method refs: take qualifier's type arguments in account

java/java-psi-api/src/com/intellij/psi/LambdaUtil.java

@@ -569,26 +569,34 @@ public class LambdaUtil {
       final PsiClassType.ClassResolveResult resolveResult = PsiUtil.resolveGenericsClassInType(left);
       final PsiMethod method = getFunctionalInterfaceMethod(resolveResult);
       if (method != null) {
-        final MethodSignature signature1 = method.getSignature(resolveResult.getSubstitutor());
-        final MethodSignature signature2 = ((PsiMethod)resolve).getSignature(JavaPsiFacade.getElementFactory(method.getProject()).createRawSubstitutor(
-          (PsiTypeParameterListOwner)resolve));
         final Ref<PsiClass> classRef = new Ref<PsiClass>();
-        methodReferenceExpression.process(classRef, new Ref<PsiSubstitutor>());
-        if (areAcceptable(signature1, signature2, classRef.get())) return true;
+        final Ref<PsiSubstitutor> substRef = new Ref<PsiSubstitutor>();
+        methodReferenceExpression.process(classRef, substRef);
+
+        final MethodSignature signature1 = method.getSignature(resolveResult.getSubstitutor());
+        final MethodSignature signature2 = ((PsiMethod)resolve).getSignature(substRef.get());
+        if (areAcceptable(signature1, signature2, classRef.get(), substRef.get())) return true;
       }
     }
     return false;
   }
 
-  public static boolean areAcceptable(MethodSignature signature1, MethodSignature signature2, PsiClass psiClass) {
+  public static boolean areAcceptable(MethodSignature signature1,
+                                      MethodSignature signature2,
+                                      PsiClass psiClass,
+                                      PsiSubstitutor psiSubstitutor) {
     int offset = 0;
     final PsiType[] signatureParameterTypes1 = signature1.getParameterTypes();
     final PsiType[] signatureParameterTypes2 = signature2.getParameterTypes();
     if (signatureParameterTypes1.length != signatureParameterTypes2.length) {
-      if (signatureParameterTypes1.length == signatureParameterTypes2.length + 1 &&
-          //todo correct check needed
-          PsiUtil.resolveClassInType(TypeConversionUtil.erasure(signatureParameterTypes1[0], signature1.getSubstitutor())) == psiClass) {
-        offset++;
+      if (signatureParameterTypes1.length == signatureParameterTypes2.length + 1) {
+        final PsiClassType classType = JavaPsiFacade.getElementFactory(psiClass.getProject()).createType(psiClass, psiSubstitutor);
+        if (signatureParameterTypes1[0].equals(classType)) {
+          offset++;
+        }
+        else {
+          return false;
+        }
       }
       else {
         return false;

java/java-psi-impl/src/com/intellij/psi/impl/source/tree/java/PsiMethodReferenceExpressionImpl.java

@@ -33,6 +33,7 @@ import com.intellij.psi.scope.processor.FilterScopeProcessor;
 import com.intellij.psi.scope.processor.MethodCandidatesProcessor;
 import com.intellij.psi.scope.util.PsiScopesUtil;
 import com.intellij.psi.tree.IElementType;
+import com.intellij.psi.util.MethodSignature;
 import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.SmartList;
 import org.jetbrains.annotations.NotNull;
@@ -216,7 +217,7 @@ public class PsiMethodReferenceExpressionImpl extends PsiReferenceExpressionBase
           final PsiType functionalInterfaceType = getFunctionalInterfaceType();
           final PsiClassType.ClassResolveResult resolveResult = PsiUtil.resolveGenericsClassInType(functionalInterfaceType);
           final PsiMethod interfaceMethod = LambdaUtil.getFunctionalInterfaceMethod(resolveResult);
-          final MethodReferenceConflictResolver conflictResolver = new MethodReferenceConflictResolver(containingClass, interfaceMethod, resolveResult.getSubstitutor());
+          final MethodReferenceConflictResolver conflictResolver = new MethodReferenceConflictResolver(containingClass, substitutor, interfaceMethod != null ? interfaceMethod.getSignature(resolveResult.getSubstitutor()) : null);
           final MethodCandidatesProcessor processor = new MethodCandidatesProcessor(PsiMethodReferenceExpressionImpl.this, 
                                                                                     new PsiConflictResolver[]{conflictResolver}, new SmartList<CandidateInfo>());
           processor.setIsConstructor(false);
@@ -234,27 +235,29 @@ public class PsiMethodReferenceExpressionImpl extends PsiReferenceExpressionBase
 
     private class MethodReferenceConflictResolver implements PsiConflictResolver {
       private final PsiClass myContainingClass;
-      private PsiMethod myFunctionalInterface;
       private final PsiSubstitutor mySubstitutor;
-
-      private MethodReferenceConflictResolver(PsiClass containingClass, @Nullable PsiMethod psiMethod, PsiSubstitutor substitutor) {
+      private final MethodSignature mySignature;
+      
+      private MethodReferenceConflictResolver(PsiClass containingClass,
+                                              PsiSubstitutor psiSubstitutor,
+                                              @Nullable MethodSignature signature) {
         myContainingClass = containingClass;
-        myFunctionalInterface = psiMethod;
-        mySubstitutor = substitutor;
+        mySubstitutor = psiSubstitutor;
+        mySignature = signature;
       }
 
       @Nullable
       @Override
       public CandidateInfo resolveConflict(List<CandidateInfo> conflicts) {
-        if (myFunctionalInterface == null) return null;
+        if (mySignature == null) return null;
 
         for (Iterator<CandidateInfo> iterator = conflicts.iterator(); iterator.hasNext(); ) {
           CandidateInfo conflict = iterator.next();
           if (!(conflict instanceof MethodCandidateInfo)) continue;
           final PsiMethod psiMethod = ((MethodCandidateInfo)conflict).getElement();
           if (psiMethod == null) continue;
-          if (!LambdaUtil.areAcceptable(myFunctionalInterface.getSignature(mySubstitutor),
-                                        psiMethod.getSignature(conflict.getSubstitutor()), myContainingClass)) {
+          if (!LambdaUtil.areAcceptable(mySignature,
+                                        psiMethod.getSignature(conflict.getSubstitutor()), myContainingClass, mySubstitutor)) {
             iterator.remove();
           }
         }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/methodRef/QualifierTypeArgs.java

@@ -0,0 +1,16 @@
+class MyTest {
+  interface I {
+    String m(Foo<String> f);
+  }
+
+  class Foo<X> {
+    String foo() {
+      return null;
+    }
+
+    {
+      I i = Foo<String> :: foo;
+      <error descr="Incompatible types. Found: '<method reference>', required: 'MyTest.I'">I i1 = Foo<Integer> :: foo;</error>
+    }
+  }
+}

java/java-tests/testSrc/com/intellij/codeInsight/daemon/lambda/MethodRefHighlightingTest.java

@@ -41,6 +41,10 @@ public class MethodRefHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testQualifierTypeArgs() throws Exception {
+    doTest();
+  }
+
   private void doTest() throws Exception {
     doTest(BASE_PATH + "/" + getTestName(false) + ".java", false, false);
   }