Re: -Wconversion versus libstdc++

["Manuel López-Ibáñez" <lopezibanez at gmail dot com>]

On 18/01/07, Paolo Carlini <pcarlini@suse.de> wrote:
> Manuel --
>
> > I read it and still don't get it. We know we should not warn about
> > system headers but we do and that is a known bug. So again, why is
> > libstdc++ using Wconversion at all?
>
> I appreciate your help with this issue, and I'm confident that we'll
> soon converge to a nice solution. Thanks, really.
>
> That said, frankly, I'm finding your saying, multiple times, "why is
> libstdc++ using Wconversion at all" particularly misleading, distracting
> and, well, annoying: libstdc++ is not using anything, by itself,
> certainly is not using Wconversion at .so and .a build time. The problem
> is that **the user of the library** may certainly compile **his own**
> code including libstdc++ headers passing a -Wconversion switch, or any
> other obscure request for warning. Then, given the bugginess of the
> pragma, which you correctly reminded (I just filed C++/30500 for that),
> warnings will be spilled from the libstdc++ headers to his face. He will
> be totally confused.
>
> Let's agree about that simple point and move ahead.

Agreed. They may certainly turn on any warning on gcc. Like
-Wunreachable-code, or -Waggregate-return.

And agreed that Wconversion is too noisy.

I just felt that the conversation was going in the direction of "we
should shut the warnings of Wconversion up because people using it
will get warnings for libstdc++". And I don't think that one thing
should be traded-off by the other (in any direction). I hope you can
understand how annoying is that the bug has been  filed just now. So
we can just forget about libstdc++ and focus on who will use
Wconversion and what for and what may be worth warning for what not.
Although it would be great if, at the end, Wconversion were useful
also for libstdc++ :-)

Sorry for the repetition and being annoying, that was not my intention at all.

Cheers,

Manuel.