Use fewer intermediate functions for short backtraces in queries #151739

Zalathar · 2026-01-27T12:34:57Z

If we make sure that compute_fn in the query's vtable is actually named __rust_begin_short_backtrace, we can avoid the need for some additional intermediate functions and stack frames.

This is similar to how the get_query_incr and get_query_non_incr functions are actually named __rust_end_short_backtrace.

Earlier draft of this PR: [EXPERIMENT] Reduce short-backtrace overhead in some query plumbing call stacks #151719
Introduction of this backtrace-trimming: Shorten backtraces for queries in ICEs #108938

rustbot · 2026-01-27T12:35:03Z

r? @fee1-dead

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Zalathar · 2026-01-27T12:36:20Z

Let's have another perf run for the non-draft PR:

@bors try @rust-timer queue

Use fewer intermediate functions for short backtraces in queries

rust-bors · 2026-01-27T14:50:17Z

☀️ Try build successful (CI)
Build commit: 21dc8d7 (21dc8d7b26dfebb8e4647a138974547b9b201161, parent: 78df2f92de1da3601d967dc8beb9f9cea267e45f)

rust-timer · 2026-01-27T15:44:41Z

Finished benchmarking commit (21dc8d7): comparison URL.

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

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.

@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)	0.0%	[0.0%, 0.1%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.2%, -0.0%]	4
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -1.6%, secondary -2.2%)

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)	-1.6%	[-1.9%, -1.3%]	2
Improvements ✅ (secondary)	-2.2%	[-3.3%, -1.7%]	3
All ❌✅ (primary)	-1.6%	[-1.9%, -1.3%]	2

Cycles

Results (secondary 1.2%)

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)	4.7%	[2.7%, 6.4%]	4
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.6%	[-3.8%, -3.4%]	3
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 472.873s -> 474.195s (0.28%)
Artifact size: 385.68 MiB -> 383.56 MiB (-0.55%)

fee1-dead · 2026-01-28T17:19:18Z

Could there be some test to show how the behavior changed? maybe ui-fulldeps? A comment showing the before and after would be nice too

If we make sure that `compute_fn` in the query's vtable is actually named `__rust_begin_short_backtrace`, we can avoid the need for some additional intermediate functions and stack frames. This is similar to how the `get_query_incr` and `get_query_non_incr` functions are actually named `__rust_end_short_backtrace`.

rustbot · 2026-01-29T03:49:58Z

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.

Zalathar · 2026-01-29T04:28:34Z

Here's some sample compiler output based on injecting code to panic from query coverage_ids_info.

The diff is noisy due to frame numbering, but we seem to have successfully removed one non-hidden closure frame, and two hidden frames.

Before:


