This method is tested to work on Visual Studio 2013. Pre-built binaries using Visual Studio 2012 and 2013 are available here, including OpenGL versions.
Step 1: The Setup
Download and install RapidEE here. RapidEE is a windows environment variables editor. It is extremely useful for the rest of this process (and just in general).
Install the DirectX 11 SDK. It is now part of the Windows 8 SDK, so you first have to install the DirectX 10 SDK, which you can get here (but see warning in next sentence). If you have the Visual C++ 2010 Redistributable Package installed, and you probably do (it is automatically installed along with VS 2010), follow the steps outlined here to assist with the DirectX 10 installation. Once you have the DirectX 10 SDK installed, download and install the Windows 8 SDK here, which contains the DirectX 11 SDK. Yes, this is a pain, but unless you know you have the DirectX 11 SDK, the Qt build will fail.
Install Python for Windows (I've heard 2.6+, working with 3.3) from Python.org or Anaconda Python.
Install Perl for Windows from ActiveState.
Step 2: Gitting (and building) Qt5 (yes, that means Git)
Follow the installation guide for Windows at the qt-project website.
Summary
To summarize the details from the above link and from the following notes (PLEASE SEE FOLLOWING NOTES if you have any errors; they might be answered):
Uninstall Avast (if you have this installed) to avoid build errors. Yes, that literally means uninstall it. Remove it 100% from your system. Deactivating it will not work. See detailed notes below.
Note for the first steps: DO NOT use SmartGit for the first git pull, below (unless you really know what you're doing), as SmartGit's defaults will pull everything, and that's not what you want.
Git for Windows must be installed.
Decide where you want to put the Qt installation, and cd to the directory that will contain the new installation from any Command Prompt window. (Because the process is so fragile and error-prone, I personally put it directly in C:, but this is likely not necessary).
From the above directory, execute:
git clone git://gitorious.org/qt/qt5.git qt5
This is fast. Once complete, you should be on the 'stable' branch, but you can always run git checkout stable after cding into the newly-created qt5 directory, just to be sure. Using git checkout 5.4.1 is confirmed to work with VS2013 64-bit.
Close out of your current command prompt window (if it's not a Visual Studio command prompt window) before proceeding to the next step. This is to make sure you're using the Visual Studio command prompt window in the next steps.
Next run the 32-bit (x86) or 64-bit VS Tools command prompt (depending on whether you're building Qt5 as 32- or 64-bit). To access this, you must find it through the Start menu - go to Program Files -> [Microsoft] Visual Studio 2012/2013 -> Visual Studio Tools, and you'll see it in there with a funny name; the name should include the phrase Native Tools; the 32-bit version will have x86 in the name and the 64-bit version will have x64 in the name.
cd into the newly-created qt5 directory from the step above.
From within the Visual Studio command prompt, the remainder of the Qt submodules must be downloaded:
perl ./init-repository --no-webkit
It takes kind of a while to execute this step, because it has to download a lot, but it's not too terrible on a decent connection.
Then download any remaining OPTIONAL submodules that init-repository does not download - SmartGit works well only starting at this stage (see comments below).
Once the download of Qt is complete, the following command prepares the build environment (it should also be executed using the [32|64] VS Native Tools Command Prompt):
configure -developer-build -opensource -confirm-license -mp -nomake examples -nomake tests -debug-and-release -c++11 -no-warnings-are-errors -platform win32-msvc2012.
Notes on this command line: the c++11 option might not be necessary with the VS2012 compiler, but works with VS2013; the -no-warnings-are-errors is necessary in case you get errors on a 64-bit automatic build of ANGLE; -platform is automatically set to win32-msvc2012, so by default the 32-bit build of Qt is used, and -platform probably does not need to be supplied at the command line (EVEN if you have previous versions of VS installed). For VS2013, use -platform win32-msvc2013.
It takes a few minutes to execute this step, but it's not so bad.
