Collect hirless def ids and skip them when iterating parents #149728

mu001999 · 2025-12-07T03:44:49Z

Bounds in binders are denied, hir items won't contain and index them. But nested items in the bounds will still be lowered to hir. And their parents, i.e., the block in bounds is not in hir. So that ICE happens when error handling requires visiting hir parents.

This PR collects hirless def ids and skips them when iterating parents.

Fixes #149695

rustbot · 2025-12-07T03:44:54Z

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mu001999 · 2025-12-18T03:50:15Z

@rustbot reroll

compiler/rustc_ast_passes/src/feature_gate.rs

jdonszelmann · 2026-01-08T23:42:59Z

@rustbot author

rustbot · 2026-01-08T23:43:03Z

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

mu001999 · 2026-01-09T01:41:50Z

@rustbot review

jdonszelmann · 2026-01-09T09:38:23Z

@rusbot author

jdonszelmann · 2026-01-09T09:38:57Z

@rustbot blocked on #149728 (comment)

mu001999 · 2026-01-09T18:09:10Z

Hi @jdonszelmann, in the lastest rough change, I tried to filter nested items in the bound, and not lower them to hir.

dbg! shows it works:

[compiler/rustc_ast_lowering/src/lib.rs:527:17] "skipping lowering of {:?}" = "skipping lowering of {:?}"
[compiler/rustc_ast_lowering/src/lib.rs:527:17] def_id = DefId(0:6 ~ bad_bounds[bee6]::produce::{constant#0}::A)
[compiler/rustc_ast_lowering/src/lib.rs:527:17] "skipping lowering of {:?}" = "skipping lowering of {:?}"
[compiler/rustc_ast_lowering/src/lib.rs:527:17] def_id = DefId(0:7 ~ bad_bounds[bee6]::produce::{constant#0}::A::{constructor#0})
[compiler/rustc_ast_lowering/src/lib.rs:527:17] "skipping lowering of {:?}" = "skipping lowering of {:?}"
[compiler/rustc_ast_lowering/src/lib.rs:527:17] def_id = DefId(0:8 ~ bad_bounds[bee6]::produce::{constant#0}::A::A)
[compiler/rustc_ast_lowering/src/lib.rs:527:17] "skipping lowering of {:?}" = "skipping lowering of {:?}"
[compiler/rustc_ast_lowering/src/lib.rs:527:17] def_id = DefId(0:10 ~ bad_bounds[bee6]::produce::{constant#0}::A#1)
[compiler/rustc_ast_lowering/src/lib.rs:527:17] "skipping lowering of {:?}" = "skipping lowering of {:?}"
[compiler/rustc_ast_lowering/src/lib.rs:527:17] def_id = DefId(0:11 ~ bad_bounds[bee6]::produce::{constant#0}::{impl#0})

But there still be errors, because they still have LocalDefId, so that they can be result of many other queries. For example, after the change, a new ICE appears because type_of(bad_bounds[bee6]::produce::{constant#0}::{impl#0}).

Concrete content of the new ICE is:

error: internal compiler error: compiler/rustc_middle/src/hir/mod.rs:385:32: No HirId for DefId(0:11 ~ bad_bounds[bee6]::produce::{constant#0}::{impl#0})


