RS.CLIPPY.UNNECESSARY_LITERAL_BOUND

Detects &str that could be &'static str in function return types

This checker is a Clippy lint created by The Rust Project Contributors. The documentation shown here is a copy of the original documentation for: unnecessary_literal_bound. Copyright ©2025 The Rust Team. All rights reserved.

What it does

Detects functions that are written to return &str that could return &\'static str but instead return a &\'a str.

Why is this bad?

This leaves the caller unable to use the &str as &\'static str, causing unnecessary allocations or confusion. This is also most likely what you meant to write.

Example

impl MyType {
    fn returns_literal(&self) -> &str {
        "Literal"
    }
}

Use instead:

impl MyType {
    fn returns_literal(&self) -> &\'static str {
        "Literal"
    }
}

Or, in case you may return a non-literal str in future:

impl MyType {
    fn returns_literal<\'a>(&\'a self) -> &\'a str {
        "Literal"
    }
}