Florian Diebold 2745cb37c1 Use correct substs for super trait assoc types
When referring to an associated type of a super trait, we used the substs of the
subtrait. That led to the #4931 crash if the subtrait had less parameters, but
it could also lead to other incorrectness if just the order was different.

Fixes #4931.
2020-06-19 21:46:47 +02:00
..
2020-06-05 17:06:07 +02:00