FIR DFA: x !is T? => x != null

^KT-22996 tag fixed-in-k2

compiler/tests-spec/testData/diagnostics/linked/expressions/when-expression/p-6/pos/1.3.fir.kt

@@ -0,0 +1,65 @@
+// SKIP_TXT
+
+// TESTCASE NUMBER: 1
+fun case_1(value_1: Any) = when (value_1) {
+    is Int -> {}
+    is Float, is Char, is Boolean -> {}
+    is String -> {}
+    else -> {}
+}
+
+// TESTCASE NUMBER: 2
+fun case_2(value_1: Any?) = when (value_1) {
+    is Float, is Char, is SealedClass? -> "" // if value is null then this branch will be executed
+    is Double, is Boolean, is ClassWithCompanionObject.Companion -> ""
+    else -> ""
+}
+
+/*
+ * TESTCASE NUMBER: 3
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-22996
+ */
+fun case_3(value_1: Any?) = when (value_1) {
+    is Float, is Char, is Int? -> "" // if value is null then this branch will be executed
+    is SealedChild2, is Boolean?, is String -> "" // redundant nullable type check
+    else -> ""
+}
+
+/*
+ * TESTCASE NUMBER: 4
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-22996
+ */
+fun case_4(value_1: Any?) = when (value_1) {
+    is Float, is Char?, is Int? -> "" // double nullable type check in the one branch
+    is SealedChild1, is Boolean, is String -> ""
+    else -> ""
+}
+
+/*
+ * TESTCASE NUMBER: 5
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-22996
+ */
+fun case_5(value_1: Any?): String {
+    when (value_1) {
+        is Float, is Char?, is Int -> return ""
+        is Double, is EmptyObject, is String -> return ""
+        <!SENSELESS_NULL_IN_WHEN!>null<!> -> return "" // null-check redundant
+        else -> return ""
+    }
+}
+
+/*
+ * TESTCASE NUMBER: 6
+ * UNEXPECTED BEHAVIOUR
+ * ISSUES: KT-22996
+ */
+fun case_6(value_1: Any?): String {
+    when (value_1) {
+        is Float, is Char?, <!SENSELESS_NULL_IN_WHEN!>null<!>, is Int -> return "" // double nullable type check in the one branch
+        is Double, is EmptyObject, is String -> return ""
+        else -> return ""
+    }
+}

compiler/tests-spec/testData/diagnostics/linked/expressions/when-expression/p-6/pos/1.3.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // SKIP_TXT
 
 /*

compiler/tests-spec/testData/diagnostics/linked/expressions/when-expression/p-6/pos/1.4.fir.kt

@@ -44,6 +44,6 @@ fun case_6(value_1: Any?): String = when (value_1) {
  * ISSUES: KT-22996
  */
 fun case_7(value_1: Any?): String = when (value_1) {
-    is Number?, null, !is SealedChild3 -> "" // triple nullable type check in the one branch
+    is Number?, <!SENSELESS_NULL_IN_WHEN!>null<!>, !is SealedChild3 -> "" // triple nullable type check in the one branch
     else -> ""
 }