Function R_UnwindProtect_C_unwind 

pub(crate) unsafe extern "C-unwind" fn R_UnwindProtect_C_unwind(
    fun: Option<unsafe extern "C-unwind" fn(*mut c_void) -> SEXP>,
    fun_data: *mut c_void,
    cleanfun: Option<unsafe extern "C-unwind" fn(*mut c_void, Rboolean)>,
    cleanfun_data: *mut c_void,
    cont: SEXP,
) -> SEXP

Version of R_UnwindProtect that accepts extern "C-unwind" function pointers