std::max_align_tis astandard-layoutTrivialType(until C++26)TriviallyCopyabletype(since C++26)whosealignment requirementis at least as strict (as large) as that of every scalar type. std::is_trivially_default_constructible_v<std::max_align_t>istrue. ...
For the record this is not something I've seen before. In any case it doesn't appear to be really a "Catch" thing - although perhaps something about the way Catch includes std lib headers brought it out? The max_align_t does not appear in Catch, at least. Glad you got it sorted,...