use smart cast info while adding constraint for receiver

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

@@ -640,6 +640,10 @@ public class CandidateResolver {
                     context.candidateCall.isSafeCall()
                     ? TypeUtils.makeNotNullable(receiverArgument.getType())
                     : receiverArgument.getType();
+            if (receiverArgument instanceof ExpressionReceiver) {
+                receiverType = updateResultTypeForSmartCasts(receiverType, ((ExpressionReceiver) receiverArgument).getExpression(),
+                                                             context.dataFlowInfo, context.trace);
+            }
             constraintSystem.addSubtypeConstraint(receiverType, receiverParameter.getType(), ConstraintPosition.RECEIVER_POSITION);
         }
 

compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.kt

@@ -0,0 +1,13 @@
+trait A
+trait B
+
+class Test {
+    fun test(a: A?, b: B, list: MutableList<Pair<A, B>>) {
+        if (a != null) {
+            list.add(<!DEBUG_INFO_AUTOCAST!>a<!> to b)
+        }
+    }
+}
+
+class Pair<out A, out B>(val first: A, val second: B)
+fun <A, B> A.to(that: B) = Pair(this, that)

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

@@ -6299,6 +6299,11 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                     doTest("compiler/testData/diagnostics/tests/smartCasts/inference/kt4009.kt");
                 }
                 
+                @TestMetadata("smartCastOnReceiver.kt")
+                public void testSmartCastOnReceiver() throws Exception {
+                    doTest("compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.kt");
+                }
+                
             }
             
             public static Test innerSuite() {