[4.1] [GSB] Ensure that we don't build an invalid potential archetype. #14102
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Queries against the generic signature might use types that are ill-formed for that generic signature, e.g., because they refer to associated types of unrelated protocols. Detect such conditions to maintain GSB invariants that all potential archetypes in a well-formed generic signature are well-formed. Fixes the crash in SR-6797 / rdar://problem/36673825. (cherry picked from commit d18ecda)
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@swift-ci please test |
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@swift-ci please nominate |
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• Explanation: Name mangling of constrained extensions could cause a crash in rare-ish cases because the code can break invariants of the
GenericSignatureBuilder.• Scope of Issue: Causes SIL crashes when compiling some fairly-complex constrained extensions. We've seen one confirmed and one suspected case of this in the wild.
• Origination: My work to optimize the mangling of generic signatures (so they don't redundantly specify the requirements of the enclosing generic context) introduced the offending code.
• Risk: Low risk; we're validating our inputs to the
GenericSignatureBuilderin a way that will only either (1) delay resolution of requirements until later, or (2) properly returnfalsefor queries that would previously have caused downstream crashes.• Reviewed By: @rudkx
• Testing: Compiler regression tests, built RandomKit project
• Radar / SR: rdar://problem/36673825 / SR-6797
Fixes the crash in SR-6797 / rdar://problem/36673825.
(cherry picked from commit d18ecda)
Replace this paragraph with a description of your changes and rationale. Provide links to external references/discussions if appropriate.
Resolves SR-NNNN.