View types experiment

[nxsaken]

Metadata
Point of contact	@scrabsha
Team(s)	compiler, lang, types
Goal document	2026/view-types-experiment

Summary

Add view types support to rustc as well as a few syntaxes proposed by project
members for experimentation purposes.

Tasks and status

---

Note: we have updated the body to match the 2026 goal. Your original text is preserved below.

Details

Metadata
Point of contact	@scrabsha
Team(s)	compiler, lang, types
Goal document	2026/view-types-experiment

Summary

Add view types support to rustc as well as a few syntaxes proposed by project
members for experimentation purposes.

Tasks and status

[nxsaken]

This issue is intended for status updates only.

For general questions or comments, please contact the owner(s) directly.

[scrabsha]

Update 2026-07-26

The following PRs got merged:

• Add feature gate for view_types experiment rust#155939
• view-types: store view types in the AST rust#156016
• view-types: HIR lowering rust#158739

I am currently working on the HIR -> rustc_middle lowering of view types (which requires a lot of changes and adjustments). There's an unfinished draft PR for this: rust-lang/rust#159291.

Blockers: none.

Help wanted: none. @nikomatsakis and I frequently discuss on what the implementation could/should look like, and I am lucky to work next to very competent people who don't mind answering to my silly questions.