clippy::new_ret_no_self: Checks for new not returning a type that contains Self

impl Foo {
    fn new() -> NotAFoo {
    }
}

struct Bar(Foo);
impl Foo {
    // Bad. The type name must contain `Self`
    fn new() -> Bar {
    }
}

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

[lints.clippy]
new_ret_no_self = "allow"

cargo clippy -- -A clippy::new-ret-no-self

Clippy's own documentation

What it does

Checks for new not returning a type that contains Self.

Why is this bad?

As a convention, new methods are used to make a new instance of a type.

Example

In an impl block:

impl Foo {
    fn new() -> NotAFoo {
    }
}

struct Bar(Foo);
impl Foo {
    // Bad. The type name must contain `Self`
    fn new() -> Bar {
    }
}

impl Foo {
    // Good. Return type contains `Self`
    fn new() -> Result<Foo, FooError> {
    }
}

Or in a trait definition:

pub trait Trait {
    // Bad. The type name must contain `Self`
    fn new();
}

pub trait Trait {
    // Good. Return type contains `Self`
    fn new() -> Self;
}

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
• needless_return_with_question_markChecks for return statements on Err paired with the ? operator
• neg_multiplyChecks for multiplication by -1 as a form of negation
• non_minimal_cfgunneeded sub `cfg` when there is only one condition
• nonstandard_macro_bracesuse of irregular braces for `vec!` macro

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