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bug#32832: [PATCH] Fix 'provided-mode-derived-p' when the parent is an a
bug#32832: [PATCH] Fix 'provided-mode-derived-p' when the parent is an alias
Mon, 24 Sep 2018 21:09:39 -0700
From: Andrew Schwartzmeyer <address@hidden>
Authors of Emacs packages often derive from an alias of a mode instead
of the mode directly. This is especially the case when deriving from
'prog-mode' as it is relatively new. Unfortunately, using
'derived-mode-p' to check if some mode is derived from an alias of
'prog-mode' does not work as expected. The bug is that
'provided-mode-derived-p' should not only return non-nil when MODE is
one of MODES, but also when MODE is an alias of one of MODES.
* lisp/subr.el (provided-mode-derived-p):
Return non-nil when MODE is an alias of any of MODES (Bug#32795).
* test/lisp/subr-tests.el: Add tests for the above.
lisp/subr.el | 9 +++++++--
test/lisp/subr-tests.el | 12 ++++++++++++
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/lisp/subr.el b/lisp/subr.el
index 7582b6cdb..6c625b40d 100644
@@ -1919,9 +1919,14 @@ delay-mode-hooks
(defun provided-mode-derived-p (mode &rest modes)
"Non-nil if MODE is derived from one of MODES.
Uses the `derived-mode-parent' property of the symbol to trace backwards.
+Non-nil even if MODE is derived from an alias of any of MODES.
If you just want to check `major-mode', use `derived-mode-p'."
- (while (and (not (memq mode modes))
- (setq mode (get mode 'derived-mode-parent))))
+ (not (memq mode modes))
+ (let* ((parent (get mode 'derived-mode-parent))
+ (parentfn (symbol-function parent)))
+ (setq mode (if (and parentfn (symbolp parentfn)) parentfn parent)))))
(defun derived-mode-p (&rest modes)
diff --git a/test/lisp/subr-tests.el b/test/lisp/subr-tests.el
index 430d71903..a9f72c26d 100644
@@ -62,6 +62,18 @@
+(ert-deftest provided-mode-derived-p ()
+ ;; base case: `derived-mode' directly derives `prog-mode'
+ (should (progn
+ (define-derived-mode derived-mode prog-mode "test")
+ (provided-mode-derived-p 'derived-mode 'prog-mode)))
+ ;; edge case: `derived-mode' derives an alias of `prog-mode'
+ (should (progn
+ (defalias 'parent-mode
+ (if (fboundp 'prog-mode) 'prog-mode 'fundamental-mode))
+ (define-derived-mode derived-mode parent-mode "test")
+ (provided-mode-derived-p 'derived-mode 'prog-mode))))
(ert-deftest number-sequence-test ()
(should (= (length
(number-sequence (1- most-positive-fixnum) most-positive-fixnum))
- bug#32832: [PATCH] Fix 'provided-mode-derived-p' when the parent is an alias,