[FIR] Check is for impossibility

^KT-58203 Fixed
^KT-62646

compiler/fir/analysis-tests/testData/resolve/exhaustiveness/positive/exhaustiveness_enum.kt

@@ -11,7 +11,7 @@ fun test_1(e: Enum) {
     val b = <!NO_ELSE_IN_WHEN!>when<!> (e) {
         Enum.A -> 1
         Enum.B -> 2
-        is String -> 3
+        <!USELESS_IS_CHECK!>is String<!> -> 3
     }
 
     val c = when (e) {

compiler/fir/analysis-tests/testData/resolve/exhaustiveness/positive/exhaustiveness_enumJava.kt

@@ -15,7 +15,7 @@ fun test_1(e: JavaEnum) {
     val b = <!NO_ELSE_IN_WHEN!>when<!> (e) {
         JavaEnum.A -> 1
         JavaEnum.B -> 2
-        is String -> 3
+        <!USELESS_IS_CHECK!>is String<!> -> 3
     }.plus(0)
 
     val c = when (e) {

compiler/fir/analysis-tests/testData/resolve/exhaustiveness/positive/exhaustiveness_sealedClass.kt

@@ -15,7 +15,7 @@ fun test_1(e: Base) {
     val b = <!NO_ELSE_IN_WHEN!>when<!> (e) {
         is Base.A -> 1
         is Base.A.B -> 2
-        is String -> 3
+        <!USELESS_IS_CHECK!>is String<!> -> 3
     }
 
     val c = when (e) {

compiler/fir/analysis-tests/testData/resolve/smartcasts/controlStructures/simpleIf.kt

@@ -17,7 +17,7 @@ fun test_2(x: Any) {
 fun test_3(x: Any) {
     when {
         x !is String -> {}
-        x !is Int -> {}
+        <!USELESS_IS_CHECK!>x !is Int<!> -> {}
         else -> {
             x.length
             x.inc()

compiler/fir/analysis-tests/testData/resolve/smartcasts/controlStructures/when.kt

@@ -16,7 +16,7 @@ fun test_1(x: Any?) {
     when {
         x !is A -> {}
         x !is B -> x.foo()
-        x is Int -> {
+        <!USELESS_IS_CHECK!>x is Int<!> -> {
             x.foo()
             x.bar()
             x.inc()
@@ -37,7 +37,7 @@ fun test_2(x: Any?) {
     when(x) {
         !is A -> {}
         !is B -> x.foo()
-        is Int -> {
+        <!USELESS_IS_CHECK!>is Int<!> -> {
             x.foo()
             x.bar()
             x.inc()
@@ -67,7 +67,7 @@ fun test_3(x: Any?) {
             x.foo()
             y.foo()
         }
-        is Int -> {
+        <!USELESS_IS_CHECK!>is Int<!> -> {
             x.foo()
             x.bar()
             x.inc()

compiler/fir/analysis-tests/testData/resolve/smartcasts/receivers/implicitReceivers.kt

@@ -53,7 +53,7 @@ fun Any?.test_4() {
         <!UNRESOLVED_REFERENCE!>foo<!>()
         this.<!UNRESOLVED_REFERENCE!>bar<!>()
         <!UNRESOLVED_REFERENCE!>bar<!>()
-    } else if (this !is B) {
+    } else if (<!USELESS_IS_CHECK!>this !is B<!>) {
         this.<!UNRESOLVED_REFERENCE!>bar<!>()
         <!UNRESOLVED_REFERENCE!>bar<!>()
         this.foo()

compiler/fir/analysis-tests/testData/resolveWithStdlib/contracts/fromSource/good/returnsImplies/safeCall.kt

@@ -13,7 +13,7 @@ fun test1(x: String?): Int? {
 @OptIn(ExperimentalContracts::class)
 fun test2(x: String?): Int? {
     <!WRONG_IMPLIES_CONDITION!>contract {
-        returnsNotNull() implies (x is Boolean)
+        returnsNotNull() implies (<!USELESS_IS_CHECK!>x is Boolean<!>)
     }<!>
 
     return x?.length

compiler/fir/analysis-tests/testData/resolveWithStdlib/intellij/PersistentStateComponent.kt

@@ -20,7 +20,7 @@ fun <T> deserializeAndLoadState(
 ) {}
 
 fun use(beforeRunTask: BeforeRunTask<*>) {
-    if (beforeRunTask is PersistentStateComponent<*>) {
+    if (<!USELESS_IS_CHECK!>beforeRunTask is PersistentStateComponent<*><!>) {
         deserializeAndLoadState(beforeRunTask)
     }
 }

compiler/fir/analysis-tests/testData/resolveWithStdlib/unaryOperators.kt

@@ -14,5 +14,5 @@ fun foo(u: U) {
     val w = +i
 
     val g = "" !in u
-    val f = "" !is Boolean
+    val f = <!USELESS_IS_CHECK!>"" !is Boolean<!>
 }