`trait Sub: const Super` has unusable `dyn`

[theemathas]

I'm not sure what the correct behavior is here, but the current behavior definitely seems weird.

#![feature(const_trait_impl)]

const trait Super {}
trait Sub: const Super {
    fn method(&self);
}

fn wut(x: &dyn Sub) {
    x.method();
}

error[E0277]: the trait bound `dyn Sub: const Super` is not satisfied
 --> src/lib.rs:9:7
  |
9 |     x.method();
  |       ^^^^^^
  |
note: required by a bound in `Sub::method`
 --> src/lib.rs:4:12
  |
4 | trait Sub: const Super {
  |            ^^^^^^^^^^^ required by this bound in `Sub::method`
5 |     fn method(&self);
  |        ------ required by a bound in this associated function

For more information about this error, try `rustc --explain E0277`.

@rustbot labels +F-const_trait_impl

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Reproducible on the playground with version 1.91.0-nightly (2025-08-09 ca77504943887037504c)

[compiler-errors]

Probably should just make const super-traits not object safe.

@rustbot claim