---
# System prepended metadata

title: 2024-02-05 Planning meeting
tags: [' T-types', weekly-meeting]

---

---
title: 2024-02-05 Planning meeting
tags: weekly-meeting, T-types
date: 2024-02-05
---

# T-types planning meeting agenda

## Updates

### [Tracking issue for shared type library](https://github.com/rust-lang/types-team/issues/16)



### [Tracking issue for AFIT and RPITIT](https://github.com/rust-lang/types-team/issues/66)



### [Tracking issue for TAITs](https://github.com/rust-lang/types-team/issues/67)



### [Tracking issue for GATs](https://github.com/rust-lang/types-team/issues/68)



### [Tracking issue for a-mir-formality](https://github.com/rust-lang/types-team/issues/69)



### [Tracking issue for subtyping refactor](https://github.com/rust-lang/types-team/issues/70)



### [Tracking issue for implied bounds refactor](https://github.com/rust-lang/types-team/issues/71)



### [Tracking issue for trait object upcasting](https://github.com/rust-lang/types-team/issues/72)



### [Tracking issue for negative impls](https://github.com/rust-lang/types-team/issues/73)



### [Tracking issue for rust trait solver refactor](https://github.com/rust-lang/types-team/issues/76)



### [Model coherence in formality](https://github.com/rust-lang/types-team/issues/103)



### [Normalize in orphan check](https://github.com/rust-lang/types-team/issues/104)



### [New solver in coherence](https://github.com/rust-lang/types-team/issues/105)



### ["Semantic outlives" for opaque aliases](https://github.com/rust-lang/types-team/issues/106)



### [Minimal version of TAITs](https://github.com/rust-lang/types-team/issues/107)



### [Prototype of Polonius](https://github.com/rust-lang/types-team/issues/108)



### [RPIT capture all lifetimes](https://github.com/rust-lang/types-team/issues/110)



### [Enforce where-clauses on type aliases via alias type](https://github.com/rust-lang/types-team/issues/111)



### [Use the new trait solver in all the places](https://github.com/rust-lang/types-team/issues/112)



### [Support negative impls in coherence](https://github.com/rust-lang/types-team/issues/113)



### [Location-sensitive polonius](https://github.com/rust-lang/types-team/issues/114)



### [UnlimiTAIT](https://github.com/rust-lang/types-team/issues/115)



### [Coinduction](https://github.com/rust-lang/types-team/issues/116)



### [Instantiate implied bounds explicitly](https://github.com/rust-lang/types-team/issues/117)



### [Perfect derive](https://github.com/rust-lang/types-team/issues/118)



### [Specialization](https://github.com/rust-lang/types-team/issues/119)



### [Avoid inference guessing in trait solver (e.g., favoring where-clauses over impls)](https://github.com/rust-lang/types-team/issues/120)



### [Avoid bounding impl trait return type by all input type parameters using existential lifetimes](https://github.com/rust-lang/types-team/issues/121)



### [Implied bounds on higher-ranked binders](https://github.com/rust-lang/types-team/issues/122)



### [Full triage of all soundness issues](https://github.com/rust-lang/types-team/issues/123)




## Nominated issues

### [Pointer casts allow switching trait parameters for trait objects, which doesnâ€™t interact soundly with trait upcasting](https://github.com/rust-lang/rust/issues/120222)




## Types FCPs

### [Prevent opaque types being instantiated twice with different regions within the same function](https://github.com/rust-lang/rust/pull/116935)



### [Allow coercions from never-type when ref binding is involved](https://github.com/rust-lang/rust/pull/118270)



### [Add `REDUNDANT_LIFETIMES` lint to detect lifetimes which are semantically redundant](https://github.com/rust-lang/rust/pull/118391)



### [Consider principal trait ref's auto-trait super-traits in dyn upcasting](https://github.com/rust-lang/rust/pull/119338)



### [instantiate higher ranked goals outside of candidate selection](https://github.com/rust-lang/rust/pull/119820)



### [more eagerly instantiate binders](https://github.com/rust-lang/rust/pull/119849)



### [remove `sub_relations` from the `InferCtxt`](https://github.com/rust-lang/rust/pull/119989)




## Major change proposals

None.




## Deep dive planning

### [Variance and Rust](https://github.com/rust-lang/types-team/issues/45)



### [discuss the `trait_alias` feature](https://github.com/rust-lang/types-team/issues/49)



### [Closure return type outlives guarantees](https://github.com/rust-lang/types-team/issues/57)



### [ Account for late-bound lifetimes in generics #103448 ](https://github.com/rust-lang/types-team/issues/62)



### [Negative trait impls check-in](https://github.com/rust-lang/types-team/issues/82)



### [Coinductive trait semantics and normalization](https://github.com/rust-lang/types-team/issues/83)



### [Specialization](https://github.com/rust-lang/types-team/issues/89)



### [Deep dive for leak check/higher ranked fn ptr subtyping](https://github.com/rust-lang/types-team/issues/96)



### [discuss "incorrect implied bounds in wfcheck"](https://github.com/rust-lang/types-team/issues/99)



### [dyn safety and coherence](https://github.com/rust-lang/types-team/issues/100)



### [`'erased` during analysis](https://github.com/rust-lang/types-team/issues/101)



### [unsound issues fun time](https://github.com/rust-lang/types-team/issues/125)


