diagnostics: suggest generic_const_args for const ops by Dnreikronos · Pull Request #156968 · rust-lang/rust

Dnreikronos · 2026-05-26T12:32:49Z

when const ops hit generic params, like [u8; size_of::<self>()], the diagnostic only points at generic_const_exprs. imo that's a stale nudge now that generic_const_args and type const items are the path we want people trying.

add help for generic_const_args and type const items in the resolve and hir_ty_lowering paths. also skip the old gce suggestion once min_generic_const_args is enabled, and emit both suggestions for the self alias path so the "alternatively" wording doesn't hang there by itself. includes the regression test from the issue. lgtm.

rustbot · 2026-05-26T12:32:53Z

HIR ty lowering was modified

cc @fmease

rustbot · 2026-05-26T12:32:56Z

r? @wesleywiser

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Dnreikronos · 2026-06-23T14:15:52Z

@wesleywiser, hi!
does you need something more from my side to help with the review here?

Dnreikronos · 2026-07-06T18:57:52Z

@rustbot reroll

petrochenkov · 2026-07-07T10:31:40Z

@bors r+

rust-bors · 2026-07-07T10:31:43Z

📌 Commit bf4bad2 has been approved by petrochenkov

It is now in the queue for this repository.

rust-bors · 2026-07-07T14:01:27Z

This pull request was unapproved.

This PR was contained in a rollup (#158909), which was unapproved.

View changes since this unapproval

Dnreikronos · 2026-07-07T15:33:20Z

@JonathanBrouwer @petrochenkov i pushed a fix for the rollup failure from the aarch64-gnu-llvm-21-1 job.

i rebased the pr on current origin/main, which brought in tests/ui/const-generics/mgca/double-inline-const.stderr, then updated that fixture to expect the new generic_const_args + type const help text. that matches the actual stderr from the failed job.

imo this was just a stale ui fixture after the rollup picked up a newer test from main. the compiler output looked right to me, the expected stderr was the part that was out of date.

i also ran git diff --check, which passes. i tried the focused ui test locally, but bootstrap did not finish within 10 min on my machine, so idk if that local run is useful signal.

could one of you re-trigger the failed job / try job for that same builder? i don't have permission to do it from here. ltm if you want anything else changed.

JonathanBrouwer · 2026-07-07T15:41:56Z

This soft conflicts with #158617 which is in the current rollup, please rebase on that after it's merged

…stics Point users at `#![feature(generic_const_args)]` and `type const` items when they hit the "generic parameters may not be used in const operations" error, not just `generic_const_exprs`.

rustbot · 2026-07-10T20:14:53Z

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.

Dnreikronos · 2026-07-11T12:06:52Z

This soft conflicts with #158617 which is in the current rollup, please rebase on that after it's merged

Hi, @JonathanBrouwer!
Can you re-validate, please?

JonathanBrouwer · 2026-07-11T12:08:52Z

@bors r=petrochenkov rollup=iffy
Iffy because this is likely to soft-conflict

rust-bors · 2026-07-11T12:08:55Z

📌 Commit 9211a89 has been approved by petrochenkov

It is now in the queue for this repository.

…gnostic-156729, r=petrochenkov diagnostics: suggest generic_const_args for const ops fixes rust-lang#156729 when const ops hit generic params, like `[u8; size_of::<self>()]`, the diagnostic only points at `generic_const_exprs`. imo that's a stale nudge now that `generic_const_args` and `type const` items are the path we want people trying. add help for `generic_const_args` and `type const` items in the resolve and hir_ty_lowering paths. also skip the old gce suggestion once `min_generic_const_args` is enabled, and emit both suggestions for the `self` alias path so the "alternatively" wording doesn't hang there by itself. includes the regression test from the issue. lgtm.

