Fix for a problem with smart cast impossible in a situation when it's not needed. A test for KT-3572. #KT-3572 Fixed.

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

@@ -653,7 +653,9 @@ public class CandidateResolver {
             context.tracing.wrongReceiverType(trace, receiverParameter, receiverArgument);
             return OTHER_ERROR;
         }
-        SmartCastUtils.recordSmartCastIfNecessary(receiverArgument, receiverParameter.getType(), context, safeAccess);
+        if (!SmartCastUtils.recordSmartCastIfNecessary(receiverArgument, receiverParameter.getType(), context, safeAccess)) {
+            return OTHER_ERROR;
+        }
 
         JetType receiverArgumentType = receiverArgument.getType();
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/SmartCastUtils.java

@@ -158,31 +158,31 @@ public class SmartCastUtils {
         return intersection;
     }
 
+    // Returns false when we need smart cast but cannot do it, otherwise true
     public static boolean recordSmartCastIfNecessary(
             @NotNull ReceiverValue receiver,
             @NotNull JetType receiverParameterType,
             @NotNull ResolutionContext context,
             boolean safeAccess
     ) {
-        if (!(receiver instanceof ExpressionReceiver)) return false;
+        if (!(receiver instanceof ExpressionReceiver)) return true;
 
         receiverParameterType = safeAccess ? TypeUtils.makeNullable(receiverParameterType) : receiverParameterType;
         if (ArgumentTypeResolver.isSubtypeOfForArgumentType(receiver.getType(), receiverParameterType)) {
-            return false;
+            return true;
         }
 
         Collection<JetType> smartCastTypesExcludingReceiver = getSmartCastVariantsExcludingReceiver(context, receiver);
         JetType smartCastSubType = getSmartCastSubType(receiverParameterType, smartCastTypesExcludingReceiver);
-        if (smartCastSubType == null) return false;
+        if (smartCastSubType == null) return true;
 
         JetExpression expression = ((ExpressionReceiver) receiver).getExpression();
         DataFlowValue dataFlowValue = DataFlowValueFactory.createDataFlowValue(receiver, context);
 
-        recordCastOrError(expression, smartCastSubType, context.trace, dataFlowValue.isPredictable(), true);
-        return true;
+        return recordCastOrError(expression, smartCastSubType, context.trace, dataFlowValue.isPredictable(), true);
     }
 
-    public static void recordCastOrError(
+    public static boolean recordCastOrError(
             @NotNull JetExpression expression,
             @NotNull JetType type,
             @NotNull BindingTrace trace,
@@ -200,6 +200,7 @@ public class SmartCastUtils {
         else {
             trace.report(SMARTCAST_IMPOSSIBLE.on(expression, type, expression.getText()));
         }
+        return canBeCast;
     }
 
     public static boolean canBeSmartCast(

compiler/testData/diagnostics/tests/smartCasts/kt3572.kt

@@ -0,0 +1,17 @@
+trait Printer {
+    fun print()
+}
+
+class OKPrinter : Printer {
+    override fun print() {  }
+}
+
+class MyClass(var printer: Printer)
+
+
+fun main(m: MyClass) {
+    if (m.printer is OKPrinter) {
+        // We do not need smart cast here, so we should not get SMARTCAST_IMPOSSIBLE
+        m.printer.print()
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/kt3572.txt

@@ -0,0 +1,26 @@
+package
+
+internal fun main(/*0*/ m: MyClass): kotlin.Unit
+
+internal final class MyClass {
+    public constructor MyClass(/*0*/ printer: Printer)
+    internal final var printer: Printer
+    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
+}
+
+internal final class OKPrinter : Printer {
+    public constructor OKPrinter()
+    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 open override /*1*/ fun print(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+internal trait Printer {
+    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 abstract fun print(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

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

@@ -10998,6 +10998,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("kt3572.kt")
+            public void testKt3572() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/kt3572.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("kt3711.kt")
             public void testKt3711() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/kt3711.kt");