As I was debugging, I found a .defs and .defs.objs file which seemed to be related to the problem, so I grepped the CMake code for .objs and found code related to WINDOWS_EXPORT_ALL_SYMBOLS.
As I was debugging, I found a .defs and .defs.objs file which seemed to be related to the problem, so I grepped the CMake code for .objs and found code related to WINDOWS_EXPORT_ALL_SYMBOLS.