CODEWITHSUNDEEP
c++linuxqtmakefile
MistyD
MistyD

Reputation: 17253

make Qt application fails on fedora 20 : /usr/bin/ld: cannot find -lGL

I am following this example here. This is the output I get for make

admin@localhost qtest$ make
g++ -Wl,-O1 -Wl,-rpath,/home/admin/Qt/5.3/gcc_64 -Wl,-rpath,/home/admin/Qt/5.3/gcc_64/lib -o qtest qtest.o   -L/home/admin/Qt/5.3/gcc_64/lib -lQt5Gui -lQt5Core -lGL -lpthread 
/usr/bin/ld: cannot find -lGL
collect2: error: ld returned 1 exit status
make: *** [qtest] Error 1
admin@localhost qtest$

My cpp file is this

#include <QtWidgets/qapplication.h>
#include <QtWidgets/qpushbutton.h>

int main( int argc, char **argv )
{
    QApplication a( argc, argv );

    QPushButton hello( "Hello world!", 0 );
    hello.resize( 100, 30 );
    hello.show();
    return a.exec();
}

Any suggestions on how I can fix this ?

Update

This is what I get after

 sudo yum install mesa-libGL-devel -y

Trying again to build :

admin@localhost qtest$ make
g++ -Wl,-O1 -Wl,-rpath,/home/admin/Qt/5.3/gcc_64 -Wl,-rpath,/home/admin/Qt/5.3/gcc_64/lib -o qtest qtest.o   -L/home/admin/Qt/5.3/gcc_64/lib -lQt5Gui -lQt5Core -lGL -lpthread 
qtest.o: In function `main':
qtest.cpp:(.text.startup+0x22): undefined reference to `QApplication::QApplication(int&, char**, int)'
qtest.cpp:(.text.startup+0x4f): undefined reference to `QPushButton::QPushButton(QString const&, QWidget*)'
qtest.cpp:(.text.startup+0x74): undefined reference to `QWidget::resize(QSize const&)'
qtest.cpp:(.text.startup+0x7c): undefined reference to `QWidget::show()'
qtest.cpp:(.text.startup+0x81): undefined reference to `QApplication::exec()'
qtest.cpp:(.text.startup+0x8c): undefined reference to `QPushButton::~QPushButton()'
qtest.cpp:(.text.startup+0x94): undefined reference to `QApplication::~QApplication()'
qtest.cpp:(.text.startup+0xab): undefined reference to `QApplication::~QApplication()'
qtest.cpp:(.text.startup+0xbe): undefined reference to `QPushButton::~QPushButton()'
qtest.cpp:(.text.startup+0xce): undefined reference to `QPushButton::~QPushButton()'
collect2: error: ld returned 1 exit status
make: *** [qtest] Error 1

Upvotes: 2

Views: 1338

Answers (2)

Nejat
Nejat

Reputation: 32685

To solve your error :

/usr/bin/ld: cannot find -lGL

you should install the missing mesa package by running the following install command as root or using sudo :

sudo yum install mesa-libGL-devel -y

Upvotes: 4

chrisb2244
chrisb2244

Reputation: 3001

Open up your foo.pro file.

You probably have something like:

######################################################################
# Automatically generated by qmake (3.0) Mon Nov 17 14:00:29 2014
######################################################################

TEMPLATE = app
TARGET = test
INCLUDEPATH += .

# Input
SOURCES += foo.cpp

Add to the top, "QT += widgets", such that your file now reads:

######################################################################
# Automatically generated by qmake (3.0) Mon Nov 17 14:00:29 2014
######################################################################

QT += widgets

TEMPLATE = app
TARGET = test
INCLUDEPATH += .

# Input
SOURCES += foo.cpp

then run qmake and make. This should allow it to find the relevant headers.

Your second error is not with libraries, but with finding the QtCore and QtWidgets modules of Qt.

Upvotes: 3

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