#pragma once is a widely supported compiler pragma, even though it is
not part of the C++ standard. Many of the issues keeping #pragma once
from being standardized (distributed filesystems, build farms, hard
links, etc.) do not apply to CMake - it is easy to build CMake on a
single machine. CMake also does not install any header files which can
be consumed by other projects (though cmCPluginAPI.h has been
deliberately omitted from this conversion in case anyone is still using
it.) Finally, #pragma once has been required to build CMake since at
least August 2017 (7f29bbe6 enabled server mode unconditionally, which
had been using #pragma once since September 2016 (b13d3e0d)). The fact
that we now require C++11 filters out old compilers, and it is unlikely
that there is a compiler which supports C++11 but does not support
#pragma once.
Create a CPack generator that uses `nuget.exe` to create packages:
https://docs.microsoft.com/en-us/nuget/what-is-nuget
NuGet packages could be easily produced from a `*.nuspec` file (running
`nuget pack` in the directory w/ the spec file). The spec filename does
not affect the result `*.nupkg` name -- only `id` and `version` elements
of the spec are used (by NuGet).
Some implementation details:
* Minimize C++ code -- use CMake script do to the job. It just let the
base class (`cmCPackGenerator`) to preinstall everything to a temp
directory, render the spec file and run `nuget pack` in it, harvesting
`*.nupkg` files...;
* Ignore package name (and use default paths) prepared by the base class
(only `CPACK_TEMPORARY_DIRECTORY` is important) -- final package
filename is a responsibility of NuGet, so after generation just scan the
temp directory for the result `*.nupkg` file(s) and update
`packageFileNames` data-member of the generator;
* The generator supports _all-in-one_ (default), _one-group-per-package_
and _one-component-per-package_ modes.
