lebedev.ri added inline comments.
================ Comment at: test/libcxx/diagnostics/force_nodiscard.pass.cpp:16 +// MODULES_DEFINES: _LIBCPP_FORCE_NODISCARD +#define _LIBCPP_DISABLE_NODISCARD_AFTER_CXX17 +#define _LIBCPP_FORCE_NODISCARD ---------------- lebedev.ri wrote: > Quuxplusone wrote: > > What is the purpose of `_LIBCPP_DISABLE_NODISCARD_AFTER_CXX17`? I guess I > > could understand a blanket opt-in "please don't warn me about discarded > > [[nodiscard]] results"; but that should be (and is) spelled > > `-Wno-unused-result`, and it has nothing to do with C++17. > > > > I like how this patch defines `_LIBCPP_NODISCARD` in non-C++17 modes; > > that's going to be very useful. But I think all these opt-in mechanisms are > > confusing and not-helpful. > > > > If we must have an opt-in/out mechanism (which I don't believe we do), > > please consider adding the following two lines to `<__config>` and removing > > the rest: > > > > #ifdef _LIBCPP_NODISCARD > > // the user has given us their preferred spelling; use it > > unconditionally > > #elif __has_cpp_attribute(nodiscard) && _LIBCPP_STD_VER > 17 > > [... etc etc ...] > > > > If we must have an opt-in/out mechanism (which I don't believe we do) > > Yes, we do. > Opt-out is pre-existing, and removing it would be an [unacceptable] > regression. > Opt-in is an enhancement. Of course, it would be nice to always default it to > on, > but as it was disscussed with @mclow.lists, this is simply not going to > happen. > This is the best we'll get. > > ``` > #ifdef _LIBCPP_NODISCARD > // the user has given us their preferred spelling; use it unconditionally > ``` > So you propose to shift the burden of picking which define to use to each and > every > libc++ user (who wants to enable nodiscard attribute for pre-C++17/whatever) > out there? > I really don't see how that would be better. I tried to do that, but completely failed to come up with testing, so i'm not going to do this here, sorry. Repository: rCXX libc++ https://reviews.llvm.org/D45179 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
