Remove `FeedConstTy` and provide ty when lowering const arg #150962

mu001999 · 2026-01-11T10:53:30Z

edit: BoxyUwU

FeedConstTy currently only provides the expected type of a const argument sometimes (e.g. previously array lengths did not do this). This causes problems with mGCA's directly represented const arguments which always need to know their expected type.

rustbot · 2026-01-11T10:53:34Z

HIR ty lowering was modified

cc @fmease

compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs

BoxyUwU

This is great :)

Can you update type_of.rs to no longer have fn const_arg_anon_type_of and replace its one call site with the logic of the wildcard arm that currently is in const_arg_anon_type_of. In theory none of the other codepaths should be necessary now that we always pass in a type during HIR ty lowering.

View changes since this review

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

src/librustdoc/clean/mod.rs

mu001999 · 2026-01-12T15:25:55Z

Seems because the removal of const_arg_anon_type_of 🤔

mu001999 · 2026-01-12T16:13:43Z

Recover const_arg_anon_type_of, seems we still need it.

BoxyUwU · 2026-01-12T18:24:59Z

Oh that's unfortunate, I wonder what's going on there

rust-bors · 2026-01-12T20:17:55Z

☔ The latest upstream changes (presumably #151003) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2026-01-13T01:45:21Z

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.

mu001999 · 2026-01-13T01:53:28Z

@BoxyUwU I think the two failed tests (tests/ui/closures/issue-90871.rs and tests/ui/type/pattern_types/nested.rs) show that we still will call type_of before lowering const args in these features' implementation.

BoxyUwU · 2026-01-13T14:15:35Z

@bors r+

cool!

rust-bors · 2026-01-13T14:15:39Z

📌 Commit d1c2e5c has been approved by BoxyUwU

It is now in the queue for this repository.

@BoxyUwU

Remove `FeedConstTy` and provide ty when lowering const arg r? @BoxyUwU edit: BoxyUwU `FeedConstTy` currently only provides the expected type of a const argument *sometimes* (e.g. previously array lengths did not do this). This causes problems with mGCA's directly represented const arguments which always need to know their expected type.

@BoxyUwU

Remove `FeedConstTy` and provide ty when lowering const arg r? @BoxyUwU edit: BoxyUwU `FeedConstTy` currently only provides the expected type of a const argument *sometimes* (e.g. previously array lengths did not do this). This causes problems with mGCA's directly represented const arguments which always need to know their expected type.

@ghost

…uwer Rollup of 13 pull requests Successful merges: - #150586 (rustdoc: Fix intra-doc link bugs involving type aliases and associated items) - #150677 (Improve std::path::Path::join documentation) - #150723 (std: move `errno` and related functions into `sys::io`) - #150737 (diagnostics: make implicit Sized bounds explicit in E0277) - #150771 (Remove legacy homu `try` and `auto` branch mentions) - #150915 (Regression test for type params on eii) - #150962 (Remove `FeedConstTy` and provide ty when lowering const arg) - #151017 (Port the rustc dump attributes to the attribute parser) - #151019 (Make `Type::of` support unsized types) - #151034 (std: Change UEFI env vars to volatile storage) - #151052 (ui: add regression test for macro resolution ICE (issue #150711)) - #151053 (Reduce flakyness for `tests/rustdoc-gui/notable-trait.goml`) - #151055 (Emit error instead of delayed bug when meeting mismatch type for const array) r? @ghost

JonathanBrouwer · 2026-01-14T13:09:30Z

@bors try jobs=dist-x86_64-linux-alt

Remove `FeedConstTy` and provide ty when lowering const arg try-job: dist-x86_64-linux-alt

rust-bors · 2026-01-14T15:44:23Z

☀️ Try build successful (CI)
Build commit: e00829c (e00829c2fbefd93907c51cdd47d31a0efb0b6cfd, parent: 4931e09e3ac3182d2a00f38cccfdf68e8e385e1c)

mu001999 · 2026-01-14T15:55:43Z

@rustbot ready

BoxyUwU · 2026-01-14T18:40:50Z

@bors r+

rust-bors · 2026-01-14T18:40:55Z

📌 Commit 12b4b72 has been approved by BoxyUwU

It is now in the queue for this repository.

