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Subject: |
Master branch: Error in forw_comment (syntax.c) handling of escaped LFs |
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Date: |
Tue, 16 May 2023 10:57:40 +0000 |
Hello, Emacs.
In the master branch:
Consider the following C++ Mode buffer:
// comment \
comment line 2
line_3();
.. The backslash at the end of line 1 extends the comment into line 2.
Put point at // on L1, and do:
M-: (setq s (parse-partial-sexp (point) (+ (point) 9)))
.. s gets the parse state of the inside of the comment.
Now put point at EOL 1, between the backslash and the LF. Do
M-: (parse-partial-sexp (point) (point-max) nil nil s 'syntax-table)
.. This ought to leave point at BOL 2, since the syntax before the LF at
EOL 1 is that of a C++ comment, otherwise neutral. Instead, it leaves
point wrongly at BOL 3.
#########################################################################
The reason for this bug is at L+42 of forw_comment (in syntax.c). There
we have
&& !(comment_end_can_be_escaped && char_quoted (from, from_byte))
.. Checking char_quoted is wrong. Instead the function should check the
current parse state.
--
Alan Mackenzie (Nuremberg, Germany).
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--- Begin Message ---
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Subject: |
Re: bug#63535: Master branch: Error in forw_comment (syntax.c) handling of escaped LFs |
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Date: |
Mon, 22 May 2023 16:16:49 +0000 |
Hello, Stefan.
On Mon, May 22, 2023 at 11:16:40 -0400, Stefan Monnier wrote:
> > I think the following patch is better. Would you please have a look at
> > it, in the hope I haven't made any other silly mistakes. Thanks!
> I don't see any silly mistake there, sorry.
Thanks! I've committed the patch, and I'm closing the bug.
> Stefan
> PS: It does remind me that we really should do ourselves a favor and get rid
> of the distinction between `Sescape` and `Scharquote`.
> IIRC there's a risk of backward incompatibility, so it has to be done
> progressively, but we should start the process. E.g. first declare one of the
> two as obsolete, then emit a warning when we see it being used, ...
Yes. I think Sescape should be the survivor. I don't know if
Scharquote is used at all in Emacs code.
--
Alan Mackenzie (Nuremberg, Germany).
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