interpreter: improve comments and error message in mir_assign_valid_types by RalfJung · Pull Request #155512 · rust-lang/rust

RalfJung · 2026-04-19T10:52:19Z

I looked at this while debugging #155477, but this makes no progress on that issue.

rustbot · 2026-04-19T10:52:22Z

Some changes occurred to the CTFE machinery

cc @oli-obk, @lcnr

Some changes occurred to the CTFE / Miri interpreter

cc @rust-lang/miri

rustbot · 2026-04-19T10:52:24Z

r? @davidtwco

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rustbot · 2026-04-19T11:23:30Z

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

RalfJung · 2026-04-19T11:44:02Z

Strangely, codegen does not seem to see the same types as the interpreter / Miri. I can't reproduce the ICE there.

RalfJung · 2026-04-19T11:51:58Z

Ah, transmute is implemented differently in codegen so we're not asking the mir_assign_valid_types question as part of the transmute. So there's not really a place outside the interpreter that could hit #155477.

It could still be worth checking mir_assign_valid_types during codegen, as a sanity check? I can also remove the 2nd commit again if you prefer. (But note that this does resolve an existing FIXME saying we need to find a better place for these utility functions.)

rustbot · 2026-04-20T06:55:53Z

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.

RalfJung · 2026-04-20T13:34:38Z

Given that relate_types is apparently buggy I think maybe we shouldn't make it more widely available then. ;) So I removed the 2nd commit.

lcnr · 2026-04-27T13:08:30Z

as stated in #155477 (comment), fixing relate_types should be straightforward

RalfJung · 2026-04-27T13:17:40Z

I think it might still make sense to first land this as a trivial comments-only PR. And the fact that codegen wouldn't see the case that caused the problem also made me less enthusiastic about running this check in codegen.
r? @lcnr

RalfJung · 2026-05-06T14:40:01Z

@lcnr any thoughts on these comments? :)
Or @oli-obk maybe?

RalfJung · 2026-06-02T08:26:02Z

Friendly ping @lcnr @oli-obk -- this should be a fairly trivial PR, not sure why it's been sitting here for 6 weeks.

oli-obk · 2026-06-03T13:17:08Z

Because I was very much not on top of my notifications and declared bankruptcy 1st of may to start over

oli-obk

@bors r+ rollup

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rust-bors · 2026-06-03T13:19:46Z

📌 Commit ab617ae has been approved by oli-obk

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 5. This pull request will be tested once the tree is reopened.

oli-obk · 2026-06-03T13:20:22Z

+        // Make sure the layout is equal, too -- just to be safe. Miri really needs layout equality.
+        // For performance reason we skip this check when the types are equal. Equal types *can*
+        // have different layouts when enum downcast is involved (as enum variants carry the type of
+        // the enum), but those should never occur in assignments.


This one was a bit confusing as the text didn't change, only line breaks in comments

View changes since the review

IIRC the old text went beyond the 100 column mark so I reflowed it. Sorry for the confusion. I wish we had better diff views for such comment changes.

…dity, r=oli-obk interpreter: improve comments and error message in mir_assign_valid_types I looked at this while debugging rust-lang#155477, but this makes no progress on that issue.

@clarfonthey

Rollup of 12 pull requests Successful merges: - #157085 (powerpc: warn against incorrect values for ABI-relevant target features) - #157170 (Use `impl` restrictions in `std`, `core`) - #157217 ([tiny] remove unecessary `.into()` calls) - #157262 (rustdoc: IXCRE: Preserve sizedness bounds on type params belonging to the parent item) - #157379 (Some more simple per-owner resolver changes) - #157381 (librustdoc: fix CSS border issue to support Firefox high contrast mode) - #155512 (interpreter: improve comments and error message in mir_assign_valid_types) - #157254 (Correct description of panic.rs) - #157290 (interpret: fix mir::UnOp layout computation) - #157332 (Rewrite target checking for `#[sanitize]`) - #157351 (Avoid leaking the query-job collection warning into the panic query stack) - #157389 (Add @clarfonthey to libs review rotation)

Rollup merge of #155512 - RalfJung:interpret-assignment-validity, r=oli-obk interpreter: improve comments and error message in mir_assign_valid_types I looked at this while debugging #155477, but this makes no progress on that issue.

@clarfonthey

Rollup of 12 pull requests Successful merges: - rust-lang/rust#157085 (powerpc: warn against incorrect values for ABI-relevant target features) - rust-lang/rust#157170 (Use `impl` restrictions in `std`, `core`) - rust-lang/rust#157217 ([tiny] remove unecessary `.into()` calls) - rust-lang/rust#157262 (rustdoc: IXCRE: Preserve sizedness bounds on type params belonging to the parent item) - rust-lang/rust#157379 (Some more simple per-owner resolver changes) - rust-lang/rust#157381 (librustdoc: fix CSS border issue to support Firefox high contrast mode) - rust-lang/rust#155512 (interpreter: improve comments and error message in mir_assign_valid_types) - rust-lang/rust#157254 (Correct description of panic.rs) - rust-lang/rust#157290 (interpret: fix mir::UnOp layout computation) - rust-lang/rust#157332 (Rewrite target checking for `#[sanitize]`) - rust-lang/rust#157351 (Avoid leaking the query-job collection warning into the panic query stack) - rust-lang/rust#157389 (Add @clarfonthey to libs review rotation)

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Apr 19, 2026

rustbot assigned davidtwco Apr 19, 2026

RalfJung mentioned this pull request Apr 19, 2026

[ICE]: Miri/consteval assertion failure due to transmuting types with HRTB #155477

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RalfJung changed the title ~~interpret: improve assignment type validity check and error messages~~ check MIR assignment type validity check during codegen Apr 19, 2026

RalfJung commented Apr 19, 2026

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Comment thread compiler/rustc_ty_utils/src/compare_types.rs

RalfJung force-pushed the interpret-assignment-validity branch from 4f96108 to 3e7a6e4 Compare April 19, 2026 11:28

RalfJung force-pushed the interpret-assignment-validity branch 2 times, most recently from 5239e33 to ec0f805 Compare April 19, 2026 12:02

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interpret: improve assignment type validity check and error messages

ab617ae

RalfJung force-pushed the interpret-assignment-validity branch from ec0f805 to 20d66f0 Compare April 20, 2026 06:55

RalfJung force-pushed the interpret-assignment-validity branch from 20d66f0 to ab617ae Compare April 20, 2026 13:34

RalfJung changed the title ~~check MIR assignment type validity check during codegen~~ interpreter: improve comments and error message in mir_assign_valid_types Apr 20, 2026

rustbot assigned lcnr and unassigned davidtwco Apr 27, 2026

oli-obk approved these changes Jun 3, 2026

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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 Jun 3, 2026

oli-obk reviewed Jun 3, 2026

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JonathanBrouwer mentioned this pull request Jun 3, 2026

Rollup of 8 pull requests #157387

Closed

jhpratt mentioned this pull request Jun 3, 2026

Rollup of 12 pull requests #157398

Merged

rust-bors Bot merged commit 1b77f84 into rust-lang:main Jun 3, 2026
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rustbot added this to the 1.98.0 milestone Jun 3, 2026

RalfJung deleted the interpret-assignment-validity branch June 4, 2026 07:41

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