Using Qt with Visual Studio Code (Windows) - c++

Question

The following are installed:
Visual Studio Code (1.45.1)
Visual Studio 2019 Community (in order to use the MSVC cl.exe compiler)
Qt 5.15.0 (installed to C:\Qt)
Visual Studio Code has been launched after running Visual Studio Command Prompt so that the environment is set correctly for cl.exe. The ms-vscode.cpptools extension has been installed in Visual Studio Code and includePath is set to:
"includePath": [
"${workspaceFolder}/**",
"${INCLUDE}",
"C:/Qt/5.15.0/msvc2019_64/include/**"
],
This file hw.cppcompiles and runs fine:
#include <iostream>
int main()
{
std::cout << "Hello world!";
return 0;
}
The command used in tasks.json is:
"command": "cl.exe",
"args": [
"/Zi",
"/EHsc",
"/Fe:",
"${fileDirname}\\${fileBasenameNoExtension}.exe",
"${file}"
],
Alternatively, from the in-built Terminal inside Visual Studio Code, the command "cl /EHsc /MD /O2 hw.cpp /link /out:hw.exe" compiles everything correctly and hw.exe can be executed.
But when I attempt to use Qt as follows it fails to compile:
#include <QString>
int main()
{
QString test("Hello world!");
qDebug() << test;
return 0;
}
The compiler reports "fatal error C1083: Cannot open include file: 'QString': No such file or directory". IntelliSense does find QString.h, which opens when I press Ctrl and click QString (at the top).
What am I missing?
UPDATE
Thanks to comments from #rioV8, I've investigated /link options for cl.exe. The task arguments have been updated to:
"args": [
"/EHsc",
"/MD",
"/O2",
"/IC:\\Qt\\5.15.0\\msvc2019_64\\include",
"/IC:\\Qt\\5.15.0\\msvc2019_64\\include\\QtCore",
"${file}",
"/link",
"/LIBPATH:C:\\Qt\\5.15.0\\msvc2019_64\\lib",
"Qt5Core.lib",
"qtmain.lib",
"/OUT:${fileDirname}\\${fileBasenameNoExtension}.exe"
],
This has improved things slightly. hw.cpp now compiles and generates hw.obj, but now I get linker errors (one for each .lib):
warning LNK4272: library machine type 'x64' conflicts with target machine type 'x86'
This is followed by fatal error LNK1120: 2 unresolved externals.
Getting closer, but still not linking.

Answer 1

There has been a detailled guide on the KDAB blog recently.
Overview of VS Code for Qt developers:
https://www.kdab.com/using-visual-studio-code-for-writing-qt-applications/
Technical guide:
https://www.kdab.com/using-visual-studio-code-for-qt-apps-pt-1/
https://www.kdab.com/using-visual-studio-code-for-qt-apps-pt-2/
The steps in the technical guide look very similar to the issues you are describing ;-)