I don't want to be "that guy," but when, exactly? "Pre-Constantine" consists of nearly the entirety of Roman history. The attitudes of various people towards witchcraft are not at all consistent across these periods. Furthermore, among whom? While witchcraft was prohibited by law as far back as the lex Cornelia, we know that it was widely practiced and attitudes towards witchcraft were completely different among different levels of society and in different parts of the Roman world. If by "tolerant" we mean tolerated (or not) by law, then that helps narrow things down a little bit, but only by a little bit--the interpretation of the lex Cornelia, which was by far the most important piece of legislation pertaining to witchcraft, changed radically within only a few centuries, and in the Dominate and late Principate the influence simultaneously of Christianity and Neoplatonism greatly shaped the way magic was understood