Unable to build OpenCV project due to build folder not containing opencv_core340.lib

I have a QT 5.4 (Visual Studio 2013 x86 compiler) project that I'm trying to port to QT 5.12(Visual Studio 2017 x64 compiler).

The project is using OpenCV 2.4.9 and I'm trying to upgrade that to OpenCV 3.4.0.

1. The first thing that I've tried was using the lib folder inside of the pre-compiled build folder that comes along the OpenCV package. But that didn't help because opencv_core340.lib didn't get compiled with the build folder.

2. I tried building the source folder that comes alongside opencv3.4.0 using CMake however that didn't yield a opencv_core340.lib file inside of the new build folder that I generated.

3. I tried building OpenCV's source folder with QT Creator which comes alongside the build folder in the initial package. This did get me closer to my goal because after the compilation I did manage to find opencv_core340.lib inside of the directory. However throughout the compilation I've gotten a bunch of errors in the compile output, more prominently something about an internal compiler error.

I'll read more about the problem throughout the weekend in hopes of finding a solution to this problem. My best guess right now is that the library opencv_core___.lib has been now merged into another library.

Let me know if you'd like me to provide more information about the issue..