internal compiler error: Encountered ambiguity selecting Binder(<[type error] as TraitA>) during codegen, presuming due to overflow

[dwrensha]

I'm seeing an internal compiler error on the following input (found by fuzz-rustc):

trait TraitA {
    const VALUE: usize;
}

struct A;
impl TraitA for A {
  const VALUE: usize = 0;
}

trait TraitB {
    type MyA: TraitA;
    const VALUE: usize = Self::MyA::VALUE;
}

struct B;
impl TraitB for B {
    type M   = A;
}

fn main() {
    let _ = [0; B::VALUE];
}

$ rustc main.rs
error[E0437]: type `M` is not a member of trait `TraitB`
  --> main.rs:17:5
   |
17 |     type M   = A;
   |     ^^^^^^^^^^^^^ not a member of trait `TraitB`

error[E0046]: not all trait items implemented, missing: `MyA`
  --> main.rs:16:1
   |
11 |     type MyA: TraitA;
   |     ----------------- `MyA` from trait
...
16 | impl TraitB for B {
   | ^^^^^^^^^^^^^^^^^ missing `MyA` in implementation

error: internal compiler error: src/librustc/traits/codegen/mod.rs:48: Encountered ambiguity selecting `Binder(<[type error] as TraitA>)` during codegen, presuming due to overflow

thread 'rustc' panicked at 'Box<Any>', src/librustc_errors/lib.rs:905:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

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: rustc 1.41.1 (f3e1a954d 2020-02-24) running on x86_64-unknown-linux-gnu

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0046, E0437.
For more information about an error, try `rustc --explain E0046`.

The error happens on stable, beta, and nightly.

[dwrensha]

This regressed in #60126.

[dwrensha]

cc @estebank @oli-obk

[pnkfelix]

triage: already has fix in pipeline. P-high. removing nomination label.