Clippy lints / Pedantic
Clippy lint · Pedantic · checked with Clippy 0.1.99
clippy::match_same_arms: Checks for match with identical arm bodies. Note: Does not lint on wildcards if the non_exhaustive_omitted_patterns_lint feature is enabled and disallowed
What it meansChecks for match with identical arm bodies. Note: Does not lint on wildcards if the non_exhaustive_omitted_patterns_lint feature is enabled and disallowed. It is in the pedantic group and off by default.
Does it matter?
This is probably a copy & paste error. If arm bodies are the same on purpose, you can factor them using |.
Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.
How to fix it
Clippy does not fix this one automatically (its suggestion may change behaviour, so it only shows it). Change the code by hand:
Flagged
match foo {
Bar => bar(),
Quz => quz(),
Baz => bar(), // <= oops
}
Write this instead
match foo {
Bar => bar(),
Quz => quz(),
Baz => baz(), // <= fixed
}
Turn it off, or on
It is off by default. To use it, set it to warn or deny:
Whole crate (Cargo.toml)
[lints.clippy]
match_same_arms = "warn"In code
#![warn(clippy::match_same_arms)]One run
cargo clippy -- -W clippy::match-same-armsThe [lints] table needs Rust 1.74 or newer. In a workspace, put it under [workspace.lints.clippy] and add [lints] workspace = true to each member.
Clippy's own documentation
What it does
Checks for match with identical arm bodies.
Note: Does not lint on wildcards if the non_exhaustive_omitted_patterns_lint feature is
enabled and disallowed.
Why is this bad?
This is probably a copy & paste error. If arm bodies
are the same on purpose, you can factor them
using |.
Example
match foo {
Bar => bar(),
Quz => quz(),
Baz => bar(), // <= oops
}
This should probably be
match foo {
Bar => bar(),
Quz => quz(),
Baz => baz(), // <= fixed
}
or if the original code was not a typo:
match foo {
Bar | Baz => bar(), // <= shows the intent better
Quz => quz(),
}
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
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All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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