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Uninhabited != NoReturn #4365

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877c77f
Uninhabited != NoReturn
CodaFi Aug 18, 2016
6b47e83
Fix Linux tests
CodaFi Aug 18, 2016
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2 changes: 1 addition & 1 deletion include/swift/AST/Types.h
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Expand Up @@ -393,7 +393,7 @@ class alignas(1 << TypeAlignInBits) TypeBase {
/// semantics?
bool hasReferenceSemantics();

/// Is this an uninhabited type, such as 'Never'?
/// Is this 'Never'?
bool isNever();

/// Is this the 'Any' type?
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4 changes: 1 addition & 3 deletions lib/AST/Type.cpp
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Expand Up @@ -92,9 +92,7 @@ bool TypeBase::hasReferenceSemantics() {
bool TypeBase::isNever() {
if (auto nominalDecl = getAnyNominal())
if (auto enumDecl = dyn_cast<EnumDecl>(nominalDecl))
if (enumDecl->getAllElements().empty())
return true;

return enumDecl == getASTContext().getNeverDecl();
return false;
}

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2 changes: 1 addition & 1 deletion lib/IRGen/GenClangType.cpp
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Expand Up @@ -493,7 +493,7 @@ GenClangType::visitBoundGenericType(CanBoundGenericType type) {
clang::CanQualType GenClangType::visitEnumType(CanEnumType type) {
// Special case: Uninhabited enums are not @objc, so we don't
// know what to do below, but we can just convert to 'void'.
if (type->isNever())
if (type->getDecl()->getAllElements().empty())
return Converter.convert(IGM, IGM.Context.TheEmptyTupleType);

assert(type->getDecl()->isObjC() && "not an @objc enum?!");
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2 changes: 1 addition & 1 deletion test/IRGen/dllexport.swift
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Expand Up @@ -20,7 +20,7 @@ public var ci : c = c()

open class d {
private func m() -> Never {
fatalError()
return fatalError()
}
}

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5 changes: 5 additions & 0 deletions test/SILOptimizer/return.swift
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Expand Up @@ -9,6 +9,11 @@ func singleBlock2() -> Int {
y += 1
} // expected-error {{missing return in a function expected to return 'Int'}}

enum NoCasesButNotNever {}

func diagnoseNoCaseEnumMissingReturn() -> NoCasesButNotNever {
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Note that this is meant to be an error even with a 'Never' return. a Never-returning function should end with a call to some other Never-returning function, or the return should be unreachable.

} // expected-error {{missing return in a function expected to return 'NoCasesButNotNever'}}

class MyClassWithClosure {
var f : (_ s: String) -> String = { (_ s: String) -> String in } // expected-error {{missing return in a closure expected to return 'String'}}
}
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