[Development] Compiler warnings

Bo Thorsen bo at vikingsoft.eu
Thu Nov 6 10:32:07 CET 2014

Den 14-10-2014 08:59, Kurt Pattyn skrev:
> Hi,
> This has already been brought up before: when compiling an application/library using Qt and setting compiler warnings to comply with e.g. the Misra C++ rules, Qt generates a lot of warnings.
> I already did some work on eliminating some of the warnings, but there are still quite a lot left.
> A number of these changes never got through, having forced me to locally patch Qt to avoid them.
> Now my questions:
> 1. Is it worth the (big) effort to try to remove these warnings from the public part of Qt?
> 2. Are there other people, esp. working in strongly regulated environments that have the same problem? I see that Qt is used a lot in the automotive industry: how do these applications comply with MISRA?

Hi Kurt,

It's almost always a good thing to have less warnings in there. You 
already know that I object to some of the things in MISRA, but that 
doesn't mean the effort is not useful.

I haven't heard others mention MISRA before, probably because Qt is 
mostly used for IVI and as one of the others said, MISRA usually doesn't 
apply for those parts.

Since this is something you don't see others need (yet?), it's a bit of 
an uphill struggle to get the patches in Qt. It's always easier if there 
are several people that need something.

So it's up to you, actually. If you can do the effort and keep following 
up on it, then I say go for it. Just keep in mind that you can't break 
the fundamental Qt rules - like keeping binary compatibility - to fix 
those warnings. There might be some of the warnings that you have to fix 
in a separate branch. But the fewer of those the better.

If you can get 99% MISRA compatible in the Qt releases, then it 
shouldn't be a big effort to keep a branch with the remaining patches. 
And maybe those can go in when 6.0 starts to happen.

Good luck with the effort.


Viking Software
Qt and C++ developers for hire

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