Auto merge of #41605 - tschottdorf:param-env, r=nikomatsakis

Store interned predicates in ParameterEnvironment

See #41444. As a first step towards untangling `ParameterEnvironment`, change
its `caller_bounds` field from a `Vec` into an interned slice of
`ty::Predicate`s.

This change is intentionally well-contained and doesn't pull on any of the
loose ends. In particular, you'll note that `normalize_param_env_or_error`
now interns twice.

0 files changed, 0 insertions, 0 deletions