Allow to choose opam version

[bikallem]

Is there a way to choose opam version, i.e. 2.0, 2.1 etc?

[dra27]

At the moment, they're all held to 2.0 because of Windows. However, opam 2.1.1 is very shortly coming out and, more importantly, a version of the opam-depext plugin which "works" with opam 2.1.x. With those, it will be possible for the macOS and Ubuntu GitHub runners to use opam 2.1 binaries but with OPAMCLI set by default to 2.0 so, by default, opam 2.0 workflows will work correctly, but if you're only interested in Ubuntu/macOS then you'd be able to override the environment variable and use it as opam 2.1. At the moment this doesn't work because there's no depext plugin for 2.1.x - it's not needed, but it is useful if you want to write opam 2.0-compatible workflows and so use the inefficient opam depext route.

opam 2.2's main feature is upstream Windows support, and it's due early next year!

[smorimoto]

If you need opam 2.1 a little early, I can implement one to support that, but if you don't really need it, I won't add it to keep the implementation simple, how about it?

[bikallem]

If you need opam 2.1 a little early, I can implement one to support that, but if you don't really need it, I won't add it to keep the implementation simple, how about it?

opam 2.1 would be most awesome as we want to use it for https://github.com/ocaml-multicore/tezos.

[dra27]

opam 2.1.1 is driving through the release process, and once ocaml-opam/opam-depext#142 is merged and released, I’d recommend we switch MacOS and Linux to use 2.1.1 by default and just allow users to override the default setting of OPAMCLI to 2.0

[dra27]

opam 2.1.1 is driving through the release process, and once ocaml-opam/opam-depext#142 is merged and released, I’d recommend we switch MacOS and Linux to use 2.1.1 by default and just allow users to override the default setting of OPAMCLI to 2.0.

[smorimoto]

I don't plan to let you choose any opam version at this point, but we can re-visit this once the native Windows opam is released. For now, close this.