// used iff the qualified expression is.
            is KtQualifiedExpression ->
                parent.receiverExpression == child || (parent.selectorExpression == child && isUsed(parent))

            // Array accesses use both receiver and index.
            is KtArrayAccessExpression ->
                child in parent.indexExpressions || parent.arrayExpression == child

            substitutedType.varargElementType().asKtType()
        else
            substitutedType.asKtType()
    }

    /**
     * Expected type of the indexing parameter in array access, for example, in the following code:
     * ```
     * val map = mapOf<Int, String>()
     * map[k] = v
     * ```
     * `k` is indexing parameter and its expected type is `Int`.
     */