Expand variables in install stanzas

[rgrinberg]

Currently ${variables} aren't expanded in install stanzas as they should be [1].

cc @dilm @wokalski

[1] https://discuss.ocaml.org/t/dune-object-file-output-is-not-using-output-complete-obj/1828/6?u=rgrinberg

[Isweet]

I've started poking at this, but first issue w/ Dune so it'll be slow. Feel free to scoop me for the sake of expedition.

[rgrinberg]

Thanks for taking intitative @Isweet .

Have a look at jbuild.ml. In particular, you're looking for uses of String_with_vars.t uses in the various t values which represent sexp parsers. This will you insert variables in the necessary fields.

Then, you'll be to eliminate String_with_vars.t values using String_with_vars.expand with a correct ~f function. Here you can refer to the expand_* family of functions in super_context.ml

Finally, keep in mind that we cannot support all variables in the installed stanza. For example, %{read:...} cannot be supported at the moment, because we're keeping the list of installed artifacts static, and hence cannot build anything before we know the full set of static artifacts.

Feel free to ask more questions.

[Isweet]

I was able to figure out the parsing yesterday. I'll open a WIP PR sometime today.

I started looking at the expand functions in super_context.ml to get an idea of how to use expand in string_with_vars.ml.

Thanks for the direction, I'll follow-up if I get stuck.

[rauanmayemir]

Has anything changed here recently?

I can compile an executable in (exe) linking mode and run it as a standalone program, but I can't link app.exe.o built in (object) mode with my XCode project because it has its own libasmrun.a dependency. (i.e I start having 'duplicate symbol' issues)

I can't remove libasmrun.a dependency in my xcode project because I'm running caml_main in its main function.

I didn't have such issues before, so I'm wondering if something changed in -output-complete-obj.

My jbuild file:

(jbuild_version 1)

(executable (
 (name app)
 (libraries (brisk_cocoa))
 (modes (object))
))

(install (
  (package brisk)
  (section lib)
  (files ((app.exe.o as app.o)))
))

And then I run jbuilder build @install.

Note: I'm on ocaml 4.06 and jbuilder 1.0.1.

[ghost]

@rauanmayemir could you open a separate issue?

[rauanmayemir]

@diml I created a discuss thread here, should I open a gh issue as well?

[ghost]

Yes, please. It's easier to track issues at a central place. I believe all dune devs are on discuss, but for instance I personally don't consult discuss on a daily basis.

[rgrinberg]

Fixed by @mseri