Move `rustc_middle::ty::Const` to `rustc_type_ir` Part 2 by Jamesbarford · Pull Request #163258 · rust-lang/rust

Jamesbarford · 2026-09-24T12:44:07Z

Split by commit;

Move all methods from ConstExt from rustc_middle, creating small helpers to aid this. Subsequently delete ConstExt.
Remove ConstExt from imports in compiler.
Remove ConstExt from imports in clippy.

r? lcnr

rustbot · 2026-09-24T12:44:10Z

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

cc @bjorn3

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Some changes occurred in rustc_ty_utils::consts.rs

cc @BoxyUwU

Some changes occurred in exhaustiveness checking

cc @Nadrieril

Some changes occurred in match checking

cc @Nadrieril

HIR ty lowering was modified

cc @fmease

Some changes occurred in match lowering

cc @Nadrieril

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

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

cc @rust-lang/clippy

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

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

cc @antoyo, @GuillaumeGomez

Some changes occurred in compiler/rustc_sanitizers

cc @rcvalle

RalfJung · 2026-09-25T08:13:28Z

Move Const from rustc_middle to rustc_type_ir

This is ty::Const, not mir::Const, right? Would be good to clarify so these PRs are easier to interpret. :)

lcnr · 2026-09-25T09:48:03Z

-        let valtree =
-            ty::ValTree::from_scalar_int(tcx, ScalarInt::try_from_uint(bits, size).unwrap());
-        ty::Const::new_value(tcx, valtree, ty)
-    }


this function is kind of scuffed :< I don't want this in rustc_type_ir if I am honest. More generally TypingEnv is in a weird state and I'd like to keep this out of rustc_type_ir for now 🤔 can we maybe keep this in an extension trait for now?

View changes since the review

Hmm what about on Interner;

fn const_from_bits(self, bits: u128, typing_env: Self::TypingEnv, ty: Self::Ty) -> Const<Self>;

Then keep the implementation in the rustc_middle's interner implementation? That way we don't need to resurrect the ConstExt and the scuffed parts stay in rustc_middle? Obviously happy to revert if that's a terrible idea.

I've given it a go in this commit; 39c689e, doesn't feel too bad as it uses a few interner methods

lcnr · 2026-09-25T09:50:53Z

+        } else {
+            const_v.try_to_leaf().map(|s| s.to_target_usize(self))
+        }
+    }


why exactly does this need to be on the interner? I guess the to_target_usize is the actually relevant part? 🤔

View changes since the review

Yes s.to_target_usize() to the relevant part. I've now made to_target_usize a method on ValueConst in inherent.rs. Could be less bad than bolting another helper method on to Interner?

I've done so in; bcc98fa

lcnr

lgtm modulo minor nits

View changes since this review

rustbot · 2026-10-06T08:10:47Z

Some changes occurred in compiler/rustc_codegen_llvm/src/debuginfo

cc @Walnut356

lcnr · 2026-10-06T11:09:02Z

@@ -228,13 +227,21 @@ impl<'tcx> Value<'tcx> {
 }

 impl<'tcx> rustc_type_ir::inherent::ValueConst<TyCtxt<'tcx>> for Value<'tcx> {


future work, we should move Value into rustc_type_ir

View changes since the review

lcnr · 2026-10-06T11:14:46Z

my only question is const_from_bits /Const::from_bits. If this method only uses rustc_type_ir internal stuff, maybe we should have it on Const after all 🤔

Why do we need the TypingEnv extension trait again?

this is partially out of cache for me unfortunately 🤔

Jamesbarford · 2026-10-06T11:26:45Z

const_from_bits

const_from_bits exists so we aren't using TypingEnv in rustc_type_ir though maybe we could put something on the inherent trait for it to implement in rustc_middle?
The inherent trait is for I::TypingEnv::fully_monomorphized() so we can use it in Const::from_bool(...) and Const::from_target_usize(...)

lcnr · 2026-10-07T12:50:21Z

That's inconsistent, is it not. If we need to use TypingEnv::fully_monomorphized for two other functions, then const_from_bits being outside to avoid that doesn't really work, does it?

