cmake --build: --parallel when used with msbuild does not enable parallelism within a project
When I use the --parallel option with a visual studio generator, it enables msbuild parallelism (build multiple projects at the same time), but not single-project parallelism. It explicitly prevents the latter by setting CL_MPcount=1. I feel it would be more similar to other platforms to instead have --parallel change CL_MPcount and leave /m at 1.
Some discussion around this is captured here: https://discourse.cmake.org/t/parallel-does-not-really-enable-parallel-compiles-with-msbuild/964/10