Clippy lint · Complexity · checked with Clippy 0.1.99

clippy::option_as_ref_deref: Checks for usage of _.as_ref().map(Deref::deref) or its aliases (such as String::as_str)

What it meansChecks for usage of _.as_ref().map(Deref::deref) or its aliases (such as String::as_str). It is in the complexity group and warns by default.

Does it matter?

Readability, this can be written more concisely as _.as_deref().

Code that does something simple in a complicated way. Warns by default.

How to fix it

Clippy can fix this one for you: run cargo clippy --fix (add --allow-dirty if you have uncommitted changes). Review the diff before you commit.

Flagged

opt.as_ref().map(String::as_str)

Write this instead

opt.as_deref()

Turn it off, or on

Allow it where it does not fit your code, as narrowly as you can:

On one item

#[allow(clippy::option_as_ref_deref)]
fn my_function() { /* ... */ }

Whole crate (Cargo.toml)

[lints.clippy]
option_as_ref_deref = "allow"

One run

cargo clippy -- -A clippy::option-as-ref-deref

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.

Settings in clippy.toml

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

Complexitygroup

warndefault level

yesfixed by cargo clippy --fix

1.42.0added in Rust

Clippy's own documentation

What it does

Checks for usage of _.as_ref().map(Deref::deref) or its aliases (such as String::as_str).

Why is this bad?

Readability, this can be written more concisely as _.as_deref().

Example

opt.as_ref().map(String::as_str)

Can be written as

opt.as_deref()

Configuration

msrv: The minimum rust version that the project supports. Defaults to the rust-version field in Cargo.toml

(default: current version)

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

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