Either have all these functions outside of rustc_type_ir or all of them in it I'd say

Jamesbarford · 2026-10-08T07:36:00Z

That's inconsistent, is it not. If we need to use TypingEnv::fully_monomorphized for two other functions, then const_from_bits being outside to avoid that doesn't really work, does it?

Either have all these functions outside of rustc_type_ir or all of them in it I'd say

Good point, I've made a fn layout_size(...) on trait TypingEnv and moved fn from_bits(...) 0bf6c48

lcnr · 2026-10-12T10:58:34Z

r=me after rebase

rustbot · 2026-10-13T06:03:04Z

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.

Jamesbarford · 2026-10-13T08:00:23Z

@bors r=lcnr

rust-bors · 2026-10-13T08:00:26Z

@Jamesbarford: 🔑 Insufficient privileges: not in review users

lcnr · 2026-10-13T08:06:56Z

@bors r+ rollup=iffy

rust-bors · 2026-10-13T08:07:00Z

📌 Commit bbefa03 has been approved by lcnr

It is now in the queue for this repository.

…uwer Rollup of 8 pull requests Successful merges: - #163258 (Move `rustc_middle::ty::Const` to `rustc_type_ir` Part 2) - #164173 (don't drop `AnyOpaqueHasInferAsHidden` when merging with `OpaqueInStorageOrAnyOpaqueHasInferAsHidden`) - #160230 (CFI: Cover each InstanceKind explicitly) - #163713 (codegen Propagate reported errors from ABI checks) - #164205 (cg_llvm: Assorted cleanups to LLVM diagnostic handling) - #164114 (restore the old behavior for `derive(Default)` on fieldless types) - #164127 (core: Ignore explicit_tail_calls doc tests on PowerPC) - #164204 (explicitly mark next-solver ICE in test suite)

Rollup merge of #163258 - Jamesbarford:chore/move-const-pt2, r=lcnr Move `rustc_middle::ty::Const` to `rustc_type_ir` Part 2 Split by commit; - Move all methods from `ConstExt` from `rustc_middle`, creating small helpers to aid this. Subsequently delete `ConstExt`. - Remove `ConstExt` from imports in compiler. - Remove `ConstExt` from imports in clippy. r? lcnr

Upstream rust-lang/rust#163258 moved `try_to_target_usize` from the `ConstExt` extension trait to an inherent method on `Const`, and removed `ConstExt`. Gate `use ty::consts::ConstExt;` behind `#[rustversion::before(2026-10-13)]` so that `cc_bindings_from_rs` compiles both on nightlies that had the temporary `ConstExt` trait (2026-09-22 to 2026-10-12) and on newer nightlies (2026-10-13+) as well as stable toolchains where `try_to_target_usize` is an inherent method. PiperOrigin-RevId: 999083269

Upstream rust-lang/rust#163258 moved `try_to_target_usize` from the `ConstExt` extension trait to an inherent method on `Const`, and removed `ConstExt`. Gate `use ty::consts::ConstExt;` behind `#[rustversion::before(2026-10-13)]` so that `cc_bindings_from_rs` compiles both on nightlies that had the temporary `ConstExt` trait (2026-09-22 to 2026-10-12) and on newer nightlies (2026-10-13+) as well as stable toolchains where `try_to_target_usize` is an inherent method. PiperOrigin-RevId: 999104756

…uwer Rollup of 8 pull requests Successful merges: - rust-lang/rust#163258 (Move `rustc_middle::ty::Const` to `rustc_type_ir` Part 2) - rust-lang/rust#164173 (don't drop `AnyOpaqueHasInferAsHidden` when merging with `OpaqueInStorageOrAnyOpaqueHasInferAsHidden`) - rust-lang/rust#160230 (CFI: Cover each InstanceKind explicitly) - rust-lang/rust#163713 (codegen Propagate reported errors from ABI checks) - rust-lang/rust#164205 (cg_llvm: Assorted cleanups to LLVM diagnostic handling) - rust-lang/rust#164114 (restore the old behavior for `derive(Default)` on fieldless types) - rust-lang/rust#164127 (core: Ignore explicit_tail_calls doc tests on PowerPC) - rust-lang/rust#164204 (explicitly mark next-solver ICE in test suite)

rustbot assigned lcnr Sep 24, 2026

This comment has been minimized.

