Overflow evaluating the requirement error could be better for trivially recursive impls

This overflow error could be better:

pub trait A {}
impl<T: A> A for T {}

pub trait B: A {}

struct C {}

impl B for C {}

fn main() {}

errors with:

error[E0275]: overflow evaluating the requirement `C: A`
 --> src/main.rs:8:6
  |
8 | impl B for C {}
  |      ^
  |
  = note: required by `B`

error: aborting due to previous error

which doesn't really point at the problem. The problem is that the impl<T: A> A for T {} is recursive.

1. Even more trivial recursion affected by this, with only one trait and no structs:

   
   trait Trait {}
   
   impl<T> Trait for T where T: Trait {}
   
   fn func<X: Trait>() {}
   
   fn main() {
       func::<u32>();
   }
   

   lcdr at 2020-06-08 10:18:18