It was a long long way, but I managed to include a shared file (libpi_pi_gcs2.so) included into C++ code under Linux Mint 17 Cinnamon 64-bit. Now as the dust is saddled I have a question left... let me summarize:
I copied libpi_pi_gcs2.so in usr/local/lib.
Trying to compile main.cpp with
g++ -Wall -o test main.cpp -lpi_pi_gcs2
faild, returning
/usr/bin/ld: skipping incompatible //usr/local/lib/libpi_pi_gcs2.so when searching for -lpi_pi_gcs2
/usr/bin/ld: cannot find -lpi_pi_gcs2
collect2: error: ld returned 1 exit status
I talked with my flatmate, and he guessed maybe the shared library is only 32bit compatible.
Using -m32 let me take a step forward! But yielding new errors.
I googled and it seemed like I needed C32 std libraries. And I installed:
apt-get install ia32-libs
Again the old error messages disappeared and new one arose, after googling around I installed:
apt-get install g++-multilib
Trying to compile it now using
g++ -Wall -o test -m32 main.cpp -lpi_pi_gcs2
Let to the error messages:
//usr/local/lib/libpi_pi_gcs2.so: undefined reference to `dlsym'
//usr/local/lib/libpi_pi_gcs2.so: undefined reference to `dlopen'
//usr/local/lib/libpi_pi_gcs2.so: undefined reference to `dlclose'
The solution was the following command:
g++ -Wall -o test -m32 main.cpp -lpi_pi_gcs2 -ldl
Now my question:
Is it necessary to explicitly state -ldl i.e. link with libdl.so because the -m32 flag declares everything what follows to be 32bit and hence the linker would without explicitly
writing -ldl search for a 32bit libdl.so? I guess mine is 64 bit I am working on a 64bit system.
What do you think? More details and background informations are appreciated.
Greetings,
newandlost
Related
I installed casacore from source using the GitHub repository on my Ubuntu 18.04. The installation completes without any errors and the respective files are written to the expected directories (the .h files to /usr/local/include & libraries to /usr/local/lib). On trying to compile a basic C++ file using these I'm given the following error:
tmp/ccBxZcf3.o: In function 'main': /home/zealouspriest/C_C++_Projects/bb++/ms.cpp:15: undefined reference to 'casacore::MeasurementSet::MeasurementSet()'
/home/zealouspriest/C_C++_Projects/bb++/ms.cpp:15: undefined reference to 'casacore::MeasurementSet::~MeasurementSet()'
collect2: error: ld returned 1 exit status
The compiler command that I use is as follows:
g++ -g -Wall -I/usr/local/include -L/usr/local/lib -lcasa_casa -lcasa_tables -lcasa_ms ms.cpp -o ms
The ms.cpp file being compiled is extremely simple and just creates an empty measurement set to test for successful linking and is as follows:
//ms.cpp
#include <iostream>
#include </usr/local/include/casacore/ms/MeasurementSets/MeasurementSet.h>
int main(){
casacore::MeasurementSet ms = casacore::MeasurementSet();
return 0;
}
Here is all that I have tried:
a) Building from source using GitHub instructions,
b) Installing from Ubuntu repository.
Thanks in advance for your time!
When compiling manually with g++ you need to first specify your sources, and then the dependencies (libraries):
g++ -o ms ms.cpp -I/usr/local/include -L/usr/local/lib -lcasa_casa -lcasa_tables -lcasa_ms -g -Wall
Better just use CMake if you plan to have something more that just one cpp.
