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Diffstat (limited to 'src/tools/clippy/src/docs/return_self_not_must_use.txt')
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1 files changed, 46 insertions, 0 deletions
diff --git a/src/tools/clippy/src/docs/return_self_not_must_use.txt b/src/tools/clippy/src/docs/return_self_not_must_use.txt new file mode 100644 index 000000000..4a4fd2c6e --- /dev/null +++ b/src/tools/clippy/src/docs/return_self_not_must_use.txt @@ -0,0 +1,46 @@ +### What it does +This lint warns when a method returning `Self` doesn't have the `#[must_use]` attribute. + +### Why is this bad? +Methods returning `Self` often create new values, having the `#[must_use]` attribute +prevents users from "forgetting" to use the newly created value. + +The `#[must_use]` attribute can be added to the type itself to ensure that instances +are never forgotten. Functions returning a type marked with `#[must_use]` will not be +linted, as the usage is already enforced by the type attribute. + +### Limitations +This lint is only applied on methods taking a `self` argument. It would be mostly noise +if it was added on constructors for example. + +### Example +``` +pub struct Bar; +impl Bar { + // Missing attribute + pub fn bar(&self) -> Self { + Self + } +} +``` + +Use instead: +``` +// It's better to have the `#[must_use]` attribute on the method like this: +pub struct Bar; +impl Bar { + #[must_use] + pub fn bar(&self) -> Self { + Self + } +} + +// Or on the type definition like this: +#[must_use] +pub struct Bar; +impl Bar { + pub fn bar(&self) -> Self { + Self + } +} +```
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