x?.y is now nullable even if y is Unit + three tests + codegen test fix + source code fix #KT-7936 Fixed #KT-8347 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CallExpressionResolver.java

@@ -373,7 +373,7 @@ public class CallExpressionResolver {
 
         //TODO move further
         if (safeCall) {
-            if (selectorReturnType != null && !KotlinBuiltIns.isUnit(selectorReturnType)) {
+            if (selectorReturnType != null) {
                 if (TypeUtils.isNullableType(receiverType)) {
                     selectorReturnType = TypeUtils.makeNullable(selectorReturnType);
                     selectorReturnTypeInfo = selectorReturnTypeInfo.replaceType(selectorReturnType);

compiler/testData/codegen/box/extensionFunctions/kt606.kt

@@ -15,7 +15,9 @@ interface ChannelPipeline  {
 }
 
 class DefaultChannelPipeline : ChannelPipeline {
-  override fun print(any: Any) = System.out?.println(any)
+  override fun print(any: Any) {
+      System.out?.println(any)
+  }
 
 }
 

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

@@ -0,0 +1,11 @@
+class My {
+    fun other() {}
+}
+
+fun another() {}
+
+fun foo(x: My?) {
+    // Both elvis parts should be alive
+    // See also KT-7936, KT-8347
+    x?.other() ?: another()
+}

compiler/testData/diagnostics/tests/nullableTypes/elvisOnUnit.txt

@@ -0,0 +1,12 @@
+package
+
+internal fun another(): kotlin.Unit
+internal fun foo(/*0*/ x: My?): kotlin.Unit
+
+internal final class My {
+    public constructor My()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    internal final fun other(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

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

@@ -0,0 +1,7 @@
+data class My(val x: Unit)
+
+fun foo(my: My?): Int? {
+    val x = my?.x
+    // ?. is required here
+    return x?.hashCode()
+}

compiler/testData/diagnostics/tests/nullableTypes/safeAccessOnUnit.txt

@@ -0,0 +1,13 @@
+package
+
+internal fun foo(/*0*/ my: My?): kotlin.Int?
+
+kotlin.data() internal final class My {
+    public constructor My(/*0*/ x: kotlin.Unit)
+    internal final val x: kotlin.Unit
+    internal final /*synthesized*/ fun component1(): kotlin.Unit
+    public final /*synthesized*/ fun copy(/*0*/ x: kotlin.Unit = ...): My
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/testsWithStdLib/elvisOnUnitInLet.kt

@@ -0,0 +1,9 @@
+fun foo(x: Int?) {
+    // Both parts of the Elvis should be alive, see KT-7936
+    x?.let {
+        smth()
+    }?: orElse()
+}
+
+fun smth() {}
+fun orElse() {}

compiler/testData/diagnostics/testsWithStdLib/elvisOnUnitInLet.txt

@@ -0,0 +1,5 @@
+package
+
+internal fun foo(/*0*/ x: kotlin.Int?): kotlin.Unit
+internal fun orElse(): kotlin.Unit
+internal fun smth(): kotlin.Unit

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

@@ -9417,6 +9417,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("elvisOnUnit.kt")
+            public void testElvisOnUnit() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/nullableTypes/elvisOnUnit.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("nullAssertOnTypeWithNullableUpperBound.kt")
             public void testNullAssertOnTypeWithNullableUpperBound() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/nullableTypes/nullAssertOnTypeWithNullableUpperBound.kt");
@@ -9441,6 +9447,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("safeAccessOnUnit.kt")
+            public void testSafeAccessOnUnit() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/nullableTypes/safeAccessOnUnit.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("safeCallOnTypeWithNullableUpperBound.kt")
             public void testSafeCallOnTypeWithNullableUpperBound() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/nullableTypes/safeCallOnTypeWithNullableUpperBound.kt");

compiler/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestWithStdLibGenerated.java

@@ -35,6 +35,12 @@ public class JetDiagnosticsTestWithStdLibGenerated extends AbstractJetDiagnostic
         JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/diagnostics/testsWithStdLib"), Pattern.compile("^(.+)\\.kt$"), true);
     }
 
+    @TestMetadata("elvisOnUnitInLet.kt")
+    public void testElvisOnUnitInLet() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/testsWithStdLib/elvisOnUnitInLet.kt");
+        doTest(fileName);
+    }
+
     @TestMetadata("instar.kt")
     public void testInstar() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/testsWithStdLib/instar.kt");

idea/src/org/jetbrains/kotlin/idea/quickfix/MigrateAnnotationMethodCallFix.kt

@@ -59,7 +59,7 @@ class MigrateAnnotationMethodCallInWholeFile : IntentionAction {
             forEach {
                 (it.getPsiElement() as? JetCallExpression)?.let { MigrateAnnotationMethodCallFix.replaceWithSimpleCall(it) }
             }
-    }
+    } ?: Unit
 
     companion object : JetSingleIntentionActionFactory() {
         override fun createAction(diagnostic: Diagnostic) = MigrateAnnotationMethodCallInWholeFile()