[WIP] Have IsBindableVisitor consider conditional conformances. #38977
+320
−106
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In order to correctly handle upper bound requirements arising from conditional conformances, we need to be able to ingest requirements introduced by conditional conformance extensions, which means recursively visiting the parent is no longer possible to do cleanly. It is simpler to substitute the generic type's entire generic context as a whole.
The upper bound on a nominal type's generic argument can have more requirements imposed on it than those written in the original nominal type's generic signature, depending on the requirements imposed on the nominal type itself, thanks to conditional conformances. IsBindableVisitor failed to take this into account when visiting the bindings of generic type arguments. This could cause Type::isBindableTo to provide a false positive for a substituted type that doesn't satisfy conditional conformances, but more importantly, SIL type lowering uses the same visitor to extract an upper bound generic signature for substituted SIL function types, and if it doesn't preserve requirements from conditional conformances on nominal types in that signature, it can end up building an incorrect substitution map. Fix this by passing down the upper bound from generic arguments even when visiting nominal types, and using those upper bounds to check for conditional conformances that add requirements to generic arguments while visiting them.
jckarter
force-pushed
the
subst-function-type-lowering-conditional-conformance
branch
from
e4f13ec to
db823e0
Compare
|
@swift-ci Please test |
|
Build failed |
|
Build failed |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The upper bound on a nominal type's generic argument can have more requirements imposed on it than those written in the original nominal type's generic signature, depending on the requirements imposed on the nominal type itself, thanks to conditional conformances.
IsBindableVisitorfailed to take this into account when visiting the bindings of generic type arguments. This could causeType::isBindableToto provide a false positive for a substituted type that doesn't satisfy conditional conformances, but more importantly, SIL type lowering uses the same visitor to extract an upper bound generic signature for substituted SIL function types, and if it doesn't preserve requirements from conditional conformances on nominal types in that signature, it can end up building an incorrect substitution map. Fix this by passing down the upper bound from generic arguments even when visiting nominal types, and using those upper bounds to check for conditional conformances that add requirements to generic arguments while visiting them.