6

I have a small project in C++ that compiled fine until I upgraded Xubuntu to 15.04. When I tried to rebuild it with cmake, this message appeared in the middle of the output:

/usr/bin/ld: cannot find -lstdc++

So, I tried writing a simple program to see if cmake was responsable for it:

int main() {
    return 0;
}

Funny thing: g++ compiles:

$ g++ main.cpp
$ ls
a.out  main.cpp
$ ./a.out
$

but when I try to use clang++...

$ clang++ main.cpp 
/usr/bin/ld: cannot find -lstdc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)
$

Trying with clang++ main.cpp -lc++ (as suggested here) or with the -static flag (here) gives the exact same error. Running with -v as suggested by clang itself, I get this:

$ clang++ main.cpp -v
Ubuntu clang version 3.6.0-2ubuntu1 (tags/RELEASE_360/final) (based on LLVM 3.6.0)
Target: x86_64-pc-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/4.9.2
Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/5.0.1
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.7.4
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.9.2
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.2
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.0.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.0.1
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
 "/usr/lib/llvm-3.6/bin/clang" -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -main-file-name main.cpp -mrelocation-model static -mthread-model posix -mdisable-fp-elim -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -target-linker-version 2.25 -v -dwarf-column-info -resource-dir /usr/lib/llvm-3.6/bin/../lib/clang/3.6.0 -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../../include/c++ -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../../include/c++/x86_64-linux-gnu -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../../include/c++/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-3.6/bin/../lib/clang/3.6.0/include -internal-externc-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fdebug-compilation-dir /home/ryu/Dropbox/Aperture/working/C/learn-sdl/src -ferror-limit 19 -fmessage-length 100 -mstackrealign -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o /tmp/main-efcd57.o -x c++ main.cpp
clang -cc1 version 3.6.0 based upon LLVM 3.6.0 default target x86_64-pc-linux-gnu
ignoring nonexistent directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../../include/c++/x86_64-linux-gnu"
ignoring nonexistent directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../../include/c++/backward"
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../../include/c++
 /usr/local/include
 /usr/lib/llvm-3.6/bin/../lib/clang/3.6.0/include
 /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
 "/usr/bin/ld" --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../x86_64-linux-gnu/crt1.o /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../x86_64-linux-gnu/crti.o /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/crtbegin.o -L/usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1 -L/usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../x86_64-linux-gnu -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../.. -L/usr/lib/llvm-3.6/bin/../lib -L/lib -L/usr/lib /tmp/main-efcd57.o -lstdc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/crtend.o /usr/bin/../lib/gcc/x86_64-linux-gnu/5.0.1/../../../x86_64-linux-gnu/crtn.o
/usr/bin/ld: cannot find -lstdc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)
$

In witch I couldn't find the source of the error.

I tried purging and reinstalling build-essential, clang and g++, but had no luck. I also googled it, but only found this link from 2013 (yes, I noticed this is for Red Hat).

So, my questions are:

  1. How do I fix this? (Apparently, reinstalling for the third/fourth time fixed this.)

  2. Why did this happen in the first place, since the only thing I did was upgrade the system?

Community
  • 1

3 Answers3

0

It is very weird, but removing gcc-go packet helped me.

vladon
  • 348
0

Check if you have linked stdc++ properly. E.g. try to build by g++, and use ldd to check where the library is. Then check if there is complete link hierarchy, e.g. (for stdc++):

lrwxrwxrwx 1 root root   40 cze 14 12:34 /usr/lib/x86_64-linux-gnu/libstdc++.so -> libstdc++.so.6
lrwxrwxrwx 1 root root   19 maj 11 02:36 /usr/lib/x86_64-linux-gnu/libstdc++.so.6 -> libstdc++.so.6.0.22
-rw-r--r-- 1 root root 1,6M maj 11 03:05 /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.22

On Ubuntu sometimes is missing (probably you don't have this first).

Pajączek
  • 1
-1

I have no idea why this is broken (I'm on a fresh Linux Mint installation and I'm getting that error) but I did this dirty fix.

In my .bashrc:

stdcxxpath() { if [ -n "${stdcxxpath:-}" ]; then echo "$stdcxxpath"; return; fi; stdcxxpath=$(g++ -xc++ /dev/null  -Wl,--print-map 2>&1 |awk '/libstdc\+\+.so/ { print $2; exit }'|sed 's|/[^/]*$||'); stdcxxpath; }
alias clang++='clang++ -L$(stdcxxpath)' #find where libstdc++.so is from gcc and use it

The memoized stdcxxpath() shell function finds libstdc++ and passes it to the linker used by clang++ (The simpler: dirname $(locate '*/libstdc++.so') works too although with a bit of a lag.

Petr Skocik
  • 249