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a40f1abaff
Introduce SingleValueStmtExpr, which allows the embedding of a statement in an expression context. This then allows us to parse and type-check `if` and `switch` statements as expressions, gated behind the `IfSwitchExpression` experimental feature for now. In the future, SingleValueStmtExpr could also be used for e.g `do` expressions. For now, only single expression branches are supported for producing a value from an `if`/`switch` expression, and each branch is type-checked independently. A multi-statement branch may only appear if it ends with a `throw`, and it may not `break`, `continue`, or `return`. The placement of `if`/`switch` expressions is also currently limited by a syntactic use diagnostic. Currently they're only allowed in bindings, assignments, throws, and returns. But this could be lifted in the future if desired.
24 lines
428 B
Swift
24 lines
428 B
Swift
// RUN: %target-swift-emit-sil -verify %s -o /dev/null
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func foo() -> Int {
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switch Bool.random() {
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case true:
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0 // expected-warning {{integer literal is unused}}
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case false:
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do {}
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}
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} // expected-error {{missing return in global function expected to return 'Int'}}
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enum E<T> {
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case x(T), y
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func foo() -> E<T> {
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switch self {
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case .x:
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while true {}
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case .y:
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fatalError()
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}
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}
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}
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