ROOT stopped supporting vmc (virtual monte carlo library) with version 6.25.01. However sci-physics/root-9999 still shows it as a valid flag. The compilation fails if you toggle it. Reproducible: Always Steps to Reproduce: 1. Add 'vmc' to sci-physics/root-9999 USE flags 2. Emerge it 3. Build fails at src_configure phase Actual Results: I got this error from cmake: CMake Error at cmake/modules/RootBuildOptions.cmake:415 (message): >>> Option 'vmc' is no longer supported in ROOT 6.25.01. Call Stack (most recent call first): CMakeLists.txt:157 (include)
ROOT upstream has deprecated and removed vmc, which is now a separate package that you can install in Gentoo: sci-physics/vmc. Since the live ebuild for ROOT can still be used to build/test old versions of ROOT that include vmc, I left the flag there on purpose, so the fact it's there is not actually a bug. I will eventually remove it, though.