clippy::same_functions_in_if_condition: Checks for consecutive ifs with the same function call

if foo() == bar {
    …
} else if foo() == bar {
    …
}

if foo() == bar {
    …
} else if foo() == baz {
    …
}

[lints.clippy]
same_functions_in_if_condition = "warn"

#![warn(clippy::same_functions_in_if_condition)]

cargo clippy -- -W clippy::same-functions-in-if-condition

Clippy's own documentation

What it does

Checks for consecutive ifs with the same function call.

Why is this bad?

This is probably a copy & paste error. Despite the fact that function can have side effects and if works as intended, such an approach is implicit and can be considered a “code smell”.

Example

if foo() == bar {
    …
} else if foo() == bar {
    …
}

This probably should be:

if foo() == bar {
    …
} else if foo() == baz {
    …
}

or if the original code was not a typo and called function mutates a state, consider move the mutation out of the if condition to avoid similarity to a copy & paste error:

let first = foo();
if first == bar {
    …
} else {
    let second = foo();
    if second == bar {
    …
    }
}

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

Related lints

• too_many_linesChecks for functions with a large amount of lines
• missing_errors_docChecks the doc comments of publicly visible functions that return a Result type and warns if there is no # Errors section
• must_use_candidateChecks for public functions that have no #[must_use] attribute, but return something not already marked must-use, have no mutable arg and mutate no statics
• ref_optionWarns when a function signature uses &Option<T> instead of Option<&T>
• ref_option_refsince `&` implements the `Copy` trait, `&Option<&T>` can be simplified to `Option<&T>`
• return_self_not_must_usemissing `#[must_use]` attribute on a method returning `Self`
• same_length_and_capacityChecks for usages of Vec::from_raw_parts and String::from_raw_parts where the same expression is used for the length and the capacity
• self_only_used_in_recursion`self` is only used in recursion
• semicolon_if_nothing_returnedconsider adding a `;` to the last statement for consistent formatting

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