"Bison" and "Flex" is required for the Windows build (Visual Studio, OpenWatcom, ...)

Please download the Windows "bison" and "flex" tools here:
https://github.com/danielmarschall/winflexbison/releases
( old versions also available here https://sourceforge.net/projects/winflexbison/ )

Place the contents of the ZIP file in this directory:
- win_bison.exe
- win_flex.exe
- data/
- ...

In case you only find bison.exe and flex.exe, then please rename
them to win_bison.exe and win_flex.exe, respectively.