rsmith added inline comments.
================ Comment at: clang/lib/AST/RecordLayoutBuilder.cpp:1891 + llvm::Triple Target = Context.getTargetInfo().getTriple(); + bool FieldPacked = (Packed && (!FieldClass || FieldClass->isPOD() || + Context.getLangOpts().getClangABICompat() <= ---------------- dblaikie wrote: > rsmith wrote: > > dblaikie wrote: > > > rsmith wrote: > > > > `isPOD` is C++ standard specific, and our ABI rule really shouldn't be. > > > > Does GCC use the C++98 rules here, the C++11 rules, or something else? > > > > (Hopefully the GCC behavior doesn't change between `-std=c++98` and > > > > `-std=c++11`!) > > > > > > > > From a quick test, it looks like GCC doesn't pack fields whose types > > > > are classes with base classes, even if they're trivially-copyable and > > > > standard-layout, suggesting that it's probably using the C++98 POD > > > > rules. > > > I /think/ `CXXRecordDecl::isPOD` doesn't use a language-varying > > > definition, according to its documentation at least: > > > https://github.com/llvm/llvm-project/blob/1e3a02162db20264e9615b1346420c8d199cb347/clang/include/clang/AST/DeclCXX.h#L1124 > > > & the code that sets the field that the accessor returns looks, to me at > > > least, consistent with that claim: > > > https://github.com/llvm/llvm-project/blob/1e3a02162db20264e9615b1346420c8d199cb347/clang/lib/AST/DeclCXX.cpp#L983 > > > > > > But if there's another way I should spell this to make it more > > > clear/correct, more test cases to add to show the difference between > > > these definitions - I'm open to that... > > Ah, right you are, I was thinking of `QualType::isPODType`, which does > > depend on the language mode: > > https://github.com/llvm/llvm-project/blob/1e3a02162db20264e9615b1346420c8d199cb347/clang/lib/AST/Type.cpp#L2350 > > > > No action necessary here, I think. > Cool - reckon it's worth renaming it to be more clear about which POD it > represents? `IsClassicPOD`, `isRetroPOD`, `isCXX03POD`? If anything I think it might make more sense to remove the language-sensitive version and always use POD to mean the C++03 thing. I think the only thing that should want standard-layout + trivially-copyable should be the `__is_pod` trait (and maybe some target-specific ABI rules?). The very notion of "POD" as a shorthand for "standard-layout and trivially-copyable" was deprecated in C++20. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D117616/new/ https://reviews.llvm.org/D117616 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
