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[Sema] NFC: Use exhaustive switches in PatternKind::Named #15540

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Mar 27, 2018
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[Sema] NFC: Use exhaustive switches in PatternKind::Named #15540

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38 changes: 26 additions & 12 deletions lib/Sema/CSGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2005,33 +2005,47 @@ namespace {

case PatternKind::Named: {
auto var = cast<NamedPattern>(pattern)->getDecl();
auto isWeak = false;
if (auto *OA = var->getAttrs().getAttribute<ReferenceOwnershipAttr>())
isWeak = OA->get() == ReferenceOwnership::Weak;

auto boundExpr = locator.trySimplifyToExpr();
auto haveBoundExpr = boundExpr && !var->hasNonPatternBindingInit();
auto ROK = ReferenceOwnership::Strong; // The default.
if (auto *OA = var->getAttrs().getAttribute<ReferenceOwnershipAttr>())
ROK = OA->get();

// If we have a type from an initializer expression, and that
// expression does not produce an InOut type, use it. This
// will avoid exponential typecheck behavior in the case of
// tuples, nested arrays, and dictionary literals.
//
// Otherwise, create a new type variable.
if (!isWeak && haveBoundExpr) {
auto boundExprTy = CS.getType(boundExpr);
if (!boundExprTy->is<InOutType>())
return boundExprTy->getRValueType();
switch (ROK) {
case ReferenceOwnership::Strong:
case ReferenceOwnership::Unowned:
case ReferenceOwnership::Unmanaged:
if (!var->hasNonPatternBindingInit()) {
if (auto boundExpr = locator.trySimplifyToExpr()) {
auto boundExprTy = CS.getType(boundExpr);
if (!boundExprTy->is<InOutType>())
return boundExprTy->getRValueType();
}
}
break;
case ReferenceOwnership::Weak:
break;
}

Type ty = CS.createTypeVariable(CS.getConstraintLocator(locator),
TVO_CanBindToInOut);

// For weak variables, use Optional<T>.
if (isWeak)
switch (ROK) {
case ReferenceOwnership::Strong:
case ReferenceOwnership::Unowned:
case ReferenceOwnership::Unmanaged:
return ty;
case ReferenceOwnership::Weak:
// For weak variables, use Optional<T>.
return CS.getTypeChecker().getOptionalType(var->getLoc(), ty);
}

return ty;
llvm_unreachable("Unhandled ReferenceOwnership kind");
}

case PatternKind::Typed: {
Expand Down