On Tue, Jun 13, 2017 at 03:03:12PM +0200, Rüdiger Meier wrote:
>
>
> On 06/13/2017 02:51 PM, Karel Zak wrote:
> > On Tue, Jun 13, 2017 at 01:16:57AM +0200, Rüdiger Meier wrote:
> > > > > BTW just for cosmetics. Maybe we should rename UL_FALLTHROUGH to
> > > > > __ul_fallthrough
> > > > > like we have already __ul_calloc_size. IMO it would look more obvious to the
> > > > > reader.
> > > >
> > > > I don't have strong opinion about that, changed to one you proposed.
> > >
> > > Thanks, let's see whether Karel likes this attribute at all ;)
> >
> > Hmm...
> >
> > I don't like "meta-programming" where language keywords are
> > replaced by local macros, for example we have fallback (in c.h) for all
> > __attribute__ rather than define local macro for all attributes.
> >
> > __attribute__((fallthrough))
> >
> > should be fine on non-__GNUC__ as in this case __attribute__ is empty
> > macro (see c.h).
> >
> > Yes, __ul_fallthrough seems better, and __attribute__((fallthrough))
> > would be the best :-)
> >
> > It's strange if clang will use a different syntax for the same
> > things. IMHO it would be better to ignore clang for this attribute.
>
> Yes, Sami's last version just ignores clang. Seems that the different syntax
> was for C++ only.
>
> So branch 2017wk23 from git@xxxxxxxxxx:kerolasa/lelux-utiliteetit.git is the
> last version for merging.
Cool, I see.
Now I read something about gcc and it seem it's able to recognize and
use comments, so __attribute__((fallthrough)) is unnecessary.
The default -Wimplicit-fallthrough setting is '3' and it means "parse
comments".
So, do we really need this patch? ;-)
https://developers.redhat.com/blog/2017/03/10/wimplicit-fallthrough-in-gcc-7/
and man gcc man page:
-Wimplicit-fallthrough=0 disables the warning altogether.
-Wimplicit-fallthrough=1 matches .* regular expression, any comment is used as fallthrough comment.
-Wimplicit-fallthrough=2 case insensitively matches .*falls?[ \t-]*thr(ough|u).* regular expression.
-Wimplicit-fallthrough=3 case sensitively matches one of the following regular expressions:
-fallthrough
@fallthrough@
lint -fallthrough[ \t]*
[ \t.!]*(ELSE,? |INTENTIONAL(LY)? )?
FALL(S | |-)?THR(OUGH|U)[ \t.!]*(-[^\n\r]*)?
[ \t.!]*(Else,? |Intentional(ly)? )?
Fall((s | |-)[Tt]|t)hr(ough|u)[ \t.!]*(-[^\n\r]*)?
[ \t.!]*([Ee]lse,? |[Ii]ntentional(ly)? )?
fall(s | |-)?thr(ough|u)[ \t.!]*(-[^\n\r]*)?
-Wimplicit-fallthrough=4 case sensitively matches one of the following regular expressions:
-fallthrough
@fallthrough@
lint -fallthrough[ \t]*
[ \t]*FALLTHR(OUGH|U)[ \t]*
-Wimplicit-fallthrough=5 doesn’t recognize any comments as fallthrough comments, only attributes disable the warning.
sounds all we need is to add -Wimplicit-fallthrough=3 to ./configure.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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