Dune developer preview: ocamllsp cannot read stdlib.cmi (corrupted compiled interface)

[edwintorok]

Expected Behavior

ocamllsp works

Actual Behavior

ocamllsp fails.

Reproduction

• PR with a reproducing test:

1. Follow steps at https://preview.dune.build/ to install dune and a build a hello world project. This builds an OCaml 5.2.1.
2. Run 'ocamllsp'. This downloads an ocamlformat and ocamllsp for 5.2.1, but it is a binary download for the musl toolchain (the one built by dune previously was using a GCC toolchain).
3. Run an editor (e.g. Helix, or probably any other editor), and observe the error message.

Specifications

• Version of dune (output of dune --version):

- "Dune Developer Preview: build 2024-12-18T09:09:58Z, git revision
3fc17eec135ab67a514c1cbb02182f7bccf6d042"

• Version of ocaml (output of ocamlc --version)
  4.14.0
  (not relevant, because dune builds its own)

• Operating system (distribution and version):

Additional information

I think this is because ocamllsp is a binary download built using the musl toolchain, and the hello world project uses a locally built OCaml compiler. Obviously interface hashes won't agree between the two, since it is a different compiler.

I assume ocamllsp would have to be built instead of downloaded as binary, since the musl version doesn't appear to be truly portable yet if it can only parse a musl based compiler.

ocamllsp
Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Locking dev-tools.locks/ocamlformat: Updating package repos "binary-packages", "                                                                                Solution for dev-tools.locks/ocamlformat:      
- ocamlformat.0.27.0+binary-ocaml-5.2.1-built-2024-12-04.0-x86_64-unknown-linux-musl
 Downloading ocamlformat.0.27.0+binary-ocaml-5.2.1-built-2024-12-04.0-x86_64-unknown-linux-musl
    Building ocamlformat.0.27.0+binary-ocaml-5.2.1-built-2024-12-04.0-x86_64-unknown-linux-musl
     Running 'ocamlformat --help'
Locking dev-tools.locks/ocaml-lsp-server: Updating package repos "binary-package                                                                                Locking dev-tools.locks/ocaml-lsp-server: Updating package repos "binary-package                                                                                Locking dev-tools.locks/ocaml-lsp-server: Updating package repos "binary-package                                                                                Locking dev-tools.locks/ocaml-lsp-server: Updating package repos "binary-package                                                                                Locking dev-tools.locks/ocaml-lsp-server: Updating package repos "binary-package                                                                                Locking dev-tools.locks/ocaml-lsp-server: Updating package repos "binary-package                                                                                Solution for dev-tools.locks/ocaml-lsp-server:      
- ocaml.5.2.1
- ocaml-base-compiler.5.2.1
- ocaml-config.3
- ocaml-lsp-server.1.20.1+binary-ocaml-5.2.1-built-2024-12-12.0-x86_64-unknown-linux-musl
 Downloading ocaml-lsp-server.1.20.1+binary-ocaml-5.2.1-built-2024-12-12.0-x86_64-unknown-linux-musl
    Building ocaml-lsp-server.1.20.1+binary-ocaml-5.2.1-built-2024-12-12.0-x86_64-unknown-linux-musl
     Running 'ocamllsp'     

dune pkg lock
Solution for dune.lock:                                              
- ocaml.5.2.1
- ocaml-base-compiler.5.2.1
- ocaml-config.3
⌛10s edwin ~/h/hello_world [default] ❯ dune exec "$PROJECT"
 Downloading ocaml-base-compiler.5.2.1
    Building ocaml-base-compiler.5.2.1
Hello, World!                      

• Link to gist with verbose output (run dune with the --verbose flag):

[edwintorok]

Not sure how to best capture the error from the LSP in a text form, so here is a screenshot of the error.

[gridbugs]

Thanks for the report! I was hoping that using a different linker between ocamllsp and the code being analyzed wouldn't be an issue but I might be wrong. Can you share what linux distro/version you're using so I can try setting up a similar environment in docker to reproduce/investigate.