clippy::branches_sharing_code: Checks if the blocks of an if/else, or the arms of a match, contain shared code that can be moved out of the branches

let foo = if … {
    println!("Hello World");
    13
} else {
    println!("Hello World");
    42
};

println!("Hello World");
let foo = if … {
    13
} else {
    42
};

[lints.clippy]
branches_sharing_code = "warn"

#![warn(clippy::branches_sharing_code)]

cargo clippy -- -W clippy::branches-sharing-code

Clippy's own documentation

What it does

Checks if the blocks of an if/else, or the arms of a match, contain shared code that can be moved out of the branches.

Why is this bad?

Duplicate code is less maintainable.

Example

let foo = if … {
    println!("Hello World");
    13
} else {
    println!("Hello World");
    42
};

Use instead:

println!("Hello World");
let foo = if … {
    13
} else {
    42
};

For a match, when every arm ends with the same expression it can be moved after the match:

match mode {
    Mode::A => { a(); Ok(()) }
    Mode::B => { b(); Ok(()) }
}

Use instead:

match mode {
    Mode::A => { a(); }
    Mode::B => { b(); }
}
Ok(())

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

Related lints

• redundant_cloneChecks for a redundant clone() (and its relatives) which clones an owned value that is going to be dropped without further use
• as_ptr_cast_mutcasting the result of `as_ptr` to *mut u8
• clear_with_drain`drain` used to clear a `Vec`
• coerce_container_to_anyProtects against unintended coercion of references to container types to &dyn Any when the container type dereferences to a dyn Any which could be directly referenced instead
• collection_is_never_readChecks for collections that are never queried

All 847 Clippy lints · Rust compiler errors · Cargo.toml checker