From 962059a878e9881a0d4df7c07168e30f3c590d94 Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <mikhail.glukhikh@jetbrains.com>
Date: Tue, 25 Aug 2020 17:58:25 +0300
Subject: [PATCH] Introduce FirProperty.hasBackingField & use it in FIR2IR

---
 .../fir/backend/Fir2IrDeclarationStorage.kt   | 39 +++++++++----------
 .../fir/declarations/FirDeclarationUtil.kt    |  9 +++++
 2 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt
index 3e5446e2cf5..64530a99caf 100644
--- a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt
+++ b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt
@@ -674,30 +674,27 @@ class Fir2IrDeclarationStorage(
                     val delegate = property.delegate
                     val getter = property.getter
                     val setter = property.setter
-                    // TODO: this checks are very preliminary, FIR resolve should determine backing field presence itself
                     if (property.isConst || (property.modality != Modality.ABSTRACT && (irParent !is IrClass || !irParent.isInterface))) {
-                        if (initializer != null ||
-                            getter is FirDefaultPropertyGetter ||
-                            property.isVar && setter is FirDefaultPropertySetter ||
-                            property.isReferredViaField == true
-                        ) {
-                            backingField = createBackingField(
-                                property, IrDeclarationOrigin.PROPERTY_BACKING_FIELD, descriptor,
-                                components.visibilityConverter.convertToOldVisibility(property.fieldVisibility),
-                                property.name, property.isVal, initializer, type
-                            ).also { field ->
-                                if (initializer is FirConstExpression<*>) {
-                                    // TODO: Normally we shouldn't have error type here
-                                    val constType = initializer.typeRef.toIrType().takeIf { it !is IrErrorType } ?: type
-                                    field.initializer = factory.createExpressionBody(initializer.toIrConst(constType))
+                        if (property.hasBackingField) {
+                            backingField = if (delegate != null) {
+                                createBackingField(
+                                    property, IrDeclarationOrigin.PROPERTY_DELEGATE, descriptor,
+                                    components.visibilityConverter.convertToOldVisibility(property.fieldVisibility),
+                                    Name.identifier("${property.name}\$delegate"), true, delegate
+                                )
+                            } else {
+                                createBackingField(
+                                    property, IrDeclarationOrigin.PROPERTY_BACKING_FIELD, descriptor,
+                                    components.visibilityConverter.convertToOldVisibility(property.fieldVisibility),
+                                    property.name, property.isVal, initializer, type
+                                ).also { field ->
+                                    if (initializer is FirConstExpression<*>) {
+                                        // TODO: Normally we shouldn't have error type here
+                                        val constType = initializer.typeRef.toIrType().takeIf { it !is IrErrorType } ?: type
+                                        field.initializer = factory.createExpressionBody(initializer.toIrConst(constType))
+                                    }
                                 }
                             }
-                        } else if (delegate != null) {
-                            backingField = createBackingField(
-                                property, IrDeclarationOrigin.PROPERTY_DELEGATE, descriptor,
-                                components.visibilityConverter.convertToOldVisibility(property.fieldVisibility),
-                                Name.identifier("${property.name}\$delegate"), true, delegate
-                            )
                         }
                         if (irParent != null) {
                             backingField?.parent = irParent
diff --git a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationUtil.kt b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationUtil.kt
index e6632573ce3..301a07261f5 100644
--- a/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationUtil.kt
+++ b/compiler/fir/tree/src/org/jetbrains/kotlin/fir/declarations/FirDeclarationUtil.kt
@@ -9,6 +9,8 @@ import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.fir.Visibilities
 import org.jetbrains.kotlin.fir.declarations.builder.FirRegularClassBuilder
 import org.jetbrains.kotlin.fir.declarations.builder.FirTypeParameterBuilder
+import org.jetbrains.kotlin.fir.declarations.impl.FirDefaultPropertyGetter
+import org.jetbrains.kotlin.fir.declarations.impl.FirDefaultPropertySetter
 import org.jetbrains.kotlin.fir.declarations.impl.FirFileImpl
 import org.jetbrains.kotlin.fir.declarations.impl.FirRegularClassImpl
 import org.jetbrains.kotlin.fir.symbols.impl.FirAnonymousObjectSymbol
@@ -119,6 +121,13 @@ var FirProperty.isFromVararg: Boolean? by FirDeclarationDataRegistry.data(IsFrom
 private object IsReferredViaField : FirDeclarationDataKey()
 var FirProperty.isReferredViaField: Boolean? by FirDeclarationDataRegistry.data(IsReferredViaField)
 
+val FirProperty.hasBackingField: Boolean
+    get() = initializer != null ||
+            getter is FirDefaultPropertyGetter ||
+            isVar && setter is FirDefaultPropertySetter ||
+            delegate != null ||
+            isReferredViaField == true
+
 inline val FirProperty.hasJvmFieldAnnotation: Boolean
     get() = annotations.any {
         val classId = it.annotationTypeRef.coneTypeSafe<ConeClassLikeType>()?.classId