Support all hex package version requirement formats

[tsloughter]

We currently don't support version requirements like ~> 1.0 or ~> 2.0. The issue being the or. We have no support for or or and. This causes transitive Elixir dependencies to often fail because they can't be resolved.

Handling the constraint once parsed I think should be to just pick the largest. So in the case of ~> 1.0 or ~> 2.0 it will be converted to ~> 2.0.

[starbelly]

Only other thing would be sorting out conflicts, not sure that's a concern for rebar. I assume the support in mix for or here is in case one dep wants 1.0.

[tsloughter]

It isn't a concern. rebar3 is resolving on its own with no mix intervention and we do it the same was as it is done for any other dependency. If another dep depends on the 1.0 version and that causes compilation to fail the user must put decimal ~> 1.0 in the top level rebar.config themselves.

[starbelly]

Note as current workaround one may use overrides. Below is an example of using myxql which has decimal at a dep with ~> 1.6 or ~> 2.0 as the version constraint :

erl_opts, [debug_info]}.
{deps, [myxql]}.
{overrides,
  [
    {override, myxql,
      [{deps, [decimal]}]
    }
  ]
}.

[essen]

Hello, just a heads up in case you get tickets opened. Cowboy 2.13 supports both Ranch 1.8 and 2.x. To make Elixir users happy I have changed the version requirement in Hex from an explicit version to ">= 1.8.0 and < 3.0.0", and did a similar requirement for Cowlib. This allows Elixir users to depend on different projects that depend on Ranch, with Hex resolving to the same version. But this breaks Rebar3. Unfortunately I don't have a solution to support both Elixir and Rebar3.

[essen]

https://github.com/jelly-beam/verl implements the full Elixir requirement processing and could be used to solve this.

1> verl:is_match(<<"2.0.17">>, <<"~> 1.0 or ~> 2.0">>).
true
2> verl:is_match(<<"1.0.1">>, <<"~> 1.0 or ~> 2.0">>).
true
3> verl:is_match(<<"1.1.0">>, <<"~> 1.0 or ~> 2.0">>).
true
4> verl:is_match(<<"3.0.0">>, <<"~> 1.0 or ~> 2.0">>).
false