Fix ICE: When Trying to check visibility of a #[type_const], check RHS instead.#151085

Keith-Cancel · 2026-01-13T22:19:15Z

This PR fixes #150956 for min_const_generic_args #132980.

The first part of this PR checks in reachable.rs if we have a type const use visit_const_item_rhs(init); instead of calling const_eval_poly_to_alloc()

The second part is I noticed that if const_eval_poly_to_alloc() returns a ErrorHandled::TooGeneric then switches to visit_const_item_rhs(). So further up const_eval_poly_to_alloc() call order it eventual gets to eval_in_interpreter(). So I added a debug_assert in eval_in_interpreter() if we happen to try and run CTFE on a type_const.

The other bit is just a test case, and some duplicated code I noticed.

While the PR does get rid of the ICE for a type_const with pub visibility. If I try using the const though it will ICE with the following:

error: internal compiler error: /home/keith/GitHub/rust_kc/compiler/rustc_const_eval/src/check_consts/qualifs.rs:355:13: expected ConstKind::Param or ConstKind::Value here, found UnevaluatedConst { def: DefId(20:4 ~ colorkit[c783]::TYPE_CONST), args: [] }


thread 'rustc' (819687) panicked at /home/keith/GitHub/rust_kc/compiler/rustc_const_eval/src/check_consts/qualifs.rs:355:13:

I suspect it is a similar issue to inherent associated consts. Since if I apply the same fix I had here:
#150799 (comment)

I then can use the const internally and in external crates without any issues.
Although, did not include that fix since if it is a similar issue it would need to be addressed elsewhere.

r? @BoxyUwU
@rustbot label +F-associated_const_equality +F-min_generic_const_args

rustbot · 2026-01-13T22:19:18Z

Some changes occurred to the CTFE machinery

cc @RalfJung, @oli-obk, @lcnr

Keith-Cancel · 2026-01-16T01:53:46Z

@BoxyUwU Any changes I need to make?

compiler/rustc_const_eval/src/const_eval/eval_queries.rs

compiler/rustc_passes/src/reachable.rs

tests/ui/const-generics/mgca/type_const-pub.rs

BoxyUwU · 2026-01-16T16:22:16Z

@rustbot author

rustbot · 2026-01-16T16:22:21Z

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

Keith-Cancel · 2026-01-16T20:13:38Z

@rustbot ready, if it looks all good. I can then flatten and rebase it with main.

compiler/rustc_passes/src/reachable.rs

BoxyUwU · 2026-01-16T22:02:06Z

You'll need to update your PR description too as the TooGeneric change is no longer present. Can you change the title to something a bit more informative (similar to the comment in the test). There's also no need to link the fixed issue in the title as it's part of the PR description

Keith-Cancel · 2026-01-16T22:20:55Z

You'll need to update your PR description too as the TooGeneric change is no longer present. Can you change the title to something a bit more informative (similar to the comment in the test). There's also no need to link the fixed issue in the title as it's part of the PR description

@BoxyUwU Fair enough I have updated the description, and title. =)

BoxyUwU

lgtm! r=me once all the commits have been squashed

View changes since this review

…S instead. We want to evaluate the rhs of a type_const. Also added an early return/guard in eval_in_interpreter which is used in functions like `eval_to_allocation_raw_provider` Lastly add a debug assert to `thir_body()` if we have gotten there with a type_const something as gone wrong. Get rid of a call to is_type_const() and instead use a match arm. Change this is_type_const() check to a debug_assert!() Change to use an if else statment instead. Update type_const-pub.rs Fix formatting. Noticed that this is the same check as is_type_const() centralize it. Add test case for pub type_const.

rustbot · 2026-01-17T04:33:24Z

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.

Keith-Cancel · 2026-01-17T04:34:49Z

@BoxyUwU Squashed and rebased onto main.

BoxyUwU · 2026-01-17T08:45:20Z

@bors r+ rollup

rust-bors · 2026-01-17T08:45:22Z

📌 Commit 4c93efa has been approved by BoxyUwU

It is now in the queue for this repository.

rust-bors · 2026-01-17T13:03:01Z

☀️ Test successful - CI
Approved by: BoxyUwU
Pushing 9f6cd6d to main...

github-actions · 2026-01-17T13:05:52Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 844f131 (parent) -> 9f6cd6d (this PR)

Test differences

Show 4 test diffs

Stage 1

[ui] tests/ui/const-generics/mgca/type_const-pub.rs: [missing] -> pass (J0)

Stage 2

[ui] tests/ui/const-generics/mgca/type_const-pub.rs: [missing] -> pass (J1)

Additionally, 2 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 9f6cd6defbd7ef13f6777aa8e43b14d69f0a830a --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

dist-aarch64-llvm-mingw: 5723.2s -> 6698.0s (+17.0%)
x86_64-gnu-llvm-20-2: 4954.6s -> 5630.0s (+13.6%)
x86_64-rust-for-linux: 2506.3s -> 2843.9s (+13.5%)
x86_64-msvc-ext3: 6627.4s -> 5833.3s (-12.0%)
aarch64-msvc-2: 6691.4s -> 6050.7s (-9.6%)
armhf-gnu: 4626.4s -> 5055.7s (+9.3%)
dist-x86_64-apple: 7377.4s -> 6734.9s (-8.7%)
x86_64-gnu-llvm-21-3: 6661.6s -> 6120.9s (-8.1%)
x86_64-gnu-tools: 3159.9s -> 3415.5s (+8.1%)
aarch64-gnu: 7072.6s -> 7635.5s (+8.0%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2026-01-17T13:45:26Z

Finished benchmarking commit (9f6cd6d): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.8%, secondary 1.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.1%	[1.1%, 1.1%]	1
Improvements ✅ (primary)	-0.8%	[-0.8%, -0.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.8%	[-0.8%, -0.8%]	1

Cycles

Results (primary 2.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.1%	[2.0%, 2.1%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.1%	[2.0%, 2.1%]	2

Binary size

Results (primary -0.1%, secondary -0.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.0%]	54
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.0%]	24
All ❌✅ (primary)	-0.1%	[-0.1%, -0.0%]	54

Bootstrap: 472.032s -> 472.543s (0.11%)
Artifact size: 383.50 MiB -> 383.42 MiB (-0.02%)

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 Jan 13, 2026

rustbot assigned BoxyUwU Jan 13, 2026

rustbot added F-associated_const_equality `#![feature(associated_const_equality)]` F-min_generic_const_args `#![feature(min_generic_const_args)]` labels Jan 13, 2026

BoxyUwU reviewed Jan 16, 2026

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Keith-Cancel changed the title ~~Fix ICE: can't type-check body of DefId for issue #150956~~ Fix ICE: When Trying to check visibility of a #[type_const], check RHS instead. Jan 16, 2026

BoxyUwU approved these changes Jan 17, 2026

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Keith-Cancel force-pushed the mgca2 branch from 7297d3d to bedb085 Compare January 17, 2026 04:30

Keith-Cancel force-pushed the mgca2 branch from bedb085 to 4c93efa Compare January 17, 2026 04:33

Keith-Cancel requested a review from BoxyUwU January 17, 2026 04:36

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rust-bors bot merged commit 9f6cd6d into rust-lang:main Jan 17, 2026
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rustbot added this to the 1.94.0 milestone Jan 17, 2026

BoxyUwU mentioned this pull request Feb 3, 2026

Tracking Issue for Generic Constant Arguments MVP #132980

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