Please update fmtlib to recent version

[jspanchu]

The version 7.1.3 of thirdparty/fmt is old. Please bring it up to date because it currently uses the deprecated base char_traits<T> template which has now been removed from LLVM's libc++ last year llvm/llvm-project#72694.

Because of this, we are unable to update the compiler for VTK.wasm

https://open.cdash.org/viewBuildError.php?buildid=10174349

[ThirdParty/diy2/vtkdiy2/include/vtkdiy2/fmt/core.h:272](https://gitlab.kitware.com/vtk/vtk/blob/ad4a5650d180f480be86fc8c98fa509e8013ee44/ThirdParty/diy2/vtkdiy2/include/vtkdiy2/fmt/core.h#L272):30: error: implicit instantiation of undefined template 'std::char_traits<fmt::char8_t>'
  272 |       : data_(s), size_(std::char_traits<Char>::length(s)) {}
      |                              ^
[ThirdParty/diy2/vtkdiy2/include/vtkdiy2/fmt/format.h:487](https://gitlab.kitware.com/vtk/vtk/blob/ad4a5650d180f480be86fc8c98fa509e8013ee44/ThirdParty/diy2/vtkdiy2/include/vtkdiy2/fmt/format.h#L487):9: note: in instantiation of member function 'fmt::basic_string_view<fmt::char8_t>::basic_string_view' requested here
  487 |       : basic_string_view<char8_t>(reinterpret_cast<const char8_t*>(s)) {}
      |         ^

[mrzv]

@jspanchu @vicentebolea Can you comment on this? Per @MehdiChinoune comment, this seems like the same issue with DIY being outdated in VTK. Can you update it, so this doesn't keep coming up?

[jspanchu]

I am right now working on updating VTK's copy of diy to 3.6.0 to test the theory that diy==3.6.0 solves my issue. Right now, there are some VTK classes which fail to compile, will look into fixing it.

C:\Users\jaswant.panchumarti\dev\vtk\Filters\ParallelDIY2\vtkPResampleToImage.cxx(340): error C2440: 'initializing': cannot convert from 'vtkdiy2::Master::Proxy::IncomingQueues' to 'vtkdiy2::Master::IncomingQueues &'
C:\Users\jaswant.panchumarti\dev\vtk\Filters\ParallelDIY2\vtkPResampleToImage.cxx(343): error C2451: a conditional expression of type '_Ty2' is not valid
        with
        [
            _Ty2=vtkdiy2::Master::RecordQueue
        ]
C:\Users\jaswant.panchumarti\dev\vtk\Filters\ParallelDIY2\vtkPResampleToImage.cxx(343): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

[jspanchu]

Not sure if it will work, but I replaced vtkdiy2::Master::IncomingQueues with vtkdiy2::Master::Proxy::IncomingQueues and it compiled. I see that the proxy type is actually totally different std::map<int, MemoryBuffer> vs concurrent_map<int, RecordQueue>

Just one more error now, should be fixable with block->BlockBounds.resize(srp.in_link().size(), diy::ContinuousBounds(0)); instead of block->BlockBounds.resize(srp.in_link().size()

C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.42.34433\include\xmemory(700): error C2248: 'vtkdiy2::Bounds<float>::Bounds': cannot access private member declared in class 'vtkdiy2::Bounds<float>'
C:\Users\jaswant.panchumarti\dev\vtk\ThirdParty\diy2\vtkdiy2\include\vtkdiy2\mpi\../types.hpp(60): note: see declaration of 'vtkdiy2::Bounds<float>::Bounds'
C:\Users\jaswant.panchumarti\dev\vtk\ThirdParty\diy2\vtkdiy2\include\vtkdiy2\mpi\../types.hpp(20): note: see declaration of 'vtkdiy2::Bounds<float>'
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.42.34433\include\xmemory(700): note: the template instantiation context (the oldest one first) is
C:\Users\jaswant.panchumarti\dev\vtk\ThirdParty\diy2\vtkdiy2\include\vtkdiy2\link.hpp(250): note: see reference to class template instantiation 'vtkdiy2::RegularLink<vtkdiy2::ContinuousBounds>' being compiled
C:\Users\jaswant.panchumarti\dev\vtk\ThirdParty\diy2\vtkdiy2\include\vtkdiy2\link.hpp(142): note: see reference to class template instantiation 'std::vector<vtkdiy2::Bounds<float>,std::allocator<vtkdiy2::Bounds<float>>>' being compiled
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.42.34433\include\vector(1584): note: while compiling class template member function 'void std::vector<vtkdiy2::Bounds<float>,std::allocator<vtkdiy2::Bounds<float>>>::resize(const unsigned __int64)'
C:\Users\jaswant.panchumarti\dev\vtk\Filters\ParallelDIY2\vtkDIYKdTreeUtilities.cxx(266): note: see the first reference to 'std::vector<vtkdiy2::Bounds<float>,std::allocator<vtkdiy2::Bounds<float>>>::resize' in 'vtkDIYKdTreeUtilities::GenerateCuts::<lambda_3f0ffc7440bc0030650058e712d7c2b7>::operator ()'

[vicentebolea]

I see, thanks @jspanchu for point this out, update it in VTK and fix the build errors, let me know if you need help to bring the changes back to DIY.