K2: Remove unreachable branch in when at SubstitutionOverrideCache

- It happens because FirSyntheticPropertySymbol <: FirPropertySymbol
- Also remove functions became unused

^KT-54345 Related

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/impl/FirClassSubstitutionScope.kt

@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.FirSessionComponent
 import org.jetbrains.kotlin.fir.caches.*
 import org.jetbrains.kotlin.fir.declarations.*
-import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
 import org.jetbrains.kotlin.fir.declarations.utils.visibility
 import org.jetbrains.kotlin.fir.dispatchReceiverClassLookupTagOrNull
 import org.jetbrains.kotlin.fir.originalForSubstitutionOverride
@@ -321,49 +320,6 @@ class FirClassSubstitutionScope(
         return FirFakeOverrideGenerator.createSubstitutionOverrideField(session, member, derivedClassLookupTag, newReturnType)
     }
 
-    fun createSubstitutionOverrideSyntheticProperty(original: FirSyntheticPropertySymbol): FirSyntheticPropertySymbol {
-        if (substitutor == ConeSubstitutor.Empty) return original
-        original.lazyResolveToPhase(FirResolvePhase.TYPES)
-        val member = original.fir as FirSyntheticProperty
-        if (skipPrivateMembers && member.visibility == Visibilities.Private) return original
-
-        val returnType = member.returnTypeRef.coneTypeSafe<ConeKotlinType>()
-        val fakeOverrideSubstitution = runIf(returnType == null) { FakeOverrideSubstitution(substitutor, original) }
-        val newReturnType = returnType?.substitute()
-
-        val newGetterParameterTypes = member.getter.valueParameters.map {
-            it.returnTypeRef.coneType.substitute()
-        }
-        val newSetterParameterTypes = member.setter?.valueParameters?.map {
-            it.returnTypeRef.coneType.substitute()
-        }.orEmpty()
-
-        val newContextReceiverTypes = member.contextReceivers.map {
-            it.typeRef.coneType.substitute()
-        }
-
-        if (original.dispatchReceiverType?.substitute(substitutor) == null &&
-            newReturnType == null &&
-            newGetterParameterTypes.all { it == null } &&
-            newSetterParameterTypes.all { it == null }
-        ) {
-            return original
-        }
-
-        return FirFakeOverrideGenerator.createSubstitutionOverrideSyntheticProperty(
-            session,
-            member,
-            derivedClassLookupTag,
-            original,
-            substitutor.substituteOrSelf(dispatchReceiverTypeForSubstitutedMembers) as ConeSimpleKotlinType?,
-            newContextReceiverTypes,
-            newReturnType,
-            newGetterParameterTypes,
-            newSetterParameterTypes,
-            fakeOverrideSubstitution
-        )
-    }
-
     override fun processDeclaredConstructors(processor: (FirConstructorSymbol) -> Unit) {
         useSiteMemberScope.processDeclaredConstructors process@{ original ->
             val constructor = substitutionOverrideCache.overridesForConstructors.getValue(original, this)
@@ -400,7 +356,6 @@ class FirSubstitutionOverrideStorage(val session: FirSession) : FirSessionCompon
                 when (original) {
                     is FirPropertySymbol -> scope.createSubstitutionOverrideProperty(original)
                     is FirFieldSymbol -> scope.createSubstitutionOverrideField(original)
-                    is FirSyntheticPropertySymbol -> scope.createSubstitutionOverrideSyntheticProperty(original)
                     else -> error("symbol $original is not overridable")
                 }
             }

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/impl/FirFakeOverrideGenerator.kt

@@ -13,8 +13,6 @@ import org.jetbrains.kotlin.fir.declarations.builder.*
 import org.jetbrains.kotlin.fir.declarations.impl.FirDefaultPropertyAccessor
 import org.jetbrains.kotlin.fir.declarations.impl.FirDefaultPropertyGetter
 import org.jetbrains.kotlin.fir.declarations.impl.FirDefaultPropertySetter
-import org.jetbrains.kotlin.fir.declarations.synthetic.FirSyntheticProperty
-import org.jetbrains.kotlin.fir.declarations.synthetic.buildSyntheticProperty
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.resolve.substitution.ChainedSubstitutor
 import org.jetbrains.kotlin.fir.resolve.substitution.ConeSubstitutor
@@ -26,11 +24,10 @@ import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
-import org.jetbrains.kotlin.fir.types.impl.FirImplicitTypeRefImplWithoutSource
 import org.jetbrains.kotlin.fir.types.impl.ConeTypeParameterTypeImpl
+import org.jetbrains.kotlin.fir.types.impl.FirImplicitTypeRefImplWithoutSource
 import org.jetbrains.kotlin.name.CallableId
 import org.jetbrains.kotlin.name.ClassId
-import org.jetbrains.kotlin.name.StandardClassIds
 import org.jetbrains.kotlin.utils.addToStdlib.runIf
 
 object FirFakeOverrideGenerator {
@@ -662,60 +659,6 @@ object FirFakeOverrideGenerator {
         return symbol
     }
 
-    fun createSubstitutionOverrideSyntheticProperty(
-        session: FirSession,
-        baseProperty: FirSyntheticProperty,
-        derivedClassLookupTag: ConeClassLikeLookupTag,
-        baseSymbol: FirSyntheticPropertySymbol,
-        newDispatchReceiverType: ConeSimpleKotlinType?,
-        newContextReceiverTypes: List<ConeKotlinType?>?,
-        newReturnType: ConeKotlinType?,
-        newGetterParameterTypes: List<ConeKotlinType?>?,
-        newSetterParameterTypes: List<ConeKotlinType?>?,
-        fakeOverrideSubstitution: FakeOverrideSubstitution?
-    ): FirSyntheticPropertySymbol {
-        val getterSymbol = FirNamedFunctionSymbol(baseSymbol.getterId)
-        val getter = createSubstitutionOverrideFunction(
-            getterSymbol,
-            session,
-            baseProperty.getter.delegate,
-            derivedClassLookupTag,
-            newDispatchReceiverType,
-            newReceiverType = null,
-            newContextReceiverTypes,
-            newReturnType,
-            newGetterParameterTypes,
-            newTypeParameters = null,
-            fakeOverrideSubstitution = fakeOverrideSubstitution
-        )
-        val setterSymbol = FirNamedFunctionSymbol(baseSymbol.getterId)
-        val baseSetter = baseProperty.setter
-        val setter = if (baseSetter == null) null else createSubstitutionOverrideFunction(
-            setterSymbol,
-            session,
-            baseSetter.delegate,
-            derivedClassLookupTag,
-            newDispatchReceiverType,
-            newReceiverType = null,
-            newContextReceiverTypes,
-            StandardClassIds.Unit.constructClassLikeType(emptyArray(), isNullable = false),
-            newSetterParameterTypes,
-            newTypeParameters = null,
-            fakeOverrideSubstitution = fakeOverrideSubstitution
-        )
-        return buildSyntheticProperty {
-            moduleData = session.moduleData
-            name = baseProperty.name
-            symbol = baseSymbol.copy()
-            delegateGetter = getter
-            delegateSetter = setter
-            status = baseProperty.status
-            deprecationsProvider = getDeprecationsProviderFromAccessors(session, getter, setter)
-        }.apply {
-            containingClassForStaticMemberAttr = derivedClassLookupTag.takeIf { shouldOverrideSetContainingClass(baseProperty) }
-        }.symbol
-    }
-
     // Returns a list of type parameters, and a substitutor that should be used for all other types
     fun createNewTypeParametersAndSubstitutor(
         useSiteSession: FirSession,