Nightly panics when using associated constant in array size

[jadpole]

In the playpen (Mode: Debug, Channel: Nightly)

I was playing with associated constants when this code made the compiler panic:

#![feature(associated_consts)]

use ::std::marker::PhantomData;

trait Num {
    const VAL: usize;
    fn val() -> usize;
}

struct N1;
impl Num for N1 {
    const VAL: usize = 1;
    fn val() -> usize { N1::VAL }
}

struct Arr<S: Num> {
    ty: PhantomData<S>,
    data: [i32; S::VAL]
}


fn main() {
}

With error message:

error: internal compiler error: unexpected panic
note: the compiler unexpectedly panicked. this is a bug.
note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
note: run with `RUST_BACKTRACE=1` for a backtrace
thread 'rustc' panicked at 'path not fully resolved: PathResolution { base_def: DefTyParam(TypeSpace, 0, DefId { krate: 0, node: 35 }, "S"(72)), last_private: LastMod(AllPublic), depth: 1 }', ../src/librustc/middle/def.rs:81


playpen: application terminated with error code 101

Playpen link: http://is.gd/dE8jbq

The line which confuses the compiler is this one:

    data: [i32; S::VAL]

Without it, the program compiles just fine.

[ghost]

I think this is a duplicate of #26922.

[jadpole]

It is indeed!