@anmonteiro If we mangle, how is the user supposed to refer to it in their file?

Unless you are thinking of doing some name mangling with certain rules. It seems pretty complicated next to just renaming your source directory. I guess having a rule like foo-bar -> foo_bar is pretty sensible.

I think it'd be beneficial to support some of those directories and document / log the mangling scheme. For melange specifically, we'll probably want to have directories called [id] and (layout) (check https://beta.nextjs.org/docs/routing/defining-routes).

I suppose another solution would be to make the module name of a directory configurable from a stanza. So we could do

(subdir foo-bar (qualified_name foo_bar))

That way when Dune wants to give module names corresponding to directories, it would query a naming map which would be overridden with these stanzas. That way you can name your directories whatever you want and not worry about name mangling.

Another benefit of this is that it allows users to give a module name directly to say src/.

With such a feature, we would of course need to keep in mind the eventuality that OCaml adds namespaces, but I don't see that happening any time soon.

I like a solution along those lines. We could even reuse include_subdirs for it:

(include_subdirs 
  (mode qualified)
  ((src foo) (src/invalid-[module]-name invalid_module_name)))

(And it goes without saying: I don't think these should be implemented in this PR). The bug fix is sensible and looks good to me.

@anmonteiro Can you open a ticket with this feature request then?

#7605

I think the feature request in #7605 makes a lot of sense. I guess two other solutions to a directory with a malformed module name would be:

1. The directory in question contains only data and one uses (data_only_dirs bar-baz) (or data_only_dirs on an ancestor of the directory with a malformed module name).

2. The directory in question could be ignored altogether. (Is there a stanza for this?)

Should I open feature requests for those as well?

1. The directory in question contains only data and one uses (data_only_dirs bar-baz) (or data_only_dirs on an ancestor of the directory with a malformed module name).

I am not sure what exactly you mean here. Could you open an issue explaining this further?

2. The directory in question could be ignored altogether. (Is there a stanza for this?)

You can use the (dirs) stanza to remove a directory from Dunes vision. Something like (dirs :standard \ ignored_dir).

cf #7620 for two examples. One is your suggestion for (dirs), which I didn't know about, and which works like a charm. The other one uses (data_only_dirs), hoping that Dune will be fine with a directory then having an invalid module name. This is however not the case. I will open a feature request for this.

Feature request in question: #7628.

@rgrinberg can this be merged?

Yes