In trying to compile allpix-squared on my MacOS from source, I kept running into the following error:
/src/modules/DetectorHistogrammer/DetectorHistogrammerModule.cpp:447:71: error: no member named ‘numbers’ in namespace ‘std’
max_pitch *= (model->is() ? std::numbers::sqrt3 / 2 : 1);
Which I realised was happening because DetectorHistogrammerModule.cpp uses std::numbers::sqrt3 (line 447) but does not include the <numbers> header.
I believe this may have been missed because GCC’s libstdc++ pulls in <numbers> transitively through other standard headers, so the missing include goes unnoticed on Linux. Apple’s libc++ is stricter and requires the header to be included explicitly.
I fixed this by adding #include <numbers> to the includes in src/modules/DetectorHistogrammer/DetectorHistogrammerModule.cpp, and it now works and compiles fine, so it may be worth adding this line to save future macOS users the trouble.