clippy::unwrap_or_default: Checks for usages of the following functions with an argument that constructs a default value (e.g., Default::default or String::new): unwrap_or unwrap_or_else or_insert or_insert_with

x.unwrap_or(Default::default());
map.entry(42).or_insert_with(String::new);

x.unwrap_or_default();
map.entry(42).or_default();

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

[lints.clippy]
unwrap_or_default = "allow"

cargo clippy -- -A clippy::unwrap-or-default

Clippy's own documentation

What it does

Checks for usages of the following functions with an argument that constructs a default value (e.g., Default::default or String::new):

• unwrap_or
• unwrap_or_else
• or_insert
• or_insert_with

Why is this bad?

Readability. Using unwrap_or_default in place of unwrap_or/unwrap_or_else, or or_default in place of or_insert/or_insert_with, is simpler and more concise.

Known problems

In some cases, the argument of unwrap_or, etc. is needed for type inference. The lint uses a heuristic to try to identify such cases. However, the heuristic can produce false negatives.

Examples

x.unwrap_or(Default::default());
map.entry(42).or_insert_with(String::new);

Use instead:

x.unwrap_or_default();
map.entry(42).or_default();

Past names

• unwrap_or_else_default

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
• unused_enumerate_indexyou seem to use `.enumerate()` and immediately discard the index
• unused_unitunneeded unit expression
• unusual_byte_groupingsWarns if hexadecimal or binary literals are not grouped by nibble or byte
• upper_case_acronymsChecks for fully capitalized names and optionally names containing a capitalized acronym
• while_let_on_iteratorChecks for while let expressions on iterators
• write_literalThis lint warns about the use of literals as write!/writeln! args

All 847 Clippy lints · Rust compiler errors · Cargo.toml checker