method refs: ensure non-resolved method refs are not marked as exact (EA-59172 - assert: TypeConversionUtil.reportHierarchyInconsistency)

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

@@ -151,6 +151,10 @@ public class PsiMethodReferenceExpressionImpl extends PsiReferenceExpressionBase
             result.add(signature.getMethod());
           }
         }
+
+        if (result.isEmpty()) {
+          return null;
+        }
         methods = result.toArray(new PsiMethod[result.size()]);
       }
       else if (isConstructor()) {

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/newMethodRef/EnsureNotResolvedMethodRefsAreNotMarkedAsExact.java

@@ -0,0 +1,10 @@
+import java.util.function.Function;
+
+class Test<A> {
+  class P {
+    {
+      g(P::<error descr="Cannot resolve method 'aa'">aa</error>);
+    }
+  }
+  <R> void g(Function<R, String> r){}
+}

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

@@ -386,6 +386,10 @@ public class NewMethodRefHighlightingTest extends LightDaemonAnalyzerTestCase {
     doTest();
   }
 
+  public void testEnsureNotResolvedMethodRefsAreNotMarkedAsExact() throws Exception {
+    doTest();
+  }
+
   private void doTest() {
     doTest(false);
   }