clang compiler: error : unknown type name 'not'

[014972304505347]

I am building json.hpp with a project using the Clang/LLVM toolset in Visual Studio 2017 Community Edition (version 15.7.2)and getting these errors (and then some):

              1>------ Build started: Project: SampleProject, Configuration: Debug Win32 ------
              1>clang-cl.exe : warning : argument unused during compilation: '/ZI' [-Wunused-command-line-argument]
              1>clang-cl.exe : warning : argument unused during compilation: '/Gm' [-Wunused-command-line-argument]
              1>In file included from Source.cpp:2:
              1>C:\Program Files\vcpkg\installed\x86-windows\include\nlohmann\json.hpp(322,66): error : unknown type name 'not'
              1>template<class B> struct negation : std::integral_constant<bool, not B::value> {};
              1>                                                                 ^
              1>C:\Program Files\vcpkg\installed\x86-windows\include\nlohmann\json.hpp(322,80): error : expected class name
              1>template<class B> struct negation : std::integral_constant<bool, not B::value> {};

(and many more errors).

Here is the compiler version:

        C:\Program Files\LLVM\bin>clang-cl.exe --version
        clang version 6.0.0 (tags/RELEASE_600/final)
        Target: x86_64-pc-windows-msvc
        Thread model: posix
        InstalledDir: C:\Program Files\LLVM\bin

I highly suspect this is a compiler issue. I successfully compiled the project when using the Microsoft Visual C++ compiler (MSVC) version 19.14.

[014972304505347]

For reference, I issued a bug report here.

[nlohmann]

Thanks for your effort!

[nlohmann]

It's a pity that there has not been any reaction yet.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[nlohmann]

To be fixed with #2259.