Issue compiling with different version of gcc and g++

Question

I want to compile a program by entering through SSH the computer at my institution. I want to compile this program by using a different version of gcc and g++ , namely a more recent one with repsect to the default installed one. This means that instead of using gcc-4.9.2 and g++-4.9.2 I would like to use gcc-6.3 and g++-6.3 . I can find them already on my computer, in fact I have the folder /opt/gcc-6.3 , so I don't have to download them. So what I do is the following

export PATH=/opt/gcc-6.3/bin/:$PATH
export LD_LIBRARY_PATH=/opt/gcc-6.3/lib/:$LD_LIBRARY_PATH

but while gcc seems to work, when I try to compile a c++ program with g++ I get

./[name_of_the_program].x: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `CXXABI_1.3.9' not found (required by ./[name_of_the_program].x)
./[name_of_the_program].x: /usr/lib/x86_64-linux-gnu/libstdc++.so.6: version `GLIBCXX_3.4.21' not found (required by ./[name_of_the_program].x)

Obviously, if that's relevant information, I am not root on this machine.

Answer 1

If you are running on a 64bit machine, you must add

/opt/linux-gnu_6.x.x/lib64 

path also to you environment. ( or which path on your machine is used for the libs of this compiler version )

If you get root access you should better add ( or maybe your admin should do! ) your library path information to

/etc/ld.so.conf.d/gcc63.conf

and run sudo ldconfig .

After that you should check with ldd comand, that all chained requirements are fulfilled.

Answer 2

Don't do this:

export PATH=/opt/gcc-6.3/bin/:$PATH
export LD_LIBRARY_PATH=/opt/gcc-6.3/lib/:$LD_LIBRARY_PATH

Instead, add:

-B/opt/gcc-6.3/lib/

to your invocation options for either of the frontends gcc or g++ (assuming that /opt/gcc-6.3/lib/ is indeed the directory that directly contains the GCC 6.3 toolchain executables and libraries).

See the documentation of the -Bprefix option

Example:

$ cat prog.cpp
#include <iostream>

int main()
{
    std::cout << "I was compiled with GCC " 
        << __GNUC__ << '.' <<  __GNUC_MINOR__ << '.' << __GNUC_PATCHLEVEL__
        << " to C++ standard " << __cplusplus << std::endl;
    return 0;
}

$ which g++-4.9
/usr/bin/g++-4.9

$ which g++-6
/usr/bin/g++-6

$ g++-4.9 -o prog prog.cpp && ./prog
I was compiled with GCC 4.9.4 to C++ standard 199711

$ g++-4.9 -B/usr/lib/gcc/x86_64-linux-gnu/6.2.0 -o prog prog.cpp && ./prog
I was compiled with GCC 6.2.0 to C++ standard 201402

As per others' comments, be aware g++ >= 5 is ABI incompatible with g++ < 5.