When I build my qpid-proton-0.17.0 program I get this link error:
undefined reference to proton::event_loop::inject(std::function<void ()>)
Here is how I build:
g++ -std=c++14 myprog.cpp -o myprog -lqpid-proton-cpp -lboost_system -lcrypto -lssl
Am I missing a library?
Also, without -std=c++14 or -std=c++11 the link issue goes away. But I will need -std=c++11 at least.
I rebuilt qpid-proton-0.17.0 libraries with -DCMAKE_CXX_FLAGS=-std=c++11 and that fixed my issue.
Related
I would like to CGO link my go program to a c++ static library linked to LLVM's libc++. With GNU's libstdc++, everything works fine.
I am calling go compiler as follows:
CGO_CXXFLAGS="-stdlib=libc++ -I/usr/lib/clang/12.0.0/include -I/usr/local/include -I/usr/include" CGO_LDFLAGS="-stdlib=libc++ -L/usr/lib/clang/12.0.0/lib -L/usr/local/lib -L/usr/lib -L/usr/lib/x86_64-linux-gnu -lpthread -lrt -lc++ -lm -lc" go test --ldflags '-extldflags "-static"' -c -a .
I was missing -lc++ -lc++abi.
I am trying to cross compile my application for a arm based system.
I have 2 libraries compiled in the following way:
$ gcc -shared --sysroot=$DIR_PATH -o $LIBPATH/libfoo.so foo.o
$ gcc -shared --sysroot=$DIR_PATH -o $LIBPATH/libbar.so bar.o
A third library is compiled:
gcc -shared -o $LIBPATH/libfoobar.so --sysroot=$DIR_PATH -L$LIBPATH -Wl,rpath=$RUN_TIME_PATH foobar.o -lfoo -lbar
Then finally I compile a binary:
gcc -o app --sysroot=$DIR_PATH -L$LIBPATH -Wl,rpath=$RUN_TIME_PATH app.o -lfoobar
However when compiling app I get
warning: libfoo.so, needed by libfoobar.so, not found (try using -rpath or -rpath-link)
I believe you need to use -Wl,-rpath-link=$LIBPATH to tell the linker where to look to resolve runtime library references during the link operation.
More info can be found in the ld documentation: https://sourceware.org/binutils/docs-2.37/ld/Options.html
I am trying to compile my first FLTK file. First I compiled it by gcc with -lfltk option, and I got this error:
/usr/bin/ld: /tmp/ccX7sPxQ.o: undefined reference to symbol '__gxx_personality_v0##CXXABI_1.3'
/usr/lib/x86_64-linux-gnu/libstdc++.so.6: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
Why do I get this error message? If I use g++ instead, it just compiles it.
edit.
fltk-config --cxxflags returns:
-I/usr/include/cairo -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include
-I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12
-I/usr/include/freetype2 -I/usr/include/cairo -I/usr/include/glib-2.0
-I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/pixman-1 -I/usr/include/freetype2
-I/usr/include/libpng12 -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_THREAD_SAFE -D_REENTRANT
-lfltk is not enough to build a minimal FLTK-based application.
I strongly suggest you to read the following page: http://www.fltk.org/doc-1.3/basics.html . It clearly explains how to compile a simple FLTK program.
Assuming your FLTK application is not using extra FLTK libraries (opengl, images, forms) and is in a single file, called myfltkapp.cpp, the absolutely quickest way to compile and link it properly would be:
fltk-config --compile myfltkapp.cpp
I guess the reason I got the error comes from the difference between gcc and g++. I thought I could compile it by gcc with fltk library, but gcc does not link c++ standard library automatically. Thus you have to include the C++ standard library for gcc. It was a silly question.
gcc myfltkapp.cpp -lstdc++ -lfltk
What is the difference between g++ and gcc?
Im developing an android app thats loading two shared libraries. One is external, its called libpcan.so . Usually its build to libpcan.so.0.6, this somehow cant be used by my android, i so changed the gcc flags compiling it from:
arm-linux-androideabi-gcc src/libpcan.c -fPIC -shared -O2 -Wall -Wl,-soname,-libpcan.so.0 -lc -I. -I../driver -DNO_RT -o -libpcan.so.0.6
ln -sf libpcan.so.0.6 libpcan.so
to
arm-linux-androideabi-gcc src/libpcan.c -fPIC -shared -O2 -Wall -lc -I. -I../driver -DNO_RT -o -libpcan.so
This .so has the same size as the so.0.6 so i assume it worked fine.
My own c-code is getting compiled with
arm-linux-androideabi -shared src/receivetest.c src/common.c -I. -I../lib -I../driver -L../lib -L/lib -L/usr/lib -L/usr/local/lib -o libreceivetest.so
I load both of these files, so the libpcan.so and the libreceivetest.so to my app
static {
System.loadLibrary("pcan");
System.loadLibrary("receivetest");
}
When I'm trying to launch that app i get the error message:
07-14 11:12:43.812: E/AndroidRuntime(753): java.lang.ExceptionInInitializerError
07-14 11:12:43.812: E/AndroidRuntime(753): Caused by: java.lang.UnsatisfiedLinkError: Cannot load library: reloc_library[1306]: 36 cannot locate 'CAN_Open'...
My receivetest is using that function, but since it declared in the libpcan.so and im also loading that library, i don't know where that error could come from.
I'd just guess its an error in my clags, since I'm new to building .so files via using gcc in the shell i don't really understand all the flags im using.
It's quite long since i solved this. But I haven't ever marked this question as solved.
Thanks to jww for reminding me.
As I've said in the comment to my question, the link to the function CAN_Open was missing due to a missing parameter at compiling the .so-file. The function CAN_Open is a part of the libpcan.so and by skipping the link to that file the CAN_Open function just never made it into the receivetest.so .
I'm using GCC 4.7.2 and LD 2.23 but when I add -flto to my compile options my compile time increases by over 20%! The manual seems to indicate that -fuse-linker-plugin is needed for the optimization to work. It also says that it's enabled by default with -flto but when I add it explicitly I see the following error in the link command:
g++: error: -fuse-linker-plugin is not supported in this configuration
According to manual, it should be supported by LD 2.21 or greater. Any idea why I'm getting this error? For reference here are examples of my full compile commands:
g++ -Wall -pipe -O3 -flto -fno-strict-aliasing -mtune=generic --no-exceptions -fPIC -c some.cc
g++ -o exec -Xlinker some1.o some2.o -static some1.a some2.a -Wl,--wrap,open -flto -fuse-linker-plugin
Running 'ld --help | grep plugin' shows "-plugin" option so I don't understand why GCC is complaining:
-plugin PLUGIN Load named plugin
-plugin-opt ARG Send arg to last-loaded plugin
Link time optimizations aren't supposed to reduce compilation time, but optimize runtime of your program.
#options, just add "-flto -fuse-linker-plugin" to your CFLAGS(or CXXFLAGS for c++) and LDFLAGS and it should work just fine.
#gold: ld --version is probably gonna return gnu LD, to switch to gold, make ld symlink which ld point to which ld.gold
e.g. ln -s /usr/bin/ld.gold /usr/bin/ld