[PATCH] Fix gcc-4.5.2 "statement with no effect" warnings in UBIFS

[Russ Dill]

On Mon, Apr 11, 2011 at 2:50 PM,  <maksim.rayskiy at gmail.com> wrote:
> From: Maksim Rayskiy <maksim.rayskiy at gmail.com>
>
> When compiling UBIFS with CONFIG_UBIFS_FS_DEBUG not set,
> gcc-4.5.2 generates a slew of "warning: statement with no effect"
> on references to non-void functions defined as 0.
> To avoid these warnings, change appropriate definitions from
>  #define dbg_xxx(a)     0
> to
>  #define dbg_xxx(a)     ({0; })
>
> Signed-off-by: Maksim Rayskiy <maksim.rayskiy at gmail.com>
> ---
>  fs/ubifs/debug.h |   50 +++++++++++++++++++++++++-------------------------
>  1 files changed, 25 insertions(+), 25 deletions(-)
>
> diff --git a/fs/ubifs/debug.h b/fs/ubifs/debug.h
> index 919f0de..e30a629 100644
> --- a/fs/ubifs/debug.h
> +++ b/fs/ubifs/debug.h
> @@ -425,34 +425,34 @@ void dbg_debugfs_exit_fs(struct ubifs_info *c);
>  #define dbg_dump_index(c)                      ({})
>  #define dbg_dump_lpt_lebs(c)                   ({})
>
> -#define dbg_walk_index(c, leaf_cb, znode_cb, priv) 0
> -#define dbg_old_index_check_init(c, zroot)         0
> +#define dbg_walk_index(c, leaf_cb, znode_cb, priv) ({0; })
> +#define dbg_old_index_check_init(c, zroot)         ({0; })
>  #define dbg_save_space_info(c)                     ({})
> -#define dbg_check_space_info(c)                    0
> -#define dbg_check_old_index(c, zroot)              0
> -#define dbg_check_cats(c)                          0
> -#define dbg_check_ltab(c)                          0
> -#define dbg_chk_lpt_free_spc(c)                    0
> -#define dbg_chk_lpt_sz(c, action, len)             0
> -#define dbg_check_synced_i_size(inode)             0
> -#define dbg_check_dir_size(c, dir)                 0
> -#define dbg_check_tnc(c, x)                        0
> -#define dbg_check_idx_size(c, idx_size)            0
> -#define dbg_check_filesystem(c)                    0
> +#define dbg_check_space_info(c)                    ({0; })
> +#define dbg_check_old_index(c, zroot)              ({0; })
> +#define dbg_check_cats(c)                          ({0; })
> +#define dbg_check_ltab(c)                          ({0; })
> +#define dbg_chk_lpt_free_spc(c)                    ({0; })
> +#define dbg_chk_lpt_sz(c, action, len)             ({0; })
> +#define dbg_check_synced_i_size(inode)             ({0; })
> +#define dbg_check_dir_size(c, dir)                 ({0; })
> +#define dbg_check_tnc(c, x)                        ({0; })
> +#define dbg_check_idx_size(c, idx_size)            ({0; })
> +#define dbg_check_filesystem(c)                    ({0; })
>  #define dbg_check_heap(c, heap, cat, add_pos)      ({})
> -#define dbg_check_lprops(c)                        0
> -#define dbg_check_lpt_nodes(c, cnode, row, col)    0
> -#define dbg_check_inode_size(c, inode, size)       0
> -#define dbg_check_data_nodes_order(c, head)        0
> -#define dbg_check_nondata_nodes_order(c, head)     0
> -#define dbg_force_in_the_gaps_enabled              0
> -#define dbg_force_in_the_gaps()                    0
> -#define dbg_failure_mode                           0
> -
> -#define dbg_debugfs_init()                         0
> +#define dbg_check_lprops(c)                        ({0; })
> +#define dbg_check_lpt_nodes(c, cnode, row, col)    ({0; })
> +#define dbg_check_inode_size(c, inode, size)       ({0; })
> +#define dbg_check_data_nodes_order(c, head)        ({0; })
> +#define dbg_check_nondata_nodes_order(c, head)     ({0; })
> +#define dbg_force_in_the_gaps_enabled              ({0; })
> +#define dbg_force_in_the_gaps()                    ({0; })
> +#define dbg_failure_mode                           ({0; })
> +
> +#define dbg_debugfs_init()                         ({0; })
>  #define dbg_debugfs_exit()
> -#define dbg_debugfs_init_fs(c)                     0
> -#define dbg_debugfs_exit_fs(c)                     0
> +#define dbg_debugfs_init_fs(c)                     ({0; })
> +#define dbg_debugfs_exit_fs(c)                     ({0; })
>
>  #endif /* !CONFIG_UBIFS_FS_DEBUG */
>  #endif /* !__UBIFS_DEBUG_H__ */
> --
> 1.7.1
>

Should these all just be:

 do {} while(0)

Stuff like:

#define dbg_debugfs_exit()

looks particularly dangerous.