* bug#56256: Emacs 28.1 gets stuck when typing some C++ code @ 2022-06-27 10:22 Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors 2022-06-28 12:52 ` Lars Ingebrigtsen 2022-06-28 16:28 ` Alan Mackenzie 0 siblings, 2 replies; 5+ messages in thread From: Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors @ 2022-06-27 10:22 UTC (permalink / raw) To: 56256 Emacs gets stuck when trying to type the '&' character at the end of the buffer when there's the following code in C++ mode (this code is from https://www.gingerbill.org/article/2015/08/19/defer-in-cpp/): ``` template <typename F> struct privDefer { F f; privDefer(F f) : f(f) {} ~privDefer() { f(); } }; template <typename F> privDefer<F> defer_func(F f) { return privDefer<F>(f); } #define DEFER_1(x, y) x##y #define DEFER_2(x, y) DEFER_1(x, y) #define DEFER_3(x) DEFER_2(x, __COUNTER__) #define defer(code) auto DEFER_3(_defer_) = defer_func([ ``` Steps to reproduce: 1. create a C++ source file with this code and open it with Emacs, if the file doesn't have a C++ source suffix, enable c++mode 2. type the '&' symbol at the last line after "defer_func([" 3. then Emacs gets stuck I can see this bug in Emacs 28.1 and git revision 5b1bb1af030597aab7f7895b6e3da9b430f9438a. I've also tried ``emacs -Q`` and ``emacs -Q -nw``, the bug still exists. ^ permalink raw reply [flat|nested] 5+ messages in thread
* bug#56256: Emacs 28.1 gets stuck when typing some C++ code 2022-06-27 10:22 bug#56256: Emacs 28.1 gets stuck when typing some C++ code Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors @ 2022-06-28 12:52 ` Lars Ingebrigtsen 2022-06-28 16:28 ` Alan Mackenzie 1 sibling, 0 replies; 5+ messages in thread From: Lars Ingebrigtsen @ 2022-06-28 12:52 UTC (permalink / raw) To: Iru Cai; +Cc: Alan Mackenzie, 56256 Iru Cai <vimacs@disroot.org> writes: > 1. create a C++ source file with this code and open it with Emacs, if > the file doesn't have a C++ source suffix, enable c++mode > > 2. type the '&' symbol at the last line after "defer_func([" > > 3. then Emacs gets stuck > > I can see this bug in Emacs 28.1 and git revision > 5b1bb1af030597aab7f7895b6e3da9b430f9438a. I've also tried ``emacs -Q`` > and ``emacs -Q -nw``, the bug still exists. Yup -- I can reproduce this on the current trunk, too -- and it hangs Emacs hard: I have to kill Emacs after typing that "&". I'm adding Alan to the CCs. -- (domestic pets only, the antidote for overdose, milk.) bloggy blog: http://lars.ingebrigtsen.no ^ permalink raw reply [flat|nested] 5+ messages in thread
* bug#56256: Emacs 28.1 gets stuck when typing some C++ code 2022-06-27 10:22 bug#56256: Emacs 28.1 gets stuck when typing some C++ code Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors 2022-06-28 12:52 ` Lars Ingebrigtsen @ 2022-06-28 16:28 ` Alan Mackenzie 2022-06-29 3:03 ` Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors 1 sibling, 1 reply; 5+ messages in thread From: Alan Mackenzie @ 2022-06-28 16:28 UTC (permalink / raw) To: Iru Cai; +Cc: Lars Ingebrigtsen, 56256 Hello, Iru. Thanks for taking the trouble to report this bug, and thanks even more for such a concise and helpful report. On Mon, Jun 27, 2022 at 18:22:15 +0800, Iru Cai wrote: > Emacs gets stuck when trying to type the '&' character at the end of the > buffer when there's the following code in C++ mode (this code is from > https://www.gingerbill.org/article/2015/08/19/defer-in-cpp/): > ``` > template <typename F> > struct privDefer { > F f; > privDefer(F f) : f(f) {} > ~privDefer() { f(); } > }; > template <typename F> > privDefer<F> defer_func(F f) { > return privDefer<F>(f); > } > #define DEFER_1(x, y) x##y > #define DEFER_2(x, y) DEFER_1(x, y) > #define DEFER_3(x) DEFER_2(x, __COUNTER__) > #define defer(code) auto DEFER_3(_defer_) = defer_func([ > ``` > Steps to reproduce: > 1. create a C++ source file with this code and open it with Emacs, if > the file doesn't have a C++ source suffix, enable c++mode > 2. type the '&' symbol at the last line after "defer_func([" > 3. then Emacs gets stuck > I can see this bug in Emacs 28.1 and git revision > 5b1bb1af030597aab7f7895b6e3da9b430f9438a. I've also tried ``emacs -Q`` > and ``emacs -Q -nw``, the bug still exists. Yes. What is triggering the bug is the newly typed & being at the end of a #define line. The CC Mode function c-font-lock-c++-lambda-captures is in a loop, handling one lambda capture at a time. At the end of the file, it has just gone forward over the whitespace, and wants to return to the &. However it wrongly uses the function c-backward-token-2, which treats all the macro lines as whitespace, hence ends up at the }, 6 lines earlier. It then searches forward for the "next" [, and ends up at the same one it was at before. This loops infinitely. I think the following patch should fix it. Could you try it out on your real C++ code, please, and tell us whether the bug is actually fixed. (If you want any help with applying the patch or byte compiling CC Mode afterwards, feel free to send me private email.): diff -r 03c932b2922b cc-fonts.el --- a/cc-fonts.el Sat Jun 18 15:40:47 2022 +0000 +++ b/cc-fonts.el Tue Jun 28 16:15:37 2022 +0000 @@ -1823,7 +1823,7 @@ ;; font-lock-keyword-face. It always returns NIL to inhibit this and ;; prevent a repeat invocation. See elisp/lispref page "Search-based ;; Fontification". - (let (mode capture-default id-start id-end declaration sub-begin sub-end) + (let (mode capture-default id-start id-end declaration sub-begin sub-end tem) (while (and (< (point) limit) (search-forward "[" limit t)) (when (progn (backward-char) @@ -1835,15 +1835,18 @@ (char-after))) ;; Is the first element of the list a bare "=" or "&"? (when mode - (forward-char) - (c-forward-syntactic-ws) - (if (memq (char-after) '(?, ?