"Replace 'if' with elvis operator": don't suggest on super type check

#KT-27016 Fixed

idea/src/org/jetbrains/kotlin/idea/intentions/FoldInitializerAndIfToElvisIntention.kt

@@ -35,9 +35,11 @@ import org.jetbrains.kotlin.psi.psiUtil.PsiChildRange
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.siblings
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 import org.jetbrains.kotlin.types.isError
 import org.jetbrains.kotlin.types.typeUtil.isNothing
+import org.jetbrains.kotlin.types.typeUtil.isSubtypeOf
 import org.jetbrains.kotlin.types.typeUtil.makeNotNullable
 import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
 
@@ -143,6 +145,16 @@ class FoldInitializerAndIfToElvisIntention :
             val then = ifExpression.then ?: return null
             val typeReference = (operationExpression as? KtIsExpression)?.typeReference
 
+            if (typeReference != null) {
+                val checkedType = ifExpression.analyze(BodyResolveMode.PARTIAL)[BindingContext.TYPE, typeReference]
+                val variableTypeReference = prevStatement.typeReference
+                val variableType = if (variableTypeReference != null)
+                    prevStatement.analyze(BodyResolveMode.PARTIAL)[BindingContext.TYPE, variableTypeReference]
+                else
+                    SpecifyTypeExplicitlyIntention.getTypeForDeclaration(prevStatement)
+                if (checkedType != null && variableType != null && !checkedType.isSubtypeOf(variableType)) return null
+            }
+
             val statement = if (then is KtBlockExpression) then.statements.singleOrNull() else then
             statement ?: return null
 

idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSameType.kt

@@ -0,0 +1,13 @@
+open class A
+
+open class B : A() {
+    fun b() {}
+}
+
+fun test() {
+    val b = B()
+    if (<caret>b !is B) {
+        return
+    }
+    b.b()
+}

idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSameType.kt.after

@@ -0,0 +1,10 @@
+open class A
+
+open class B : A() {
+    fun b() {}
+}
+
+fun test() {
+    val b = B() as? B ?: return
+    b.b()
+}

idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSubType.kt

@@ -0,0 +1,17 @@
+open class A
+
+open class B : A() {
+    fun b() {}
+}
+
+open class C : B() {
+    fun c() {}
+}
+
+fun test() {
+    val b = B()
+    if (<caret>b !is C) {
+        return
+    }
+    b.b()
+}

idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSubType.kt.after

@@ -0,0 +1,14 @@
+open class A
+
+open class B : A() {
+    fun b() {}
+}
+
+open class C : B() {
+    fun c() {}
+}
+
+fun test() {
+    val b = B() as? C ?: return
+    b.b()
+}

idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSuperType.kt

@@ -0,0 +1,14 @@
+// IS_APPLICABLE: false
+open class A
+
+open class B : A() {
+    fun b() {}
+}
+
+fun test() {
+    val b = B()
+    if (<caret>b !is A) {
+        return
+    }
+    b.b()
+}

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -8749,6 +8749,21 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
             runTest("idea/testData/intentions/foldInitializerAndIfToElvis/NotIsNullableType.kt");
         }
 
+        @TestMetadata("NotIsSameType.kt")
+        public void testNotIsSameType() throws Exception {
+            runTest("idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSameType.kt");
+        }
+
+        @TestMetadata("NotIsSubType.kt")
+        public void testNotIsSubType() throws Exception {
+            runTest("idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSubType.kt");
+        }
+
+        @TestMetadata("NotIsSuperType.kt")
+        public void testNotIsSuperType() throws Exception {
+            runTest("idea/testData/intentions/foldInitializerAndIfToElvis/NotIsSuperType.kt");
+        }
+
         @TestMetadata("OtherVar1.kt")
         public void testOtherVar1() throws Exception {
             runTest("idea/testData/intentions/foldInitializerAndIfToElvis/OtherVar1.kt");