subtyping constraint: accept array types if left type is assignable from array, e.g Serializable (IDEA-146592)

java/java-psi-impl/src/com/intellij/psi/impl/source/resolve/graphInference/constraints/StrictSubtypingConstraint.java

@@ -105,9 +105,13 @@ public class StrictSubtypingConstraint implements ConstraintFormula {
               }
             }
           }
-        } else if (myS instanceof PsiClassType) {
+        }
+        else if (myS instanceof PsiClassType) {
           SResult = ((PsiClassType)myS).resolveGenerics();
         }
+        else if (myS instanceof PsiArrayType) {
+          return myT.isAssignableFrom(myS);
+        }
 
         if (SResult == null) return false;
         PsiClass SClass = SResult.getElement();

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/graphInference/ArrayTypeAssignability.java

@@ -0,0 +1,10 @@
+import java.io.Serializable;
+import java.util.List;
+
+class Test {
+  public void serialize(Serializable o) {}
+
+  public void foo(List<String> strings) {
+    serialize(strings.toArray(new String[0]));
+  }
+}

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

@@ -307,6 +307,10 @@ public class GraphInferenceHighlightingTest extends LightDaemonAnalyzerTestCase
     doTest();
   }
 
+  public void testArrayTypeAssignability() throws Exception {
+    doTest();
+  }
+
   private void doTest() throws Exception {
     doTest(false);
   }