Re: [GCC 4.0 PATCH] devfs_vnops.c

On Wed, May 25, 2005 at 10:01:43PM -0400, Craig Rodrigues wrote:
> Hi,
> 
> When I tried to compile src/sys/fs/devfs/devs_vnops.c
> with GCC 4.0, I got the following compilation errors:
> 
> /usr/src/sys/fs/devfs/devfs_vnops.c:1389: error: static declaration of 'devfs_vnodeops' follows non-static declaration
> /usr/src/sys/fs/devfs/devfs_vnops.c:114: error: previous declaration of 'devfs_vnodeops' was here
> /usr/src/sys/fs/devfs/devfs_vnops.c:1411: error: static declaration of 'devfs_specops' follows non-static declaration
> /usr/src/sys/fs/devfs/devfs_vnops.c:115: error: previous declaration of 'devfs_specops' was here
> 
> Apparently, it is not valid C to define something as extern
> and then later on static in the same file, like:
> 
> extern struct foo bar;
> static struct foo bar = { .... };

Yes.

> What do people think of the following patch to fix it?
> 
> http://people.freebsd.org/~rodrigc/devfs_vnops.c.diff.txt

Contrary to what Poul-Henning said, in this case it's perfectly legal to
use:

static struct foo bar;
[...]
static struct foo bar = { ... };

The first declaration is a tentative definition (it defines the object
only if no `real' definition with an initialiser is found), the second
declaration defines the object bar.  There is only a problem if bar had
array type and bar's initialiser was used to define the array size,
because then the tentative definition

static struct foo bar[];

would be illegal since bar has an incomplete type (6.9.2#3).

Stefan