jyknight added a comment. In D144889#4156974 <https://reviews.llvm.org/D144889#4156974>, @rsmith wrote:
> Likely because of GCC's perspective on this, the set of C headers provided by > GCC, Clang, ICC, etc. has included the complete list of freestanding headers > and more or less no others, with some libc implementations providing the full > set and some providing just the non-freestanding ones. If we're moving away > from that, we'll presumably need a new agreement between compiler folks and > libc folks about which headers are provided by whom (and I expect it'll be > "compilers provide what the C standard said before this change to > freestanding and we pretend the change never happened"). Yeah...this seems like a pretty big divergence from the historical view compilers have for "freestanding" mode, and I think the implementation should be more along the lines of a "micro-libc", than something built into clang. Especially considering the potential future additions e.g. `errno.h`. If we look at this as a specification for what to provide in a "micro-libc", having such global state is not a major issue, but if we look at this as a "compiler builtin" sort of thing (ala traditional freestanding), then it's quite a problem. So, I think the correct solution here is to just document what parts of a C2x-conforming "freestanding" Clang provides itself, and what remains for an external "mini-libc" implementation to provide. It probably makes sense for one such external implementation to be provided by llvm-libc in the future -- I suspect it should have a separate "freestanding" target mode, which would omit all the runtime features like memory allocation and threads, and provide just the pure library functionality. But I'd also expect such an llvm-libc freestanding mode would also provide a lot more functionality than just the minimum requirements -- there's a whole lot more "pure library" functions in C than just the ones required in the new "freestanding" standard. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D144889/new/ https://reviews.llvm.org/D144889 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
