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bug#63535: Master branch: Error in forw_comment (syntax.c) handling of e
From: |
Alan Mackenzie |
Subject: |
bug#63535: Master branch: Error in forw_comment (syntax.c) handling of escaped LFs |
Date: |
Mon, 22 May 2023 14:59:32 +0000 |
Hello, Stefan.
On Wed, May 17, 2023 at 18:01:32 -0400, Stefan Monnier wrote:
> Hi Alan,
[ .... ]
> AFAIK this is your code, so you should know better, but AFAICT
> `prev_syntax` is not updated in the loop, so it only reflects the syntax
> before the beginning of the scanned text, rather than anything near `from`.
> Are you sure this is right?
Thanks, you are correct, the patch was not good.
It turned out to be quite tricky to get working. As well as
forw_comment, I had to amend scan_sexps_forward to make it return a
quoted state to its caller when this happens at the limit of the scan.
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!
diff --git a/src/syntax.c b/src/syntax.c
index e9e04e2d638..94b2ac2b591 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -2338,13 +2338,16 @@ forw_comment (ptrdiff_t from, ptrdiff_t from_byte,
ptrdiff_t stop,
return 0;
}
c = FETCH_CHAR_AS_MULTIBYTE (from_byte);
+ prev_syntax = syntax;
syntax = SYNTAX_WITH_FLAGS (c);
code = syntax & 0xff;
if (code == Sendcomment
&& SYNTAX_FLAGS_COMMENT_STYLE (syntax, 0) == style
&& (SYNTAX_FLAGS_COMMENT_NESTED (syntax) ?
(nesting > 0 && --nesting == 0) : nesting < 0)
- && !(comment_end_can_be_escaped && char_quoted (from, from_byte)))
+ && !(comment_end_can_be_escaped
+ && ((prev_syntax & 0xff) == Sescape
+ || (prev_syntax & 0xff) == Scharquote)))
/* We have encountered a comment end of the same style
as the comment sequence which began this comment
section. */
@@ -2368,7 +2371,11 @@ forw_comment (ptrdiff_t from, ptrdiff_t from_byte,
ptrdiff_t stop,
inc_both (&from, &from_byte);
UPDATE_SYNTAX_TABLE_FORWARD (from);
if (from == stop) continue; /* Failure */
- }
+ c = FETCH_CHAR_AS_MULTIBYTE (from_byte);
+ prev_syntax = syntax;
+ syntax = Smax;
+ code = syntax;
+ }
inc_both (&from, &from_byte);
UPDATE_SYNTAX_TABLE_FORWARD (from);
@@ -3349,7 +3356,14 @@ do { prev_from = from; \
are invalid now. Luckily, the `done' doesn't use them
and the INC_FROM sets them to a sane value without
looking at them. */
- if (!found) goto done;
+ if (!found)
+ {
+ if ((prev_from_syntax & 0xff) == Sescape
+ || (prev_from_syntax & 0xff) == Scharquote)
+ goto endquoted;
+ else
+ goto done;
+ }
INC_FROM;
state->incomment = 0;
state->comstyle = 0; /* reset the comment style */
> Stefan
--
Alan Mackenzie (Nuremberg, Germany).
bug#63535: Master branch: Error in forw_comment (syntax.c) handling of escaped LFs, Eli Zaretskii, 2023/05/16