Clippy lint · Restriction · checked with Clippy 0.1.99

clippy::shadow_unrelated: Checks for bindings that shadow other bindings already in scope, either without an initialization or with one that does not even use the original value

What it meansChecks for bindings that shadow other bindings already in scope, either without an initialization or with one that does not even use the original value. It is in the restriction group and off by default.

Does it matter?

Shadowing a binding with a closely related one is part of idiomatic Rust, but shadowing a binding by accident with an unrelated one may indicate a mistake. Additionally, name shadowing in general can hurt readability, especially in large code bases, because it is easy to lose track of the active binding at any place in the code. If linting against all shadowing is desired, you may wish to use the shadow_same and shadow_reuse lints as well.

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. Change the code by hand:

Flagged

let x = y;
let x = z; // shadows the earlier binding

Write this instead

let x = y;
let w = z; // use different variable name

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]
shadow_unrelated = "warn"

In code

#![warn(clippy::shadow_unrelated)]

One run

cargo clippy -- -W clippy::shadow-unrelated

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

pre 1.29.0added in Rust

Clippy's own documentation

What it does

Checks for bindings that shadow other bindings already in scope, either without an initialization or with one that does not even use the original value.

Why restrict this?

Shadowing a binding with a closely related one is part of idiomatic Rust, but shadowing a binding by accident with an unrelated one may indicate a mistake.

Additionally, name shadowing in general can hurt readability, especially in large code bases, because it is easy to lose track of the active binding at any place in the code. If linting against all shadowing is desired, you may wish to use the shadow_same and shadow_reuse lints as well.

Example

let x = y;
let x = z; // shadows the earlier binding

Use instead:

let x = y;
let w = z; // use different variable name

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

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