The problem occurs when building KMyMoney on MinGW in CI system. Log of compilation is here . Although libgpgmepp.dll.a and libgpgme.dll.a are linked, the linker cannot resolve GpgME::Data::seek(long, int). It can resolve e.g.
ssize_t GpgME::Data::write(const void *buffer, size_t length)
which is from the same header.
I narrowed it down to the use of
off_t GpgME::Data::seek(off_t offset, int whence)
If I would use
GpgME::Data::Data(const char *filename, off_t offset, size_t length)
, which also contains off_t, then this constructor would be undefined as well.
GpgMe++ is being build according to this script, so nothing special.
The problem is present on MS Windows. It's not present neither on Linux nor on MacOS.