Dont warn on prerelease dependencies with less than ("<")

[deivid-rodriguez]

Description:

I just saw this warning when installing my gem:

WARNING:  prerelease dependency on rails (< 6.0.x, >= 5.2) is not recommended

I can see the rationale for the "prerelease warning" but doesn't look reasonable when the requirement is using "<", since in that case we're filtering out prereleases. Right?

---

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[segiddins]

In bundler, this sort of requirement will start allowing pre-releases

[deivid-rodriguez]

I don't understand, can you elaborate?

[deivid-rodriguez]

Elaborating myself, note that this is only removing a warning message in some cases where I think doesn't make sense. It's not changing behavior other than that.

[segiddins]

Right, but if you have ">= 1", "< 2.pre" as a dependency, bundler will resolve that differently than "~> 1.0", even though they seem equivalent

[deivid-rodriguez]

You mean that they may get different, both correct, resolutions? I think that's fine, this is just a recommendation. In any case, that seems like a comment against introducing #2266 and #2242, not this PR. Or I'm missing something?

[segiddins]

What I’m trying to say is that a prerelease requirement in a < is just as “harmful” as with any other operator

[deivid-rodriguez]

Ok, so I don't understand then.

If I specify s.add_dependency "rails", "< 6.0.x", ">= 5.2" as a dependency of my gem, I don't think I'm depending on any pre-release version of rails, so the warning WARNING: prerelease dependency on rails (< 6.0.x, >= 5.2) is not recommended doesn't make sense to me. Are you saying that this requirement actually allows prereleases of rails, i.e., that #2266 is incorrect? That's definitely not my experience with bundler.

[segiddins]

Are you saying that this requirement actually allows prereleases of rails

I believe that is the case, though I could be wrong

[deivid-rodriguez]

I think you might be wrong, yeah. I just tried it and got:

Fetching gem metadata from https://rubygems.org/.........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies.....
Bundler could not find compatible versions for gem "decidim":
  In snapshot (Gemfile.lock):
    decidim (= 0.13.0.pre1)

  In Gemfile:
    decidim (= 0.13.0.pre1)

    my_test_gem was resolved to 0.1.0, which depends on
      decidim (< 0.13.x, >= 0.12)

Running `bundle update` will rebuild your snapshot from scratch, using only
the gems in your Gemfile, which may resolve the conflict.

And then running bundle update leads to

Fetching gem metadata from https://rubygems.org/.........
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Bundler could not find compatible versions for gem "decidim":
  In Gemfile:
    decidim (= 0.13.0.pre1)

    my_test_gem was resolved to 0.1.0, which depends on
      decidim (< 0.13.x, >= 0.12)

If I change the dependency to >= 0.12, < 0.13, it properly resolves and allows the prerelease.

[deivid-rodriguez]

This warning might be confusing and not very easy to understand / agree with, so we might consider entirely dropping it as you suggested in #2228 (comment). But if the warning stays, I think this PR should go in.

[deivid-rodriguez]

I opened #2351 as a (better, I think) alternative.

[bronzdoc]

closing in favor of #2351