Finally, the command to actually build Qt on the system (also run within the VS Native Tools Command Prompt) is simply:
nmake
Expect to wait hours for the build to complete. If you specified an output folder with -prefix (see notes below), then use nmake install, otherwise that's it.
NOTES:
General Notes
In case you're confused from the above-linked documentation, just an FYI that the ANGLE library will be used (by default) instead of OpenGL, and that's why you had to install DirectX 11, above.
Make sure that you use the VS Native Tools Command Prompt to run all commands from the above link (that is, perl .init-repository --no-webkit, configure, and nmake). You will use the [32|64] bit command prompt (x86 or x64), depending on whether you are building Qt as 32-bit or 64-bit. If you install perl with the Command Prompt open (make sure it is in the PATH), you will need to restart the Command Prompt for perl to be recognized as a command.
When running "init-repository" (from the steps in the above link), it's not clear from the documentation, but you must execute this via perl; i.e. perl ./init-repository --no-webkit. The configure and nmake commands, however, are called directly.
One very useful option to pass to configure is -mp, which causes Qt to build on multiple cores in parallel, significantly speeding up the (long) build time.
To specify an output folder add the -prefix [outfolder] to the configure command. For example, use -prefix %CD%outputx64vc12 would be a suitable output (sub)folder for a 64-bit Visual Studio 2013 (12.0) build.
Unicode Support (ICU)
If you want Unicode support (via ICU), pay special attention to the instructions noted within the link above. In summary, ICU must be built from scratch in VS 2012, as the only prebuilt ICU binaries for Windows are for VS 2010. Building in VS 2012 is painless - simply locate the ICU solution (.sln) in <icuroot>icusourceallinone, and build in both Debug and Release mode (either in 32-bit or 64-bit mode, depending on which mode you're building Qt in - DO NOT build in the other bitness, because ICU will overwrite the output folder with the binaries). (The Qt build process will properly locate the debug vs. release build of ICU.) It should build without errors. Then, add the path to <icuroot>lib as a string entry in a (probably) NEW Windows environment variable called "LIB" (you can use Rapid EE for this; make LIB an "expandable string" in RapidEE even though there's only 1 entry), and also add the path to <icuroot>include as a string entry in a (probably) NEW Windows environment variable called "INCLUDE". (Note: Adding these paths to the PATH variable will not work.) After Qt is built, you can remove all of these entries you've just added. Also, do add the runtime path to the ICU dll's (<icuroot>in) to the environment's PATH variable, or the Qt build process (specifically, when uic.exe runs) will give a deceptive and misleading error. Finally, on the configure command line (below), be sure to add -icu as an additional command-line parameter.
ICU Failure:
Currently, there seems to be a bug building Qt5 with the VS2012 compiler WHEN ICU IS ENABLED. Specifically, qtbasesrccorelibcodecsqtextcodec.cpp Line 688 (Qt5 v5.02) fails to return a codec for codec name "US-ASCII" (the codec is NULL), causing "lrelease.exe" to crash when trying to dereference the codec later (I have lost track of that file/line number, but it is an obvious dereference of the NULL codec variable). Unfortunately, this means that to my knowledge, WebKit cannot be built with (at least the) 32-bit build of Qt5 with the VS2012 compiler, because WebKit requires ICU.
If anyone is able to build Qt5 with the VS2012 compiler with ICU enabled, please update this Wiki saying so.
ICU Clarification:
If you have ICU in your path, Qt will automatically built it. In other words, the flag "-icu" is there implicitly. However, this causes an error with "lrelease.exe" as mentioned above. So the way around this would be to add the flag, -no-icu to the configure command
Additional Submodules
If you want submodules in addition to the default submodules, you can use SmartGit (or command line) after you complete the init-repository command. SmartGit is perhaps easiest, because you do not need to copy the path to the command line, but can use the user interface directly.
WARNING: DO NOT DOWNLOAD THE OPTIONAL qlalr SUBMODULE, as it will not build in combination with the
