: [nil 25592 52026 4
======================================================================
1 -> (eglot--update-hints 65051 66551)
1 <- eglot--update-hints: [nil 25592 52026 4
======================================================================
1 -> (eglot--update-hints-1 63551 66551)
1 <- eglot--update-hints-1: nil
======================================================================
1 -> (eglot--update-hints 63551 65051)
1 <- eglot--update-hints: [nil 25592 52026 4
======================================================================
1 -> (eglot--update-hints 65051 66551)
1 <- eglot--update-hints: [nil 25592 52026 5
======================================================================
1 -> (eglot--update-hints-1 63551 66551)
1 <- eglot--update-hints-1: nil

This continues forever at a very fast rate and saturates the LSP
channel.

At first I thought that it was because eglot--update-hints-1 is
actually causing the buffer to be modified with overlays sometime in
the future, but it is not so!  It seems that merely calling

   (goto-char (eglot--lsp-position-to-point position))

(from the LSP request handler in eglot--update-hints-1) will cause
this bug.

* lisp/progmodes/eglot.el (eglot--update-hints): Fix bugs.
This commit is contained in:
João Távora 2023-02-24 14:48:01 +00:00
parent 5db75ec7d3
commit 55d29c9bac
1 changed files with 25 additions and 6 deletions
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31
lisp/progmodes/eglot.el
View file

@ -3492,12 +3492,15 @@ If NOERROR, return predicate, else erroring function."
(defvar-local eglot--outstanding-inlay-hints-region (cons nil nil)
"Jit-lock-calculated (FROM . TO) region with potentially outdated hints")
(defvar-local eglot--outstanding-inlay-hints-last-region nil)
(defvar-local eglot--outstanding-inlay-regions-timer nil
"Helper timer for `eglot--update-hints'")
(defun eglot--update-hints (from to)
"Jit-lock function for Eglot inlay hints."
(cl-symbol-macrolet ((region eglot--outstanding-inlay-hints-region)
(last-region eglot--outstanding-inlay-hints-last-region)
(timer eglot--outstanding-inlay-regions-timer))
(setcar region (min (or (car region) (point-max)) from))
(setcdr region (max (or (cdr region) (point-min)) to))
@ -3513,12 +3516,28 @@ If NOERROR, return predicate, else erroring function."
;; not introducing any more delay over jit-lock's timers.
(when (= jit-lock-context-unfontify-pos (point-max))
(if timer (cancel-timer timer))
(setq timer (run-at-time
0 nil
(lambda ()
(eglot--update-hints-1 (max (car region) (point-min))
(min (cdr region) (point-max)))
(setq region (cons nil nil) timer nil)))))))
(let ((buf (current-buffer)))
(setq timer (run-at-time
0 nil
(lambda ()
(eglot--when-live-buffer buf
;; HACK: In some pathological situations
;; (Emacs's own coding.c, for example),
;; jit-lock is calling `eglot--update-hints'
;; repeatedly with same sequence of
;; arguments, which leads to
;; `eglot--update-hints-1' being called with
;; the same region repeatedly. This happens
;; even if the hint-painting code does
;; nothing else other than widen, narrow,
;; move point then restore these things.
;; Possible Emacs bug, but this fixes it.
(unless (equal last-region region)
(eglot--update-hints-1 (max (car region) (point-min))
(min (cdr region) (point-max)))
(setq last-region region))
(setq region (cons nil nil)
timer nil)))))))))
(defun eglot--update-hints-1 (from to)
"Do most work for `eglot--update-hints', including LSP request."