@BoxyUwU

Remove `FeedConstTy` and provide ty when lowering const arg r? @BoxyUwU edit: BoxyUwU `FeedConstTy` currently only provides the expected type of a const argument *sometimes* (e.g. previously array lengths did not do this). This causes problems with mGCA's directly represented const arguments which always need to know their expected type.

@ghost

…uwer Rollup of 16 pull requests Successful merges: - #150585 (Add a context-consistency check before emitting redundant generic-argument suggestions) - #150586 (rustdoc: Fix intra-doc link bugs involving type aliases and associated items) - #150590 (Don't try to recover keyword as non-keyword identifier ) - #150817 (cleanup: remove borrowck handling for inline const patterns) - #150939 (resolve: Relax some asserts in glob overwriting and add tests) - #150962 (Remove `FeedConstTy` and provide ty when lowering const arg) - #150966 (rustc_target: Remove unused Arch::PowerPC64LE) - #150971 (Disallow eii in statement position) - #151016 (fix: WASI threading regression by disabling pthread usage) - #151046 (compiler: Make Externally Implementable Item (eii) macros "semiopaque") - #151099 (Recover parse gracefully from `<const N>`) - #151117 (Avoid serde dependency in build_helper when not necessary) - #151127 (Delete `MetaItemOrLitParser::Err`) - #151128 (Add temporary new bors e-mail address to the mailmap) - #151130 (resolve: Downgrade `ambiguous_glob_imports` to warn-by-default) - #151138 (Rename `rust.use-lld` to `rust.bootstrap-override-lld` in INSTALL.md) r? @ghost

@ghost

…uwer Rollup of 15 pull requests Successful merges: - #150585 (Add a context-consistency check before emitting redundant generic-argument suggestions) - #150586 (rustdoc: Fix intra-doc link bugs involving type aliases and associated items) - #150590 (Don't try to recover keyword as non-keyword identifier ) - #150817 (cleanup: remove borrowck handling for inline const patterns) - #150939 (resolve: Relax some asserts in glob overwriting and add tests) - #150962 (Remove `FeedConstTy` and provide ty when lowering const arg) - #150966 (rustc_target: Remove unused Arch::PowerPC64LE) - #150971 (Disallow eii in statement position) - #151016 (fix: WASI threading regression by disabling pthread usage) - #151046 (compiler: Make Externally Implementable Item (eii) macros "semiopaque") - #151099 (Recover parse gracefully from `<const N>`) - #151117 (Avoid serde dependency in build_helper when not necessary) - #151127 (Delete `MetaItemOrLitParser::Err`) - #151128 (Add temporary new bors e-mail address to the mailmap) - #151138 (Rename `rust.use-lld` to `rust.bootstrap-override-lld` in INSTALL.md) r? @ghost

@BoxyUwU

Rollup merge of #150962 - rm/feed_const_ty, r=BoxyUwU Remove `FeedConstTy` and provide ty when lowering const arg r? @BoxyUwU edit: BoxyUwU `FeedConstTy` currently only provides the expected type of a const argument *sometimes* (e.g. previously array lengths did not do this). This causes problems with mGCA's directly represented const arguments which always need to know their expected type.

