Problem with linking the `ssl` lib on macos

Learning
,
1

Hi,

I’m trying to use the ocaml-ssl lib (GitHub - savonet/ocaml-ssl: OCaml SSL bindings.) in a project on macos.
I installed it with opam install ssl (no problem during installation).

However, I doesn’t build.

Minimal .ml file:

let () = 
Ssl.init();
print_endline "Hello, World!"

Dune file:

(executable
 (public_name test2)
 (name main)
 (libraries test2 ssl))

I get this error:

File "bin/dune", line 3, characters 7-11:
3 |  (name main)
           ^^^^
ld: warning: directory not found for option '-L/opt/homebrew/Cellar/openssl@3/3.1.0/lib'
ld: library not found for -lssl
clang: error: linker command failed with exit code 1 (use -v to see invocation)
File "caml_startup", line 1:
Error: Error during linking (exit code 1)

I seem to understand that the compiler can’t find the open-ssl directory, but the path in the error message is the right one and has a bunch of files that look legit inside.

Does anyone know how to make it compile, and can you explain what is failing here please?

2

It’s possible your libraries are out of date. Did you make sure to opam update && opam upgrade?

3

I should have though of that, sorry.
I just updated everthing and it fixed the problem. I only had a few libs out of date, and none of them were ssl, but I guess it depended on one of them because that did the trick.

Thank you for your help!

1 Like
4

On MacOS I used to have to run opam reinstall ssl after I had installed everything already (including ssl!). And only then would it work.
I’ve long switched to the tls library but I’d bet that’s the issue you ran into.

5

Yes, on macOS the installation location of OpenSSL keeps changing. So when you install ssl it remembers to add -L/opt/homebrew/Cellar/openssl@3/3.1.0/lib to the flags. If you upgrade openssl using brew to say 3.1.1 it will live in a new folder, presumably /opt/homebrew/Cellar/openssl@3/3.1.1/lib and delete the older one, thus when OCaml is building your library, L/opt/homebrew/Cellar/openssl@3/3.1.0/lib does not point to a place where the OpenSSL code is located.