[Libguestfs] [PATCH nbdkit v2 0/2] Use of attribute(()).

v1 was here: https://www.redhat.com/archives/libguestfs/2019-January/msg00008.html In v2 I have provided two patches: The first patch extends attribute((nonnull)) to most internal functions, but not to the external API. The second patch uses a macro so that attribute((format)) is only used in the public API on GCC or Clang. At least in theory these headers could be used by a C compiler which only supports the C99 standard. Note that I don't propose to use attribute((nonnull)) in the public API until we have a bit more knowledge about: (1) Which version of GCC fixed this. (2) Whether it really works well with new GCC or if we find there are unexpected problems. Rich.