Strange error with directory targets

[ejgallego]

Hi folks, using this simple dune file:

(rule
 (targets (dir node_modules))
 (deps package.json)
 (action (run npm install --no-save)))

(alias
 (name node)
 (deps node_modules))

dune build @node fails with

File "dune", line 1, characters 0-95:
1 | (rule
2 |  (targets (dir node_modules))
3 |  (deps package.json)
4 |  (action (run npm install --no-save)))
Error: This rule defines a directory target "node_modules" that matches the
requested path "node_modules" but the rule's action didn't produce it
-> required by alias node in dune:6

however npm install generates the directory just fine; this is in today's main. Adding sandboxing doesn't alter the result.

[Alizter]

Do you have directory targets enabled?

[ejgallego]

Yup dune-project is:

(lang dune 3.4)
(using directory-targets 0.1)

[emillon]

to confirm, the action ran in _build/default and created _build/default/node_modules/?

[ejgallego]

Yes @emillon (it is very easy to reproduce, so if someone can confirm it'd be great)

[ejgallego]

I'm adding this to the milestone as it could be understood as a regression.

[Alizter]

@ejgallego Does it work on a previous version of Dune?

[ejgallego]

Yes (tho 3.3 didn't like the symlinks inside node, but we just clean them up and that works)

[ejgallego]

@rgrinberg if that serves as a clue, it seems still related to links somehow, the following action still works fine on main:

 (action
  (progn
   (run npm install --no-save)
   (run find node_modules -type l -exec rm {} ";"))))

[Alizter]

Repro case here #6189

[ejgallego]

Thanks a lot @Alizter ! This was a tricky one actually

[Alizter]

The digest computation for directory targets is broken because when it recuses on the subdirectory it forgets that symlinks are allowed inside and fails instead.

[emillon]

As this is related to directory targets which are experimental, we said that it would be fine to release 3.5 without a fix to this.

[rgrinberg]

Bumping this back to 3.5.0 as I have a fix ready.