Dune compiles fine, but VSCode gives a false positive "module missing" using the WSL2 and ocamllsp

Ecosystem
1

Sorry if this is already resolved, but I’ve been sifting through the internet and following tutorials with no results.
Reproducing the issue from zero:
I installed ocaml on the WSL(2) of Windows 11. I don’t understand a lot of the compiling, but I use Dune as a build system, and VSCode as IDE (running on the WSL).
I initialize a project on Ubuntu with: $ dune init proj Test
I open VSCode, and create two files FileA.ml and FileB.ml, with FileB depending on FileA and main.ml being the executable.
main.ml (default generated by Dune):

let () = print_endline "Hello, World!"

FileA.ml:

let testA = true;;

FileB.ml:

let testB = FileA.testA;;

And the dune file contains:

(executable
 (public_name Test)
 (name main)
 (libraries Test))

I can then run $ dune build, which compiles fine (and even $ dune exec Test).
However VSCode indicates the error on FileA.testA:

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image820×204 9.29 KB

I can also reinstall OCaml, restart the OCaml Language Server or change the dune file to contain:

(executable
 (public_name Test)
 (name main)
 (libraries Test)
 (modules main FileA FileB))

and it always gives the same error.
Weird thing is that on my original project with a dozen files, this error only appears on some files even when there is nothing special in the dune files.
Thanks for your help.

2

I’ve been getting false positives for this error for some time now as well. Usually, restarting the VS Code extension host (or the entire window) fixes it for a while, but maybe we ought to open an issue on their tracker.

I’ve also been seeing dune build --watch miss change events, forcing me to restart it; the overall OCaml editing experience is becoming increasingly unstable lately.

3

Thanks for your input. In my case, restarting anything doesn’t even fixes it temporarily…