Related topics:
linking files in g++
gcc-g++-parameter-order
Alternatively, you can use the -Wl,--no-as-needed options:
g++ -g -Wall -I/usr/local/include -L/usr/local/lib -Wl,--no-as-needed -lcasa_ms ms.cpp -o ms
I am trying to build an image processing program written in C++ that depends on the following libraries using MinGW + MSYS (with GCC4.8.1) that I downloaded from www.mingw.org/ on a Windows 8 64bit computer
LibJPEG
BLAS and LAPACK
Armadillo
OpenMP
I have successfully compiled all the source code files (with -fopenmp flag of course), then I linked with the following statement:
g++ -o ./build/rspfitter {a list of .o files}
-L{paths to libraries} -ljpeg -lopenblas -lgomp -lpthread
The executable was correctly produced. However, it asks for the following dlls:
libgomp-1.dll
libpthread-2.dll
pthreadGC2.dll
I think it might a better idea to link libgomp and libpthread statically, so that I can minimize the number of dlls I need to deploy my program with (the above three dlls are not the only ones the program depends on). So I tried to link only libgomp and libpthread statically with the following command:
g++ -o ./build/rspfitter {a list of .o files}
-L{paths to libraries} -ljpeg -lopenblas -Wl,-static -lgomp -lpthread
But this time it fails with the following error message:
d:/mingw/bin/../lib/gcc/mingw32/4.8.1\libgomp.a(env.o):(.text.startup+0xbfe):
undefined reference to `_imp__pthread_attr_init'
d:/mingw/bin/../lib/gcc/mingw32/4.8.1\libgomp.a(env.o):(.text.startup+0xc13):
undefined reference to `_imp__pthread_attr_setdetachstate'
d:/mingw/bin/../lib/gcc/mingw32/4.8.1\libgomp.a(env.o):(.text.startup+0x3c):
undefined reference to `_imp__pthread_attr_setstacksize'
d:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe:
d:/mingw/bin/../lib/gcc/mingw32/4.8.1\libgomp.a(env.o): bad reloc
address 0x0 in section `.ctors'
d:/mingw/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe:
final link failed: Invalid operation
Then I tried to execute the exact same compiling and linking commands using the MinGW + GCC 4.8.1 environment that was installed together with CodeLite. It fails again with different error messages：
./tmp/hshfitcmdline.o:hshfitcmdline.cpp:(.text.unlikely+0x105):
undefined reference to `_Unwind_Resume'
./tmp/hshfitcmdline.o:hshfitcmdline.cpp:(.text$_ZN9NormalMapD1Ev[__ZN9NormalMapD1Ev]+0xb4):
undefined reference to `_Unwind_Resume'
d:/mingw-4.8.1/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe:
./tmp/hshfitcmdline.o: bad reloc address 0xb4 in section
`.text$_ZN9NormalMapD1Ev[__ZN9NormalMapD1Ev]'
d:/mingw-4.8.1/bin/../lib/gcc/mingw32/4.8.1/../../../../mingw32/bin/ld.exe:
final link failed: Invalid operation collect2.exe: error: ld returned
1 exit status make: *** [build/rspfitter] Error 1
I confirmed that the file "libgomp.a"/"libgomp.dll.a" was present on the [MinGW dir]/lib/gcc/mingw32/4.8.1/ for both installations of MinGW. However, they are of different sizes! In installation downloaded from MinGW.org, 'libgomp.a' is of 86kb, and "libgomp.dll.a" is of 87kb; In the CodeLite installation, however, the sizes are 74kB and 148Kb respectively.
Now I am wondering:
What could be the cause of the error messages given by the two MinGW systems? Could it be that the statically libraries that I downloaded from MinGW are corrputed? But dynamically linking was perfectly fine on both systems.
How on earth can I correctly link libgomp statically?
Thanks
To link libgomp statically you can do
ln -s `g++ --print-file-name=libgomp.a` && \
g++ foo.o -static-libgcc -static-libstdc++ -L. -o foo -fopenmp -ljpeg -lopenblas
However your executable will still depend on a pthread dll. The reason you are getting the error is that libc is still linking dynamically. To fix this you have to link libc statically as well
ln -s `g++ --print-file-name=libpthread.a` && \
ln -s `g++ --print-file-name=libc.a` && \
g++ foo.o -static-libgcc -static-libstdc++ -L. -o foo -fopenmp -ljpeg -lopenblas
However, if openblas or jpeg libraries depend on libc then there will likely still be undefined references.
I am compiling using arm-linux-gnueabi-g++ version 4.7.3.
I have the arm-linux-gnueabi libraries installed at location:
/usr/arm-linux-gnueabi/lib, it contains libdl.a, libdl.so, libdl.so.2,
and libdl-2.19.so.
libdl.so links to libdl.so.2 which links to libdl-2.19.so.
I am trying to link against the dl library (see command string below), but I always get the undefined reference errors.
arm-linux-gnueabi-g++ -I. -I../ -I../Comms/Linux -Wall -DLINUX -fpic -o ../../work/MyProgram main.o
-L../../work -L/usr/arm-linux-gnueabi/lib -lComms -lConsole -lUtilities -ldl
../../work/libUtilities.so: undefined reference to `dlsym'
../../work/libUtilities.so: undefined reference to `dlopen'
collect2: error: ld returned 1 exit status
If I compile using g++ 4.8.2 using the following commend then my program compiles, links, and executes fine.
g++ -I. -I../ -I../Comms/Linux -Wall -DLINUX -fpic -o ../../work/MyProgram main.o
-L../../work -lComms -lConsole -lUtilities -ldl
Obviously it can't find the libdl.so library; I thought that by adding the path to the location of the appropriate library by using the -L flag would fix the problem, but it didn't.
