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bug#46374: Regression: erronous calls to PRED switch major-mode of unrel
From: |
Hauke Rehfeld |
Subject: |
bug#46374: Regression: erronous calls to PRED switch major-mode of unrelated modified buffers |
Date: |
Sat, 28 Aug 2021 18:25:23 +0200 |
User-agent: |
mu4e 1.6.3; emacs 28.0.50 |
Hmmm, I'm pretty sure the changes to `save-some-buffers` here
regarding the predicate indirection caused a regression and/or
very unexpected behavior that causes bugs in previously working
code.
Consider
`(save-some-buffers t (lambda () (derived-mode-p 'org-mode)))'
called from an org-mode buffer. It runs through the part of
`save-some-buffers' that is trying to resolve the PRED
indirection:
https://github.com/emacs-mirror/emacs/blob/692da8c6a82f8de376a2eec9304773b3e85205f3/lisp/files.el#L5792
``` emacs-lisp
;; Allow `pred' to be a function that returns a predicate
;; with lexical bindings in its original environment
(bug#46374).
(let ((pred-fun (and (functionp pred) (funcall pred))))
(when (functionp pred-fun)
(setq pred pred-fun)))
```
which evaluates the predicate to check if it returns a function --
which `(derived-mode-p)' does, as it simply returns the major-mode
symbol on success! In this case, it would be `#'org-mode'. So then
`org-mode' is called on any unsaved buffers as a PREDICATE,
switching those buffers to org-mode.
Compare this usage in org-mode, org.el:15357:
``` emacs-lisp
(defun org-save-all-org-buffers ()
"Save all Org buffers without user confirmation."
(interactive)
(message "Saving all Org buffers...")
(save-some-buffers t (lambda () (derived-mode-p 'org-mode)))
(when (featurep 'org-id) (org-id-locations-save))
(message "Saving all Org buffers... done"))
```
- bug#46374: Regression: erronous calls to PRED switch major-mode of unrelated modified buffers,
Hauke Rehfeld <=