Fix the case of safe call and elvis operators: flexible types may be nullable

compiler/frontend/src/org/jetbrains/jet/lang/resolve/calls/CallExpressionResolver.java

@@ -56,7 +56,8 @@ import java.util.Collections;
 
 import static org.jetbrains.jet.lang.diagnostics.Errors.*;
 import static org.jetbrains.jet.lang.resolve.calls.context.ContextDependency.INDEPENDENT;
-import static org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiversPackage.*;
+import static org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiversPackage.createQualifier;
+import static org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiversPackage.resolveAsStandaloneExpression;
 import static org.jetbrains.jet.lang.types.TypeUtils.NO_EXPECTED_TYPE;
 
 public class CallExpressionResolver {
@@ -300,7 +301,7 @@ public class CallExpressionResolver {
         //TODO move further
         if (expression.getOperationSign() == JetTokens.SAFE_ACCESS) {
             if (selectorReturnType != null && !KotlinBuiltIns.getInstance().isUnit(selectorReturnType)) {
-                if (receiverType.isNullable()) {
+                if (TypeUtils.isNullableType(receiverType)) {
                     selectorReturnType = TypeUtils.makeNullable(selectorReturnType);
                 }
             }

compiler/testData/diagnostics/tests/nullableTypes/safeCallOnTypeWithNullableUpperBound.kt

@@ -1,11 +1,11 @@
-fun <T> test(t: T): String {
+fun <T> test(t: T): String? {
     if (t != null) {
         return t<!UNNECESSARY_SAFE_CALL!>?.<!>toString()
     }
     return t?.toString()
 }
 
-fun <T> T.testThis(): String {
+fun <T> T.testThis(): String? {
     if (this != null) {
         return this<!UNNECESSARY_SAFE_CALL!>?.<!>toString()
     }

compiler/testData/diagnostics/tests/platformTypes/elvis.kt

@@ -0,0 +1,14 @@
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public String s() { return null; }
+}
+
+// FILE: k.kt
+import p.*
+
+fun test(j: J) {
+    j.s()?.length ?: ""
+}

compiler/testData/diagnostics/tests/platformTypes/safeCall.kt

@@ -0,0 +1,15 @@
+// !CHECK_TYPE
+// FILE: p/J.java
+
+package p;
+
+public class J {
+    public String s() { return null; }
+}
+
+// FILE: k.kt
+import p.*
+
+fun test(j: J) {
+    j.s()?.length.checkType { it : _<Int?> }
+}

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -7697,7 +7697,20 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
             
             @TestMetadata("dereference.kt")
             public void testDereference() throws Exception {
-                doTest("compiler/testData/diagnostics/tests/platformTypes/dereference.kt");
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/dereference.kt");
+                doTest(fileName);
+            }
+            
+            @TestMetadata("elvis.kt")
+            public void testElvis() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/elvis.kt");
+                doTest(fileName);
+            }
+            
+            @TestMetadata("safeCall.kt")
+            public void testSafeCall() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/safeCall.kt");
+                doTest(fileName);
             }
             
             @TestMetadata("compiler/testData/diagnostics/tests/platformTypes/methodCall")
@@ -7722,22 +7735,26 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 
                 @TestMetadata("javaCollectionToKotlin.kt")
                 public void testJavaCollectionToKotlin() throws Exception {
-                    doTest("compiler/testData/diagnostics/tests/platformTypes/methodCall/javaCollectionToKotlin.kt");
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/methodCall/javaCollectionToKotlin.kt");
+                    doTest(fileName);
                 }
                 
                 @TestMetadata("javaToJava.kt")
                 public void testJavaToJava() throws Exception {
-                    doTest("compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToJava.kt");
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToJava.kt");
+                    doTest(fileName);
                 }
                 
                 @TestMetadata("javaToKotlin.kt")
                 public void testJavaToKotlin() throws Exception {
-                    doTest("compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToKotlin.kt");
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/methodCall/javaToKotlin.kt");
+                    doTest(fileName);
                 }
                 
                 @TestMetadata("kotlinCollectionToJava.kt")
                 public void testKotlinCollectionToJava() throws Exception {
-                    doTest("compiler/testData/diagnostics/tests/platformTypes/methodCall/kotlinCollectionToJava.kt");
+                    String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/methodCall/kotlinCollectionToJava.kt");
+                    doTest(fileName);
                 }
                 
                 @TestMetadata("list.kt")

core/descriptors/src/org/jetbrains/jet/lang/types/TypeUtils.java

@@ -423,6 +423,9 @@ public class TypeUtils {
         if (type.getConstructor().getDeclarationDescriptor() instanceof TypeParameterDescriptor) {
             return hasNullableSuperType(type);
         }
+        if (TypesPackage.isFlexible(type) && isNullableType(((FlexibleType) type).getUpperBound())) {
+            return true;
+        }
         return false;
     }