private static TailType getReturnTail(PsiElement position) {
PsiElement scope = position;
while (true) {
if (scope instanceof PsiFile || scope instanceof PsiClassInitializer) {
return TailType.NONE;
}
if (scope instanceof PsiMethod) {
final PsiMethod method = (PsiMethod) scope;
if (method.isConstructor() || PsiType.VOID.equals(method.getReturnType())) {
return TailType.SEMICOLON;
}
return TailType.HUMBLE_SPACE_BEFORE_WORD;
}
if (scope instanceof PsiLambdaExpression) {
final PsiType returnType =
LambdaUtil.getFunctionalInterfaceReturnType(((PsiLambdaExpression) scope));
if (PsiType.VOID.equals(returnType)) {
return TailType.SEMICOLON;
}
return TailType.HUMBLE_SPACE_BEFORE_WORD;
}
scope = scope.getParent();
}
}
public static String checkReturnType(
PsiMethodReferenceExpression expression,
JavaResolveResult result,
PsiType functionalInterfaceType) {
final PsiElement resolve = result.getElement();
if (resolve instanceof PsiMethod) {
final PsiClass containingClass = ((PsiMethod) resolve).getContainingClass();
LOG.assertTrue(containingClass != null);
PsiSubstitutor subst = result.getSubstitutor();
PsiClass qContainingClass = getQualifierResolveResult(expression).getContainingClass();
if (qContainingClass != null
&& isReceiverType(functionalInterfaceType, containingClass, (PsiMethod) resolve)) {
subst = TypeConversionUtil.getClassSubstitutor(containingClass, qContainingClass, subst);
LOG.assertTrue(subst != null);
}
final PsiType interfaceReturnType =
LambdaUtil.getFunctionalInterfaceReturnType(functionalInterfaceType);
PsiType returnType =
PsiTypesUtil.patchMethodGetClassReturnType(
expression,
expression,
(PsiMethod) resolve,
null,
PsiUtil.getLanguageLevel(expression));
if (returnType == null) {
returnType = ((PsiMethod) resolve).getReturnType();
}
PsiType methodReturnType = subst.substitute(returnType);
if (interfaceReturnType != null && interfaceReturnType != PsiType.VOID) {
if (methodReturnType == null) {
methodReturnType =
JavaPsiFacade.getElementFactory(expression.getProject())
.createType(containingClass, subst);
}
if (!TypeConversionUtil.isAssignable(interfaceReturnType, methodReturnType, false)) {
return "Bad return type in method reference: cannot convert "
+ methodReturnType.getCanonicalText()
+ " to "
+ interfaceReturnType.getCanonicalText();
}
}
}
return null;
}
