Clippy lint · Restriction · checked with Clippy 0.1.99

clippy::wildcard_enum_match_arm: Checks for wildcard enum matches using _

What it meansChecks for wildcard enum matches using _. It is in the restriction group and off by default.

Does it matter?

New enum variants added by library updates can be missed.

Lints that forbid language features for specific codebases (no unwrap, no indexing...). Off by default; pick them one by one, never the whole group.

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 x {
    Foo::A(_) => {},
    _ => {},
}

Write this instead

match x {
    Foo::A(_) => {},
    Foo::B(_) => {},
}

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]
wildcard_enum_match_arm = "warn"

In code

#![warn(clippy::wildcard_enum_match_arm)]

One run

cargo clippy -- -W clippy::wildcard-enum-match-arm

The [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.

Restrictiongroup

allowdefault level

nofixed by cargo clippy --fix

1.34.0added in Rust

Clippy's own documentation

What it does

Checks for wildcard enum matches using _.

Why restrict this?

New enum variants added by library updates can be missed.

Known problems

Suggested replacements may be incorrect if guards exhaustively cover some variants, and also may not use correct path to enum if it’s not present in the current scope.

Example

match x {
    Foo::A(_) => {},
    _ => {},
}

Use instead:

match x {
    Foo::A(_) => {},
    Foo::B(_) => {},
}

From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.

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