Qt vulkan classes not defined during make on windows - c++

Question

I have been trying to compile a Qt/Vulkan project that works fine on Linux, on Windows. I am using QtCreator, Qt (5.11.0), and MingW.
I can qmake without problems, but make crashes with errors for each reference to a QVulkan* class, such as "not defined in this scope", but seems to have found and included the headers for that class.
I have tried compiling the qt vulkan examples, and got the same problem.
I ran configure -v, and found :
Qt Gui:
Vulkan ................................. yes
Here is an example of a header that crashes :
#ifndef WINDU_H
#define WINDU_H
#include <QWindow>
#include <QVulkanInstance>
#include <QVulkanFunctions>
#include <QVulkanDeviceFunctions>
class Windu : public QWindow {
public :
Windu();
~Windu();
void render();
void start();
void reset();
QVulkanInstance inst;
QVulkanFunctions* vki;
QVulkanDeviceFunctions* vkd;
};
#endif
I have stripped it down to the important : this gives not defined errors for QWindow, QVulkanInstance, QVulkanFunctions, QVulkanDeviceFunctions.
I have tried building qtgui separately, but it also crashes because it can't find Qt OpenGLES sources files.
I don't know much about C++ on windows.
This is my .pro file :
SHADERS = $$files(*.comp, true)
SHADERS += $$files(*.frag, true)
SHADERS += $$files(*.vert, true)
spirv.output = ${QMAKE_FILE_NAME}.spv
spirv.commands = glslangValidator -V ${QMAKE_FILE_NAME} -o ${QMAKE_FILE_OUT}
spirv.depends = $$SHADERS
spirv.input = SHADERS
spirv.variable_out = COMPILED_SHADERS
spirv.CONFIG = target_predeps
SOURCES = $$files(*.cpp, true)
HEADERS = $$files(*.h, true)
# install
target.path = build
target.depends = spirv
DESTDIR=bin #Target file directory
OBJECTS_DIR=build #Intermediate object files directory
MOC_DIR=build #Intermediate moc files directory
CONFIG+=debug
QMAKE_EXTRA_COMPILERS += spirv
and here is the repo if needed :
https://github.com/Paul-Hubert/fantastic-octree/blob/master/fantastic-octree.pro

Answer 1

So I found out that on Windows, the only way to get the Vulkan classes is to build Qt yourself. I had done this, but something i had done wrong made the build unuseable. You have to build the sources as described here : http://doc.qt.io/qt-5/build-sources.html, and use that to build the project. I added a kit in QtCreator to do this.