CMake install does not reliably install shared library and C++ headers in standard include path

[piotrekoo]

While packaging lib3mf for Homebrew we noticed install layout issues with this configuration:

cmake -S . -B build \
  -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
  -DUSE_INCLUDED_ZLIB=OFF \
  -DUSE_INCLUDED_LIBZIP=OFF \
  -DUSE_INCLUDED_SSL=OFF \
  -DLIB3MF_TESTS=OFF
cmake --build build
cmake --install build --prefix <prefix>

Observed:

1. In some builds, Homebrew cannot rely on the shared library being installed by upstream install rules and needs a fallback copy from build artifacts.
2. C++ public headers are not available in the standard top-level include path expected by downstream consumers, so Homebrew needs to copy *.hpp manually.

Current Homebrew workaround:

dylibs = Dir["build/**/lib3mf*.{dylib,so}*"]
lib.install dylibs if dylibs.any?
include.install Dir["#{include}/Bindings/Cpp/*.hpp"]

[vijaiaeroastro]

@piotrekoo Thanks a lot for the effort you’ve put into the Homebrew support.

We already provide packages for Debian and RPM, and we also support vcpkg, which works across Linux, Windows, and macOS. The only concern with your proposed solution is that it supports only the Cpp variant of lib3mf. We actually provide four variants: Cpp, C, CDynamic, and CppDynamic. That said, having support for Cpp only is still better than having no Homebrew support at all.

I will review your PR on my Mac Mini this week. In the meantime, I recommend using vcpkg, as it is an officially maintained recipe and is updated with every release.