LibQtGui.so brings 51 undefined reference errors when linking Qt.

blissfreak

Hi, I'm on Sabayon Linux ( a fork of Gentoo), and while I've just started using Qt, I've been able to compile and run my programs in Qt Creator for a while now without any issues. It's only when I pass Config += qt that I get issues. I've tried passing in core or gui, just as is, but that still won't allow the actual project to compile.

Here are my errors:

@/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_read_info@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_gAMA@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_get_tRNS@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_PLTE@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_filler@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_get_text@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_packing@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_write_rows@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_invert_mono@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_error_fn@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_write_chunk@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_get_image_width@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_IHDR@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_sig_bytes@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_read_update_info@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_interlace_handling@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_write_fn@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_write_end@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_create_read_struct@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_read_image@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_set_gray_to_rgb@PNG12_0' /home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to png_get_IHDR@PNG12_0'
/home/holland/QtSDK/Desktop/Qt/4.8.0/gcc/lib/libQtGui.so: undefined reference to `png_get_channels@PNG12_0'@

I'm not quite sure what to do about this. I've tried reinstalling the sdk, and while that has gone fairly smoothly, I still haven't been able to get this working on my development machine. Everything is up to date, as well.

QMake File

@TEMPLATE = app
win32:CONFIG += console
CONFIG += qt core gui

QMAKE_CXX_FLAGS += -std=c++0x

SOURCES +=
VI_GL.cpp
VI_Initialize.cpp
VI_Unix.cpp
VI_Util.cpp
VI_Win.cpp
VI_ByteBuf.cpp

HEADERS +=
VI_Includes.h
VI_Win.h
VI_Unix.h
VI_Math.h
VI_GL.h
VI_Util.h
VI_ByteBuf.h

win32:LIBS += -glew32 -lglu32 -lopengl32 -lkernel32 -lgdi32 -luser32 -lws2_32

unix:LIBS += -lX11 -lGLEW -lGLU -lGL -lXext -L/usr/X11R6/lib@

Thank you to anyone who can provide assistance. :)

mlong

Perhaps libpng isn't available in the library path.

blissfreak

Should I just do export PATH = /path/to/libpng/?

mlong

If it's not seeing it at compile time,
@
LIBS += -L/path/to/libpng/location
@

blissfreak

Hmm...I've tried both export PATH and your LIBS method; unfortunately, they don't work. Do you have any other ideas?

Edit

It looks like I'm able to pass CONFIG = opengl | core | gui, just no += operator.

I can't get CONFIG = qt, however.

goetz

Looks like you're missing

@
unix:LIBS += -lpng
@

It's strange that it's not added by qmake, though, as it is a dependency of QtGui lib, and not directly of your code.

One cause could be that you have libpng installed, but the version doesn't match with that required by the SDK.

blissfreak

Damn, that one didn't work either. :(

I think you're right, though: my libpng version is 1.5.6 AND 1.4.8, so I'm guessing Qt must not be referencing these properly. Is there somewhere I can go and edit a few things to tinker around with this?

Edit

I got it to work!

For Sabayon users, just do:

@
equo search libpng
equo install libpng-1.2.46
@

It seems like Qt's version is a few versions behind, but regardless, this will definitely allow you do build your projects with Qt now!

:)