src/test/ui/issues/issue-43483.rs

// build-pass (FIXME(62277): could be check-pass?)
#![allow(dead_code)]
#![allow(unused_variables)]
trait VecN {
    const DIM: usize;
}

trait Mat {
    type Row: VecN;
}

fn m<M: Mat>() {
    let x = M::Row::DIM;
}

fn main() {}