[6.1][SILOptimizer] Prevent devirtualization of call to distributed witness requirements #80375
+157
−0
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Cherry-pick of #80373
Explanation:
Fixes a crash in optimized mode related to use of distributed requirements.
This is a narrow fix, we are going to work on fixing this properly and allowing both devirtualization and specialization for distributed requirement witnesses.
Anything that uses an ad-hoc serialization requirement scheme cannot be devirtualized because that would result in loss of ad-hoc conformance in new substitution map.
Main Branch PR: [SILOptimizer] Prevent devirtualization of call to distributed witnes… #80373
Risk: Very low (narrow fix that only affects uses of witnesses to distributed requirements with ad-hoc serialization requirement).
Resolves: Assertion failure swift::ProtocolConformanceRef::subst with 6.1 in release build #79318
Resolves: rdar://146101172
Reviewed By: @slavapestov
Testing: Added new tests to the Distributed test suite.
(cherry picked from commit 0415b40)