Check separately auto casts for nullable types.

It's necessary for functions with generics: constraint system ignores nullability divergence,
the error checks are made afterwards, the auto cast check should be made similarly.

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

@@ -892,9 +892,14 @@ public class CandidateResolver {
         BindingContext bindingContext = trace.getBindingContext();
         boolean safeAccess = isExplicitReceiver && !implicitInvokeCheck && candidateCall.isSafeCall();
         if (!safeAccess && !receiverParameter.getType().isNullable() && receiverArgument.getType().isNullable()) {
+            if (!AutoCastUtils.isNotNull(receiverArgument, bindingContext, context.dataFlowInfo)) {
 
-            context.tracing.unsafeCall(trace, receiverArgumentType, implicitInvokeCheck);
-            return UNSAFE_CALL_ERROR;
+                context.tracing.unsafeCall(trace, receiverArgumentType, implicitInvokeCheck);
+                return UNSAFE_CALL_ERROR;
+            }
+            if (isExplicitReceiver) {
+                AutoCastUtils.recordAutoCastToNotNullableType(receiverArgument, context.trace);
+            }
         }
         DataFlowValue receiverValue = DataFlowValueFactory.createDataFlowValue(receiverArgument, bindingContext);
         if (safeAccess && !context.dataFlowInfo.getNullability(receiverValue).canBeNull()) {

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

@@ -18,6 +18,7 @@ package org.jetbrains.jet.lang.resolve.calls.autocasts;
 
 import com.google.common.collect.Lists;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.jet.lang.psi.JetExpression;
 import org.jetbrains.jet.lang.resolve.BindingContext;
 import org.jetbrains.jet.lang.resolve.BindingTrace;
 import org.jetbrains.jet.lang.resolve.calls.context.ResolutionContext;
@@ -25,6 +26,7 @@ import org.jetbrains.jet.lang.resolve.scopes.receivers.ExpressionReceiver;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ReceiverValue;
 import org.jetbrains.jet.lang.resolve.scopes.receivers.ThisReceiver;
 import org.jetbrains.jet.lang.types.JetType;
+import org.jetbrains.jet.lang.types.TypeUtils;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -117,4 +119,36 @@ public class AutoCastUtils {
             }
         }
     }
+
+    public static void recordAutoCastToNotNullableType(@NotNull ReceiverValue receiver, @NotNull BindingTrace trace) {
+        if (!(receiver instanceof ExpressionReceiver)) return;
+
+        JetType receiverType = receiver.getType();
+        if (!receiverType.isNullable()) return;
+        JetType notNullableType = TypeUtils.makeNotNullable(receiverType);
+
+        DataFlowValue dataFlowValue = DataFlowValueFactory.createDataFlowValue(receiver, trace.getBindingContext());
+        JetExpression expression = ((ExpressionReceiver) receiver).getExpression();
+        if (dataFlowValue.isStableIdentifier()) {
+            trace.record(AUTOCAST, expression, notNullableType);
+            trace.record(EXPRESSION_TYPE, expression, notNullableType);
+        }
+        else {
+            trace.report(AUTOCAST_IMPOSSIBLE.on(expression, notNullableType, expression.getText()));
+        }
+    }
+
+    public static boolean isNotNull(
+            @NotNull ReceiverValue receiver,
+            @NotNull BindingContext bindingContext,
+            @NotNull DataFlowInfo dataFlowInfo
+    ) {
+        if (!receiver.getType().isNullable()) return true;
+
+        List<ReceiverValue> autoCastVariants = getAutoCastVariants(receiver, bindingContext, dataFlowInfo);
+        for (ReceiverValue autoCastVariant : autoCastVariants) {
+            if (!autoCastVariant.getType().isNullable()) return true;
+        }
+        return false;
+    }
 }

compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/smartCastedReceiverWithGenerics.kt

@@ -0,0 +1,7 @@
+fun test(a: Any?) {
+    if (a != null) {
+        <!DEBUG_INFO_AUTOCAST!>a<!>.foo(11)
+    }
+}
+
+fun <T> Any.foo(t: T) = t

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

@@ -4702,6 +4702,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/senslessComparisonWithNullOnTypeParameters.kt");
             }
             
+            @TestMetadata("smartCastedReceiverWithGenerics.kt")
+            public void testSmartCastedReceiverWithGenerics() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/smartCastedReceiverWithGenerics.kt");
+            }
+            
         }
         
         @TestMetadata("compiler/testData/diagnostics/tests/nullableTypes")
@@ -6182,7 +6187,7 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
             public void testPublicVal() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/smartCasts/publicVal.kt");
             }
-
+            
             @TestMetadata("thisWithLabel.kt")
             public void testThisWithLabel() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/smartCasts/thisWithLabel.kt");