[4.1] [SubstitutionMap] Handle conformance lookup via superclass requirements. #14850
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
Conformances that discoverably for a type parameter via a superclass requirement occupy a bit of a gray area in the type checker and generic signature handling right now: we have a type parameter (so the paths that handle concrete conformances don't kick in), but the conformance itself isn't modeled as a requirement because it is available via lookup. Teach SubstitutionMap's conformance lookup to detect this case and perform conformance lookup in the generic signature (i.e., falling back to global lookup) in this case, replicating the hack that IRGen uses to address the same issue when accessing the conformance (see GenArchetype.cpp's TODO where we lookup a conformance on the superclass). The removal of that hack (as well as this one) are tracked by rdar://problem/34609744. For now, fixes SR-7072 / rdar://problem/37904576.
|
@swift-ci please test |
|
@swift-ci please nominate |
|
Build failed |
|
Build failed |
|
Ugh, it's a mangling change. |
|
@swift-ci please test |
1 similar comment
|
@swift-ci please test |
|
@swift-ci please nominate |
|
Build failed |
|
Build failed |
|
@swift-ci please test |
|
@swift-ci please test Linux |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
Explanation: Teach SubstitutionMap's conformance lookup to
detect the case where a conformance can only be determined by lookup for a
concrete conformance on the superclass bound of a type variable, which otherwise
would fail (causing a crash).
Scope: Affects projects that make use of superclass bounds in certain specific cases, potentially triggered by the optimizer.
Risk: Very low; we're only changing behavior along a path that would otherwise fail (and crash).
Testing: Regression tests, including a new test reduced by @eeckstein
Reviewer: @eeckstein, who developed this with me
SR / Radar: SR-7072 / rdar://problem/37904576.