Fix trait constraint type checking order for supertraits.

[tritao]

This fixes a stack overflow caused by interaction between type checking order for trait constraits for supertraits.

trait MyTrait {
    fn f(self) -> bool;
} {
    fn f2(self) -> bool {
        self.f()
    }
}

trait MyTrait2: MyTrait {
}

impl<T1> MyTrait for (T1,)
where
    T1: MyTrait2,
{
    fn f(self) -> bool { self.0.f() }
}

fn main() -> bool {
    true
}

Fixes #6898.

[codspeed-hq]

CodSpeed Performance Report

Merging #7022 will not alter performance

_{Comparing tritao:fix-trait-constraint-type-check-order (805bc3d) with master (f46a2dc)}

Summary

✅ 22 untouched benchmarks