"could be const_fn" False "positive" i.e., makes a recommendation that does not compile

[EdmundsEcho]

This is a great tool to help accelerate my learning of the language.

Clippy seems to suggest that take_inner could be a const fn. However, when that change is made, the code does not compile: "destructors cannot be evaluated at compile-time".

I'm using the "late bounds" pattern for declaring a type parameter only in the "smart" constructor.

pub struct Wrapper<I> {
    inner: I,
}
impl<I> Wrapper<I> 
where
    I: Debug
{
    pub fn new(a: I) -> Self
    // fn:: I -> Wrapper I
    {
        Wrapper { inner: a }
    }
    pub fn inspect(&self)
    // fn:: Wrapper I -> ()
    {
        println!("{:?}", self.inner);
    }
}
pub fn take_inner<I>(w: Wrapper<I>) -> I {  // <<< lint suggestion here fails to compile
    w.inner
}

[oli-obk]

I opened rust-lang/rust#60964 on the rustc repo, because that should be allowed as const fn.

[phansch]

@oli-obk Is this the same underlying cause as #4041?

[oli-obk]

yes. I just immediately assumed one needs generics for this