Version migration tool

[brson]

It would be great to have a tool that automatically updates old Rust code for compatibility with new Rust.

We could use cargo (#1453) to automatically test which packages break between versions and whether this tool converts them correctly.

[marijnh]

Too early, I think. As long as the std libs and the language are changing regularly, being forced to write an upgrade shim for each change is a serious burden.

[brson]

I agree it's too early to use, maybe not too early to start working on.

[graydon]

still very relevant! required for any reasonable statement about backward compatibility.

[graydon]

Marking as a metabug and collecting some version-related stuff together: #3567 #3392 #3795 #5684 #456

[pcwalton]

I don't believe this is backwards incompatible, renominating.

[graydon]

accepted for backwards-compatible milestone

[emberian]

Visiting for triage; nothing to add.

[sinistersnare]

Are people still interested in this? It probably will not be done for 1.0, and we probably will not need it near as much post 1.0.

[steveklabnik]

I think in general it would be neat when idioms change, even post 1.0.

[steveklabnik]

I'm pulling a massive triage effort to get us ready for 1.0. As part of this, I'm moving stuff that's wishlist-like to the RFCs repo, as that's where major new things should get discussed/prioritized.

This issue has been moved to the RFCs repo: rust-lang/rfcs#606