redundant cast: test inference errors when applicability is checked (IDEA-151091)

java/java-psi-api/src/com/intellij/psi/util/RedundantCastUtil.java

@@ -370,8 +370,9 @@ public class RedundantCastUtil {
               }
             } else {
               final JavaResolveResult newResult = newCall.resolveMethodGenerics();
-              if (oldMethod.equals(newResult.getElement()) && newResult.isValidResult() &&
-                  Comparing.equal(((PsiCallExpression)newCall).getType(), ((PsiCallExpression)expression).getType())) {
+              if (oldMethod.equals(newResult.getElement()) &&
+                  Comparing.equal(((PsiCallExpression)newCall).getType(), ((PsiCallExpression)expression).getType()) &&
+                  newResult.isValidResult()) {
                 final PsiMethod newFunctionalInterfaceMethod = LambdaUtil.getFunctionalInterfaceMethod(newArgs[i]);
                 if (oldFunctionalInterfaceMethod == null ||
                     newFunctionalInterfaceMethod != null && (newFunctionalInterfaceMethod == oldFunctionalInterfaceMethod || 

java/java-tests/testData/inspection/redundantCast/lambda/InferApplicabilityError/expected.xml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<problems/>

java/java-tests/testData/inspection/redundantCast/lambda/InferApplicabilityError/src/Test.java

@@ -0,0 +1,16 @@
+class RedundantCast {
+  ParentStrategy strategy;
+
+  public void cast() {
+    use((ChildStrategy) strategy);
+  }
+
+  private <T> void use(ChildStrategy<T> strategy) {
+  }
+}
+
+interface ParentStrategy<T> {
+}
+
+interface ChildStrategy<T> extends ParentStrategy<T> {
+}

java/java-tests/testSrc/com/intellij/codeInspection/RedundantCast18Test.java

@@ -34,6 +34,7 @@ public class RedundantCast18Test extends InspectionTestCase {
   public void testExpectedSupertype() throws Exception { doTest(); }
   public void testForeachValue() throws Exception { doTest(); }
   public void testConditional() throws Exception { doTest(); }
+  public void testInferApplicabilityError() throws Exception { doTest(); }
 
   @Override
   protected Sdk getTestProjectSdk() {