Qt MinGW 64-bit

satysin · 14 Jan 2017, 19:19

Hello,

I am just looking at/getting started with Qt on Windows but am a surprised to see there is no direct option for 64-bit MinGW whereas for MSVC both 32-bit and 64-bit are options.

Other than building myself what options are there for building 64-bit Qt executables with MinGW? Third party builds I have found are old and appear to be abandoned (although I could have missed some).

Is there a reason that Digia do not provide a 64-bit Qt as an install option?

Many thanks.

koahnig · wrote on 14 Jan 2017, 19:19

@satysin

Hi and welcome to devnet forum

It is merely a question of limiting the different versions for compilation. You can download the source and compile a 64 bit version, if really have to have one. As you already indicated there are "outside" versions prepared, but they apparently stopped this. At the time being I am not aware of sites for direct download.

Out of personal experience, I had used a (self-compiled) 64 bit version, ut simply switched to the 32 bit version because of convenience. In most cases you do not really 64 bit and the 32 bit vesion is sufficient. Especially when you are starting with Qt, I would use 32 bit version.

satysin · 14 Jan 2017, 19:56

@koahnig

Thank you for the warm welcome :)

Yeah I am using the 32-bit build which is fine for now but I just found it a little strange that in 2017 they still don't provide an official 64-bit build for MinGW when they do for MSVC.

Would be great if Digia could provide one in the future, perhaps for Qt 5.8?

mrjj · 14 Jan 2017, 20:00

well they also stopped making a 32 bit linux. It all depends on download stats
etc and the huge cost of making pre-compiled.

mingw is always treated a bit as the stepchild (from all)
as most projects is using visual studio and its de facto standard for windows development.
Also the new web engine stuff is NOT supported in mingw.

So it makes more sense to focus on 32/64 for VS for PRO development and
mingw for the more casual and works out of the box experience.

But yes, it might come. Like 32 out and only 64 bit.
Most new windows are 64 bit and xp is finally dying.

koahnig · wrote on 14 Jan 2017, 19:56

@satysin

I do not know anything about the release plans for a 64 bit version.
I believe the choices for 64 bits are too many. I think there has been an extended discussion in the past.

From development point I was not convinced that it is a good idea to continue with 64 bit MinGW version. I was a bit surprised when I had noticed that at that time it was slower especially when debugging. However, that have been because of machine limitations. The debug versions were relatively large. Presumably I could tweak the parameters for speeding up. Anyway, as long as I do not see a real need, it does not make sense to switch for me.

satysin · 14 Jan 2017, 20:03

@mrjj Yes I guess I should just go with MSVC then. I have Visual Studio 2017 RC installed but currently the Qt installer does not detect it, I assume this is because they do not have a Qt build for it yet.

mrjj · wrote on 14 Jan 2017, 20:03

@satysin

Yes. The Qt must match the VS version. ( due to DLL loading)
I think VS2015 is the newest. ( didnt check)

Its not very hard to compile qt with minge 64 but it does take long time.

koahnig · wrote on 14 Jan 2017, 20:04

@satysin

When go MSVC, make sure that can install a compatible, pre-compiled version of Qt libs. Otherwise you have to do a compilation yourself as well.

satysin · wrote on 14 Jan 2017, 21:10

Thank you all. I have marked as solved.

SGaist · 15 Jan 2017, 09:27

Hi and welcome to devnet,

Certainly not with 5.8. However there was a thread talking about that here.

As to why there was not yet a MinGW64, the answer is always the same: it's about manpower and hardware.

The CI has its limits and is already under heavy pressure building Qt for the 5.6 to 5.8 branches as well as dev. Each pre-built package is also tested. For Windows alone it means 5 different versions to generate and test.

satysin · S SGaist 14 Jan 2017, 21:23

@SGaist Yes I can understand the difficulties in supporting yet another build. Also with MSVC now being "free" for open source projects (with Visual Studio Community) I guess it means MinGW will see a drop in users going forward.

SGaist · wrote on 15 Jan 2017, 21:47

Not necessarily, some people prefer to stay with OpenSource Tools and keep the same compiler as much as possible.

Also, to get started with Qt on Windows, the MinGW build is ideal since it doesn't require to go somewhere else for additional downloads and setup like Visual Studio does. You just have to select MinGW in the additional software in the installer. Furthermore, it's only been recently that the C++ tools can be downloaded independently, otherwise you had to install the whole of VS just to get the compiler and you also need to install the debugging tools separately. And by whole of VS, you also have to be sure to check C++ otherwise it's installed without it.

And from a compatibility point of view, the various versions of VS are not compatible with each others so you always have to ensure that you have all C++ dependencies built correctly.

yigene · 8 Jan 2018, 14:12

32bit could crash when it reach to 4GB memory right

don't like that as we have some vendor products which is 32bit and then the process crash when it reach to 4GB memory!

mrjj · Y yigene 8 Jan 2018, 13:53

@yigene

Well anything can crash when it runs out of memory
and the app is not programmed correctly to handle it.
So if you run a 64 bit app on 32 bit OS with 1 GB ram it could just as easy crash as 32 bit version.

jsulm · Y yigene 8 Jan 2018, 13:53

@yigene To add to @mrjj : does your app need that amount of memory? If not and it does not have memory leaks than there is no real reason to have it as 64bit.