zoecarver added a comment. > If it is not possible to copy or move the type at all, it is not possible to > copy or move it trivially.
This was a bit confusing to me because I think this changed between C++14 and 17. In C++14, a class was trivially copyable if it had no non-trivial copy/move constructors. But now the standard requires at least one non-trivial move/copy constructor. It looks like <https://godbolt.org/z/47W7qK> the type traits maybe haven't caught up. > So S0 may representationally depend on its address, and we should > ignore/diagnose trivial_abi on aggregates containing an S0. I guess the question is, does a type with all copy/move constructors deleted //and the trivial_abi attribute// depend on its address? And the whole point of this patch is to make that answer, "no." But, a type //without// the attribute, //does// depend on its address. And therefore a type holding `S0` (without the attribute) also depends on its address because it implicitly has no copy/move constructors. I'm not sure I understand why we need to diagnose aggregates containing an `S0` or why the trivial_abi attribute couldn't be applied to those types, though. > Similarly, if a subobject type has only non-trivial copy/move constructors > (but a trivial destructor), we should assume that it representationally > depends on its address and prevent aggregates containing it from being passed > directly, even if the containing type deletes all its copy/move constructors > and uses trivial_abi. I concur with the first part of this, at least. That is, `S3` should //not// be passed directly because it is non-trivially copyable (because of its member) and does not have the attribute. Similar to above, I don't understand why we couldn't pass it directly if it had the attribute, though. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D92361/new/ https://reviews.llvm.org/D92361 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
