Using Q_OBJECT in VS2010 project gives unresolved externals

Question

I'm trying to use the Q_OBJECT macro in my Visual Studio 2010 Ultimate project, and it gives me unresolved external errors:

1>Application.obj : error LNK2001: unresolved external symbol "public: virtual int __thiscall MyButton::qt_metacall(enum QMetaObject::Call,int,void * *)" (?qt_metacall@MyButton@@UAEHW4Call@QMetaObject@@HPAPAX@Z)
1>Application.obj : error LNK2001: unresolved external symbol "public: virtual void * __thiscall MyButton::qt_metacast(char const *)" (?qt_metacast@MyButton@@UAEPAXPBD@Z)
1>Application.obj : error LNK2001: unresolved external symbol "public: virtual struct QMetaObject const * __thiscall MyButton::metaObject(void)const " (?metaObject@MyButton@@UBEPBUQMetaObject@@XZ)

I've had a similar project using QMaker, and solved it by doing clean project and re-running qmake. The thing is, there's no "Qmake" button in VS!

I have read few articles like this one and done everything they told me to. Though it didnt really help, because I've got an existing project of a few .cpp and a few header files, and I would like to avoid creating a .pro file and moving code into it.

I've installed VS Qt add-in, it gave me new cool "Qt" button on VS panel, though didn't help with unresolved externals (probably I don't know how to use it properly).

I have ran moc with via custom build tool in VS on my Application.h file (the only one that has Q_OBJECT), but that still didn't help:

C:\Utilities\QtSDK\Desktop\Qt\4.8.1\msvc2010\bin\moc Application.h -o tmp\moc\moc_Application.cpp

What might cause my problem and how do I solve it?

Answer 1

I would guess that you forgot to add the file generated by MOC (moc_Application.cpp in this case) into your Visual Studio project. You have to do this to make sure it gets built. I'm pretty sure this should resolve the linker errors you see.