Clang linking with a .so file

Question

I keep getting

ld: library not found for -lchaiscript_stdlib-5.3.1.so
clang: error: linker command failed with exit code 1 (use -v to see invocation)

When trying to link to a .so file.

I'm using this command:

clang++ Main.cpp -o foo -L./ -lchaiscript_stdlib-5.3.1.so

What am I doing wrong?

File libchaiscript_stdlib-5.3.1.so is in the same directory as file Main.cpp. I thought the -L./ would add the .so to the library search paths.

Solution

Yes, the -L option adds the search path, but the linker adds the .so (or .a) suffix itself (just like it adds the lib prefix). So you only need to have -lchaiscript_stdlib-5.3.1 and the linker will find it.

You can also skip the adding of the path, and link directly with the file:

clang++ Main.cpp -o foo libchaiscript_stdlib-5.3.1.so

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Note that the runtime linker (which is what actually loads the shared libraries when you run your program) might not be able to find the library if it's not in the runtime linker's path. You can tell the (compile time) linker to add a path to the shared-library path in the generated program though:

clang++ Main.cpp -o foo libchaiscript_stdlib-5.3.1.so -Wl,-rpath,/absolute/path

The -Wl option tells the compiler front-end to pass an option to the linker, and the linker option -rpath adds a path to the runtime-linker search path.

Comments

[Searene]

What's the difference between -L and -rpath? Seems to me that both are used to specify library paths.

[Some programmer dude]

@Searene -L adds to the build-time linker path. -rpath adds to the load-time library path (when the OS loads the library).