Sema: Ban existentials with associated types from appearing in 'switch' patterns #6244
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…h' patterns This was allowed on accident in Swift 3, and caused a build regression with the JaySON project (https://github.com/DanToml/Jay).
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@swift-ci Please smoke test |
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@DougGregor @jrose-apple Just to double-check, this was not intentional right? |
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Note that we already prohibit this for However I'm wondering if there's a more fundamental ASTWalker bug that's causing us to miss these -- why do we need to special-case SwitchStmt here? |
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Looks like a reasonable stopgap. I thought we validated |
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@jckarter We do this check after because doing it while resolving types leads to recursion into validateDecl() which can crash -- the check visits all protocol members and caches the result. |
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This was not intentional. Thank you for fixing! |
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This was allowed on accident in Swift 3, and caused a build regression
with the JaySON project (https://github.com/DanToml/Jay).