Pavel Yaskevich a01692ace1 [CSOptimizer] Skip ?? if it's involved in optional chain with unresolved result type ...

`??` operator is overloaded on optionality of its result. When the
first argument matches exactly, the ranking is going to be skewed
towards selecting an overload choice that returns a non-optional type.
This is not always correct i.e. when operator is involved in optional
chaining. To avoid producing an incorrect favoring, let's skip the this
disjunction when constraints associated with result type indicate
that it should be optional.

Simply adding it as a binding won't work because if the second argument
is non-optional the overload that returns `T?` would still have a lower
score.

Resolves: rdar://164201746

2025-11-11 15:21:33 -08:00

74 KiB

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