Re: Add a __nowarn__ keyword

["Manuel López-Ibáñez" <lopezibanez@gmail.com>]

On 08/08/07, Kaveh R. GHAZI <ghazi@caip.rutgers.edu> wrote:
> On Wed, 8 Aug 2007, Paolo Bonzini wrote:
>
> So this is encouraging, I added OPT_Wcast_qual to the warning statement
> and now it obeys the #pragma (or _Pragma).  However I'm still having one
> last problem.  The pragma interface is still on/off, not push/pop.  I.e.:

Can you commit that fix as obvious before we forget about it? Thanks.

> Assuming you've corrected the missing OPT_Wcast_qual in c-typeck.c, if you
> compile the above with -Wcast-qual -Werror, the code correctly avoids the
> warnings on the line marked WARNING1.  However we should still get a
> warning for WARNING2 but we don't.  I believe the pragma has changed the
> behavior of gcc for the rest of the entire file.  There is no "pop" at the
> end of the inline function CONST_CAST.

I don't think there should be any implicit "pop". The pragma is at
file-scope level, so it makes sense it applies to the whole file
unless you provide another pragma later. Even if the pragma were at
function-body scope, I am not sure why you would assume an implicit
"pop" at the end of the function. Making this particular pragmas
context-aware or just location-aware (like #if-#endif) is a matter of
the design we wish to implement. I don't think either of them would be
easier than the other, specially for warnings that don't come from the
front-end.

> In order to see WARNING2, I have to uncomment the second pragma.  But this
> is bad IMHO because it overrides the command line.

Does it change the warning to an error? If that works, we only need a
new keyword "restore" or "default" that changes it to the command-line
value (or default value if there was no command-line setting) and et
voilá, it will work (at least for this case). It is not push/pop but
it is a step forward and I think that would be completely equivalent
to __nowarn__ but more powerful (although arguably, a bit more
verbose, so perhaps __nowarn__ would be still useful). I had a look at
diagnostics.c and I think the implementation would be easy. But
without regular internet connection at home, I cannot really work on
this right now.

Kaveh, DJ, what do you think about this? Am I talking nonsense?

Manuel.