The typedefs in the header foward-declared new structs of the same names in the DFHack namespace, e.g. DFHack::xlsxio_read_struct. Apparently the constructors that used these typedefs are not inlined on Windows, so libdfhack was compiled with a constructor taking a "DFHack::xlsxio_read_sheet_struct", and xlsxreader was looking for a constructor taking just a "xlsxio_read_sheet_struct", which didn't exist.
lethosor
Myk Taylor