jlebar added a comment. Thank you, Marshall.
In https://reviews.llvm.org/D25403#572998, @mclow.lists wrote: > My build setup is similar to yours (on Mac OS X): > > cd $LLVM_BUILD ; rm -rf libcxx ; mkdir libcxx ; cd libcxx > CXX=$LLVM_BIN/clang++ cmake -DLLVM_PATH=$LLVM/llvm > -DLIBCXX_CXX_ABI=libcxxabi -DLIBCXX_CXX_ABI_INCLUDE_PATHS=/usr/include $LIBCXX > make # build libc++ > make check-libcxx # run the tests Ah, it's -DLIBCXX_CXX_ABI and -DLIBCXX_CXX_ABI_INCLUDE_PATHS that I was missing. Is this the recommended way of building libcxx? Should I update the documentation? Likewise, should I update the documentation to indicate that check-cxx may fail with a clang built from tip of tree, due to c++17 support being experimental? Or do you all want to change the target so that it doesn't run the c++17 tests by default? This burned about an hour of developer time yesterday, I guess because we couldn't believe that check-cxx would be intentionally broken like that, so it would be nice to have some sort of fix. > I don't see how this can possibly be constexpr. > it calls isfinite(), which is hoisted from ::isfinite(), which comes from > the C library. > Since C knows nothing about constexpr, we're stuck. Functions that call non-constexpr things can be marked constexpr; you just can't evaluate them in a constexpr context (as you demonstrated). All I need is for the function to be marked as constexpr; I do not need the function be constexpr-evaluatable. I think the implications of this change would be that, if you evaluated this function in a constexpr context, before the change would be a compile error when calling __libcpp_isnan, and after this change it would be a compile error at calling ::isnan. Since the function should not be called outside of libc++ anyway, I was hoping that wouldn't make a difference to anyone. https://reviews.llvm.org/D25403 _______________________________________________ cfe-commits mailing list firstname.lastname@example.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits