@Nullable
private static JetType computeUnsafeReturnType(
@NotNull JetFunctionLiteralExpression expression,
@NotNull ExpressionTypingContext context,
@NotNull SimpleFunctionDescriptorImpl functionDescriptor,
@Nullable JetType expectedReturnType) {
JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
JetBlockExpression bodyExpression = functionLiteral.getBodyExpression();
assert bodyExpression != null;
JetScope functionInnerScope =
FunctionDescriptorUtil.getFunctionInnerScope(
context.scope, functionDescriptor, context.trace);
JetTypeReference returnTypeRef = functionLiteral.getReturnTypeRef();
JetType declaredReturnType = null;
if (returnTypeRef != null) {
declaredReturnType =
context
.expressionTypingServices
.getTypeResolver()
.resolveType(context.scope, returnTypeRef, context.trace, true);
// This is needed for ControlStructureTypingVisitor#visitReturnExpression() to properly
// type-check returned expressions
functionDescriptor.setReturnType(declaredReturnType);
if (expectedReturnType != null) {
if (!JetTypeChecker.INSTANCE.isSubtypeOf(declaredReturnType, expectedReturnType)) {
context.trace.report(EXPECTED_RETURN_TYPE_MISMATCH.on(returnTypeRef, expectedReturnType));
}
}
}
// Type-check the body
ExpressionTypingContext newContext =
context
.replaceScope(functionInnerScope)
.replaceExpectedType(
declaredReturnType != null
? declaredReturnType
: (expectedReturnType != null ? expectedReturnType : NO_EXPECTED_TYPE));
JetType typeOfBodyExpression =
context
.expressionTypingServices
.getBlockReturnedType(bodyExpression, COERCION_TO_UNIT, newContext)
.getType();
List<JetType> returnedExpressionTypes =
Lists.newArrayList(
getTypesOfLocallyReturnedExpressions(
functionLiteral, context.trace, collectReturns(bodyExpression)));
ContainerUtil.addIfNotNull(returnedExpressionTypes, typeOfBodyExpression);
if (declaredReturnType != null) return declaredReturnType;
if (returnedExpressionTypes.isEmpty()) return null;
return CommonSupertypes.commonSupertype(returnedExpressionTypes);
}
@Override
public JetType visitFunctionLiteralExpression(
JetFunctionLiteralExpression expression, ExpressionTypingContext context) {
JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
JetBlockExpression bodyExpression = functionLiteral.getBodyExpression();
if (bodyExpression == null) return null;
JetType expectedType = context.expectedType;
boolean functionTypeExpected =
expectedType != TypeUtils.NO_EXPECTED_TYPE
&& JetStandardClasses.isFunctionType(expectedType);
NamedFunctionDescriptorImpl functionDescriptor =
createFunctionDescriptor(expression, context, functionTypeExpected);
List<JetType> parameterTypes = Lists.newArrayList();
List<ValueParameterDescriptor> valueParameters = functionDescriptor.getValueParameters();
for (ValueParameterDescriptor valueParameter : valueParameters) {
parameterTypes.add(valueParameter.getOutType());
}
ReceiverDescriptor receiverParameter = functionDescriptor.getReceiverParameter();
JetType receiver = receiverParameter != NO_RECEIVER ? receiverParameter.getType() : null;
JetType returnType = TypeUtils.NO_EXPECTED_TYPE;
JetScope functionInnerScope =
FunctionDescriptorUtil.getFunctionInnerScope(
context.scope, functionDescriptor, context.trace);
JetTypeReference returnTypeRef = functionLiteral.getReturnTypeRef();
if (returnTypeRef != null) {
returnType = context.getTypeResolver().resolveType(context.scope, returnTypeRef);
context
.getServices()
.checkFunctionReturnType(
expression,
context
.replaceScope(functionInnerScope)
.replaceExpectedType(returnType)
.replaceExpectedReturnType(returnType)
.replaceDataFlowInfo(context.dataFlowInfo));
} else {
if (functionTypeExpected) {
returnType = JetStandardClasses.getReturnTypeFromFunctionType(expectedType);
}
returnType =
context
.getServices()
.getBlockReturnedType(
functionInnerScope,
bodyExpression,
CoercionStrategy.COERCION_TO_UNIT,
context.replaceExpectedType(returnType).replaceExpectedReturnType(returnType));
}
JetType safeReturnType =
returnType == null ? ErrorUtils.createErrorType("<return type>") : returnType;
functionDescriptor.setReturnType(safeReturnType);
boolean hasDeclaredValueParameters = functionLiteral.getValueParameterList() != null;
if (!hasDeclaredValueParameters && functionTypeExpected) {
JetType expectedReturnType = JetStandardClasses.getReturnTypeFromFunctionType(expectedType);
if (JetStandardClasses.isUnit(expectedReturnType)) {
functionDescriptor.setReturnType(JetStandardClasses.getUnitType());
return DataFlowUtils.checkType(
JetStandardClasses.getFunctionType(
Collections.<AnnotationDescriptor>emptyList(),
receiver,
parameterTypes,
JetStandardClasses.getUnitType()),
expression,
context);
}
}
return DataFlowUtils.checkType(
JetStandardClasses.getFunctionType(
Collections.<AnnotationDescriptor>emptyList(),
receiver,
parameterTypes,
safeReturnType),
expression,
context);
}