From: Dmitry Gutov <dmitry@gutov.dev>
To: Yuan Fu <casouri@gmail.com>, Eli Zaretskii <eliz@gnu.org>,
Arteen Abrishami <arteen@linux.ucla.edu>
Cc: 67417@debbugs.gnu.org
Subject: bug#67417: 29.1.50; c-ts-mode syntax issues with no brackets
Date: Tue, 28 Nov 2023 17:31:05 +0200 [thread overview]
Message-ID: <ab88c85d-25e1-bab1-5e0d-cf6a8977ec11@gutov.dev> (raw)
In-Reply-To: <720463fd-c6d8-4c31-8240-7017984084a4@gmail.com>
On 28/11/2023 08:55, Yuan Fu wrote:
>
>
> On 11/26/23 6:22 PM, Dmitry Gutov wrote:
>> On 27/11/2023 03:47, Yuan Fu wrote:
>>> I pushed two commits which should fix the indentation for "break"
>>> after "else", and indentation for empty lines after if/else/for/while
>>> in general. The fix for the general case doesn't use the parse tree,
>>> since the parse tree is often incomplete when you type if (...) and
>>> hit return. Instead it uses a plain regexp match to see if the
>>> previous line starts with if/else/for/while. This seems like a
>>> reasonable heuristic to use before user types more things, at which
>>> point more accurate indentation rules would be used, since the parse
>>> tree should be more complete then.
>>
>> Sorry, two counter-examples right away:
>>
>> Type 'elsewhere();' and RET -> the next line is indented 1 level
>> extra, at least until you type some more and then have the line
>> reindented either with pressing TAB or adding semicolon.
>>
>> Type 'for (;;) {}' and RET -> same.
>>
>> The first case is easy to guard against (just check that the next char
>> is either space of opening paren), but the second one less so. OTOH,
>> the second case is likely to have a parse tree without errors, so if
>> we also check for that... the heuristic might work.
>
> Well, darn it. And you're right, the second case is a bit hard to
> check... Well I guess for the moment we can remove this heuristic. (I
> tried a bit, and checking for no errors is not so easy.)
Maybe it's possible to salvage this heuristic a bit, at least for
"else", and as long as it's followed by "}" somewhere (e.g. when
electric-pair-mode is used).
diff --git a/lisp/progmodes/c-ts-mode.el b/lisp/progmodes/c-ts-mode.el
index 31a9d0fc886..20689dc1862 100644
--- a/lisp/progmodes/c-ts-mode.el
+++ b/lisp/progmodes/c-ts-mode.el
@@ -373,8 +373,17 @@ c-ts-mode--indent-styles
;; point on the empty line to be indented; this rule
;; does that.
((and no-node
+ ;; Could be a matcher 'prev-sibling-p'.
+ (lambda (_ parent bol &rest _)
+ (equal
+ "ERROR"
+ (treesit-node-type
+ (treesit-node-prev-sibling
+ (treesit-node-first-child-for-pos
+ parent bol)
+ t))))
(c-ts-mode--prev-line-match
- ,(rx (or "if" "else" "while" "do" "for"))))
+ ,(rx "else" symbol-end)))
prev-line c-ts-mode-indent-offset)
((parent-is "translation_unit") column-0 0)
The rest of the nodes (if/while/do/for) don't result in parse errors
here, as long as the condition in parentheses is typed out correctly.
I tried some additional clauses looking for "previous sibling", checking
whether it's for_statement, etc, which ends with "expression statement",
and that one is empty... but it a fair amount of code which will likely
miss other edge cases anyway. Or breaks when the grammar changes.
next prev parent reply other threads:[~2023-11-28 15:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-23 20:55 bug#67417: 29.1.50; c-ts-mode syntax issues with no brackets Arteen Abrishami via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-24 7:23 ` Eli Zaretskii
2023-11-24 18:26 ` Dmitry Gutov
2023-11-27 1:47 ` Yuan Fu
2023-11-27 2:22 ` Dmitry Gutov
2023-11-28 6:55 ` Yuan Fu
2023-11-28 14:27 ` Eli Zaretskii
2023-11-28 15:31 ` Dmitry Gutov [this message]
2023-12-01 7:58 ` Yuan Fu
2023-12-09 8:27 ` Eli Zaretskii
2023-12-10 9:29 ` Yuan Fu
2023-12-11 0:29 ` Dmitry Gutov
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