Enhance the logic in `applyInverses` to also take into account same-type constraints spelled in
the generic signature, so that same-type-constraining a type parameter to a type that is itself
not `Copyable` or `Escapable` suppresses the default application of those constraints on the
type parameter. Fixes rdar://147757973.
- It's wasteful to cache because each invocation is unique
- Inference sources only need to be Types and not TypeLocs
- We can pass in an explicit SourceLoc for diagnostics
(cherry picked from commit 4e39dac206dd8e0818ca509f5f09f93425a48c62)
We already need to track the inverses separate from the members in a
ProtocolCompositionType, since inverses aren't real types. Thus, the
only purpose being served by InverseType is to be eliminated by
RequirementLowering when it appears in a conformance requirement.
Instead, we introduce separate type InverseRequirement just to keep
track of which inverses we encounter to facilitate cancelling-out
defaults and ensuring that the inverses are respected after running
the RequirementMachine.
Refactor the code to match what's written up in generics.tex.
It's easier to understand what's going on if requirement inference
first introduces a bunch of requirements that might be trivial,
and then all user-written and inferred requirements are desugared
at the end in a separate pass.
Previously, inverses were only accounted-for in inheritance clauses.
This batch of changes handles inverses appearing in other places, like:
- Protocol compositions
- `some ~Copyable`
- where clauses
with proper attribution of default requirements in their absence.
We want to allow this for all conformance requirements written in protocols
or the `where` clause of protocol extensions.
Fixes rdar://problem/91304291.
See the comment at the top of ConcreteContraction.cpp for a detailed explanation.
This can be turned off with the -disable-requirement-machine-concrete-contraction
pass, mostly meant for testing. A few tests now run with this pass both enabled
and disabled, to exercise code paths which are otherwise trivially avoided by
concrete contraction.
Fixes rdar://problem/88135912.
When building a rewrite system for a generic signature or protocol,
we would add requirements from the requirement signature of every
protocol dependency. Now, also add protocol typealias rules as well.
Conditional requirement inference needs to be able to add rewrite rules
from the requirement signatures of hitherto-unseen protocols, so to
help with that, extract out the RuleBuilder's ProtocolMap and move it
into the RewriteSystem.
