Qt/mingw32 undefined reference errors... unable to link a .lib

Question

I am new to Qt and have one error I am unable to fix.

I have a bunch of windows (VS2005) static library file (.lib). And I am testing if they work well with Qt. So I took the most simple library that I have. (Called MessageBuffer).

So I added MessageBuffer.h to the main.cpp, and added the location of those file in the INCLUDEPATH of the .pro.

Until then everything seem fine, I can use the class and Qt IDE show all method and everything. So to me it look like it found the .h file.

Now I added the MessageBuffer.lib (VS2005/Debug build) in the .pro like this:

LIBS += E:/SharedLibrary/lib/MessageBufferd.lib

I have also tried the following:

win32:LIBS += E:/SharedLibrary/lib/MessageBufferd.lib
LIBS += -LE:/SharedLibrary/lib -lMessageBufferd
win32:LIBS += -LE:/SharedLibrary/lib -lMessageBufferd

Here is the content of my .pro file:

QT += opengl
TARGET = SilverEye
TEMPLATE = app
INCLUDEPATH += E:/SharedLibrary/MessageBuffer
SOURCES += main.cpp \
    silvereye.cpp
HEADERS += silvereye.h
FORMS += silvereye.ui
OTHER_FILES += 
win32:LIBS += E:/SharedLibrary/lib/MessageBufferd.lib

They all give me the same errors: (and I get the same even if I don't include the .lib)

Running build steps for project SilverEye...
Configuration unchanged, skipping QMake step.
Starting: C:/Qt/2009.03/mingw/bin/mingw32-make.exe -w 
mingw32-make: Entering directory `C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye'
C:/Qt/2009.03/mingw/bin/mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory `C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye'
g++ -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc -mthreads -Wl -Wl,-subsystem,windows -o debug\SilverEye.exe debug/main.o debug/silvereye.o debug/moc_silvereye.o -L"c:\Qt\2009.03\qt\lib" -lopengl32 -lglu32 -lgdi32 -luser32 -lmingw32 -lqtmaind E:/SharedLibrary/lib/MessageBufferd.lib -lQtOpenGLd4 -lQtGuid4 -lQtCored4
mingw32-make[1]: Leaving directory `C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye'
mingw32-make: Leaving directory `C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye'
debug/main.o: In function `Z5qMainiPPc':
C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye/main.cpp:12: undefined reference to `MessageBuffer::MessageBuffer()'
C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye/main.cpp:13: undefined reference to `MessageBuffer::Append(char*, int)'
C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye/main.cpp:17: undefined reference to `MessageBuffer::~MessageBuffer()'
C:/Documents and Settings/JP/My Documents/QTProjects/SilverEye/main.cpp:17: undefined reference to `MessageBuffer::~MessageBuffer()'
collect2: ld returned 1 exit status
mingw32-make[1]: *** [debug\SilverEye.exe] Error 1
mingw32-make: *** [debug] Error 2
Exited with code 2.
Error while building project SilverEye
When executing build step 'Make'

Can anyone help please?

Solution

Based on the question Use libraries compiled with visual studio in an application compiled by g++ (mingw) and the MSDN forum post I can't mix VC & GCC it does not appear you can link a gcc application with visual c++ compiled libraries.

The solution would be to recompile everything with the same compiler.

Comments

[Admin]

d is the actual name, d is added for the debug version of the .lib

[user982201]

@xcimo makes sense...just wanted to check

[Admin]

I do not know if MessageBuffer class is exported. I dont not have any "export" keyword in the messageBuffer class, since I have been able to use this library in many other Visual studio c++ project. Does a static library need an export? or maybe its something that mingw need? Thanks for helping.

[user982201]

To be honest, not sure if it needs it...but the error seems to imply that they cannot be found.

[Admin]

do you think its not finding the .h or the .lib?

[user982201]

Try using the "nm" command that comes with minigw to see what is being exported by your lib.

[user982201]

If you have not tried it yet, tack a -l on the front of the library in the pro file

[Admin]

This is actually what I was going to post, I found this: These libraries, like many other precompiled Windows development packages such as the MySQL client library, were compiled with Ms Visual C++ (MSVC). MSVC and MinGW, we discovered, use different naming conventions for stdcall functions. MSVC exports them as _name@ordinal, but MinGW exports them as name. As a result, the MinGW build failed with “undefined references” link errors when calling stdcall functions exported from the MSVC library.

[Admin]

Please look here for solutions: blog.outofhanwell.com/2006/05/01/…