On 2/11/2014 7:48 AM, Richard Sandiford wrote:
The patch deliberately didn't affect Ada's diagnostic routines given your comments from the first round. Calling this a "huge earthquake" for other languages seems like a gross overstatement.
Actually it's much less of an impact for Ada for two reasons. First we only just started tagging warnings. In fact we have only just released an official version with the facility for tagging warnings. Second, this tagging of warnings is not the default (that would have been a big earthquake) but you have to turn it on explicitly. But I do indeed think it will have a significant impact for users of other languages, where this has been done for a while, and if I am not mistaken, done by default?
I don't think gcc, g++, gfortran, etc, have ever made a commitment to producing textually identical warnings and errors for given inputs across different releases. It seems ridiculous to require that, especially if it stands in the way of improving the diagnostics or introducing finer-grained -W control. E.g. Florian's complaint was that we shouldn't have warnings that are not under the control of any -W options. But by your logic we couldn't change that either, because all those "[enabled by default]"s would become "[-Wnew-option]"s.
I am not saying you can't change it, just that it is indeed a big earthquake. No of course there is no commitment not to make changes. But you have to be aware that when you make changes like this, the impact is very significant in real production environments, and gcc is as you know extensively used in such environments. What I am saying here is that this is worth some discussion on what the best approach is. Ideally indeed it would be better if all warnings were controlled by some specific warning category. I am not sure a warning switch that default-covered all otherwise uncovered cases (as suggested by one person at least) would be a worthwhile approach.
