Prevent ranges from getting collapsed in patterns by ytmimi · Pull Request #6871 · rust-lang/rustfmt

ytmimi · 2026-04-17T23:31:27Z

Expression rewriting handled this correctly, but there was distinct logic implemented for patterns. I've extracted the range formatting logic used by expressions into a common rewrite_range function and reused that when rewriting ranges in patterns and types. Was able to remove a nice amount of code after these changes were done.

PR is broken up into logical commits. Feel free to review the PR as a whole or commit by commit.

ytmimi · 2026-04-17T23:40:26Z

Just to be sure these changes wouldn't impact things I ran the Diff-Check --edition=2021 --style-edition=2021. Things seem to be working as expected.

matthewhughes934

nice refactor

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jieyouxu

Thanks, this looks good to me. This impacts stable default format but previously this was working code -> broken code on ranges in patterns. AFAICT this shouldn't affect other cases (though it's possible there are edge cases that I failed to consider and that DiffCheck is only run on a limited set of repos, and that this code pattern is comparatively rare to hit in practice).

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jieyouxu · 2026-05-28T10:09:23Z

@rustbot author

rustbot · 2026-05-28T10:09:28Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

ytmimi · 2026-05-28T13:54:52Z

Thanks, this looks good to me. This impacts stable default format but previously this was working code -> broken code on ranges in patterns. AFAICT this shouldn't affect other cases (though it's possible there are edge cases that I failed to consider and that DiffCheck is only run on a limited set of repos, and that this code pattern is comparatively rare to hit in practice).

I think we should be good here. Especially since the formatting rustfmt produced broke the code. I also wouldn't expect this to impact any other stable formatting because I feel like we have enough range formatting coverage in the test suite, but just to be sure I'll expand on the tests I add here.

Move the range rewrite logic from `src/exrp.rs` to `src/range.rs`. There are a few different places where we rewrite ranges so centralizing the logic in a single location is ideal.

Cleans up the syntax a little. Was suggested in the PR review.

Reuse the range rewrite logic that we abstracted into `src/range.rs`.

Now that we've centralized the logic into `rewrite_range` we no longer need a dedicated `rewrite_range_pat` function. Getting rid of that also lets us remove some other unnecessary code which is nice.

…ero` tests

rustbot · 2026-05-30T03:46:00Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

ytmimi · 2026-05-30T03:52:57Z

@rustbot ready

@jieyouxu when you have a chance can you take another look. I added a lot of different test cases with both the spaces_around_ranges and float_literal_trailing_zero option. Both options are unstable and don't impact the default formatting for either float_literal_trailing_zero=Preserve and spaces_around_ranges=false so I think these changes are okay.

ytmimi · 2026-05-30T03:55:17Z

Running the Diff-Check for good measure, but as you mentioned we might not hit the bug case in real code. Will still be good to check and make sure that the formatting produced by the main branch matches this issue_6869 branch.

jieyouxu · 2026-05-30T10:00:32Z

New DiffCheck looks clean 👍, though as discussed, it won't be too representative, but still better than nothing :)

jieyouxu

Thanks, the new tests looks good 👍

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rustbot added the S-waiting-on-review Status: awaiting review from the assignee but also interested parties. label Apr 17, 2026

matthewhughes934 approved these changes Apr 21, 2026

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Comment thread src/types.rs Outdated

matthewhughes934 reviewed Apr 21, 2026

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Comment thread src/range.rs Outdated

ytmimi force-pushed the issue_6869 branch from b4e65d4 to a50ec8a Compare April 21, 2026 20:02

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jieyouxu self-assigned this Apr 23, 2026

jieyouxu added the F-impacts-stable-default-format Expected formatting impact: affects stable default format configuration (caution) label May 28, 2026

jieyouxu approved these changes May 28, 2026

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jieyouxu added the pr-ready-to-merge Status: PR is largely ready for merge, waiting for secondary review / last nits label May 28, 2026

jieyouxu reviewed May 28, 2026

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Comment thread tests/target/issue_6869.rs

rustbot added S-waiting-on-author Status: awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: awaiting review from the assignee but also interested parties. labels May 28, 2026

ytmimi added 8 commits May 29, 2026 23:44

refactor: centralize range rewriting in src/range.rs

adbef5e

Move the range rewrite logic from `src/exrp.rs` to `src/range.rs`. There are a few different places where we rewrite ranges so centralizing the logic in a single location is ideal.

refactor: simplify explicit ref and deref

9459323

Cleans up the syntax a little. Was suggested in the PR review.

feat: add util function to help format ast::RangeEnd

4726790

refactor: use rewrite_range for PatKind::Range

d4774a8

Reuse the range rewrite logic that we abstracted into `src/range.rs`.

refactor: use rewrite_range for ast::TyPatKind::Range

4d7a194

Reuse the range rewrite logic that we abstracted into `src/range.rs`.

chore: remove rewrite_range_pat and unused imports and impls

c0a81f7

Now that we've centralized the logic into `rewrite_range` we no longer need a dedicated `rewrite_range_pat` function. Getting rid of that also lets us remove some other unnecessary code which is nice.

test: add a test cast for issue 6869

d0ef092

test: additional spaces_around_ranges and `float_literal_trailing_z…

b145a2b

…ero` tests

ytmimi force-pushed the issue_6869 branch from a50ec8a to b145a2b Compare May 30, 2026 03:45

rustbot added S-waiting-on-review Status: awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: awaiting some action (such as code changes or more information) from the author. labels May 30, 2026

jieyouxu approved these changes May 30, 2026

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ytmimi merged commit b3b6e28 into rust-lang:main May 30, 2026
30 checks passed

rustbot added release-notes Needs an associated changelog entry and removed S-waiting-on-review Status: awaiting review from the assignee but also interested parties. labels May 30, 2026

ytmimi deleted the issue_6869 branch May 30, 2026 11:49

rustbot mentioned this pull request May 30, 2026

Fix Issue 6470: Preserve Space after colon if followed by absolute path declaration (::) #6475

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