[Commonizer] Lift up identical const properties

^KMM-241

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/builder/propertyDescriptors.kt

@@ -24,10 +24,16 @@ internal fun CirPropertyNode.buildDescriptors(
     containingDeclarations: List<DeclarationDescriptor?>
 ) {
     val commonProperty = common()
-    val markAsExpectAndActual = commonProperty != null && commonProperty.kind != CallableMemberDescriptor.Kind.SYNTHESIZED
 
-    target.forEachIndexed { index, property ->
-        property?.buildDescriptor(components, output, index, containingDeclarations, isActual = markAsExpectAndActual)
+    val isLiftedUp = commonProperty?.isLiftedUp == true
+    val markAsExpectAndActual = commonProperty != null
+            && commonProperty.kind != CallableMemberDescriptor.Kind.SYNTHESIZED
+            && !isLiftedUp
+
+    if (!isLiftedUp) {
+        target.forEachIndexed { index, property ->
+            property?.buildDescriptor(components, output, index, containingDeclarations, isActual = markAsExpectAndActual)
+        }
     }
 
     commonProperty?.buildDescriptor(components, output, indexOfCommon, containingDeclarations, isExpect = markAsExpectAndActual)

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/CirDeclaration.kt

@@ -53,5 +53,13 @@ interface CirCallableMemberWithParameters {
     val hasSynthesizedParameterNames: Boolean
 }
 
+/**
+ * Indicates a declaration that could be completely lifted up to "common" fragment.
+ * NOTE: Interning can't be applied to the whole lifted declaration, only to its parts!
+ */
+interface CirLiftedUpDeclaration : CirDeclaration {
+    val isLiftedUp: Boolean
+}
+
 /** Indicates presence of recursion in lazy calculations. */
 interface CirRecursionMarker : CirDeclaration

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/CirProperty.kt

@@ -7,7 +7,7 @@ package org.jetbrains.kotlin.descriptors.commonizer.cir
 
 import org.jetbrains.kotlin.resolve.constants.ConstantValue
 
-interface CirProperty : CirFunctionOrProperty {
+interface CirProperty : CirFunctionOrProperty, CirLiftedUpDeclaration {
     val isVar: Boolean
     val isLateInit: Boolean
     val isConst: Boolean

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/factory/CirPropertyFactory.kt

@@ -51,7 +51,8 @@ object CirPropertyFactory {
             setter = source.setter?.let(CirPropertySetterFactory::create),
             backingFieldAnnotations = source.backingField?.annotations?.map(CirAnnotationFactory::create),
             delegateFieldAnnotations = source.delegateField?.annotations?.map(CirAnnotationFactory::create),
-            compileTimeInitializer = source.compileTimeInitializer
+            compileTimeInitializer = source.compileTimeInitializer,
+            isLiftedUp = false
         )
     }
 
@@ -75,7 +76,8 @@ object CirPropertyFactory {
         setter: CirPropertySetter?,
         backingFieldAnnotations: List<CirAnnotation>?,
         delegateFieldAnnotations: List<CirAnnotation>?,
-        compileTimeInitializer: ConstantValue<*>?
+        compileTimeInitializer: ConstantValue<*>?,
+        isLiftedUp: Boolean
     ): CirProperty {
         return CirPropertyImpl(
             annotations = annotations,
@@ -96,7 +98,8 @@ object CirPropertyFactory {
             setter = setter,
             backingFieldAnnotations = backingFieldAnnotations,
             delegateFieldAnnotations = delegateFieldAnnotations,
-            compileTimeInitializer = compileTimeInitializer
+            compileTimeInitializer = compileTimeInitializer,
+            isLiftedUp = isLiftedUp
         )
     }
 }

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/impl/CirPropertyImpl.kt

@@ -31,5 +31,6 @@ data class CirPropertyImpl(
     override val setter: CirPropertySetter?,
     override val backingFieldAnnotations: List<CirAnnotation>?,
     override val delegateFieldAnnotations: List<CirAnnotation>?,
-    override val compileTimeInitializer: ConstantValue<*>?
+    override val compileTimeInitializer: ConstantValue<*>?,
+    override val isLiftedUp: Boolean
 ) : CirProperty

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/core/PropertyCommonizer.kt

@@ -9,13 +9,16 @@ import org.jetbrains.kotlin.descriptors.commonizer.cir.CirProperty
 import org.jetbrains.kotlin.descriptors.commonizer.cir.factory.CirPropertyFactory
 import org.jetbrains.kotlin.descriptors.commonizer.cir.factory.CirPropertyGetterFactory
 import org.jetbrains.kotlin.descriptors.commonizer.mergedtree.CirClassifiersCache
+import org.jetbrains.kotlin.resolve.constants.ConstantValue
 
 class PropertyCommonizer(cache: CirClassifiersCache) : AbstractFunctionOrPropertyCommonizer<CirProperty>(cache) {
     private val setter = PropertySetterCommonizer()
     private var isExternal = true
+    private var constCompileTimeInitializer: ConstantValue<*>? = null
 
     override fun commonizationResult(): CirProperty {
         val setter = setter.result
+        val constCompileTimeInitializer = constCompileTimeInitializer
 
         return CirPropertyFactory.create(
             annotations = emptyList(),
@@ -30,20 +33,43 @@ class PropertyCommonizer(cache: CirClassifiersCache) : AbstractFunctionOrPropert
             kind = kind,
             isVar = setter != null,
             isLateInit = false,
-            isConst = false,
+            isConst = constCompileTimeInitializer != null,
             isDelegate = false,
             getter = CirPropertyGetterFactory.DEFAULT_NO_ANNOTATIONS,
             setter = setter,
             backingFieldAnnotations = null,
             delegateFieldAnnotations = null,
-            compileTimeInitializer = null
+            compileTimeInitializer = constCompileTimeInitializer,
+            isLiftedUp = constCompileTimeInitializer != null
         )
     }
 
+    override fun initialize(first: CirProperty) {
+        super.initialize(first)
+
+        if (first.isConst) {
+            constCompileTimeInitializer = first.compileTimeInitializer
+        }
+    }
+
     override fun doCommonizeWith(next: CirProperty): Boolean {
-        when {
-            next.isConst -> return false // expect property can't be const because expect can't have initializer
-            next.isLateInit -> return false // expect property can't be lateinit
+        if (next.isLateInit) {
+            // expect property can't be lateinit
+            return false
+        }
+
+        val constCompileTimeInitializer = constCompileTimeInitializer
+        if (next.isConst) {
+            // const properties should be lifted up
+            // otherwise commonization should fail: expect property can't be const because expect can't have initializer
+
+            if (constCompileTimeInitializer == null || constCompileTimeInitializer != next.compileTimeInitializer) {
+                // previous property was not constant or const properties have different constants
+                return false
+            }
+        } else if (constCompileTimeInitializer != null) {
+            // previous property was constant but this one is not
+            return false
         }
 
         val result = super.doCommonizeWith(next)