What am I missing with the ARM compiler command?
Well, I found the answer, I needed -Wl,--no-as-needed flag before the -ldl. I had run across this flag before I asked the question, but apparently mistyped it because it hadn't worked for me.
I don't understand why the flag is needed, but the code does finish linking now.
A SO user here says that it has to do with recent (2013 as of the user's post) versions of gcc linking to --as-needed.
I have downloaded gtest 1.7.0 sources from here:
https://code.google.com/p/googletest/downloads/list
and build the gtest .a files (lib files) on ubuntu 13.10:
Linux ubuntu 3.11.0-15-generic #23-Ubuntu SMP Mon Dec 9 18:17:04 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
and the resulting lib is called: libgtest.a. In my main.cpp file Have:
#include <iostream>
#include "gtest/gtest.h"
int main(){
std::cout << "Test \n";
int argc = 2;
char* cp01;
char* cp02;
char* argv[] = {cp01, cp02};
testing::InitGoogleTest(&argc, argv);
return 0;
}
From a terminal I build with:
g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -lpthread -lgtest
which gives the following errors:
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_key_create'
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_getspecific'
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_key_delete'
/home/user/gtest-1.7.0/lib/.libs/libgtest.so: undefined reference to `pthread_setspecific'
collect2: error: ld returned 1 exit status
Based on this:
error during making GTest
I have also tried -pthread instead of -lpthread but gives same error:
g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -pthread -lgtest
EDIT: I have also tried to specifying -pthread as the last argument:
g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -lgtest -pthread
same error
What am I doing wrong?
You need to specify -pthread after -lgtest. The linker takes libraries in order, and only takes as much as it needs to resolve references which are undefined at that point.
Nope, the problem is with Gtest's build.
If you build it using the standard configure approach, it isn't supplying the -lpthread correctly to create libgtest.so. Hence, when you try building a final shared library that actually uses the pthread capability it fails.
Instead, use the Cmake approach:
cd gtest-1.7.0
mkdir build
cd build
cmake -DBUILD_SHARED_LIBS=ON ..
make
And then manually install these into /usr/lib/
This version correctly links in libpthread into libgtest.
The option -lgtest is attempting to link the dynamic library libgtest.so. You
wish to link the static library /home/user/gtest-1.7.0/lib/.libs/libgtest.a.
Instead of:
g++ main.cpp -I/home/user/gtest-1.7.0/include -L/home/user/gtest-1.7.0/lib/.libs -lgtest -pthread
use:
g++ main.cpp -I/home/user/gtest-1.7.0/include /home/user/gtest-1.7.0/lib/.libs/libgtest.a -pthread
Note that your commandline supplies no name for the resulting executable, which will default
to a.out. If you want it called, e.g. mytest, then do:
g++ -o mytest main.cpp -I/home/user/gtest-1.7.0/include /home/user/gtest-1.7.0/lib/.libs/libgtest.a -pthread
Use -pthread instead of -lpthread (for linking with pthread-library), while you using gtest in your executable.
OR
Move the -lpthread after libgtest.a (sequence matters).
To answer we probably need more information, are you on a 64 bit machine and downloaded a 32 bit library?
when I had tried to compile the example code for glfw3 on http://www.glfw.org/documentation.html (copy/pasted to test compilation), I got the following errors:
/tmp/ccCdEKoi.o: In function main':
example.cpp:(.text+0x38): undefined reference toglfwCreateWindow'
example.cpp:(.text+0x5b): undefined reference to glfwMakeContextCurrent'
example.cpp:(.text+0x7a): undefined reference toglfwWindowShouldClose'
collect2: error: ld returned 1 exit status
I am compiling with g++ example.cpp -o example -lGL -lglfw and when I installed the latest glfw 3.0.2, it installed without problems.
GLFW3 builds as libglfw3 by default, not libglfw as GLFW2 did. So you're probably still linking against your GLFW2 installation.
Solution:
g++ example.cpp -o example -lGL -lglfw3