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* src/data.c (set_internal): Fix bug#44733

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Set the default value when `set` encounters a PER_BUFFER variable
which has been let-bound globally, to match the behavior seen with
`make-variable-buffer-local`.

* test/src/data-tests.el (binding-test--let-buffer-local):
Add corresponding test.
(data-tests--set-default-per-buffer): Add tentative test for the
performance problem encountered in bug#41029.
This commit is contained in:
Stefan Monnier 2020-11-19 17:13:04 -05:00
parent 70773e5b97
commit 8fac244464
2 changed files with 56 additions and 4 deletions
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10
src/data.c
View file

@ -1440,10 +1440,12 @@ set_internal (Lisp_Object symbol, Lisp_Object newval, Lisp_Object where,
{
int offset = XBUFFER_OBJFWD (innercontents)->offset;
int idx = PER_BUFFER_IDX (offset);
if (idx > 0
&& bindflag == SET_INTERNAL_SET
&& !let_shadows_buffer_binding_p (sym))
SET_PER_BUFFER_VALUE_P (buf, idx, 1);
if (idx > 0 && bindflag == SET_INTERNAL_SET
&& !PER_BUFFER_VALUE_P (buf, idx))
if (let_shadows_buffer_binding_p (sym))
set_default_internal (symbol, newval, bindflag);
else
SET_PER_BUFFER_VALUE_P (buf, idx, 1);
}
if (voide)

50
test/src/data-tests.el
View file

@ -345,6 +345,25 @@ comparing the subr with a much slower lisp implementation."
(setq-default binding-test-some-local 'new-default))
(should (eq binding-test-some-local 'some))))
(ert-deftest data-tests--let-buffer-local ()
(let ((blvar (make-symbol "blvar")))
(set-default blvar nil)
(make-variable-buffer-local blvar)
(dolist (var (list blvar 'left-margin))
(let ((def (default-value var)))
(with-temp-buffer
(should (equal def (symbol-value var)))
(cl-progv (list var) (list 42)
(should (equal (symbol-value var) 42))
(should (equal (default-value var) (symbol-value var)))
(set var 123)
(should (equal (symbol-value var) 123))
(should (equal (default-value var) (symbol-value var)))) ;bug#44733
(should (equal (symbol-value var) def))
(should (equal (default-value var) (symbol-value var))))
(should (equal (default-value var) def))))))
(ert-deftest binding-test-makunbound ()
"Tests of makunbound, from the manual."
(with-current-buffer binding-test-buffer-B
@ -381,6 +400,37 @@ comparing the subr with a much slower lisp implementation."
"Test setting a keyword to itself"
(with-no-warnings (should (setq :keyword :keyword))))
(ert-deftest data-tests--set-default-per-buffer ()
:expected-result t ;; Not fixed yet!
;; FIXME: Performance tests are inherently unreliable.
;; Using wall-clock time makes it even worse, so don't bother unless
;; we have the primitive to measure cpu-time.
(skip-unless (fboundp 'current-cpu-time))
;; Test performance of set-default on DEFVAR_PER_BUFFER variables.
;; More specifically, test the problem seen in bug#41029 where setting
;; the default value of a variable takes time proportional to the
;; number of buffers.
(let* ((fun #'error)
(test (lambda ()
(with-temp-buffer
(let ((st (car (current-cpu-time))))
(dotimes (_ 1000)
(let ((case-fold-search 'data-test))
;; Use an indirection through a mutable var
;; to try and make sure the byte-compiler
;; doesn't optimize away the let bindings.
(funcall fun)))
;; FIXME: Handle the wraparound, if any.
(- (car (current-cpu-time)) st)))))
(_ (setq fun #'ignore))
(time1 (funcall test))
(bufs (mapcar (lambda (_) (generate-new-buffer " data-test"))
(make-list 1000 nil)))
(time2 (funcall test)))
(mapc #'kill-buffer bufs)
;; Don't divide one time by the other since they may be 0.
(should (< time2 (* time1 5)))))
;; More tests to write -
;; kill-local-variable
;; defconst; can modify