[vim/vim] the % command does not skip parens in comments (PR #20491)

h_east

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7:05 AM (6 hours ago) 7:05 AM

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Problem:  The "%" command jumps to parens and braces inside comments,
          unlike the "=" operator which ignores them.
Solution: When 'comments' defines C-style "//" or "/*" comments, skip
          matching parens inside such comments, except when the cursor
          is inside a comment so a match there can still be found.

fixes: #20329
related: #20111

Problem

The % command jumps to parens and braces inside comments, unlike the = operator (cindent), which ignores them. So on code like

foo(  // )
);

% on the first ( jumps to the ) inside the // comment instead of the real one on the next line.

Background

FM_SKIPCOMM has been implemented in findmatchlimit() since v9.2.0447 (#20111), where it was added so that cindent ignores {/}/parens inside // and /* */ comments. So the = operator already skips comment parens.

The same behavior for % was requested afterwards in #20329 and closed with a pointer to the matchit plugin — even though the infrastructure to do it cleanly (FM_SKIPCOMM) already existed at that point. So this is not a new matching feature: it is a small, natural application of code that already landed for =/cindent, and it makes the two consistent.

Solution

When 'comments' defines C-style // or /* comments, nv_percent() calls findmatchlimit() with FM_SKIPCOMM instead of findmatch(). The rule, matching what a user expects:

if the paren the cursor acts on is inside a comment, jump to its match inside that comment (a match there can still be found);
if it is outside a comment, jump to its match, ignoring parens inside comments.

The "inside a comment" case is handled naturally: for a line comment the flag is not set when the cursor is past the comment leader, and for a block comment FM_SKIPCOMM does not skip the comment the cursor already sits in. Buffers without C-style comments are unaffected, so non-C filetypes keep the current behavior.

Notes

Reuses the merged FM_SKIPCOMM from #20111 (v9.2.0447); no new matching logic.
Gated on 'comments', so it only applies to filetypes with C-style comments.
Tests in Test_normal_percent_skip_comment cover forward/backward skipping, cursor inside a // and a /* */ comment, and the no-C-style-comments case. make test_normal passes.
motion.txt documents the new behavior.

You can view, comment on, or merge this pull request online at:

https://github.com/vim/vim/pull/20491

Commit Summary

d0a8bfa the % command does not skip parens in comments

File Changes

(4 files)

Patch Links:

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Christian Brabandt

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9:23 AM (3 hours ago) 9:23 AM

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chrisbra left a comment (vim/vim#20491)

Thanks. I think the buf_has_cstyle_comments() should return a bool. Also, this is also slightly backwards incompatible change. Do we have to worry about this and need a separate 'cpoption' value for it?

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h_east

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10:00 AM (3 hours ago) 10:00 AM

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h-east left a comment (vim/vim#20491)

Thanks for the review.

buf_has_cstyle_comments() should return a bool.

Done.

this is also slightly backwards incompatible change. Do we have to worry about this and need a separate 'cpoption' value for it?

I don't think we need a new flag — we can reuse the existing cpo-%
(CPO_MATCH). Its documentation already says that when % is included in
'cpoptions', % matching "Does not recognize /* and */", which implies
that when it is excluded (the Vim default) % should recognize them.
findmatchlimit() already reads cpo_match, so I'd gate the comment-skipping
on cpo-% being absent: skip parens in comments only when % is not in
'cpoptions'. That makes it opt-out through the existing Vi-compatibility
mechanism (% is in the Vi / all-flags set but not in the Vim default), and it
actually implements the behavior cpo-% already documents. 'comments' still
keeps it limited to C-style filetypes, so no new flag is needed.

Does reusing cpo-% sound good to you?

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