Put Lin and STM libraries in a standalone package

[OlivierNicole]

This creates packages containing the Lin and STM libraries, called lin and stm respectively. It allows users to install and use these libraries in a simple way, independently of the multicoretests test suite—which is restricted to the multicoretests package. It also allows to install lin and stm without some dependencies of multicoretests such as ounit2, lockfree or ppx_deriving.

The package multicoretests now depends on lin and stm.

[OlivierNicole]

The readme should probably be adapted to mention the three packages, too.

[jmid]

Thanks a bunch for this!
I think there's a couple of unused pin-depends, which I commented on inline.

You are very welcome to add a short mention of the three opam packages to the README
now that I've merged the other README PR.

Having to make package-annotations on each rule saddens me.
Is there by chance a way to mark an entire (sub-)directory part of the multicoretests package?

[OlivierNicole]

Having to make package-annotations on each rule saddens me.
Is there by chance a way to mark an entire (sub-)directory part of the multicoretests package?

I'm only starting with dune and reading the docs, but maybe using the scopes feature? IIUC this implies to put all the tests and the multicoretests.opam file in a subtree.

[OlivierNicole]

To avoid the many (package multicoretests) annotations, I have tried to use dune scopes in two ways:

• Put all the tests in a multicoretests/ subdirectory, along with multicoretests.opam.
• Put lin.opam and stm.opam.

Both failed with errors like:

Entering directory '/home/olivier/opam-pins/multicoretests'
File "lib/dune", line 8, characters 14-17:
8 |  (public_name stm)
                  ^^^
Error: The current scope doesn't define package "stm".
The only packages for which you can declare elements to be installed in this
directory are:
- multicoretests (because of multicoretests.opam)

That is, dune seems to ignore the <package>.opam files when they are not at the project root. I am here on unfamiliar grounds, so to go further I would need to ask advice to more knowledgeable users.

[jmid]

OK, thanks for trying!
I'll merge and then we can adjust later (if we figure it out).