On Fri, Jun 21, 2019 at 7:41 PM Neil Horman <nhor...@tuxdriver.com> wrote:
> On Fri, Jun 21, 2019 at 06:47:31PM +0200, David Marchand wrote:
> > On Fri, Jun 21, 2019 at 6:28 PM Neil Horman <nhor...@tuxdriver.com>
> wrote:
> >
> > > On Fri, Jun 21, 2019 at 02:45:45PM +0200, David Marchand wrote:
> > > > Ok, did a new pass on the tree.. found quite some sites where we have
> > > > issues (and other discrepancies... I started a new patchset).
> > > > Looked at gcc documentation [1], and to me the safer approach would
> be to
> > > > enforce that __rte_experimental is the first thing of a symbol
> > > declaration.
> > > >
> > > > Comments?
> > > >
> > > Yes, thats the only way it works, in fact I'm suprised gcc didn't
> throw an
> > > error
> > > about expecting an asm statement if you put it anywhere else
> > >
> >
> > - I tried this, but then I hit issues with inlines.
> > Like for example:
> >
> > static inline char * __rte_experimental
> > rte_mbuf_buf_addr(struct rte_mbuf *mb, struct rte_mempool *mp)
> > {
> > return (char *)mb + sizeof(*mb) + rte_pktmbuf_priv_size(mp);
> > }
> >
> > I did not find a way to move the __rte_experimental tag without getting
> > warnings.
> Right, thats the way its supposed to work on gcc/icc/clang. function
> attributes
> must be declared between the return type and the function name, anything
> else
> will generate compiler warnings/errors. Because __rte_experimental
> expands to a
> __attribute__(...), you have to place it there.
>
> > If I try to compile some sources which includes rte_mbuf.h but without
> > -DALLOW_EXPERIMENTAL_API, then gcc errors at including the header,
> > complaining that rte_mbuf_buf_addr() is deprecated, even if this inline
> is
> > not called.
> >
> Thats...odd. I wonder if thats an artifact of the function being marked as
> inline. The compiler is supposed to insert the warning for any remaining
> calls
> after dead code eliminitaion. If the function is inline, I wonder if the
> compiler conservatively inserts the warning because it got expanded into
> another
> function, when it can't tell if it will be entirely elimintated. Can you
> provide a code sample that demonstrates this?
>
>
rte_mbuf_buf_addr() is called in rte_mbuf_data_addr_default(), both of them
are unused by the includers of rte_mbuf.h.
Reproduced it like this:
[dmarchan@dmarchan ~]$ cat deprecated.c
__attribute__((deprecated)) static inline void *plap(void)
{
return 0;
}
__attribute__((deprecated)) static inline void *plep(void)
{
plap();
return 0;
}
int main(int argc, char *argv[])
{
return 0;
}
[dmarchan@dmarchan ~]$ gcc -o deprecated -Wall deprecated.c
deprecated.c: In function ‘plep’:
deprecated.c:8:2: warning: ‘plap’ is deprecated (declared at
deprecated.c:1) [-Wdeprecated-declarations]
plap();
^
--
David Marchand
