This ensures that opened archetypes always inherit any outer generic parameters from the context in which they reside. This matters because class bounds may bind generic parameters from these outer contexts, and without the outer context you can wind up with ill-formed generic environments like
<τ_0_0, where τ_0_0 : C<T>, τ_0_0 : P>
Where T is otherwise unbound because there is no entry for it among the generic parameters of the environment's associated generic signature.
Computing the type relation for every item in the code completion cache is way to expensive (~4x slowdown for global completion that imports `SwiftUI`). Instead, compute a type’s supertypes (protocol conformances and superclasses) once and write their USRs to the cache. To compute a type relation we can then check if the contextual type is in the completion item’s supertypes.
This reduces the overhead of computing the type relations (again global completion that imports `SwiftUI`) to ~6% – measured by instructions executed.
Technically, we might miss some conversions like
- retroactive conformances inside another module (because we can’t cache them if that other module isn’t imported)
- complex generic conversions (just too complicated to model using USRs)
Because of this, we never report an `unrelated` type relation for global items but always default to `unknown`.
But I believe this change covers the most common cases and is a good tradeoff between accuracy and performance.
rdar://83846531
Computing the type relation for every item in the code completion cache is way to expensive (~4x slowdown for global completion that imports `SwiftUI`). Instead, compute a type’s supertypes (protocol conformances and superclasses) once and write their USRs to the cache. To compute a type relation we can then check if the contextual type is in the completion item’s supertypes.
This reduces the overhead of computing the type relations (again global completion that imports `SwiftUI`) to ~6% – measured by instructions executed.
Technically, we might miss some conversions like
- retroactive conformances inside another module (because we can’t cache them if that other module isn’t imported)
- complex generic conversions (just too complicated to model using USRs)
Because of this, we never report an `unrelated` type relation for global items but always default to `unknown`.
But I believe this change covers the most common cases and is a good tradeoff between accuracy and performance.
rdar://83846531