thread 'rustc' (6902108) panicked at compiler/rustc_middle/src/hir/mod.rs:385:32:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
             at /rustc/1b6e21e163baa0b20f119e17e3871910978a60b6/library/std/src/panicking.rs:761:5
   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
             at /rustc/1b6e21e163baa0b20f119e17e3871910978a60b6/library/std/src/panic.rs:260:5
   2: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
             at ./compiler/rustc_errors/src/diagnostic.rs:63:9
   3: <rustc_errors::diagnostic::Diag<rustc_errors::diagnostic::BugAbort>>::emit
             at ./compiler/rustc_errors/src/diagnostic.rs:1405:9
   4: <rustc_errors::DiagCtxtHandle>::bug::<alloc::string::String>
             at ./compiler/rustc_errors/src/lib.rs:1231:30
   5: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>::{closure#0}
             at ./compiler/rustc_middle/src/util/bug.rs:39:48
   6: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
             at ./compiler/rustc_middle/src/ty/context/tls.rs:136:23
   7: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
             at ./compiler/rustc_middle/src/ty/context/tls.rs:79:18
   8: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>
             at ./compiler/rustc_middle/src/ty/context/tls.rs:134:5
   9: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>
             at ./compiler/rustc_middle/src/util/bug.rs:33:5
  10: rustc_middle::util::bug::bug_fmt
             at ./compiler/rustc_middle/src/util/bug.rs:16:5
  11: rustc_middle::hir::provide::{closure#0}
             at ./compiler/rustc_middle/src/macros.rs:18:9
  12: <rustc_middle::hir::provide::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
             at /rustc/1b6e21e163baa0b20f119e17e3871910978a60b6/library/core/src/ops/function.rs:250:5
  13: rustc_query_impl::query_impl::local_def_id_to_hir_id::dynamic_query::{closure#2}::{closure#0}
             at ./compiler/rustc_query_impl/src/plumbing.rs:298:9
      [... omitted 22 frames ...]
  14: rustc_middle::query::inner::query_get_at::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>>
             at ./compiler/rustc_middle/src/query/inner.rs:33:17
  15: <rustc_middle::query::plumbing::TyCtxtAt>::local_def_id_to_hir_id::<rustc_span::def_id::LocalDefId>
             at ./compiler/rustc_middle/src/query/plumbing.rs:415:31
  16: <rustc_middle::ty::context::TyCtxt>::local_def_id_to_hir_id::<rustc_span::def_id::LocalDefId>
             at ./compiler/rustc_middle/src/query/plumbing.rs:406:35
  17: rustc_hir_analysis::collect::type_of::type_of::{closure#0}
             at ./compiler/rustc_hir_analysis/src/collect/type_of.rs:56:22
  18: rustc_hir_analysis::collect::type_of::type_of
             at ./compiler/rustc_hir_analysis/src/collect/type_of.rs:21:1
  19: rustc_query_impl::query_impl::type_of::dynamic_query::{closure#2}::{closure#0}
             at ./compiler/rustc_query_impl/src/plumbing.rs:302:13
      [... omitted 22 frames ...]
  20: rustc_middle::query::inner::query_get_at::<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 8]>>>
             at ./compiler/rustc_middle/src/query/inner.rs:33:17
  21: <rustc_middle::query::plumbing::TyCtxtAt>::type_of::<rustc_span::def_id::DefId>
             at ./compiler/rustc_middle/src/query/plumbing.rs:415:31
  22: <rustc_middle::ty::context::TyCtxt>::type_of::<rustc_span::def_id::DefId>
             at ./compiler/rustc_middle/src/query/plumbing.rs:406:35
  23: rustc_middle::ty::trait_def::trait_impls_of_provider
             at ./compiler/rustc_middle/src/ty/trait_def.rs:227:32
  24: rustc_query_impl::query_impl::trait_impls_of::dynamic_query::{closure#2}::{closure#0}
             at ./compiler/rustc_query_impl/src/plumbing.rs:298:9
      [... omitted 22 frames ...]
  25: rustc_middle::query::inner::query_get_at::<rustc_query_system::query::caches::DefIdCache<rustc_middle::query::erase::Erased<[u8; 8]>>>
             at ./compiler/rustc_middle/src/query/inner.rs:33:17
  26: <rustc_middle::query::plumbing::TyCtxtAt>::trait_impls_of::<rustc_span::def_id::DefId>
             at ./compiler/rustc_middle/src/query/plumbing.rs:415:31
  27: <rustc_middle::ty::context::TyCtxt>::trait_impls_of::<rustc_span::def_id::DefId>
             at ./compiler/rustc_middle/src/query/plumbing.rs:406:35
  28: <rustc_middle::ty::context::TyCtxt>::all_impls
             at ./compiler/rustc_middle/src/ty/trait_def.rs:194:68

mu001999 · 2026-01-09T18:11:01Z

I think at least it's more difficult than I expected. Do you have any suggestions?

mu001999 · 2026-01-26T11:23:45Z

@jdonszelmann hi, why is this PR closed?

