new_without_default could include blanket impls

What it does

Playground link

The existing new_without_default lint could be expanded to catch smart pointers that have a blanket impl Default, such as Arc, Mutex, etc.

Advantage

Expands on the advantages of the existing new_without_default lint.

Drawbacks

No response

Example

pub struct Bar;

impl Bar {
    #[expect(clippy::new_without_default)]
    pub fn new() -> std::sync::Arc<Self> { Arc::new(Self) }
}

Start by reproducing the Playground example and reading the existing new_without_default lint and its tests. Identify how the lint recognizes return types, then verify the desired behavior for Arc, Mutex, and other smart pointers with blanket Default implementations. Done means suitable cases are reported without false positives and the test suite covers the expanded behavior.