Clippy lints / Style
Clippy lint · Style · checked with Clippy 0.1.99
clippy::manual_ok_or: this pattern reimplements `Option::ok_or`
What it meansFinds patterns that reimplement Option::ok_or. It is in the style group and warns by default.
What you see
warning: this pattern reimplements `Option::ok_or` --> main.rs:4:1 | 4 | foo.map_or(Err("error"), |v| Ok(v)); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace with: `foo.ok_or("error")` | = help: for further information visit https://rust-lang.github.io/rust-clippy/stable/index.html#manual_ok_or = note: `#[warn(clippy::manual_ok_or)]` on by default
Real output of Clippy 0.1.99 (Rust 1.99) on the example below. Names and line numbers in yours will differ.
Does it matter?
Concise code helps focusing on behavior instead of boilerplate.
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
let foo: Option<i32> = None;
foo.map_or(Err("error"), |v| Ok(v));
Write this instead
let foo: Option<i32> = None;
foo.ok_or("error");
Turn it off, or on
Allow it where it does not fit your code, as narrowly as you can:
On one item
#[allow(clippy::manual_ok_or)]
fn my_function() { /* ... */ }Whole crate (Cargo.toml)
[lints.clippy]
manual_ok_or = "allow"One run
cargo clippy -- -A clippy::manual-ok-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.
Clippy's own documentation
What it does
Finds patterns that reimplement Option::ok_or.
Why is this bad?
Concise code helps focusing on behavior instead of boilerplate.
Examples
let foo: Option<i32> = None;
foo.map_or(Err("error"), |v| Ok(v));
Use instead:
let foo: Option<i32> = None;
foo.ok_or("error");
From the Clippy lint list (0.1.99), part of the Rust project, MIT or Apache-2.0. Official entry.
Related lints
- needless_returnunneeded `return` statement
- 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
- manual_mapmanual implementation of `Option::map`
- manual_next_backChecks for .rev().next() on a DoubleEndedIterator
- manual_non_exhaustiveChecks for manual implementations of the non-exhaustive pattern
- manual_pattern_char_comparisonthis manual char comparison can be written more succinctly
- manual_range_containsmanual `Range::contains` implementation
- manual_repeat_nthis `repeat().take()` can be written more concisely
All 847 Clippy lints · Rust compiler errors · Cargo.toml checker
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