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

[Tim Blechmann]

>>> 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
>>>       [-Werror,-Wdynamic-class-memaccess]>       
>>>             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
>> xcode-6.1.1
> 
> 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:

* 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)

* 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 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
application.

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

cheers,
tim