Sign in to view

Jamesbarford changed the title ~~Move Const from rustc_middle to rustc_type_ir Part 2~~ Move rustc_middle::ty::Const to rustc_type_ir Part 2 Sep 25, 2026

lcnr reviewed Sep 25, 2026

View reviewed changes

Comment thread compiler/rustc_middle/src/ty/consts/valtree.rs

lcnr reviewed Sep 25, 2026

View reviewed changes

Comment thread compiler/rustc_type_ir/src/inherent.rs Outdated

lcnr reviewed Sep 25, 2026

View reviewed changes

This comment has been minimized.

Sign in to view

Jamesbarford force-pushed the chore/move-const-pt2 branch from 4f1d48f to 828380b Compare September 29, 2026 07:22

This comment has been minimized.

Sign in to view

Jamesbarford force-pushed the chore/move-const-pt2 branch from 39c689e to 2255191 Compare October 6, 2026 08:10

This comment has been minimized.

Sign in to view

lcnr reviewed Oct 6, 2026

View reviewed changes

This comment has been minimized.

Sign in to view

Jamesbarford added 3 commits October 13, 2026 07:02

Move all Const methods to rustc_type_ir

f8ee6bb

Remove ConstExt from ./compiler

df74b1f

Remove ConstExt from ./src

bbefa03

Jamesbarford force-pushed the chore/move-const-pt2 branch from 0bf6c48 to bbefa03 Compare October 13, 2026 06:02

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 Oct 13, 2026

JonathanBrouwer mentioned this pull request Oct 13, 2026

Rollup of 8 pull requests #164256

Merged

rust-bors Bot merged commit 7a0029b into rust-lang:main Oct 13, 2026
14 checks passed

rustbot added this to the 1.101.0 milestone Oct 13, 2026

copybara-service Bot mentioned this pull request Oct 14, 2026

Fix cc_bindings_from_rs build on nightly Rust after ConstExt removal. google/crubit#2329

Merged

		@@ -228,13 +227,21 @@ impl<'tcx> Value<'tcx> {
		}

		impl<'tcx> rustc_type_ir::inherent::ValueConst<TyCtxt<'tcx>> for Value<'tcx> {

Conversation

Jamesbarford commented Sep 24, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

rustbot commented Sep 24, 2026

Uh oh!

This comment has been minimized.

RalfJung commented Sep 25, 2026

Uh oh!

Uh oh!

lcnr Sep 25, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Jamesbarford Sep 29, 2026 • 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!

Jamesbarford Sep 29, 2026

Choose a reason for hiding this comment

Uh oh!

Uh oh!

lcnr Sep 25, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Jamesbarford Sep 29, 2026

Choose a reason for hiding this comment

Uh oh!

lcnr left a comment • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

This comment has been minimized.

This comment has been minimized.

This comment has been minimized.

This comment has been minimized.

rustbot commented Oct 6, 2026

Uh oh!

This comment has been minimized.

This comment has been minimized.

This comment has been minimized.

lcnr Oct 6, 2026 • edited by rustbot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

lcnr commented Oct 6, 2026

Uh oh!

Jamesbarford commented Oct 6, 2026

Uh oh!

lcnr commented Oct 7, 2026

Uh oh!

Jamesbarford commented Oct 8, 2026

Uh oh!

This comment has been minimized.

lcnr commented Oct 12, 2026

Uh oh!

rustbot commented Oct 13, 2026

Uh oh!

Jamesbarford commented Oct 13, 2026

Uh oh!

rust-bors Bot commented Oct 13, 2026

Uh oh!

lcnr commented Oct 13, 2026

Uh oh!

rust-bors Bot commented Oct 13, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

Jamesbarford commented Sep 24, 2026 •

edited by rustbot

Loading

lcnr Sep 25, 2026 •

edited by rustbot

Loading

Jamesbarford Sep 29, 2026 •

edited

Loading

lcnr Sep 25, 2026 •

edited by rustbot

Loading

lcnr left a comment •

edited by rustbot

Loading

lcnr Oct 6, 2026 •

edited by rustbot

Loading