When I try to use pip install . to install the python wrapper with MSVC, which compiles core, it throws error C3688 invalid literal suffix

This is caused by files BitMatrixIO.cpp, BitMatrix.cpp and WriteBarcode.cpp contains non ascii characters, and on my system the default code page does not support these characters.

As a solution, either save these files as UTF-8 with BOM, or add /utf-8 switch in cmake with something like

add_compile_options("$<$<C_COMPILER_ID:MSVC>:/utf-8>")
add_compile_options("$<$<CXX_COMPILER_ID:MSVC>:/utf-8>")