const_generic_issues_lib.rs

#![cfg_attr(full, feature(const_generics))]
#![cfg_attr(full, allow(incomplete_features))]
#![cfg_attr(min, feature(min_const_generics))]

// All of these three items must be in `lib2` to reproduce the error

pub trait TypeFn {
    type Output;
}

pub struct GenericType<const B: i8>;

// Removing the braces around `42` resolves the crash
impl TypeFn for GenericType<{ 42 }> {
    type Output = ();
}