[FIR] Assume nullable types as good types for ILT approximation

#KT-41982 Fixed

compiler/fir/analysis-tests/testData/resolve/delegates/kt41982.kt

@@ -0,0 +1,17 @@
+// ISSUE: KT-41982
+
+import kotlin.reflect.KProperty
+
+class Delegate<R, T> {
+    operator fun getValue(thisRef: R, property: KProperty<*>): T = null!!
+
+    operator fun setValue(thisRef: R, property: KProperty<*>, value: T) {}
+}
+
+abstract class DelegateProvider<in Type>
+
+fun <Type : Base, Base : DelegateProvider<Base>> Type.long(initializer: (() -> Long?)? = null): Delegate<Type, Long> = null!!
+
+class Test : DelegateProvider<Any>() {
+    var start by long { 0 }
+}

compiler/fir/analysis-tests/testData/resolve/delegates/kt41982.txt

@@ -0,0 +1,40 @@
+FILE: kt41982.kt
+    public final class Delegate<R, T> : R|kotlin/Any| {
+        public constructor<R, T>(): R|Delegate<R, T>| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final operator fun getValue(thisRef: R|R|, property: R|kotlin/reflect/KProperty<*>|): R|T| {
+            ^getValue Null(null)!!
+        }
+
+        public final operator fun setValue(thisRef: R|R|, property: R|kotlin/reflect/KProperty<*>|, value: R|T|): R|kotlin/Unit| {
+        }
+
+    }
+    public abstract class DelegateProvider<in Type> : R|kotlin/Any| {
+        public constructor<in Type>(): R|DelegateProvider<Type>| {
+            super<R|kotlin/Any|>()
+        }
+
+    }
+    public final fun <Type : R|Base|, Base : R|DelegateProvider<Base>|> R|Type|.long(initializer: R|() -> kotlin/Long?| = Null(null)): R|Delegate<Type, kotlin/Long>| {
+        ^long Null(null)!!
+    }
+    public final class Test : R|DelegateProvider<kotlin/Any>| {
+        public constructor(): R|Test| {
+            super<R|DelegateProvider<kotlin/Any>|>()
+        }
+
+        public final var start: R|kotlin/Long|by this@R|/Test|.R|/long|<R|Test?|, R|Test?|>(<L> = long@fun <anonymous>(): R|kotlin/Long?| {
+            ^ Long(0)
+        }
+        )
+            public get(): R|kotlin/Long| {
+                ^ this@R|/Test|.D|/Test.start|.R|FakeOverride</Delegate.getValue: R|kotlin/Long|>|(this@R|/Test|, ::R|/Test.start|)
+            }
+            public set(<set-?>: R|kotlin/Long|): R|kotlin/Unit| {
+                this@R|/Test|.D|/Test.start|.R|FakeOverride</Delegate.setValue: R|kotlin/Unit|>|(this@R|/Test|, ::R|/Test.start|, R|<local>/start|)
+            }
+
+    }

compiler/fir/analysis-tests/tests/org/jetbrains/kotlin/fir/FirDiagnosticsTestGenerated.java

@@ -898,6 +898,11 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
             runTest("compiler/fir/analysis-tests/testData/resolve/delegates/extensionGetValueWithTypeVariableAsReceiver.kt");
         }
 
+        @TestMetadata("kt41982.kt")
+        public void testKt41982() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/delegates/kt41982.kt");
+        }
+
         @TestMetadata("provideDelegate.kt")
         public void testProvideDelegate() throws Exception {
             runTest("compiler/fir/analysis-tests/testData/resolve/delegates/provideDelegate.kt");

compiler/fir/analysis-tests/tests/org/jetbrains/kotlin/fir/FirDiagnosticsWithLightTreeTestGenerated.java

@@ -898,6 +898,11 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
             runTest("compiler/fir/analysis-tests/testData/resolve/delegates/extensionGetValueWithTypeVariableAsReceiver.kt");
         }
 
+        @TestMetadata("kt41982.kt")
+        public void testKt41982() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/delegates/kt41982.kt");
+        }
+
         @TestMetadata("provideDelegate.kt")
         public void testProvideDelegate() throws Exception {
             runTest("compiler/fir/analysis-tests/testData/resolve/delegates/provideDelegate.kt");

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

@@ -64,9 +64,11 @@ class ConeIntegerLiteralTypeImpl : ConeIntegerLiteralType {
     }
 
     override fun getApproximatedType(expectedType: ConeKotlinType?): ConeClassLikeType {
-        val approximatedType = when (val expectedTypeForApproximation = expectedType?.lowerBoundIfFlexible()) {
+        val expectedTypeForApproximation = (expectedType?.lowerBoundIfFlexible() as? ConeClassLikeType)
+            ?.withNullability(ConeNullability.NOT_NULL)
+        val approximatedType = when (expectedTypeForApproximation) {
             null, !in possibleTypes -> possibleTypes.first()
-            else -> expectedTypeForApproximation as ConeClassLikeType
+            else -> expectedTypeForApproximation
         }
         return approximatedType.withNullability(nullability)
     }

compiler/testData/codegen/box/annotations/annotationTargets.kt

@@ -1,5 +1,3 @@
-// TARGET_BACKEND: JVM
-// IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
 // FULL_JDK
 

compiler/testData/codegen/box/jvmName/fileFacades/javaAnnotationOnFileFacade.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: StringHolder.java

compiler/testData/codegen/box/reflection/createAnnotation/callByJava.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 
 // WITH_REFLECT

compiler/testData/codegen/box/reflection/createAnnotation/createJdkAnnotationInstance.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 
 // WITH_REFLECT

compiler/testData/ir/irText/expressions/primitivesImplicitConversions.fir.txt

@@ -63,9 +63,9 @@ FILE fqName:<root> fileName:/primitivesImplicitConversions.kt
       VAR name:test2 type:kotlin.Long [val]
         CONST Long type=kotlin.Long value=42
       VAR name:test3 type:kotlin.Long? [val]
-        CONST Int type=kotlin.Int value=42
+        CONST Long type=kotlin.Long value=42
       VAR name:test4 type:kotlin.Long? [val]
-        CONST Int type=kotlin.Int value=-1
+        CONST Long type=kotlin.Long value=-1
       VAR name:test5 type:kotlin.Long? [val]
         CONST Int type=kotlin.Int value=-1
       VAR name:test6 type:kotlin.Short? [val]