[Development] [5.7-beta] compile error with xcode-6.4

Jake Petroules Jake.Petroules at qt.io
Wed May 4 08:31:11 CEST 2016

On May 3, 2016, at 10:55 PM, Tim Blechmann <tim at klingt.org<mailto:tim at klingt.org>> wrote:

r.h:759:21: error: destination for this 'memmove' call is a pointer to
class containing a dynamic class>
     'QPixmap'; vtable pointer will be overwritten
           memmove(abegin, aend, (d->size - itemsToErase -
           itemsUntouched) * sizeof(T)); ~~~~~~~ ^

has support for xcode-6.4 been dropped?

Not officially. You should always use the latest XCode, no matter what, though.

https://wiki.qt.io/Qt_5.7_Tools_and_Versions still lists OSX 10.9 with

Indeed, but we're changing policies. Users are expected to use the latest and
greatest OS X and XCode, since they're now free for upgrading. I'm not sure
whether this applies to 5.7 or not.

pricing should not be the only point to consider: requiring latest xcode
versions implies requiring the latest sdk. requiring the latest sdk
means that:

Technically you can copy a newer SDK into an older Xcode version (provided the toolchain supports it).

* legacy code using deprecated sdk functions might not compile a certain
codebase (depending on the age of your codebase this maybe lead to
significant effort)

As I've said many times before, the SDK we use to build Qt has no bearing on the SDK you use to build your applications. We can build with the 10.11 SDK, you can build with the 10.8 SDK, and that's completely fine.

* compiling with a minimum osx version X of sdk version Y is different
than compiling against minimum osx version X of sdk version X. there are
subtle differences

...which is exactly why we want to support M+N configuration instead of M*N configurations.

and this should not be the case if the code were
bug-free ... but we've experienced (toolchain) bugs in the past were the
only workaround was to downgrade the osx sdk, which implies downgrading
the compiler. end-users won't care if a crash is caused by a bug in
application code or in qt or in the apple toolchain. they will blame the

Rightly so, because in those rare cases it'll always be a bug in your application and not in Qt. See above.

And before you say it's more difficult to build Qt on one platform and your applications on another, (a) how often do you actually need to build Qt?, and (b) it is not in our interests to spend the significant effort to test and support 16 (vs 4) different configurations that are unnecessary for 99.9% of users in 99.9% of cases.

... but we had this discussion already in the past :)


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Jake Petroules - jake.petroules at theqtcompany.com<mailto:jake.petroules at theqtcompany.com>
Consulting Services Engineer - The Qt Company
Qbs build system evangelist - qbs.io<http://qbs.io>

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