rust-lang / rust-lang/rustfmt

rustfmt deletes comment at start of array length expression

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A-comments C-bug
Dominant language
Rust
Stars
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Forks
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Avg merge
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Merged PRs (30d)
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Description

I write this code:

struct Abc([u8;
// five
5 +
// ten
10 +
// thirteen
13
]);

rustfmt formats this to:

struct Abc(
    [u8; 5 +
// ten
10 +
// thirteen
13],
);

It has lost the // five comment. The remainder of the formatting is not great.

playground

version:

rustfmt 1.8.0-stable (90b35a6239 2024-11-26)

Contributor guide

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First steps

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  4. Open a pull request that references the issue number.

Research direction

Reproduce the example from the linked Rust Playground using rustfmt 1.8.0-stable and compare the formatted output with the issue report. Trace the formatting of comments at the start of an array length expression; done means the // five comment is preserved and the resulting formatting is covered by a regression test.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
48/100

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