https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64747
--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> ---
If compiling the Fortran version, it shows:
!$acc kernels loop gang(32), vector(16)
1
Error: Clause GANG conflicts with VECTOR at (1)
Possibly, that's the reason for the (oddly worded) C error message. Given that
PGI supports it, one should re-check whether it is permitted or not. If it is
permitted, also the Fortran FE should be modified.
