FIR: Fix exception on remaining flexible ILT in lambda

^KT-49191 Related

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirBlackBoxCodegenTestGenerated.java

@@ -16336,6 +16336,12 @@ public class FirBlackBoxCodegenTestGenerated extends AbstractFirBlackBoxCodegenT
             runTest("compiler/testData/codegen/box/fir/Fir2IrClassifierStorage.kt");
         }
 
+        @Test
+        @TestMetadata("flexibleIntegerLiterals.kt")
+        public void testFlexibleIntegerLiterals() throws Exception {
+            runTest("compiler/testData/codegen/box/fir/flexibleIntegerLiterals.kt");
+        }
+
         @Test
         @TestMetadata("implicitNothingInDelegate.kt")
         public void testImplicitNothingInDelegate() throws Exception {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/ConeIntegerLiteralTypeImpl.kt

@@ -145,11 +145,27 @@ class ConeIntegerLiteralTypeImpl : ConeIntegerLiteralType {
     }
 }
 
-fun ConeKotlinType.approximateIntegerLiteralType(expectedType: ConeKotlinType? = null): ConeKotlinType =
-    (this as? ConeIntegerLiteralType)?.getApproximatedType(expectedType) ?: this
+fun ConeKotlinType.approximateIntegerLiteralType(expectedType: ConeKotlinType? = null): ConeKotlinType {
+    return when (this) {
+        is ConeIntegerLiteralType -> getApproximatedType(expectedType)
+        is ConeFlexibleType -> approximateIntegerLiteralBounds(expectedType)
+        else -> this
+    }
+}
 
-fun ConeKotlinType.approximateIntegerLiteralTypeOrNull(expectedType: ConeKotlinType? = null): ConeKotlinType? =
-    (this as? ConeIntegerLiteralType)?.getApproximatedType(expectedType)
+private fun ConeFlexibleType.approximateIntegerLiteralBounds(expectedType: ConeKotlinType? = null): ConeFlexibleType {
+    val newLowerBound = lowerBound.approximateIntegerLiteralType(expectedType)
+    val newUpperBound = upperBound.approximateIntegerLiteralType(expectedType)
+
+    if (newLowerBound !== lowerBound || newUpperBound !== upperBound) {
+        return ConeFlexibleType(
+            newLowerBound.lowerBoundIfFlexible(),
+            newUpperBound.upperBoundIfFlexible()
+        )
+    }
+
+    return this
+}
 
 private fun ConeClassLikeType.withNullability(nullability: ConeNullability): ConeClassLikeType {
     if (nullability == this.nullability) return this

compiler/testData/codegen/box/fir/flexibleIntegerLiterals.kt

@@ -0,0 +1,18 @@
+// TARGET_BACKEND: JVM
+// IGNORE_BACKEND: JVM, JVM_IR, ANDROID, ANDROID_IR
+// IGNORE_LIGHT_ANALYSIS
+// WITH_RUNTIME
+// FULL_JDK
+
+// This test fails on FE 1.0, but works in production compiler (see KT-49191):
+// Caused by: java.lang.AssertionError: Lower bound Function<in (String..String?), out (IntegerLiteralType[Int,Long,Byte,Short]..IntegerLiteralType[Int,Long,Byte,Short]?)> of a flexible type must be a subtype of the upper bound Function<in (String..String?), out (IntegerLiteralType[Int,Long,Byte,Short]..IntegerLiteralType[Int,Long,Byte,Short]?)>?
+// at org.jetbrains.kotlin.types.FlexibleTypeImpl.runAssertions(flexibleTypes.kt:105)
+fun box(): String {
+    val x = Comparator.comparing { x: String ->
+        1
+    }
+
+    if (x.compare("O", "K") != 0) return "fail"
+
+    return "OK"
+}

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

@@ -16246,6 +16246,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/fir/Fir2IrClassifierStorage.kt");
         }
 
+        @Test
+        @TestMetadata("flexibleIntegerLiterals.kt")
+        public void testFlexibleIntegerLiterals() throws Exception {
+            runTest("compiler/testData/codegen/box/fir/flexibleIntegerLiterals.kt");
+        }
+
         @Test
         @TestMetadata("incorrectBytecodeWithEnhancedNullability.kt")
         public void testIncorrectBytecodeWithEnhancedNullability() throws Exception {

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

@@ -16336,6 +16336,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/fir/Fir2IrClassifierStorage.kt");
         }
 
+        @Test
+        @TestMetadata("flexibleIntegerLiterals.kt")
+        public void testFlexibleIntegerLiterals() throws Exception {
+            runTest("compiler/testData/codegen/box/fir/flexibleIntegerLiterals.kt");
+        }
+
         @Test
         @TestMetadata("implicitNothingInDelegate.kt")
         public void testImplicitNothingInDelegate() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -13349,6 +13349,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)
     public static class Fir extends AbstractLightAnalysisModeTest {
+        @TestMetadata("flexibleIntegerLiterals.kt")
+        public void ignoreFlexibleIntegerLiterals() throws Exception {
+            runTest("compiler/testData/codegen/box/fir/flexibleIntegerLiterals.kt");
+        }
+
         @TestMetadata("SuspendExtension.kt")
         public void ignoreSuspendExtension() throws Exception {
             runTest("compiler/testData/codegen/box/fir/SuspendExtension.kt");