Code coverage in clang

Question

I'm trying to generate code coverage files for a small C program compiled with clang on Debian Linux. Here's what I've done:

neuron@debian:~/temp$ ls
main.c  test.c  test.h
neuron@debian:~/temp$ clang *.c
neuron@debian:~/temp$ ./a.out 
0

This is exactly as expected, I can compile and run things. Now trying to enable coverage.

neuron@debian:~/temp$ clang --coverage *.c
/usr/bin/ld: cannot find /usr/bin/../lib/libprofile_rt.a: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Trying to include the library for linking.

neuron@debian:~/temp$ clang --coverage -lprofile_rt *.c
/usr/bin/ld: cannot find -lprofile_rt
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Finding the library:

neuron@debian:~/temp$ find / -name \*profile_rt\* 2>/dev/null
/usr/lib/llvm-3.0/lib/libprofile_rt.so
/usr/lib/llvm-3.0/lib/libprofile_rt.a
neuron@debian:~/temp$ clang --coverage -lprofile_rt -L/usr/lib/llvm-3.0/lib *.c
/usr/bin/ld: cannot find /usr/bin/../lib/libprofile_rt.a: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Here's more verbose output of the last command: http://pastie.org/8468331. What concerns me there:

• the linker uses tons of gcc libraries to link with (though this may be a result of llvm not having it's own binunitls);
• profiling library is being searched for at /usr/bin/../lib/libprofile_rt.a instead of the path I provided.

If we pass the arguments to the linker the output is the same:

neuron@debian:~/temp$ clang --coverage  -Wl,-L/usr/lib/llvm-3.0/lib *.c -lprofile_rt
/usr/bin/ld: cannot find /usr/bin/../lib/libprofile_rt.a: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)

What do I do wrong?

Answer 1

Try changing the order of your link line from

clang --coverage -lprofile_rt -L/usr/lib/llvm-3.0/lib *.c

to

clang --coverage  -L/usr/lib/llvm-3.0/lib *.c -lprofile_rt

Ok, doesn't seem like the linker is getting your -L for some reason. Maybe try

clang --coverage  -Wl,L/usr/lib/llvm-3.0/lib *.c -lprofile_rt