Re: [PATCH v2 27/27] btrfs-progs: deprecate libbtrfs helpers

[Omar Sandoval <osandov@osandov.com>]

On Wed, Feb 21, 2018 at 04:04:28PM +0100, David Sterba wrote:
> On Thu, Feb 15, 2018 at 11:05:12AM -0800, Omar Sandoval wrote:
> > diff --git a/btrfs-list.c b/btrfs-list.c
> > index a2fdb3f9..56aa2455 100644
> > --- a/btrfs-list.c
> > +++ b/btrfs-list.c
> > @@ -34,6 +34,12 @@
> >  #include "btrfs-list.h"
> >  #include "rbtree-utils.h"
> >  
> > +/*
> > + * The deprecated functions in this file depend on each other, so silence the
> > + * warnings.
> > + */
> > +#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
> 
> How does this behave under clang?

Clang supports it.

> > +
> >  /* we store all the roots we find in an rbtree so that we can
> >   * search for them later.
> >   */
> > diff --git a/btrfs-list.h b/btrfs-list.h
> > index 54e1888f..774bcece 100644
> > --- a/btrfs-list.h
> > +++ b/btrfs-list.h
> > @@ -82,10 +82,15 @@ struct root_info {
> >  };
> >  
> >  int btrfs_list_find_updated_files(int fd, u64 root_id, u64 oldest_gen);
> > -int btrfs_list_get_default_subvolume(int fd, u64 *default_id);
> > -char *btrfs_list_path_for_root(int fd, u64 root);
> > -int btrfs_list_get_path_rootid(int fd, u64 *treeid);
> > -int btrfs_get_subvol(int fd, struct root_info *the_ri);
> > -int btrfs_get_toplevel_subvol(int fd, struct root_info *the_ri);
> > +int btrfs_list_get_default_subvolume(int fd, u64 *default_id)
> > +	__attribute__((deprecated("use btrfs_util_get_default_subvolume_fd()")));
> 
> IIRC the parametrized deprecated("...") is not supported on older
> compilers, see 1b1fd2c190ddb896a010a4c704ec1c2d46922aaf . We might avoid
> using raw __attirbute__ anyway, so a wrapper __deprecated("with string")
> could make it ifdef-ed properly. With some configure-time detection.

This should probably be a compile-time check because clients using the
libbtrfs headers might be compiled with a different setup than what was
used to build btrfs-progs, but yes, I'll try to do this. Failing that,
I'll just remove the string. Thanks!