Fix "if to safe access" false positive for check on incorrect type

So #KT-21881 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/branchedTransformations/IfThenToSafeAccessInspection.kt

@@ -27,6 +27,7 @@ import org.jetbrains.kotlin.idea.util.application.runWriteAction
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
 import org.jetbrains.kotlin.resolve.bindingContextUtil.isUsedAsExpression
+import org.jetbrains.kotlin.resolve.calls.callUtil.getType
 
 class IfThenToSafeAccessInspection : AbstractApplicabilityBasedInspection<KtIfExpression>(KtIfExpression::class.java) {
 
@@ -84,6 +85,6 @@ class IfThenToSafeAccessInspection : AbstractApplicabilityBasedInspection<KtIfEx
         negatedClause == null && baseClause.isUsedAsExpression(context) -> false
         negatedClause != null && !negatedClause.isNullExpression() -> false
         else -> baseClause.evaluatesTo(receiverExpression) || baseClause.hasFirstReceiverOf(receiverExpression) ||
-                receiverExpression is KtThisExpression && hasImplicitReceiver()
+                receiverExpression is KtThisExpression && getImplicitReceiver()?.let { it.type == receiverExpression.getType(context) } == true
     }
 }

idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/IfThenUtils.kt

@@ -40,6 +40,7 @@ import org.jetbrains.kotlin.resolve.calls.callUtil.getType
 import org.jetbrains.kotlin.resolve.calls.resolvedCallUtil.getImplicitReceiverValue
 import org.jetbrains.kotlin.resolve.calls.smartcasts.DataFlowValueFactory
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
+import org.jetbrains.kotlin.resolve.scopes.receivers.ImplicitReceiver
 import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.types.typeUtil.isSubtypeOf
 import org.jetbrains.kotlin.utils.addToStdlib.constant
@@ -190,8 +191,9 @@ data class IfThenToSelectData(
         }
     }
 
-    internal fun hasImplicitReceiver(): Boolean =
-            baseClause.getResolvedCall(context)?.getImplicitReceiverValue() != null
+    internal fun getImplicitReceiver(): ImplicitReceiver? = baseClause.getResolvedCall(context)?.getImplicitReceiverValue()
+
+    internal fun hasImplicitReceiver(): Boolean = getImplicitReceiver() != null
 }
 
 internal fun KtIfExpression.buildSelectTransformationData(): IfThenToSelectData? {

idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/implicitReceiverInApply.kt

@@ -0,0 +1,17 @@
+// PROBLEM: none
+// WITH_RUNTIME
+class Foo
+
+class Test {
+    fun foo(): Any = ""
+
+    fun bar() {}
+
+    fun test(a: Any) {
+        foo().apply {
+            <caret>if (this is Foo) {
+                bar()
+            }
+        }
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -140,6 +140,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("implicitReceiverInApply.kt")
+            public void testImplicitReceiverInApply() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/implicitReceiverInApply.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("isCheckSimple.kt")
             public void testIsCheckSimple() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/branched/ifThenToSafeAccess/isCheckSimple.kt");