Fix for C4146 Error in CPUNegElementKernel with Unsigned Types

[eclipse0922]

Fix the compile error.
UnaryEWCPU.cpp(100): error C4146: unary minus operator applied to unsigned type, result still unsigned

Type

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves #
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

The CPUNegElementKernel function in UnaryEWCPU.cpp triggers a compilation error (C4146) when instantiated with an unsigned scalar_t type.
This error is caused by applying the unary minus operator to an unsigned type, where the result remains unsigned, leading to undefined behavior.

I am tyring to write port for vpckg.
I got C4146 error during the compilations.

manual build option( other options are default)

        -DBUILD_SHARED_LIBS=OFF
        -DWITH_OPENMP=OFF
        -DBUILD_EXAMPLES=OFF
        -DBUILD_UNIT_TESTS=OFF
        -DBUILD_BENCHMARKS=OFF
        -DBUILD_GUI=OFF
        -DBUILD_ISPC_MODULE=OFF
        -DUSE_SYSTEM_EIGEN3=ON
        -DUSE_SYSTEM_CURL=ON
        -DUSE_SYSTEM_GLEW=ON
        -DUSE_SYSTEM_GLFW=ON
        -DUSE_SYSTEM_JPEG=ON
        -DUSE_SYSTEM_LIBLZF=OFF
        -DUSE_SYSTEM_PNG=OFF
        -DUSE_SYSTEM_TINYGLTF=ON
        -DUSE_SYSTEM_TINYOBJLOADER=ON
        -DUSE_SYSTEM_FMT=ON
        -DUSE_SYSTEM_PYBIND11=ON
        -DUSE_SYSTEM_GOOGLETEST=ON
        -DUSE_SYSTEM_IMGUI=ON
        -DBUILD_PYTHON_MODULE=OFF
        -DBUILD_LIBREALSENSE=OFF
        -DBUILD_AZURE_KINECT=OFF
        -DBUILD_FILAMENT_FROM_SOURCE=OFF
        -DSTATIC_WINDOWS_RUNTIME=${STATIC_WINDOWS_RUNTIME}
        -DBUILD_CUDA_MODULE=OFF
        -DBUILD_TENSORFLOW_OPS=OFF
        -DGLIBCXX_USE_CXX11_ABI=ON
        -DDEVELOPER_BUILD=OFF

OS: windows 11
Compiler:MSVC (visuals studio 2022 17.8)

[update-docs]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[ssheorey]

Hi @eclipse0922 thank you for submitting this PR. Can you check the CI errors, please?

[eclipse0922]

@ssheorey Sure!

[eclipse0922]

FYI,
If c++17 is the baseline, we can use if constexpr, but it does not seem to use c++17 by default.

[ssheorey]

Thanks for submitting this! Btw, at this point one of the main issues with not switching to C++17 is some build errors with MSVC in Visual Studio 2019. If you are interested, we would welcome a PR switching over to C++17. I think Visual Studio 2022 is now available in GIthub CI if that is required.