std::char_traits is deprecated in clang 18 and removed in clang 19

[Myoldmopar]

Some minor deprecation warnings after a system update on @nrel-bot-3. They are here: https://myoldmopar.github.io/EnergyPlusBuildResults/EnergyPlus-0c0cdaa269e7b5939c46b710f4dbdef68db8fdac-x86_64-MacOS-10.18-clang-15.0.0.html. There is a related issue that might be helpful here: jtv/libpqxx#738.

[jmarrec]

Is this still a thing? If so, can I get a link to a log that exists?

[jmarrec]

@Myoldmopar Closing for lack of activity. We can reopen if you see them again

[jmarrec]

Can't build with clang 19 now that it's fully removed. happens in both fmt and nlohmann json.

• Fix char_traits deprecation warning nlohmann/json#4179

In file included from /Users/julien/Software/Others/EnergyPlus/third_party/btwxt/src/regular-grid-interpolator.cpp:5:
In file included from /opt/homebrew/opt/llvm@18/bin/../include/c++/v1/iostream:43:
In file included from /opt/homebrew/opt/llvm@18/bin/../include/c++/v1/ios:223:
In file included from /opt/homebrew/opt/llvm@18/bin/../include/c++/v1/__locale:23:
In file included from /opt/homebrew/opt/llvm@18/bin/../include/c++/v1/string:625:
In file included from /opt/homebrew/opt/llvm@18/bin/../include/c++/v1/string_view:213:
/opt/homebrew/opt/llvm@18/bin/../include/c++/v1/__fwd/string_view.h:22:41: warning: 'char_traits<fmt::detail::char8_type>' is deprecated: char_traits<T> for T not equal to char, wchar_t, char8_t, char16_t or char32_t is non-standard and is provided for a temporary period. It will be removed in LLVM 19, so please migrate off of it. [-Wdeprecated-declarations]
   22 | template <class _CharT, class _Traits = char_traits<_CharT> >
      |                                         ^
/Users/julien/Software/Others/EnergyPlus/third_party/fmt-8.0.1/include/fmt/core.h:389:26: note: in instantiation of default argument for 'basic_string_view<fmt::detail::char8_type>' required here
  389 | template <typename Char> using std_string_view = std::basic_string_view<Char>;
      |                          ^~~~~
/Users/julien/Software/Others/EnergyPlus/third_party/fmt-8.0.1/include/fmt/core.h:485:50: note: in instantiation of template type alias 'std_string_view' requested here
  485 |                                       S, detail::std_string_view<Char>>::value)>
      |                                                  ^
/Users/julien/Software/Others/EnergyPlus/third_party/fmt-8.0.1/include/fmt/format.h:562:57: note: in instantiation of template class 'fmt::basic_string_view<fmt::detail::char8_type>' requested here
  562 | inline auto compute_width(basic_string_view<char8_type> s) -> size_t {
      |                                                         ^
/opt/homebrew/opt/llvm@18/bin/../include/c++/v1/__string/char_traits.h:81:8: note: 'char_traits<fmt::detail::char8_type>' has been explicitly marked deprecated here
   81 | struct _LIBCPP_DEPRECATED_(

[jmarrec]

LLVM 19:

[ 39%][520/1331] Building CXX object src/EnergyPlus/CMakeFiles/energypluslib.dir/InputProcessing/InputProcessor.cc.o
FAILED: src/EnergyPlus/CMakeFiles/energypluslib.dir/InputProcessing/InputProcessor.cc.o
/opt/homebrew/bin/ccache /opt/homebrew/opt/llvm@19/bin/clang++ -DDEBUG_ARITHM_GCC_OR_CLANG -DEP_cache_GlycolSpecificHeat -DEP_psych_errors -DFMT_LOCALE -DJSON_USE_IMPLICIT_CONVERSIONS=1 -DLINK_WITH_PYTHON -DOBJEXXFCL_ALIGN=64 -DXML_STATIC -I/Users/julien/.pyenv/versions/3.12.2/include/python3.12 -I/Users/julien/Software/Others/EnergyPlus/idd -I/Users/julien/Software/Others/EnergyPlus/third_party/fmt-8.0.1/include -I/Users/julien/Software/Others/EnergyPlus/src -I/Users/julien/Software/Others/EnergyPlus/third_party -I/Users/julien/Software/Others/EnergyPlus/third_party/btwxt/include -I/Users/julien/Software/Others/EnergyPlus/third_party/re2 -I/Users/julien/Software/Others/EnergyPlus/third_party/doj -I/Users/julien/Software/Others/EnergyPlus/third_party/nlohmann -I/Users/julien/Software/Others/EnergyPlus/third_party/fast_float -I/Users/julien/Software/Others/EnergyPlus/third_party/valijson -I/Users/julien/Software/Others/EnergyPlus/third_party/ObjexxFCL/src -I/Users/julien/Software/Others/EnergyPlus/third_party/CLI -I/Users/julien/Software/Others/EnergyPlus/third_party/eigen -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/Chromogenics/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/Common/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/Gases/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/MultiLayerOptics/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/SingleLayerOptics/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/SpectralAveraging/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/Tarcog/include -I/Users/julien/Software/Others/EnergyPlus/third_party/Windows-CalcEngine/src/Viewer/include -I/Users/julien/Software/Others/EnergyPlus/third_party/ssc -I/Users/julien/Software/Others/EnergyPlus/third_party/penumbra/include -I/Users/julien/Software/Others/EnergyPlus/third_party/kiva/src -I/Users/julien/Software/Others/EnergyPlus-build-clang/third_party/kiva/src/libkiva -I/Users/julien/Software/Others/EnergyPlus/third_party/cpgfunctionEP -I/Users/julien/Software/Others/EnergyPlus/third_party/cpgfunctionEP/include -I/Users/julien/Software/Others/EnergyPlus/third_party/kiva/src/libkiva -I/Users/julien/Software/Others/EnergyPlus/third_party/kiva/vendor/boost-1.77.0 -I/Users/julien/Software/Others/EnergyPlus/third_party/kiva/vendor/eigen -I/Users/julien/Software/Others/EnergyPlus/third_party/btwxt/vendor/courierr/include -I/Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/AirflowNetwork/include -I/Users/julien/Software/Others/EnergyPlus/third_party/ssc/jsoncpp/src/lib_json/../../include -I/Users/julien/Software/Others/EnergyPlus-build-clang/third_party/ssc/jsoncpp/include/json -I/Users/julien/Software/Others/EnergyPlus/third_party/libtk205/include/libtk205 -I/Users/julien/Software/Others/EnergyPlus/third_party/libtk205/vendor/btwxt/include -isystem /Users/julien/Software/Others/EnergyPlus/third_party/SQLite -isystem /Users/julien/Software/Others/EnergyPlus/third_party/Expat -isystem /Users/julien/Software/Others/EnergyPlus/third_party/Expat/lib -isystem /Users/julien/Software/Others/EnergyPlus/third_party/kiva/vendor/boost-1.61.0 -isystem /Users/julien/Software/Others/EnergyPlus/nlohmann -g -arch arm64 -isysroot /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk -mmacosx-version-min=12.1 -fPIC -DOBJEXXFCL_ARRAY_INIT_DEBUG -pipe -fcolor-diagnostics -Wno-deprecated-declarations -w -fPIC -Wpedantic -Wall -Wextra -Wno-unknown-pragmas -Wno-attributes -Wno-delete-non-virtual-dtor -Wno-missing-braces -Wno-unused-but-set-parameter -Wno-unused-but-set-variable -Wno-vexing-parse -Wno-invalid-source-encoding -Winvalid-pch -Xclang -include-pch -Xclang /Users/julien/Software/Others/EnergyPlus-build-clang/src/EnergyPlus/CMakeFiles/energypluslib.dir/cmake_pch.hxx.pch -Xclang -include -Xclang /Users/julien/Software/Others/EnergyPlus-build-clang/src/EnergyPlus/CMakeFiles/energypluslib.dir/cmake_pch.hxx -MD -MT src/EnergyPlus/CMakeFiles/energypluslib.dir/InputProcessing/InputProcessor.cc.o -MF src/EnergyPlus/CMakeFiles/energypluslib.dir/InputProcessing/InputProcessor.cc.o.d -o src/EnergyPlus/CMakeFiles/energypluslib.dir/InputProcessing/InputProcessor.cc.o -c /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/InputProcessing/InputProcessor.cc
