clippy::bind_instead_of_map: Checks for usage of _.and_then(|x| Some(y)), _.and_then(|x| Ok(y)) or _.or_else(|x| Err(y))

Does it matter?

This can be written more concisely as _.map(|x| y) or _.map_err(|x| y).

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

let _ = opt().and_then(|s| Some(s.len()));
let _ = res().and_then(|s| if s.len() == 42 { Ok(10) } else { Ok(20) });
let _ = res().or_else(|s| if s.len() == 42 { Err(10) } else { Err(20) });

Write this instead

let _ = opt().map(|s| s.len());
let _ = res().map(|s| if s.len() == 42 { 10 } else { 20 });
let _ = res().map_err(|s| if s.len() == 42 { 10 } else { 20 });

Turn it off, or on

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

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

[lints.clippy]
bind_instead_of_map = "allow"

cargo clippy -- -A clippy::bind-instead-of-map

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.