dyn* trait

[nikomatsakis]

Proposal

Summary and problem statement

• Introduce a new type (strawsyntax dyn* Trait) that represents "some pointer-sized type T that implements Trait"
• Define a new notion of dyn safety (dyn* safety) that is broader for use with this type

Motivation, use-cases, and solution sketches

See this blog post:

https://smallcultfollowing.com/babysteps//blog/2022/03/29/dyn-can-we-make-dyn-sized/

Initial people involved

• Owner, if known: maybe @eholk, maybe @tmandry, maybe @nikomatsakis ?
• Liaison: maybe @cramertj ?

What happens now?

This issue is part of the lang-team initiative process. Once this issue is filed, a Zulip topic will be opened for discussion, and the lang-team will review open proposals in its weekly triage meetings. You should receive feedback within a week or two.

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

[rustbot]

This issue is not meant to be used for technical discussion. There is a Zulip stream for that. Use this issue to leave procedural comments, such as volunteering to review, indicating that you second the proposal (or third, etc), or raising a concern that you would like to be addressed.

[nikomatsakis]

Per the new process, this is an active experiment, with myself as the lang-team champion. Tracking issue is here rust-lang/rust#102425.