In file included from <built-in>:1:
In file included from /Users/julien/Software/Others/EnergyPlus-build-clang/src/EnergyPlus/CMakeFiles/energypluslib.dir/cmake_pch.hxx:6:
In file included from /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/DataGlobals.hh:60:
In file included from /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/IOFiles.hh:62:
In file included from /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/FileSystem.hh:56:
/Users/julien/Software/Others/EnergyPlus/third_party/nlohmann/json.hpp:5346:19: error: implicit instantiation of undefined template 'std::char_traits<unsigned char>'
 5346 |     typename std::char_traits<char_type>::int_type get_character()
      |                   ^
/Users/julien/Software/Others/EnergyPlus/third_party/nlohmann/json.hpp:21116:19: note: in instantiation of template class 'nlohmann::detail::iterator_input_adapter<const unsigned char *>' requested here
 21116 |         auto ia = detail::input_adapter(std::forward<InputType>(i));
       |                   ^
/Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/InputProcessing/InputProcessor.cc:111:43: note: in instantiation of function template specialization 'nlohmann::basic_json<>::from_cbor<const gsl::span<const unsigned char>>' requested here
  111 |     static const auto json_schema = json::from_cbor(EmbeddedEpJSONSchema::embeddedEpJSONSchema()); // (AUTO_OK_OBJ)
      |                                           ^
/opt/homebrew/Cellar/llvm/19.1.4/bin/../include/c++/v1/__fwd/string.h:23:29: note: template is declared here
   23 | struct _LIBCPP_TEMPLATE_VIS char_traits;
      |                             ^
In file included from <built-in>:1:
In file included from /Users/julien/Software/Others/EnergyPlus-build-clang/src/EnergyPlus/CMakeFiles/energypluslib.dir/cmake_pch.hxx:6:
In file included from /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/DataGlobals.hh:60:
In file included from /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/IOFiles.hh:62:
In file included from /Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/FileSystem.hh:56:
/Users/julien/Software/Others/EnergyPlus/third_party/nlohmann/json.hpp:8239:41: error: implicit instantiation of undefined template 'std::char_traits<unsigned char>'
 8239 |     using char_int_type = typename std::char_traits<char_type>::int_type;
      |                                         ^
/Users/julien/Software/Others/EnergyPlus/third_party/nlohmann/json.hpp:21117:26: note: in instantiation of template class 'nlohmann::detail::binary_reader<nlohmann::basic_json<>, nlohmann::detail::iterator_input_adapter<const unsigned char *>>' requested here
 21117 |         const bool res = binary_reader<decltype(ia)>(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler);
       |                          ^
/Users/julien/Software/Others/EnergyPlus/src/EnergyPlus/InputProcessing/InputProcessor.cc:111:43: note: in instantiation of function template specialization 'nlohmann::basic_json<>::from_cbor<const gsl::span<const unsigned char>>' requested here
  111 |     static const auto json_schema = json::from_cbor(EmbeddedEpJSONSchema::embeddedEpJSONSchema()); // (AUTO_OK_OBJ)
      |                                           ^
/opt/homebrew/Cellar/llvm/19.1.4/bin/../include/c++/v1/__fwd/string.h:23:29: note: template is declared here
   23 | struct _LIBCPP_TEMPLATE_VIS char_traits;