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bug#49197: [PATCH] 28.0.50; Inability to find "diff" prevents `font-lock
From: |
Jim Porter |
Subject: |
bug#49197: [PATCH] 28.0.50; Inability to find "diff" prevents `font-lock-add-keywords' from working in `diff-mode' |
Date: |
Wed, 23 Jun 2021 14:00:05 -0700 |
This is a very minor issue that I happened to stumble upon. On systems
without "diff", adding a new font-lock rule via
`font-lock-add-keywords' doesn't do anything. This is (if I'm
understanding things correctly) because the diff-refined code will
signal an error, terminating the font-lock code early. Since
`diff--font-lock-refined' is normally the last element in the list,
this only causes issues when a user has added more font-lock rules. To
see the problem in action, you can do the following:
emacs -Q
(setq diff-command "nonexist")
(add-hook 'diff-mode-hook
(lambda ()
(font-lock-add-keywords
nil
'(("^..*?\\([[:blank:]]+\\)$" 1
'trailing-whitespace prepend))
t)))
C-x C-f diff-trailing-ws.patch ;; Attached
;; The added line should be highlighted with `trailing-whitespace',
;; but it isn't.
I've attached a patch for this which ignores `file-missing' errors
when using diff-refined during font-locking. With the patch, running
the above steps correctly highlights trailing whitespace.
0001-Ignore-file-missing-errors-during-diff-refined-font-.patch
Description: Binary data
diff-trailing-ws.patch
Description: Binary data
- bug#49197: [PATCH] 28.0.50; Inability to find "diff" prevents `font-lock-add-keywords' from working in `diff-mode',
Jim Porter <=