Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::option_map_or_none: Checks for usage of _.map_or(None, _)
What it meansChecks for usage of _.map_or(None, _). It is in the style group and warns by default.
Does it matter?
Readability, this can be written more concisely as _.and_then(_).
Code that works but is not idiomatic Rust. 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.map_or(None, |a| Some(a + 1));
Write this instead
opt.and_then(|a| Some(a + 1));
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_map_or_none)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
option_map_or_none = "allow"One run
cargo clippy -- -A clippy::option-map-or-noneThe [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.
Clippy's own documentation
What it does
Checks for usage of _.map_or(None, _).
Why is this bad?
Readability, this can be written more concisely as
_.and_then(_).
Known problems
The order of the arguments is not in execution order.
Example
opt.map_or(None, |a| Some(a + 1));
Use instead:
opt.and_then(|a| Some(a + 1));
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
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- new_without_defaultChecks for public types with a pub fn new() -> Self method and no implementation of Default
- len_zeroChecks for getting the length of something via .len() just to compare to zero, and suggests using .is_empty() where applicable
- obfuscated_if_elsethis method chain can be written more clearly with `if .. else ..`
- ok_expectChecks for usage of ok().expect(..). Note: This lint only triggers for code marked compatible with versions of the compiler older than Rust 1.82.0
- op_refChecks for arguments to == which have their address taken to satisfy a bound and suggests to dereference the other argument instead
- owned_cowneedlessly owned Cow type
- partialeq_to_nonebinary comparison to literal `Option::None`
- print_literalliteral with an empty format string
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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