Ah yeah, now I remember. Because if I pass

-std=c11

to clang during bindgen, I get errors like:

c
home/exbigboss/cpp/liburing/target/debug/build/axboe-liburing-a150c08fad8c0d5e/out/src/include/liburing.h:410:22: error: unknown type name 'sigset_t'
  /home/exbigboss/cpp/liburing/target/debug/build/axboe-liburing-a150c08fad8c0d5e/out/src/include/liburing.h:1007:28: error: use of undeclared identifier 'AT_FDCWD'