Dune crashes when editing a file in exec watch mode

[LAC-Tech]

Expected Behavior

Dune not to crash when editing data.ml

Actual Behavior

Dune crashes when data.ml is edited, even if you just save the file without changing anything, with this output:

Error: _build/default/.hello.eobjs/dune__exe__Hello.impl.d: No such file or
directory
-> required by _build/default/.hello.eobjs/dune__exe__Hello.impl.all-deps
-> required by _build/default/hello.exe
Had 1 error, waiting for filesystem changes...      

Reproduction

clone https://github.com/LAC-Tech/dunebug
run

dune exec -w ./hello.exe

Save file data.ml in your editor. (saving hello.ml works fine). You may sometimes have to save 2 or 3 times to get it to crash.

Specifications

dune 3.16.0
The OCaml toplevel, version 5.2.0
Arch Linux, kernel 6.10.6, x86_64

[maiste]

This might be related to #10959.

[maiste]

@LAC-Tech could you try again and tell me if it is working with the latest version of dune? It seems to have been fixed with #10960. I can't reproduce with your example again using main version of dune.

[LAC-Tech]

Hi, excuse the late reply and basic question - but what's the best way to get this main dune version? build myself, install with opam flag? Just point me in the right direction.

[maiste]

You can either build it yourself or use the binary version from https://preview.dune.build (nightly version of dune built from the main branch).

[LAC-Tech]

Thanks. Exact same issue I'm afraid.

$ ~/.dune/bin/dune --version
"Dune Developer Preview: build 2024-11-02T02:13:00Z, git revision
c2e0160fd0b593c63536c7081238da1da5140720"

Then running with: ~/.dune/bin/dune exec -w ./hello.exe, and saving data.ml (which seems to be what's causing the race condition), I get the same error message.

Tried with a plain neovim, default config no plugins incase an LSP was causing an issue. But no luck.

Is there any information I can provide that might help?

[maiste]

Thanks for trying! I was betting on the fact that the mentioned PR introduced delays in computation that could possibly solve the issue. Apparently not.

You already provided a reproduction case so we don't need extra information.