Tracking Issue for Field Projections

[BennoLossin]

This is a tracking issue for work on Field Projections.
The feature gate for the issue is #![feature(field_projections)].

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.
Discussion comments will get marked as off-topic or deleted.
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Steps

• Approve as lang experiment
  • We accepted this experiment in the 2025-08-13 lang design meeting.
• implement field projections. design according to the section "the current approach" in the design meeting document from 2025-08-13:
  • add field reflection via field representing types and Field trait
  • add projection traits & implementations on std types
  • add new operator & syntax
  • implement the borrow check for the projections
• coordinate with t-libs-api to create {Arc,Rc}Ref<T>
• experiment with allowing overlapping implementations of &T and &Custom<U> using compiler magic

Unresolved Questions

TODO.

Implementation history

None

[BennoLossin]

@rustbot labels +T-lang +B-experimental +F-field_projection

[rustbot]

Error: Label B-experimental can only be set by Rust team members

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