K2: add test for KT-57649

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

@@ -16377,6 +16377,12 @@ public class DiagnosticCompilerTestFE10TestdataTestGenerated extends AbstractDia
                     runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/covariance.kt");
                 }
 
+                @Test
+                @TestMetadata("emptyIntersectionOnIf.kt")
+                public void testEmptyIntersectionOnIf() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.kt");
+                }
+
                 @Test
                 @TestMetadata("kt45461.kt")
                 public void testKt45461() throws Exception {

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

@@ -16377,6 +16377,12 @@ public class LLFirPreresolvedReversedDiagnosticCompilerFE10TestDataTestGenerated
                     runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/covariance.kt");
                 }
 
+                @Test
+                @TestMetadata("emptyIntersectionOnIf.kt")
+                public void testEmptyIntersectionOnIf() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.kt");
+                }
+
                 @Test
                 @TestMetadata("kt45461.kt")
                 public void testKt45461() throws Exception {

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

@@ -16377,6 +16377,12 @@ public class FirLightTreeOldFrontendDiagnosticsTestGenerated extends AbstractFir
                     runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/covariance.kt");
                 }
 
+                @Test
+                @TestMetadata("emptyIntersectionOnIf.kt")
+                public void testEmptyIntersectionOnIf() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.kt");
+                }
+
                 @Test
                 @TestMetadata("kt45461.kt")
                 public void testKt45461() throws Exception {

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

@@ -16383,6 +16383,12 @@ public class FirPsiOldFrontendDiagnosticsTestGenerated extends AbstractFirPsiDia
                     runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/covariance.kt");
                 }
 
+                @Test
+                @TestMetadata("emptyIntersectionOnIf.kt")
+                public void testEmptyIntersectionOnIf() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.kt");
+                }
+
                 @Test
                 @TestMetadata("kt45461.kt")
                 public void testKt45461() throws Exception {

compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.fir.kt

@@ -0,0 +1,8 @@
+// ISSUE: KT-57649
+
+open class A
+abstract class B {
+    fun test(current: A): A? =
+        // K2 reports empty intersection here due to the smart cast from A to B, where A & B aren't compatible
+        <!INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION_WARNING("K; B?, A?; multiple incompatible classes; : B, A")!>if (current === this) current else null<!>
+}

compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.kt

@@ -0,0 +1,8 @@
+// ISSUE: KT-57649
+
+open class A
+abstract class B {
+    fun test(current: A): A? =
+        // K2 reports empty intersection here due to the smart cast from A to B, where A & B aren't compatible
+        if (current === this) current else null
+}

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

@@ -16383,6 +16383,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/covariance.kt");
                 }
 
+                @Test
+                @TestMetadata("emptyIntersectionOnIf.kt")
+                public void testEmptyIntersectionOnIf() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/emptyIntersectionTypes/emptyIntersectionOnIf.kt");
+                }
+
                 @Test
                 @TestMetadata("kt45461.kt")
                 public void testKt45461() throws Exception {