SR-12486: T.self is Any.Protocol is broken
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This turned out to be fallout from swiftlang#27572 which was in turn motivated by our confusing metatype syntax when generic variables are bound to protocols. In particular, the earlier PR was an attempt to make the expression `x is T.Type` (where `T` is a generic type variable bound to a protocol `P`) behave the same as `x is P.Type` (where `P` is a protocol). Unfortunately, the generic `T.Type` actually binds to `P.Protocol` in this case (not `P.Type`), so the original motivation was flawed, and as it happens, `x is T.Type` already behaved the same as `x is P.Protocol` in this situation. This PR reverts that earlier change and beefs up some of the tests around these behaviors. Resolves SR-12486 Resolves rdar://62201613 Reverts PR#27572
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jckarter
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May 8, 2020
mikeash
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May 8, 2020
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Testing again after PR #32664 |
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tbkka
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Jul 6, 2020
* SR-12486: `T.self is Any.Protocol` is broken This turned out to be fallout from swiftlang#27572 which was in turn motivated by our confusing metatype syntax when generic variables are bound to protocols. In particular, the earlier PR was an attempt to make the expression `x is T.Type` (where `T` is a generic type variable bound to a protocol `P`) behave the same as `x is P.Type` (where `P` is a protocol). Unfortunately, the generic `T.Type` actually binds to `P.Protocol` in this case (not `P.Type`), so the original motivation was flawed, and as it happens, `x is T.Type` already behaved the same as `x is P.Protocol` in this situation. This PR reverts that earlier change and beefs up some of the tests around these behaviors. Resolves SR-12486 Resolves rdar://62201613 Reverts PR#27572
tbkka
added a commit
that referenced
this pull request
Jul 7, 2020
* SR-12486: `T.self is Any.Protocol` is broken This turned out to be fallout from #27572 which was in turn motivated by our confusing metatype syntax when generic variables are bound to protocols. In particular, the earlier PR was an attempt to make the expression `x is T.Type` (where `T` is a generic type variable bound to a protocol `P`) behave the same as `x is P.Type` (where `P` is a protocol). Unfortunately, the generic `T.Type` actually binds to `P.Protocol` in this case (not `P.Type`), so the original motivation was flawed, and as it happens, `x is T.Type` already behaved the same as `x is P.Protocol` in this situation. This PR reverts that earlier change and beefs up some of the tests around these behaviors. Resolves SR-12486 Resolves rdar://62201613 Reverts PR#27572
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This turned out to be fallout from #27572
which was in turn motivated by our confusing metatype syntax when generic variables are bound to protocols.
In particular, the earlier PR was an attempt to make the expression
x is T.Type(whereTis a generic type variable bound to a protocolP)behave the same as
x is P.Type(wherePis a protocol).Unfortunately, the generic
T.Typeactually binds toP.Protocolin this case (notP.Type), so the original motivation was flawed, and as it happens,x is T.Typealready behaved the same asx is P.Protocolin this situation.This PR reverts that earlier change and beefs up some of the tests around these behaviors.
Resolves SR-12486
Resolves rdar://62201613
Reverts PR #27572