[FIR] Introduce cache for not-yet-enhanced synthetic properties

The original synthetic properties from Java were not cached anywhere and
created anew for every session. However, the enhanced properties are
(along with their originals) saved inside the session's cache, causing
inconsistency with newly created symbols via referential equality.

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirOriginalSyntheticPropertiesStorage.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.java
+
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.FirSessionComponent
+import org.jetbrains.kotlin.fir.caches.FirCache
+import org.jetbrains.kotlin.fir.caches.createCache
+import org.jetbrains.kotlin.fir.caches.firCachesFactory
+import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirSyntheticPropertySymbol
+import org.jetbrains.kotlin.name.Name
+
+class FirOriginalSyntheticPropertiesStorage(session: FirSession) : FirSessionComponent {
+    private val cachesFactory = session.firCachesFactory
+
+    val cacheByOwner: FirCache<FirRegularClassSymbol, FirCache<Name, FirSyntheticPropertySymbol, FirSyntheticPropertySymbol>, Nothing?> =
+        cachesFactory.createCache { _ ->
+            cachesFactory.createCache { _, symbol -> symbol }
+        }
+
+}
+
+val FirSession.originalSyntheticPropertiesStorage: FirOriginalSyntheticPropertiesStorage by FirSession.sessionComponentAccessor()

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/scopes/JavaClassUseSiteMemberScope.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.fir.java.declarations.FirJavaMethod
 import org.jetbrains.kotlin.fir.java.declarations.buildJavaMethodCopy
 import org.jetbrains.kotlin.fir.java.declarations.buildJavaValueParameterCopy
 import org.jetbrains.kotlin.fir.java.symbols.FirJavaOverriddenSyntheticPropertySymbol
+import org.jetbrains.kotlin.fir.java.originalSyntheticPropertiesStorage
 import org.jetbrains.kotlin.fir.java.toConeKotlinTypeProbablyFlexible
 import org.jetbrains.kotlin.fir.resolve.defaultType
 import org.jetbrains.kotlin.fir.scopes.*
@@ -59,19 +60,21 @@ class JavaClassUseSiteMemberScope(
     declaredMemberScope
 ) {
     private val typeParameterStack = klass.javaTypeParameterStack
-    private val syntheticPropertyByNameMap = hashMapOf<Name, FirSyntheticPropertySymbol>()
 
     private val canUseSpecialGetters: Boolean by lazy { !klass.hasKotlinSuper(session) }
 
     private val javaOverrideChecker: JavaOverrideChecker get() = overrideChecker as JavaOverrideChecker
 
+    private val syntheticPropertyCache = session.originalSyntheticPropertiesStorage.cacheByOwner.getValue(klass.symbol, null)
+
     private fun generateSyntheticPropertySymbol(
         getterSymbol: FirNamedFunctionSymbol,
         setterSymbol: FirNamedFunctionSymbol?,
         property: FirProperty,
         takeModalityFromGetter: Boolean,
     ): FirSyntheticPropertySymbol {
-        return syntheticPropertyByNameMap.getOrPut(property.name) {
+        return syntheticPropertyCache.getValue(
+            property.name,
             buildSyntheticProperty {
                 moduleData = session.moduleData
                 name = property.name
@@ -90,7 +93,7 @@ class JavaClassUseSiteMemberScope(
                 )
                 deprecationsProvider = getDeprecationsProviderFromAccessors(session, delegateGetter, delegateSetter)
             }.symbol
-        }
+        )
     }
 
     private fun chooseModalityForAccessor(property: FirProperty, getter: FirSimpleFunction): Modality? {