view-types: lower view types from HIR by scrabsha · Pull Request #165565 · rust-lang/rust

scrabsha · 2026-11-06T20:48:07Z

this PR is big but most of the changes come from the second commit and are quite boring. it leaves a whole lot of unimplemented!() in the codebase, but i believe this is ok for a nightly feature that nobody is seriously using. i will fix them later.

scrabsha · 2026-11-09T09:49:47Z

r? oli-obk

rustbot · 2026-11-09T10:26:37Z

changes to the core type system

cc @lcnr

Some changes occurred in compiler/rustc_sanitizers

cc @rcvalle

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

HIR ty lowering was modified

cc @fmease

Some changes occurred in exhaustiveness checking

cc @Nadrieril

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

clippy is developed in its own repository. If possible, consider making this change to rust-lang/rust-clippy instead.

cc @rust-lang/clippy

This PR changes rustc_public

cc @oli-obk, @celinval, @ouz-a, @makai410

Some changes occurred in compiler/rustc_codegen_llvm/src/debuginfo

cc @Walnut356

oli-obk

~~should also add a test showing that view types are actually unsized.~~ nevermind, just saw #165694

View changes since this review

rustbot · 2026-11-11T10:52:01Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

after some discussion, we decided we want view types to be `!Sized`, at least at the beginning. this commit updates the test suite so that view types are not passed by value anymore.

this commit is quite big because we want to always exhaustively match on all the `TyKind` variants. none of the `unimplemented!()` is reachable because we don't *actually* lower view types (yet!).

/!\ the test suite is has not been updated /!\ the `unreachable!()`s added previously are suddenly reached, triggering literally all the view types test suite to ICE. this is fixed by the next commit.

rustbot · 2026-11-12T08:56:36Z

rustfmt is developed in its own repository. If possible, consider making this change to rust-lang/rustfmt instead.

cc @rust-lang/rustfmt

rustbot · 2026-11-12T08:56:40Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

scrabsha · 2026-11-12T08:56:44Z

force-push contains:

formatting tests
removal of unimplemented!() in rustdoc and clippy
rebase to main (this PR soft-conflicts with Migrate built-in macros pattern_type & view_type to macros 2.0 that expand to internal syntax #165487)

@rustbot ready

oli-obk · 2026-11-12T11:49:44Z

@bors r+ rollup

rust-bors · 2026-11-12T11:49:48Z

📌 Commit 8ec4983 has been approved by oli-obk

It is now in the queue for this repository.

…g, r=oli-obk view-types: lower view types from HIR

…uwer Rollup of 5 pull requests Successful merges: - #165854 (Explicitly drop job server helper thread) - #164077 (replace `TypingEnv::post_analysis()` with `mir::Body::typing_env()`) - #165305 (hexagon: pass small aggregates on the stack when registers run out) - #165417 (Mention width limit panic in fmt doc) - #165565 (view-types: lower view types from HIR)

rust-bors · 2026-11-12T15:04:14Z

⚠️ A new commit 70801970ae81e3513c0f0ce15d3b95e338f2ace8 was pushed.

This pull request was unapproved.

This PR was contained in a rollup (#165866), which was closed.

scrabsha · 2026-11-12T15:08:14Z

@rustbot ready

scrabsha mentioned this pull request Nov 6, 2026

Tracking Issue for view types #155938

Open

2 of 14 tasks

scrabsha force-pushed the view-types/middle-lowering branch from 48b4287 to cca7f38 Compare November 6, 2026 21:27

rustbot assigned oli-obk Nov 9, 2026

scrabsha marked this pull request as ready for review November 9, 2026 09:49

scrabsha mentioned this pull request Nov 9, 2026

view-types: propagate view types to rustc_middle #159291

Closed

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 9, 2026

rustbot removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Nov 9, 2026

This was referenced Nov 9, 2026

view-types: make sure view types are !Sized #165694

Open

view-types: handle field accesses #165764

Draft

scrabsha commented Nov 11, 2026

View reviewed changes

Comment thread src/tools/clippy/clippy_lints/src/dereference.rs Resolved

oli-obk requested changes Nov 11, 2026

View reviewed changes

Comment thread compiler/rustc_hir_analysis/src/check/wfcheck.rs Resolved

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 11, 2026

scrabsha added 5 commits November 12, 2026 09:33

view-types: don't pass view types by value in tests

d0c53d4

after some discussion, we decided we want view types to be `!Sized`, at least at the beginning. this commit updates the test suite so that view types are not passed by value anymore.

view-types: add View variant to TyKind

94add96

this commit is quite big because we want to always exhaustively match on all the `TyKind` variants. none of the `unimplemented!()` is reachable because we don't *actually* lower view types (yet!).

outline TyCtxt::new_adt's DefKind check

8bb5d1d

view-types: lower view types from HIR types

292f9b1

/!\ the test suite is has not been updated /!\ the `unreachable!()`s added previously are suddenly reached, triggering literally all the view types test suite to ICE. this is fixed by the next commit.

view-types: remove FIXMEs reachable from the test suite

c74615e

scrabsha force-pushed the view-types/middle-lowering branch from cca7f38 to 3601d42 Compare November 12, 2026 08:56

rustbot added T-rustdoc-frontend Relevant to the rustdoc-frontend team, which will review and decide on the web UI/UX output. T-rustfmt Relevant to the rustfmt team, which will review and decide on the PR/issue. labels Nov 12, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Nov 12, 2026

scrabsha commented Nov 12, 2026

View reviewed changes

Comment thread src/librustdoc/clean/types.rs Resolved

This comment has been minimized.

Sign in to view

scrabsha force-pushed the view-types/middle-lowering branch from 3601d42 to 8ec4983 Compare November 12, 2026 09:10

scrabsha requested a review from oli-obk November 12, 2026 09:18

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 12, 2026

oli-obk approved these changes Nov 12, 2026

View reviewed changes

JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Nov 12, 2026

Rollup merge of rust-lang#165565 - scrabsha:view-types/middle-lowerin…

dd623bc

…g, r=oli-obk view-types: lower view types from HIR

JonathanBrouwer mentioned this pull request Nov 12, 2026

Rollup of 5 pull requests #165866

Closed

rdrpenguin04 reviewed Nov 12, 2026

View reviewed changes

Comment thread tests/ui/view-types/tuple-structs.rs Resolved

scrabsha added 4 commits November 12, 2026 16:02

view-types: allow types that dereference to views to be receivers

65d368e

view-types: add format tests

87f5568

clippy: teach dereference lints about view types

af3705f

rustdoc: teach about view types

7080197

scrabsha force-pushed the view-types/middle-lowering branch from 8ec4983 to 7080197 Compare November 12, 2026 15:04

rust-bors Bot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Nov 12, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Nov 12, 2026

Conversation

scrabsha commented Nov 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

scrabsha commented Nov 9, 2026

Uh oh!

rustbot commented Nov 9, 2026

Uh oh!

Uh oh!

oli-obk left a comment • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!

rustbot commented Nov 11, 2026

Uh oh!

rustbot commented Nov 12, 2026

Uh oh!

rustbot commented Nov 12, 2026

Uh oh!

scrabsha commented Nov 12, 2026

Uh oh!

Uh oh!

This comment has been minimized.

oli-obk commented Nov 12, 2026

Uh oh!

rust-bors Bot commented Nov 12, 2026

Uh oh!

Uh oh!

rust-bors Bot commented Nov 12, 2026

Uh oh!

scrabsha commented Nov 12, 2026

Uh oh!

This branch has not been deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

scrabsha commented Nov 6, 2026 •

edited

Loading

oli-obk left a comment •

edited

Loading