JVM: use a safer version of fileParent for Java declarations

Java declarations do not have a file parent, their outer element is
IrExternalPackageFragment.

The test did not fail in K1 only by accident, because there's an extra
IrTypeOperatorCall on the property reference's dispatch receiver, which
automatically makes it non-inlinable. In K2, it's IrGetField, so we were
trying to compute if its dispatch receiver is inlinable and for that we
tried to get its fileParent, which resulted in exception if it comes
from Java.

Also refactor PropertyReferenceDelegationTransformer.canInline a bit.

 #KT-57955 Fixed

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

@@ -15142,6 +15142,12 @@ public class FirLightTreeBlackBoxCodegenTestGenerated extends AbstractFirLightTr
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt50019_noOptimizedCallableReferences.kt");
             }
 
+            @Test
+            @TestMetadata("kt57955.kt")
+            public void testKt57955() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt");
+            }
+
             @Test
             @TestMetadata("mutable.kt")
             public void testMutable() throws Exception {

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

@@ -15142,6 +15142,12 @@ public class FirPsiBlackBoxCodegenTestGenerated extends AbstractFirPsiBlackBoxCo
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt50019_noOptimizedCallableReferences.kt");
             }
 
+            @Test
+            @TestMetadata("kt57955.kt")
+            public void testKt57955() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt");
+            }
+
             @Test
             @TestMetadata("mutable.kt")
             public void testMutable() throws Exception {

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceDelegationLowering.kt

@@ -11,7 +11,7 @@ import org.jetbrains.kotlin.backend.common.lower.parents
 import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
 import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
 import org.jetbrains.kotlin.backend.jvm.ir.createJvmIrBuilder
-import org.jetbrains.kotlin.backend.jvm.ir.fileParent
+import org.jetbrains.kotlin.backend.jvm.ir.fileParentOrNull
 import org.jetbrains.kotlin.backend.jvm.lower.JvmPropertiesLowering.Companion.createSyntheticMethodForPropertyDelegate
 import org.jetbrains.kotlin.builtins.StandardNames
 import org.jetbrains.kotlin.descriptors.Modality
@@ -21,7 +21,8 @@ import org.jetbrains.kotlin.ir.builders.declarations.buildField
 import org.jetbrains.kotlin.ir.builders.declarations.buildVariable
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.expressions.*
-import org.jetbrains.kotlin.ir.expressions.impl.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrCompositeImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrPropertyReferenceImpl
 import org.jetbrains.kotlin.ir.symbols.impl.IrAnonymousInitializerSymbolImpl
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
@@ -89,15 +90,28 @@ private class PropertyReferenceDelegationTransformer(val context: JvmBackendCont
 
     // Some receivers don't need to be stored in fields and can be reevaluated every time an accessor is called:
     private fun IrExpression.canInline(visibleScopes: Set<IrDeclarationParent>): Boolean = when (this) {
-        // Reads of immutable variables are stable, but value parameters of the constructor are not in scope:
-        is IrGetValue -> symbol.owner.let { !(it is IrVariable && it.isVar) && it.parent in visibleScopes }
-        // Reads of final fields of stable values are stable, but fields in other files can become non-final:
-        is IrGetField -> symbol.owner.let { it.isFinal && it.fileParent in visibleScopes } && receiver?.canInline(visibleScopes) != false
-        // Same applies to reads of properties with default getters, but non-final properties may be overridden by `var`s:
-        is IrCall -> symbol.owner.let { it.isFinalDefaultValGetter && it.fileParent in visibleScopes } &&
-                dispatchReceiver?.canInline(visibleScopes) != false && extensionReceiver?.canInline(visibleScopes) != false
-        // Constants and singleton object accesses are always stable:
-        else -> isTrivial()
+        is IrGetValue -> {
+            // Reads of immutable variables are stable, but value parameters of the constructor are not in scope:
+            val value = symbol.owner
+            !(value is IrVariable && value.isVar) && value.parent in visibleScopes
+        }
+        is IrGetField -> {
+            // Reads of final fields of stable values are stable, but fields in other files can become non-final:
+            val field = symbol.owner
+            field.isFinal && field.fileParentOrNull.let { it != null && it in visibleScopes }
+                    && receiver?.canInline(visibleScopes) != false
+        }
+        is IrCall -> {
+            // Same applies to reads of properties with default getters, but non-final properties may be overridden by `var`s:
+            val callee = symbol.owner
+            callee.isFinalDefaultValGetter && callee.fileParentOrNull.let { it != null && it in visibleScopes }
+                    && dispatchReceiver?.canInline(visibleScopes) != false
+                    && extensionReceiver?.canInline(visibleScopes) != false
+        }
+        else -> {
+            // Constants and singleton object accesses are always stable:
+            isTrivial()
+        }
     }
 
     private val IrSimpleFunction.isFinalDefaultValGetter: Boolean

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/ir/JvmIrUtils.kt

@@ -441,11 +441,14 @@ fun IrMemberAccessExpression<*>.getBooleanConstArgument(i: Int): Boolean =
     } ?: throw AssertionError("Value argument #$i should be a Boolean const: ${dump()}")
 
 val IrDeclaration.fileParent: IrFile
-    get() {
-        return when (val myParent = parent) {
-            is IrFile -> myParent
-            else -> (myParent as IrDeclaration).fileParent
-        }
+    get() = fileParentOrNull ?: error("No file parent: $this")
+
+@Suppress("RecursivePropertyAccessor")
+val IrDeclaration.fileParentOrNull: IrFile?
+    get() = when (val myParent = parent) {
+        is IrFile -> myParent
+        is IrDeclaration -> myParent.fileParentOrNull
+        else -> null
     }
 
 private val RETENTION_PARAMETER_NAME = Name.identifier("value")

compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt

@@ -0,0 +1,16 @@
+// TARGET_BACKEND: JVM
+// WITH_STDLIB
+// FILE: box.kt
+
+class C {
+    val x: Int? by J().s::length
+}
+
+fun box(): String =
+    if (C().x == 0) "OK" else "Fail"
+
+// FILE: J.java
+
+public class J {
+    public final String s = "";
+}

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

@@ -14806,6 +14806,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt50019_noOptimizedCallableReferences.kt");
             }
 
+            @Test
+            @TestMetadata("kt57955.kt")
+            public void testKt57955() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt");
+            }
+
             @Test
             @TestMetadata("mutable.kt")
             public void testMutable() throws Exception {

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

@@ -15142,6 +15142,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt50019_noOptimizedCallableReferences.kt");
             }
 
+            @Test
+            @TestMetadata("kt57955.kt")
+            public void testKt57955() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt");
+            }
+
             @Test
             @TestMetadata("mutable.kt")
             public void testMutable() throws Exception {

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

@@ -15142,6 +15142,12 @@ public class IrBlackBoxCodegenWithIrInlinerTestGenerated extends AbstractIrBlack
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt50019_noOptimizedCallableReferences.kt");
             }
 
+            @Test
+            @TestMetadata("kt57955.kt")
+            public void testKt57955() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt");
+            }
+
             @Test
             @TestMetadata("mutable.kt")
             public void testMutable() throws Exception {

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

@@ -12115,6 +12115,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt50019_noOptimizedCallableReferences.kt");
             }
 
+            @TestMetadata("kt57955.kt")
+            public void testKt57955() throws Exception {
+                runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/kt57955.kt");
+            }
+
             @TestMetadata("mutable.kt")
             public void testMutable() throws Exception {
                 runTest("compiler/testData/codegen/box/delegatedProperty/delegateToAnother/mutable.kt");