Clippy lints / Pedantic
Clippy lint · Pedantic · checked with Clippy 0.1.99
clippy::map_unwrap_or: Checks for usage of option.map(_).unwrap_or(_) or option.map(_).unwrap_or_else(_) or result.map(_).unwrap_or_else(_)
What it meansChecks for usage of option.map(_).unwrap_or(_) or option.map(_).unwrap_or_else(_) or result.map(_).unwrap_or_else(_). It is in the pedantic group and off by default.
Does it matter?
Readability, these can be written more concisely (resp.) as option.map_or(_, _), option.map_or_else(_, _) and result.map_or_else(_, _).
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 + 1).unwrap_or(0);
option.map(|a| a > 10).unwrap_or(false);
result.map(|a| a + 1).unwrap_or_else(some_function);
Write this instead
option.map_or(0, |a| a + 1);
option.is_some_and(|a| a > 10);
result.map_or_else(some_function, |a| a + 1);
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]
map_unwrap_or = "warn"In code
#![warn(clippy::map_unwrap_or)]One run
cargo clippy -- -W clippy::map-unwrap-orThe [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
Clippy's own documentation
What it does
Checks for usage of option.map(_).unwrap_or(_) or option.map(_).unwrap_or_else(_) or
result.map(_).unwrap_or_else(_).
Why is this bad?
Readability, these can be written more concisely (resp.) as
option.map_or(_, _), option.map_or_else(_, _) and result.map_or_else(_, _).
Known problems
The order of the arguments is not in execution order
Examples
option.map(|a| a + 1).unwrap_or(0);
option.map(|a| a > 10).unwrap_or(false);
result.map(|a| a + 1).unwrap_or_else(some_function);
Use instead:
option.map_or(0, |a| a + 1);
option.is_some_and(|a| a > 10);
result.map_or_else(some_function, |a| a + 1);
Past names
- option_map_unwrap_or
- option_map_unwrap_or_else
- result_map_unwrap_or_else
Configuration
-
msrv: The minimum rust version that the project supports. Defaults to therust-versionfield inCargo.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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All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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