FIR: Remove FirCallableSymbol::overriddenSymbol

compiler/fir/tree/src/org/jetbrains/kotlin/fir/ClassMembers.kt

@@ -34,13 +34,13 @@ val FirCallableDeclaration<*>.isIntersectionOverride get() = origin == FirDeclar
 val FirCallableDeclaration<*>.isSubstitutionOverride get() = origin == FirDeclarationOrigin.SubstitutionOverride
 
 inline val <reified D : FirCallableDeclaration<*>> D.originalForSubstitutionOverride: D?
-    get() = if (isSubstitutionOverride) symbol.overriddenSymbol?.fir as D? else null
+    get() = if (isSubstitutionOverride) originalForSubstitutionOverrideAttr else null
 
 inline val <reified S : FirCallableSymbol<*>> S.originalForSubstitutionOverride: S?
     get() = fir.originalForSubstitutionOverride?.symbol as S?
 
 inline val <reified D : FirCallableDeclaration<*>> D.baseForIntersectionOverride: D?
-    get() = if (isIntersectionOverride) symbol.overriddenSymbol?.fir as D? else null
+    get() = if (isIntersectionOverride) originalForIntersectionOverrideAttr else null
 
 inline val <reified S : FirCallableSymbol<*>> S.baseForIntersectionOverride: S?
     get() = fir.baseForIntersectionOverride?.symbol as S?
@@ -61,3 +61,11 @@ inline fun <reified D : FirCallableDeclaration<*>> D.unwrapFakeOverrides(): D {
 }
 
 inline fun <reified S : FirCallableSymbol<*>> S.unwrapFakeOverrides(): S = fir.unwrapFakeOverrides().symbol as S
+
+private object SubstitutedOverrideOriginalKey : FirDeclarationDataKey()
+var <D : FirCallableDeclaration<*>>
+        D.originalForSubstitutionOverrideAttr: D? by FirDeclarationDataRegistry.data(SubstitutedOverrideOriginalKey)
+
+private object IntersectionOverrideOriginalKey : FirDeclarationDataKey()
+var <D : FirCallableDeclaration<*>>
+        D.originalForIntersectionOverrideAttr: D? by FirDeclarationDataRegistry.data(IntersectionOverrideOriginalKey)

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/PossiblyFirFakeOverrideSymbol.kt

@@ -8,6 +8,4 @@ package org.jetbrains.kotlin.fir.symbols
 import org.jetbrains.kotlin.fir.FirSymbolOwner
 import org.jetbrains.kotlin.fir.declarations.FirDeclaration
 
-interface PossiblyFirFakeOverrideSymbol<E, S : FirBasedSymbol<E>> : FirBasedSymbol<E> where E : FirSymbolOwner<E>, E : FirDeclaration {
-    val overriddenSymbol: S?
-}
+interface PossiblyFirFakeOverrideSymbol<E, S : FirBasedSymbol<E>> : FirBasedSymbol<E> where E : FirSymbolOwner<E>, E : FirDeclaration

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirCallableSymbol.kt

@@ -14,9 +14,6 @@ import org.jetbrains.kotlin.fir.symbols.CallableId
 
 abstract class FirCallableSymbol<D : FirCallableDeclaration<D>> : AbstractFirBasedSymbol<D>() {
     abstract val callableId: CallableId
-
-    open val overriddenSymbol: FirCallableSymbol<D>?
-        get() = null
 }
 
 val FirCallableSymbol<*>.isStatic: Boolean get() = (fir as? FirMemberDeclaration)?.status?.isStatic == true

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirFunctionSymbol.kt

@@ -24,12 +24,10 @@ sealed class FirFunctionSymbol<D : FirFunction<D>>(
 
 open class FirNamedFunctionSymbol(
     callableId: CallableId,
-    override val overriddenSymbol: FirNamedFunctionSymbol? = null,
 ) : FirFunctionSymbol<FirSimpleFunction>(callableId), PossiblyFirFakeOverrideSymbol<FirSimpleFunction, FirNamedFunctionSymbol>
 
 class FirConstructorSymbol(
-    callableId: CallableId,
-    override val overriddenSymbol: FirConstructorSymbol? = null
+    callableId: CallableId
 ) : FirFunctionSymbol<FirConstructor>(callableId)
 
 open class FirAccessorSymbol(

compiler/fir/tree/src/org/jetbrains/kotlin/fir/symbols/impl/FirVariableSymbol.kt

@@ -23,7 +23,6 @@ open class FirVariableSymbol<D : FirVariable<D>>(override val callableId: Callab
 
 open class FirPropertySymbol(
     callableId: CallableId,
-    override val overriddenSymbol: FirPropertySymbol? = null,
 ) : FirVariableSymbol<FirProperty>(callableId), PossiblyFirFakeOverrideSymbol<FirProperty, FirPropertySymbol> {
     // TODO: should we use this constructor for local variables?
     constructor(name: Name) : this(CallableId(name))