Clippy lint · Pedantic · checked with Clippy 0.1.99

clippy::manual_is_variant_and: Checks for usage of option.map(f).unwrap_or_default() and result.map(f).unwrap_or_default() where f is a function or closure that returns the bool type. Also checks for equality comparisons like option.map(f) == Some(true) and result.map(f) == Ok(true), as well as result.ok().is_some_and(f)

What it meansChecks for usage of option.map(f).unwrap_or_default() and result.map(f).unwrap_or_default() where f is a function or closure that returns the bool type. Also checks for equality comparisons like option.map(f) == Some(true) and result.map(f) == Ok(true), as well as result.ok().is_some_and(f). It is in the pedantic group and off by default.

Does it matter?

Readability. These can be written more concisely as option.is_some_and(f) and result.is_ok_and(f).

Stricter lints with some false positives. Off by default; opt in with clippy::pedantic.

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

option.map(|a| a > 10).unwrap_or_default();
result.map(|a| a > 10).unwrap_or_default();

option.map(|a| a > 10) == Some(true);
result.map(|a| a > 10) == Ok(true);
option.map(|a| a > 10) != Some(true);
result.map(|a| a > 10) != Ok(true);

result.ok().is_some_and(|a| a > 10);

Write this instead

option.is_some_and(|a| a > 10);
result.is_ok_and(|a| a > 10);

option.is_some_and(|a| a > 10);
result.is_ok_and(|a| a > 10);
option.is_none_or(|a| a > 10);
!result.is_ok_and(|a| a > 10);

result.is_ok_and(|a| a > 10);

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]
manual_is_variant_and = "warn"

In code

#![warn(clippy::manual_is_variant_and)]

One run

cargo clippy -- -W clippy::manual-is-variant-and

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

Pedanticgroup

allowdefault level

yesfixed by cargo clippy --fix

1.77.0added in Rust

Clippy's own documentation

What it does

Checks for usage of option.map(f).unwrap_or_default() and result.map(f).unwrap_or_default() where f is a function or closure that returns the bool type.

Also checks for equality comparisons like option.map(f) == Some(true) and result.map(f) == Ok(true), as well as result.ok().is_some_and(f).

Why is this bad?

Readability. These can be written more concisely as option.is_some_and(f) and result.is_ok_and(f).

Example

option.map(|a| a > 10).unwrap_or_default();
result.map(|a| a > 10).unwrap_or_default();

option.map(|a| a > 10) == Some(true);
result.map(|a| a > 10) == Ok(true);
option.map(|a| a > 10) != Some(true);
result.map(|a| a > 10) != Ok(true);

result.ok().is_some_and(|a| a > 10);

Use instead:

option.is_some_and(|a| a > 10);
result.is_ok_and(|a| a > 10);

option.is_some_and(|a| a > 10);
result.is_ok_and(|a| a > 10);
option.is_none_or(|a| a > 10);
!result.is_ok_and(|a| a > 10);

result.is_ok_and(|a| a > 10);

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.

Up next

Also worth your time

Did this answer your question?