jdonszelmann · 2026-01-26T13:31:58Z

Oh my bad, that's a mistake haha

mu001999 · 2026-01-26T13:32:46Z

@rustbot author

rustbot · 2026-01-26T16:10:43Z

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 · 2026-01-27T04:46:17Z

@rustbot ready

jdonszelmann · 2026-01-27T21:33:31Z

@bors try @rust_timer queue

Collect hirless def ids and skip them when iterating parents

jdonszelmann · 2026-01-27T21:34:49Z

@rust-timer queue

rust-bors · 2026-01-27T23:48:21Z

☀️ Try build successful (CI)
Build commit: 74e2474 (74e24745a7d5831643e67b95d8c895bb8c9a9b3f, parent: e96bb7e44fbcc23c1e6009e8d0ee8ab208668fb4)

rust-timer · 2026-01-28T00:29:11Z

Finished benchmarking commit (74e2474): comparison URL.

Overall result: ❌✅ regressions and improvements - 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)	9.7%	[0.1%, 68.0%]	77
Regressions ❌ (secondary)	11.5%	[0.1%, 99.8%]	16
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	2
All ❌✅ (primary)	9.7%	[0.1%, 68.0%]	77

Max RSS (memory usage)

Results (primary 8.3%, 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)	8.5%	[2.4%, 28.3%]	54
Regressions ❌ (secondary)	3.3%	[0.5%, 6.7%]	10
Improvements ✅ (primary)	-1.4%	[-1.4%, -1.4%]	1
Improvements ✅ (secondary)	-4.8%	[-5.2%, -4.1%]	7
All ❌✅ (primary)	8.3%	[-1.4%, 28.3%]	55

Cycles

Results (primary 15.3%, secondary 14.4%)

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

	mean	range	count
Regressions ❌ (primary)	15.6%	[2.6%, 57.3%]	55
Regressions ❌ (secondary)	19.7%	[8.7%, 52.6%]	7
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-4.1%	[-4.3%, -4.0%]	2
All ❌✅ (primary)	15.3%	[-2.7%, 57.3%]	56

Binary size

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

Bootstrap: 470.891s -> 473.436s (0.54%)
Artifact size: 383.44 MiB -> 385.76 MiB (0.61%)

jdonszelmann · 2026-01-28T03:06:24Z

Welp

jdonszelmann · 2026-01-28T03:06:51Z

Maybe that's not great for perf, mostly in visiting all those extra nodes I'm afraid

mu001999 · 2026-01-28T04:02:39Z

Yep, I think this adds excessive overhead to the hot path.

rustbot assigned wesleywiser Dec 7, 2025

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 Dec 7, 2025

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mu001999 force-pushed the fix/149695 branch from 888f87a to 84a0f1e Compare December 7, 2025 10:36

mu001999 changed the title ~~Emit ForbiddenBound fatally~~ Emit ForbiddenBound fatally if meeting complex bounds Dec 7, 2025

rustbot assigned jdonszelmann and unassigned wesleywiser Dec 18, 2025

jdonszelmann reviewed Jan 5, 2026

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mu001999 force-pushed the fix/149695 branch from 84a0f1e to 10657b6 Compare January 9, 2026 12:02

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mu001999 marked this pull request as draft January 9, 2026 15:56

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jdonszelmann reopened this Jan 26, 2026

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mu001999 force-pushed the fix/149695 branch from 2b73c39 to 20fc999 Compare January 26, 2026 16:10

mu001999 changed the title ~~Emit ForbiddenBound fatally if meeting complex bounds~~ Collect hirless def ids and skip them when iterating parents Jan 26, 2026

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Collect hirless def ids and skip them when iterating parents

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mu001999 force-pushed the fix/149695 branch from 20fc999 to f06b317 Compare January 27, 2026 01:40

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rust-bors bot pushed a commit that referenced this pull request Jan 27, 2026

Auto merge of #149728 - mu001999-contrib:fix/149695, r=<try>

74e2474

Collect hirless def ids and skip them when iterating parents

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Jan 28, 2026

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Collect hirless def ids and skip them when iterating parents #149728

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rust-timer commented Jan 28, 2026

Overall result: ❌✅ regressions and improvements - please read the text below

Instruction count

Max RSS (memory usage)

Cycles

Binary size

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