Cargo script edition policy (lang/edition aspects)

Nobody has claimed this yet.

Update: For the detailed articulation of this concern, see the document:

Edition policy for Rust scripting

In the @rust-lang/cargo team RFC for cargo script (RFC 3502), the document stated a policy that when the edition is not specified in the frontmatter, cargo script will use the latest edition, whatever that is, while linting about this. Cargo script is now up for stabilization (https://github.com/rust-lang/cargo/pull/16569).

As part of this, people are raising concerns about this lint and this behavior (see https://github.com/rust-lang/cargo/issues/16598).

In some sense, the only fixed decisions at the time of stabilization are 1) that cargo script will work without an edition set and 2) that it will use Rust 2024 by default. We could always later decide to never change the default from Rust 2024. Due to that, if we're all happy with these two decisions (I am), I think it's OK for the stabilization to proceed. No need to block that.

But I do want to mention, as a policy matter for what happens in the next edition, that I think the @rust-lang/lang and @rust-lang/edition teams are stakeholders in this.

From an edition side, Cargo changing a default over an edition represents an edition change; I'd expect this to be an edition item.

From a lang side, for my part, I believe the language that we choose to put in front of people "using Rust™" is a lang team matter, and I think that people using cargo script will feel that they're "using Rust™". If we update the edition of Rust automatically when someone updates the toolchain, then this would make our story that editions only cause breakage in an opt-in way less true (some might say untrue). Further, breakage in scripts will not be caught by crater and so will be difficult to predict confidently.

I'd be concerned that these factors would eventually constrain our ability to use editions in the intended way to evolve the language.

As mentioned, I don't believe this needs to block the cargo script stabilization as the edition policy can be worked out later, but I do want to raise the matter for awareness in case anyone feels something about this policy matter might affect anything about the stabilization.

Start with the linked Edition policy for Rust scripting document and RFC 3502, then review cargo issues 12207 and 16598 and the stabilization pull request 16569. Done means reaching and recording a decision on the policy for edition defaults and linting in cargo script, including the roles of the lang and edition teams.

Written by the indexing model from the issue text.

Description

Related

Contributor guide

First steps

Research direction

Assessment