[FIR] Create test case to validate KT-56988 is working as expected

^KT-56988 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosticCompilerTestFE10TestdataTestGenerated.java

@@ -47140,6 +47140,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
         runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/unsoundSmartcast.kt");
       }
 
+      @Test
+      @TestMetadata("whileLoopNotNull.kt")
+      public void testWhileLoopNotNull() {
+        runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.kt");
+      }
+
       @Test
       @TestMetadata("withChangesToNull.kt")
       public void testWithChangesToNull() {

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated.java

@@ -47140,6 +47140,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
         runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/unsoundSmartcast.kt");
       }
 
+      @Test
+      @TestMetadata("whileLoopNotNull.kt")
+      public void testWhileLoopNotNull() {
+        runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.kt");
+      }
+
       @Test
       @TestMetadata("withChangesToNull.kt")
       public void testWithChangesToNull() {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirLightTreeOldFrontendDiagnosticsTestGenerated.java

@@ -44770,6 +44770,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
         runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/unsoundSmartcast.kt");
       }
 
+      @Test
+      @TestMetadata("whileLoopNotNull.kt")
+      public void testWhileLoopNotNull() {
+        runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.kt");
+      }
+
       @Test
       @TestMetadata("withChangesToNull.kt")
       public void testWithChangesToNull() {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirPsiOldFrontendDiagnosticsTestGenerated.java

@@ -44908,6 +44908,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
         runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/unsoundSmartcast.kt");
       }
 
+      @Test
+      @TestMetadata("whileLoopNotNull.kt")
+      public void testWhileLoopNotNull() {
+        runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.kt");
+      }
+
       @Test
       @TestMetadata("withChangesToNull.kt")
       public void testWithChangesToNull() {

compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.fir.kt

@@ -0,0 +1,22 @@
+// FIR_DUMP
+
+fun Int?.swap(): Int = 1
+fun Int.swap(): Int? = null
+
+var result = false
+
+fun b(): Boolean {
+    result = !result
+    return result
+}
+
+fun test() {
+    var x: Int? = 1
+    if (x != null) {
+        while (b()) {
+            val tmp = x.swap()
+            x = tmp
+        }
+        x.plus(1)
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.fir.txt

@@ -0,0 +1,28 @@
+FILE: whileLoopNotNull.fir.kt
+    public final fun R|kotlin/Int?|.swap(): R|kotlin/Int| {
+        ^swap Int(1)
+    }
+    public final fun R|kotlin/Int|.swap(): R|kotlin/Int?| {
+        ^swap Null(null)
+    }
+    public final var result: R|kotlin/Boolean| = Boolean(false)
+        public get(): R|kotlin/Boolean|
+        public set(value: R|kotlin/Boolean|): R|kotlin/Unit|
+    public final fun b(): R|kotlin/Boolean| {
+        R|/result| = R|/result|.R|kotlin/Boolean.not|()
+        ^b R|/result|
+    }
+    public final fun test(): R|kotlin/Unit| {
+        lvar x: R|kotlin/Int?| = Int(1)
+        when () {
+            !=(R|<local>/x|, Null(null)) ->  {
+                while(R|/b|()) {
+                    lval tmp: R|kotlin/Int| = R|<local>/x|.R|/swap|()
+                    R|<local>/x| = R|<local>/tmp|
+                }
+
+                R|<local>/x|.R|kotlin/Int.plus|(Int(1))
+            }
+        }
+
+    }

compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.kt

@@ -0,0 +1,22 @@
+// FIR_DUMP
+
+fun Int?.swap(): Int = 1
+fun Int.swap(): Int? = null
+
+var result = false
+
+fun b(): Boolean {
+    result = !result
+    return result
+}
+
+fun test() {
+    var x: Int? = 1
+    if (x != null) {
+        while (b()) {
+            val tmp = x.swap()
+            x = tmp
+        }
+        x<!UNSAFE_CALL!>.<!>plus(1)
+    }
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -47198,6 +47198,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
         runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/unsoundSmartcast.kt");
       }
 
+      @Test
+      @TestMetadata("whileLoopNotNull.kt")
+      public void testWhileLoopNotNull() {
+        runTest("compiler/testData/diagnostics/testsWithStdLib/smartcasts/whileLoopNotNull.kt");
+      }
+
       @Test
       @TestMetadata("withChangesToNull.kt")
       public void testWithChangesToNull() {