[ConstraintSystem] Use witnesses for makeIterator and next refs in for-in context
#61091
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This is an alternative approach to #61075. |
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@swift-ci please test |
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@swift-ci please test source compatibility |
…aint" This reverts commit ef0523f.
…in for-in Reference to `makeIterator` in for-in loop context needs to be treated as a reference to a witness of `Sequence#makeIterator` requirement, otherwise it could lead to problems with retroactive conformances.
Reference to `$geneator.next` in for-in loop context needs to be treated as a reference to a witness of `IteratorProtocol#next` requirement, otherwise it could lead to problems with retroactive conformances.
hborla
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Sep 14, 2022
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@swift-ci please test |
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@swift-ci please test |
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@swift-ci please test source compatibility |
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🎉🎉🎉 Can we nominate for 5.7 branch? |
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References to
makeIteratorandnextinfor-inloop context have to betreated as references to witnesses of
Sequence#makeIteratorandIteratorProtocol#nextrequirements. Letting overload resolution decide as-ifloop was written direct use of
makeIterator()andwhile let ... = next()statementcould lead to problems with retroactive conformances and difference in runtime
behavior.
For example:
makeIteratordeclared in theArrayextension is not a witness toSequence#makeIteratorand shouldn't be used because that would change runtime behavior.
Resolves: #60514
Resolves: #60958