clippy::range_minus_one: Checks for inclusive ranges where 1 is subtracted from the upper bound, e.g., x..=(y-1)

for i in x..=(y-1) {
    // ..
}

for i in x..y {
    // ..
}

[lints.clippy]
range_minus_one = "warn"

#![warn(clippy::range_minus_one)]

cargo clippy -- -W clippy::range-minus-one

Clippy's own documentation

What it does

Checks for inclusive ranges where 1 is subtracted from the upper bound, e.g., x..=(y-1).

Why is this bad?

The code is more readable with an exclusive range like x..y.

Limitations

The lint is conservative and will trigger only when switching from an inclusive to an exclusive range is provably safe from a typing point of view. This corresponds to situations where the range is used as an iterator, or for indexing.

Example

for i in x..=(y-1) {
    // ..
}

Use instead:

for i in x..y {
    // ..
}

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
• ptr_cast_constness`as` casting between raw pointers while changing only its constness
• ptr_offset_by_literaluse of `offset` with a literal
• pub_underscore_fieldsChecks whether any field of the struct is prefixed with an _ (underscore) and also marked pub (public)
• range_plus_oneChecks for exclusive ranges where 1 is added to the upper bound, e.g., x..(y+1)
• redundant_closure_for_method_callsredundant closure
• redundant_elseredundant else block

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