How to compile a Qt application through the command line with MinGW?

Question

I have downloaded the latest Qt version for MinGW, and I have the correct MinGW version which is compatible with Qt. When I try to make the project, g++ is unable to find my source file even if it's in the same folder as the project file.

Those are the steps I followed (all project and source files are in T:\QtTest ):

T:\QtTest> qmake -project
T:\QtTest> qmake
T:\QtTest> make

And the output is this:

T:\QtTest> make
mingw32-make -f Makefile.Debug
mingw32-make1: Entering directory `T:/QtTest’
g++ -c -g -frtti -fexceptions -mthreads -Wall -DUNICODE -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_GUI_LIB -DQT_CORE_LIB -DQT_HAVE_MMX -DQT_HAVE_3DNOW -DQT_HAVE_SSE -DQT_HAVE_MMXEXT -DQT_HAVE_SSE2 -DQT_THREAD_SUPPORT -DQT_NEEDS_QMAIN -I“c:\Qt\4.8.0\include\QtCore” -I“c:\Qt\4.8.0\include\QtGui” -I“c:\Qt\4.8.0\include” -I”.” -I“c:\Qt\4.8.0\include\ActiveQt” -I“debug” -I“c:\Qt\4.8.0\mkspecs\default” -o debug\main.o main.cpp
g++: main.cpp: no such file or directory
g++: no input files
mingw32-make1: *** [debug/main.o] Error 1
mingw32-make1: Leaving directory `T:/QtTest’
mingw32-make: *** [debug] Error 2

I have no idea why it can't find "main.cpp" file when it's in the same directory as the project files. Even if I replace "main.cpp" with the full path ("T:\QtTest\main.cpp") it still won't find it. What am I doing wrong?

The following is my project structure: (main.cpp is the only file that I wrote, all the others were generated by qmake)

T:\QtTest\main.cpp 
T:\QtTest\Makefile
T:\QtTest\Makefile.debug
T:\QtTest\Makefile.release
T:\QtTest\QtTest.pro
T:\QtTest\debug\
T:\QtTest\release\

My g++ version is 4.4.0, which is the version suggested by the Qt installer and available for download in the same page as the Qt for MinGW installer.

Answer 1

Problem solved.

It had nothing to do with MinGW or Qt or the makefiles generated by qmake. I found it was caused solely by a custom entry in the Windows registry. I'm posting this solution for anyone who encounters the same problem:

Sometime ago I had created an entry in the Windows registry under HKEY_CURRENT_USER \ Software \ Microsoft \ Command Processor called Autorun, which makes CMD.exe start in a custom working directory, which was something I wanted to do (so I followed the steps detailed in this page about "How to change the default startup directory for Command Prompt": http://windowsxp.mvps.org/autoruncmd.htm).

Well, I completely neglected the CAUTION part in that page, which states that "Changing the current directory using Autorun value as mentioned in this article, might affect the functionality of batch scripts". Yes, shame on me.

So, if you have the same problem of being unable to make your Qt projects using qmake, and everything else looks OK in your project structure and makefiles, verify that you don't have something in the Windows registry which might change the startup directory for the command prompt.

Answer 2

Do you have MSYS installed? If sh.exe from MSYS is on the system path, it may conflict with the interpretation of windows style paths. Check the documentation here.

If that isn't the problem, then delete everything in your project folder except the source files and start over again with qmake -project. After that step, open the .pro file and verify that things look correct. For a very basic project, I get something like this:

TEMPLATE = app
TARGET = 
DEPENDPATH += .
INCLUDEPATH += .
# Input
HEADERS += widget.h
FORMS += widget.ui
SOURCES += main.cpp widget.cpp

The next two steps, running qmake and then make should work correctly. If not, there is nothing wrong with the steps you followed and there is something wrong with your system/environment.