[NI] Add test to check how behavior will be changed after few commits

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirOldFrontendDiagnosticsTestGenerated.java

@@ -21215,6 +21215,11 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirOldFronte
             public void testSmartCastOnReceiver() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.kt");
             }
+
+            @TestMetadata("stabilityOfSmartcastsAgainstGenericFunctions.kt")
+            public void testStabilityOfSmartcastsAgainstGenericFunctions() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
+            }
         }
 
         @TestMetadata("compiler/testData/diagnostics/tests/smartCasts/intersectionScope")

compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.fir.kt

@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_LAMBDA_EXPRESSION -VARIABLE_WITH_REDUNDANT_INITIALIZER -UNUSED_EXPRESSION
+
+object Test {
+    fun <T> foo(actual: T) {}
+    fun <T : Number> foo(actual: T) {}
+}
+
+fun main() {
+    var y: Number? = null
+    y = 2
+    { y = 1 }
+    Test.foo(y)
+}

compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt

@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -UNUSED_LAMBDA_EXPRESSION -VARIABLE_WITH_REDUNDANT_INITIALIZER -UNUSED_EXPRESSION
+
+object Test {
+    fun <T> foo(actual: T) {}
+    fun <T : Number> foo(actual: T) {}
+}
+
+fun main() {
+    var y: Number? = null
+    y = 2
+    { y = 1 }
+    Test.foo(<!SMARTCAST_IMPOSSIBLE, SMARTCAST_IMPOSSIBLE!>y<!>)
+}

compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.txt

@@ -0,0 +1,12 @@
+package
+
+public fun main(): kotlin.Unit
+
+public object Test {
+    private constructor Test()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final fun </*0*/ T> foo(/*0*/ actual: T): kotlin.Unit
+    public final fun </*0*/ T : kotlin.Number> foo(/*0*/ actual: T): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -21292,6 +21292,11 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 public void testSmartCastOnReceiver() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.kt");
                 }
+
+                @TestMetadata("stabilityOfSmartcastsAgainstGenericFunctions.kt")
+                public void testStabilityOfSmartcastsAgainstGenericFunctions() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
+                }
             }
 
             @TestMetadata("compiler/testData/diagnostics/tests/smartCasts/intersectionScope")

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -21217,6 +21217,11 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 public void testSmartCastOnReceiver() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/smartCasts/inference/smartCastOnReceiver.kt");
                 }
+
+                @TestMetadata("stabilityOfSmartcastsAgainstGenericFunctions.kt")
+                public void testStabilityOfSmartcastsAgainstGenericFunctions() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/smartCasts/inference/stabilityOfSmartcastsAgainstGenericFunctions.kt");
+                }
             }
 
             @TestMetadata("compiler/testData/diagnostics/tests/smartCasts/intersectionScope")