@ghost

…uwer Rollup of 15 pull requests Successful merges: - rust-lang/rust#150585 (Add a context-consistency check before emitting redundant generic-argument suggestions) - rust-lang/rust#150586 (rustdoc: Fix intra-doc link bugs involving type aliases and associated items) - rust-lang/rust#150590 (Don't try to recover keyword as non-keyword identifier ) - rust-lang/rust#150817 (cleanup: remove borrowck handling for inline const patterns) - rust-lang/rust#150939 (resolve: Relax some asserts in glob overwriting and add tests) - rust-lang/rust#150962 (Remove `FeedConstTy` and provide ty when lowering const arg) - rust-lang/rust#150966 (rustc_target: Remove unused Arch::PowerPC64LE) - rust-lang/rust#150971 (Disallow eii in statement position) - rust-lang/rust#151016 (fix: WASI threading regression by disabling pthread usage) - rust-lang/rust#151046 (compiler: Make Externally Implementable Item (eii) macros "semiopaque") - rust-lang/rust#151099 (Recover parse gracefully from `<const N>`) - rust-lang/rust#151117 (Avoid serde dependency in build_helper when not necessary) - rust-lang/rust#151127 (Delete `MetaItemOrLitParser::Err`) - rust-lang/rust#151128 (Add temporary new bors e-mail address to the mailmap) - rust-lang/rust#151138 (Rename `rust.use-lld` to `rust.bootstrap-override-lld` in INSTALL.md) r? @ghost

JonathanBrouwer · 2026-01-15T07:58:42Z

@rust-timer queue 8ea72d4

rust-timer · 2026-01-15T07:58:45Z

Error occurred while parsing comment: Invalid command argument 8ea72d4988a359ba48641ca81b9ec044007c9a99 (there may be no spaces around the = character)

JonathanBrouwer · 2026-01-15T07:59:23Z

@rust-timer build 8ea72d4

rust-timer · 2026-01-15T08:40:27Z

Finished benchmarking commit (8ea72d4): comparison URL.

Overall result: ❌ regressions - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +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)	1.3%	[0.6%, 2.1%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.6%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.6%	[2.6%, 2.6%]	1

Cycles

Results (secondary 0.8%)

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)	0.8%	[0.8%, 0.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 475.838s -> 473.206s (-0.55%)
Artifact size: 383.64 MiB -> 383.65 MiB (0.00%)

JonathanBrouwer · 2026-01-15T08:44:07Z

This caused the perf regression in #151144

BoxyUwU · 2026-01-15T14:35:35Z

wild

BoxyUwU · 2026-01-15T14:46:09Z

unsure what caused this, all the logic in this PR is either const generics only or diagnostics path stuff 🤔 this bench doesn't have any const generics 🤔 given it's a stress test though I'd be inclined to accept this given it's likely to be very minimal affect on real world code? It would be nice to fix this though

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. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Jan 11, 2026

rustbot assigned BoxyUwU Jan 11, 2026

fmease reviewed Jan 11, 2026

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mu001999 force-pushed the rm/feed_const_ty branch from 037210a to d0247c8 Compare January 11, 2026 11:24

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mu001999 force-pushed the rm/feed_const_ty branch from 25c3068 to 7055784 Compare January 12, 2026 14:30

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mu001999 force-pushed the rm/feed_const_ty branch from 7055784 to dbf5ee8 Compare January 12, 2026 15:50

mu001999 force-pushed the rm/feed_const_ty branch from dbf5ee8 to d95613a Compare January 13, 2026 01:45

This was referenced Jan 13, 2026

ICE: unsupported const array #151054

Open

ICE const tuple lack type information #151048

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Rollup of 14 pull requests #151062

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Rollup of 13 pull requests #151070

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rust-bors bot pushed a commit that referenced this pull request Jan 14, 2026

Auto merge of #150962 - mu001999-contrib:rm/feed_const_ty, r=<try>

e00829c

Remove `FeedConstTy` and provide ty when lowering const arg try-job: dist-x86_64-linux-alt

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 Jan 14, 2026

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 Jan 14, 2026

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Rollup of 16 pull requests #151139

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Rollup of 15 pull requests #151144

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rust-bors bot merged commit 27e6ef9 into rust-lang:main Jan 15, 2026
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mu001999 deleted the rm/feed_const_ty branch January 15, 2026 02:54

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rustbot added the perf-regression Performance regression. label Jan 15, 2026

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Remove FeedConstTy and provide ty when lowering const arg #150962

Remove FeedConstTy and provide ty when lowering const arg #150962

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Overall result: ❌ regressions - please read the text below

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Binary size

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Remove `FeedConstTy` and provide ty when lowering const arg #150962

Remove `FeedConstTy` and provide ty when lowering const arg #150962

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