\])) - (progn - (setq capture-default mode) - (when (eq (char-after) ?,) - (forward-char) - (c-forward-syntactic-ws))) - (c-backward-token-2))) + (setq tem nil) + (save-excursion + (forward-char) + (c-forward-syntactic-ws) + (if (memq (char-after) '(?, ?\])) + (progn + (setq capture-default mode) + (when (eq (char-after) ?,) + (forward-char) + (c-forward-syntactic-ws)) + (setq tem (point))))) + (if tem (goto-char tem))) ;; Go round the following loop once per captured item. We use "\\s)" ;; rather than "\\]" here to avoid infinite looping in this situation: -- Alan Mackenzie (Nuremberg, Germany). ^ permalink raw reply [flat|nested] 5+ messages in thread
* bug#56256: Emacs 28.1 gets stuck when typing some C++ code 2022-06-28 16:28 ` Alan Mackenzie @ 2022-06-29 3:03 ` Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors 2022-07-02 16:23 ` Alan Mackenzie 0 siblings, 1 reply; 5+ messages in thread From: Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors @ 2022-06-29 3:03 UTC (permalink / raw) To: Alan Mackenzie; +Cc: Lars Ingebrigtsen, 56256 On 2022/6/29 00:28, Alan Mackenzie wrote: > I think the following patch should fix it. Could you try it out on your > real C++ code, please, and tell us whether the bug is actually fixed. > (If you want any help with applying the patch or byte compiling CC Mode > afterwards, feel free to send me private email.): Thanks, this fixes this bug, and I haven't found a issue when editing some of my C++ code. > diff -r 03c932b2922b cc-fonts.el > --- a/cc-fonts.el Sat Jun 18 15:40:47 2022 +0000 > +++ b/cc-fonts.el Tue Jun 28 16:15:37 2022 +0000 > @@ -1823,7 +1823,7 @@ > ;; font-lock-keyword-face. It always returns NIL to inhibit this and > ;; prevent a repeat invocation. See elisp/lispref page "Search-based > ;; Fontification". > - (let (mode capture-default id-start id-end declaration sub-begin sub-end) > + (let (mode capture-default id-start id-end declaration sub-begin sub-end tem) > (while (and (< (point) limit) > (search-forward "[" limit t)) > (when (progn (backward-char) > @@ -1835,15 +1835,18 @@ > (char-after))) > ;; Is the first element of the list a bare "=" or "&"? > (when mode > - (forward-char) > - (c-forward-syntactic-ws) > - (if (memq (char-after) '(?, ?\])) > - (progn > - (setq capture-default mode) > - (when (eq (char-after) ?,) > - (forward-char) > - (c-forward-syntactic-ws))) > - (c-backward-token-2))) > + (setq tem nil) > + (save-excursion > + (forward-char) > + (c-forward-syntactic-ws) > + (if (memq (char-after) '(?, ?\])) > + (progn > + (setq capture-default mode) > + (when (eq (char-after) ?,) > + (forward-char) > + (c-forward-syntactic-ws)) > + (setq tem (point))))) > + (if tem (goto-char tem))) > > ;; Go round the following loop once per captured item. We use "\\s)" > ;; rather than "\\]" here to avoid infinite looping in this situation: > > ^ permalink raw reply [flat|nested] 5+ messages in thread
* bug#56256: Emacs 28.1 gets stuck when typing some C++ code 2022-06-29 3:03 ` Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors @ 2022-07-02 16:23 ` Alan Mackenzie 0 siblings, 0 replies; 5+ messages in thread From: Alan Mackenzie @ 2022-07-02 16:23 UTC (permalink / raw) To: Iru Cai; +Cc: acm, Lars Ingebrigtsen, 56256-done Hello, Iru. On Wed, Jun 29, 2022 at 11:03:47 +0800, Iru Cai wrote: > On 2022/6/29 00:28, Alan Mackenzie wrote: > > I think the following patch should fix it. Could you try it out on your > > real C++ code, please, and tell us whether the bug is actually fixed. > > (If you want any help with applying the patch or byte compiling CC Mode > > afterwards, feel free to send me private email.): > Thanks, this fixes this bug, and I haven't found a issue when editing > some of my C++ code. [ .... ] Thanks for the testing! I've committed the patch to the release branch of our git tree, and I'm closing the bug with this post. -- Alan Mackenzie (Nuremberg, Germany). ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2022-07-02 16:23 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2022-06-27 10:22 bug#56256: Emacs 28.1 gets stuck when typing some C++ code Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors 2022-06-28 12:52 ` Lars Ingebrigtsen 2022-06-28 16:28 ` Alan Mackenzie 2022-06-29 3:03 ` Iru Cai via Bug reports for GNU Emacs, the Swiss army knife of text editors 2022-07-02 16:23 ` Alan Mackenzie
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