…uwer Rollup of 8 pull requests Successful merges: - #159126 (Fix PR number in bootstrap's change tracker) - #156968 (diagnostics: suggest generic_const_args for const ops) - #159012 (Shrink mir::Statement to 40 bytes) - #158182 (std: use `OnceLock` for SGX argument storage) - #159114 (Add regression test for $-prefixed fragment specifier in repetition) - #159060 (Look for the cdb architecture that corresponds to the target triple) - #159089 (riscv: update c-variadic test for LLVM changes) - #159093 (pretty-print: use inline asm's actual macro name)

…uwer Rollup of 14 pull requests Successful merges: - #159126 (Fix PR number in bootstrap's change tracker) - #155811 (Include AtomicU128/AtomicI128 in docs for any target) - #156968 (diagnostics: suggest generic_const_args for const ops) - #159012 (Shrink mir::Statement to 40 bytes) - #156618 (rustdoc: test ignoring rustc lints in CLI) - #158182 (std: use `OnceLock` for SGX argument storage) - #159114 (Add regression test for $-prefixed fragment specifier in repetition) - #158523 (Fix feature gate for `repr(simd)`) - #158876 (Fix multiple logic bugs in `Arc::make_mut`) - #158928 (std: fix Xous UDP send_to length mismatch and truncation) - #159060 (Look for the cdb architecture that corresponds to the target triple) - #159089 (riscv: update c-variadic test for LLVM changes) - #159093 (pretty-print: use inline asm's actual macro name) - #159122 (doc: use ptr::addr in offset_from docs) Failed merges: - #158732 (Apply MCP 1003 and move diagnostics.rs into its own module)

Rollup merge of #156968 - Dnreikronos:fix/gca-const-item-diagnostic-156729, r=petrochenkov diagnostics: suggest generic_const_args for const ops fixes #156729 when const ops hit generic params, like `[u8; size_of::<self>()]`, the diagnostic only points at `generic_const_exprs`. imo that's a stale nudge now that `generic_const_args` and `type const` items are the path we want people trying. add help for `generic_const_args` and `type const` items in the resolve and hir_ty_lowering paths. also skip the old gce suggestion once `min_generic_const_args` is enabled, and emit both suggestions for the `self` alias path so the "alternatively" wording doesn't hang there by itself. includes the regression test from the issue. lgtm.

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 May 26, 2026

rustbot assigned wesleywiser May 26, 2026

Dnreikronos force-pushed the fix/gca-const-item-diagnostic-156729 branch 4 times, most recently from a43c40b to d890018 Compare May 26, 2026 13:31

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Dnreikronos force-pushed the fix/gca-const-item-diagnostic-156729 branch from f883d0e to a9b91d1 Compare June 17, 2026 03:33

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rustbot added has-merge-commits PR has merge commits, merge with caution. S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 25, 2026

Dnreikronos force-pushed the fix/gca-const-item-diagnostic-156729 branch from c02ce98 to bf4bad2 Compare June 25, 2026 12:58

rustbot removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. has-merge-commits PR has merge commits, merge with caution. labels Jun 25, 2026

Dnreikronos changed the title ~~Suggest generic_const_args + type const items in const operation diagnostics~~ diagnostics: suggest generic_const_args for const ops Jun 25, 2026

rustbot assigned petrochenkov and unassigned wesleywiser Jul 6, 2026

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Suggest generic_const_args + type const in const operation diagno…

920f3f1

…stics Point users at `#![feature(generic_const_args)]` and `type const` items when they hit the "generic parameters may not be used in const operations" error, not just `generic_const_exprs`.

Dnreikronos force-pushed the fix/gca-const-item-diagnostic-156729 branch from 7958796 to c394716 Compare July 10, 2026 20:14

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Dnreikronos force-pushed the fix/gca-const-item-diagnostic-156729 branch from c394716 to 382f1a0 Compare July 10, 2026 20:51

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Update const generic diagnostic fixture

9211a89

Dnreikronos force-pushed the fix/gca-const-item-diagnostic-156729 branch from 382f1a0 to 9211a89 Compare July 10, 2026 22:04

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 Jul 11, 2026

JonathanBrouwer mentioned this pull request Jul 11, 2026

Rollup of 8 pull requests #159132

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JonathanBrouwer mentioned this pull request Jul 11, 2026

Rollup of 14 pull requests #159142

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rust-bors Bot merged commit aa8cf33 into rust-lang:main Jul 11, 2026
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rustbot added this to the 1.99.0 milestone Jul 11, 2026

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