[AST] Choose an implied conformance source next to the type, if possible. #17832
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…nce tests. The special handling of interleaved decls and statements is confusing and makes other testing hard.
…ble.
If a conformance to a protocol is implied by several other
conformances (i.e. protocol P: Equatable {} and protocol Q: Equatable {} and a
type declares conformance to both P and Q), we should choose a source that's in
the same file as the type, if we can, because automatic synthesis of
conformances (for Equatable, Hashable, etc.) only works in that case.
Fixes rdar://problem/41852654.
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@swift-ci please test |
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@swift-ci please nominate |
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Explanation: Requirements for some stdlib protocols can be automatically synthesised if the conformance is declared (either on the type or in an extension) in the same file as the type declaration. This also works for implied conformances, e.g.
Hashableinherits fromEquatablemeaning declaring conformance toHashablecan synthesiseEquatable's==requirement. If there was a second implied conformance in an earlier file (e.g. if some other file declaredextension Type: Comparable) this overrode the one in the same file as the type, causing synthesis to fail.Scope: Fixing a regression since 4.1.
Origination: Caused by the change to allow synthesis in extensions, which meant that the code started to consider the other-file extension whereas previously it was completely ignored.
Risk: Low, little-to-no other code compares about the source file of an implied conformance.
Testing: CI tests.
Reviewed By: Slava Pestov
Fixes rdar://problem/41852654.
4.2 merge of #17786