On Mon, 10 Oct 2022 at 13:13, Hasselmann Mathias <math...@taschenorakel.de> wrote: > > I am surprised by the question: "It's non-standard and it's behavior is > undefined" actually should be enough to avoid such feature. > > Actually if a reliable implementation of "#pragma once" would be > possible, that feature would have been included in the C++ standard for > a long time already, wouldn't it?
Oh, there is a reliable implementation, no problem there. :D It's called "hash the file contents". Various implementations have different modes of operation where they desperately try to avoid doing that, or do that just partially. The last time standardizing a "#once" was discussed in the standard committee was 2012, and compiler vendors' feedback killed the idea dead, and it hasn't come back since. We have spent our energy standardizing modules instead. The C committee has been recently considering standardizing a "#once". It has been attempted to make them aware of the compiler vendor feedback on the C++ side of things. It will be a glorious day when we stop doing textual inclusion, and don't need to talk about its myriad problems any more. _______________________________________________ Development mailing list Development@qt-project.org https://lists.qt-project.org/listinfo/development
