tokio 0.1.8 contains a breaking change

[jonas-schievink]

Comparing the difference between 0.1.7 and 0.1.8 (tokio-0.1.7...tokio-0.1.8) I saw that the minimum supported Rust version was bumped from 1.21.0 to 1.25.0, which is considered a breaking change.

This inadvertently broke CI for xmlrpc, which still supports Rust 1.21.0.

[carllerche]

tl;dr Tokio does not consider this a breaking change.

The change was explicitly made here.

Tokio follows the same policy as rust-lang libs, which is to support a Rust version at least 3 months old (i.e. 2 release cycles ago).

It is true that this is not an ideal situation, but IMO it is the best that can be done. It has been hotly debated.

That said, Rust is addressing the problem w/ an introduction of an LTS channel. At this point, Tokio will switch to officially support the latest LTS.

Hope this clarifies things and sorry for the inconvenience.

[jonas-schievink]

Oh, okay. Everyone I've ever talked to said that requiring a newer Rust version is a breaking change.

[carllerche]

Do you have any official references to point to? My understanding is the release train strategy implies the opposite: it is expected to float on the latest stable. The LTS channel won’t change this fact, it will just codify the policy to 6 months (instead of 3 that Tokio and others follow)

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On Fri, Aug 24, 2018 at 11:14 AM Jonas Schievink ***@***.***> wrote: Oh, okay. Everyone I've ever talked to said that requiring a newer Rust version is a breaking change. — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#574 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAAYJEk3vR1hxLaj6DsZYkzI3q_G_Ci8ks5uUEJ4gaJpZM4WLu4t> .

[jonas-schievink]

No, I've been asking on IRC (multiple times) because I wanted to decide on a Rust versioning policy for my own crates. Additionally, I've observed a handful of popular crates supporting really old Rust versions that also consider bumping the required version a breaking change. I haven't found much information on the "official" policy for rust-lang(-nursery) crates either.

That said, supporting the latest 3 versions does make sense and should not cause any problems for users, so I've now adopted this policy.