override val token: KtLifetimeToken,
    override val firSymbol: FirFunctionSymbol<*>,
    override val firSymbolBuilder: KtSymbolByFirBuilder,
) : KtFirFunctionLikeSignature<S>() {
    @Suppress("UNCHECKED_CAST")
    override val symbol: S
        get() = withValidityAssertion { firSymbol.buildSymbol(firSymbolBuilder) as S }
    override val returnType: KtType
        get() = withValidityAssertion { symbol.returnType }