thread 'rustc' (63142030) panicked at compiler/rustc_mir_transform/src/coverage/query.rs:85:15:
@@ (injected panic message)
stack backtrace:
   0: __rustc::rust_begin_unwind
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:689:5
   1: core::panicking::panic_fmt
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/panicking.rs:80:14
   2: coverage_ids_info
             at ./compiler/rustc_mir_transform/src/coverage/query.rs:85:15
   3: {closure#0}
             at ./compiler/rustc_query_impl/src/plumbing.rs:296:9
      [... omitted 22 frames ...]
   4: query_get_at<rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::instance::InstanceKind, rustc_middle::query::erase::Erased<[u8; 8]>>>
             at ./compiler/rustc_middle/src/query/inner.rs:33:17
   5: coverage_ids_info
             at ./compiler/rustc_middle/src/query/plumbing.rs:414:31
   6: coverage_ids_info
             at ./compiler/rustc_middle/src/query/plumbing.rs:405:35
   7: add_coverage
             at ./compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs:110:37
   8: codegen_coverage<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs:17:12
   9: codegen_statement<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/statement.rs:68:22
  10: codegen_block<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/block.rs:1394:22
  11: codegen_mir<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/mod.rs:309:12
  12: codegen_instance<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/base.rs:395:5
  13: define<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mono_item.rs:49:21
  14: module_codegen
             at ./compiler/rustc_codegen_llvm/src/base.rs:119:27
  15: with_task<rustc_middle::dep_graph::DepsType, rustc_middle::ty::context::TyCtxt, rustc_span::symbol::Symbol, rustc_codegen_ssa::ModuleCodegen<rustc_codegen_llvm::ModuleLlvm>>
             at ./compiler/rustc_query_system/src/dep_graph/graph.rs:273:22
  16: compile_codegen_unit
             at ./compiler/rustc_codegen_llvm/src/base.rs:65:37
  17: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend>
             at ./compiler/rustc_codegen_ssa/src/base.rs:806:42
  18: codegen_crate
             at ./compiler/rustc_codegen_llvm/src/lib.rs:354:18
  19: {closure#0}
             at ./compiler/rustc_interface/src/passes.rs:1264:29
  20: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
             at ./compiler/rustc_data_structures/src/profiling.rs:844:9
  21: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
             at ./compiler/rustc_session/src/utils.rs:17:50
  22: start_codegen
             at ./compiler/rustc_interface/src/passes.rs:1252:28
  23: codegen_and_build_linker
             at ./compiler/rustc_interface/src/queries.rs:33:43
  24: {closure#2}
             at ./compiler/rustc_driver_impl/src/lib.rs:391:18
  25: {closure#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
             at ./compiler/rustc_interface/src/passes.rs:1018:27
  26: {closure#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context.rs:1643:37
  27: {closure#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context/tls.rs:60:9
  28: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/thread/local.rs:513:12
  29: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/thread/local.rs:477:20
  30: enter_context<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context/tls.rs:57:9
  31: enter<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context.rs:1643:9
  32: create_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
             at ./compiler/rustc_middle/src/ty/context.rs:1850:13
  33: {closure#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
             at ./compiler/rustc_interface/src/passes.rs:985:9
  34: call_once<rustc_interface::passes::create_and_enter_global_ctxt::{closure_env#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, (&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2})>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/ops/function.rs:250:5
  35: call_once<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), dyn core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), Output=core::option::Option<rustc_interface::queries::Linker>>, alloc::alloc::Global>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/alloc/src/boxed.rs:2206:9
  36: create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
             at ./compiler/rustc_interface/src/passes.rs:1026:5
  37: {closure#0}
             at ./compiler/rustc_driver_impl/src/lib.rs:348:22
  38: {closure#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
             at ./compiler/rustc_interface/src/interface.rs:532:80
  39: call_once<(), rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/panic/unwind_safe.rs:274:9
  40: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:581:40
  41: catch_unwind<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:544:19
  42: catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panic.rs:359:14
  43: {closure#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
             at ./compiler/rustc_interface/src/interface.rs:532:23
  44: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>
             at ./compiler/rustc_interface/src/util.rs:204:17
  45: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
             at ./compiler/rustc_interface/src/util.rs:158:24
  46: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
             at /Users/stuart/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/scoped-tls-1.0.1/src/lib.rs:137:9
  47: create_session_globals_then<(), rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>>
             at ./compiler/rustc_span/src/lib.rs:142:21
  48: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
             at ./compiler/rustc_interface/src/util.rs:154:17
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/Users/stuart/Dev/rust/rust/rustc-ice-2026-01-29T04_21_17-77558.txt` to your bug report

note: rustc 1.95.0-dev running on aarch64-apple-darwin

note: compiler flags: -C instrument-coverage

query stack during panic:
#0 [coverage_ids_info] retrieving coverage IDs info from MIR for `main`
end of query stack

After:


thread 'rustc' (63128998) panicked at compiler/rustc_mir_transform/src/coverage/query.rs:85:15:
@@ (injected panic message)
stack backtrace:
   0: __rustc::rust_begin_unwind
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:689:5
   1: core::panicking::panic_fmt
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/panicking.rs:80:14
   2: coverage_ids_info
             at ./compiler/rustc_mir_transform/src/coverage/query.rs:85:15
      [... omitted 20 frames ...]
   3: query_get_at<rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::instance::InstanceKind, rustc_middle::query::erase::Erased<[u8; 8]>>>
             at ./compiler/rustc_middle/src/query/inner.rs:33:17
   4: coverage_ids_info
             at ./compiler/rustc_middle/src/query/plumbing.rs:414:31
   5: coverage_ids_info
             at ./compiler/rustc_middle/src/query/plumbing.rs:405:35
   6: add_coverage
             at ./compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs:110:37
   7: codegen_coverage<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs:17:12
   8: codegen_statement<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/statement.rs:68:22
   9: codegen_block<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/block.rs:1394:22
  10: codegen_mir<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mir/mod.rs:309:12
  11: codegen_instance<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/base.rs:395:5
  12: define<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
             at ./compiler/rustc_codegen_ssa/src/mono_item.rs:49:21
  13: module_codegen
             at ./compiler/rustc_codegen_llvm/src/base.rs:119:27
  14: with_task<rustc_middle::dep_graph::DepsType, rustc_middle::ty::context::TyCtxt, rustc_span::symbol::Symbol, rustc_codegen_ssa::ModuleCodegen<rustc_codegen_llvm::ModuleLlvm>>
             at ./compiler/rustc_query_system/src/dep_graph/graph.rs:273:22
  15: compile_codegen_unit
             at ./compiler/rustc_codegen_llvm/src/base.rs:65:37
  16: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend>
             at ./compiler/rustc_codegen_ssa/src/base.rs:806:42
  17: codegen_crate
             at ./compiler/rustc_codegen_llvm/src/lib.rs:354:18
  18: {closure#0}
             at ./compiler/rustc_interface/src/passes.rs:1264:29
  19: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
             at ./compiler/rustc_data_structures/src/profiling.rs:844:9
  20: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
             at ./compiler/rustc_session/src/utils.rs:17:50
  21: start_codegen
             at ./compiler/rustc_interface/src/passes.rs:1252:28
  22: codegen_and_build_linker
             at ./compiler/rustc_interface/src/queries.rs:33:43
  23: {closure#2}
             at ./compiler/rustc_driver_impl/src/lib.rs:391:18
  24: {closure#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
             at ./compiler/rustc_interface/src/passes.rs:1018:27
  25: {closure#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context.rs:1643:37
  26: {closure#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context/tls.rs:60:9
  27: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/thread/local.rs:513:12
  28: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/thread/local.rs:477:20
  29: enter_context<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context/tls.rs:57:9
  30: enter<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
             at ./compiler/rustc_middle/src/ty/context.rs:1643:9
  31: create_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
             at ./compiler/rustc_middle/src/ty/context.rs:1850:13
  32: {closure#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
             at ./compiler/rustc_interface/src/passes.rs:985:9
  33: call_once<rustc_interface::passes::create_and_enter_global_ctxt::{closure_env#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, (&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2})>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/ops/function.rs:250:5
  34: call_once<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), dyn core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), Output=core::option::Option<rustc_interface::queries::Linker>>, alloc::alloc::Global>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/alloc/src/boxed.rs:2206:9
  35: create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
             at ./compiler/rustc_interface/src/passes.rs:1026:5
  36: {closure#0}
             at ./compiler/rustc_driver_impl/src/lib.rs:348:22
  37: {closure#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
             at ./compiler/rustc_interface/src/interface.rs:532:80
  38: call_once<(), rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/panic/unwind_safe.rs:274:9
  39: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:581:40
  40: catch_unwind<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:544:19
  41: catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
             at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panic.rs:359:14
  42: {closure#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
             at ./compiler/rustc_interface/src/interface.rs:532:23
  43: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>
             at ./compiler/rustc_interface/src/util.rs:204:17
  44: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
             at ./compiler/rustc_interface/src/util.rs:158:24
  45: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
             at /Users/stuart/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/scoped-tls-1.0.1/src/lib.rs:137:9
  46: create_session_globals_then<(), rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>>
             at ./compiler/rustc_span/src/lib.rs:142:21
  47: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
             at ./compiler/rustc_interface/src/util.rs:154:17
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/Users/stuart/Dev/rust/rust/rustc-ice-2026-01-29T04_19_21-75821.txt` to your bug report

note: rustc 1.95.0-dev running on aarch64-apple-darwin

note: compiler flags: -C instrument-coverage

query stack during panic:
#0 [coverage_ids_info] retrieving coverage IDs info from MIR for `main`
end of query stack

Diff:

--- _before.txt	2026-01-29 15:21:18
+++ _after.txt	2026-01-29 15:19:21
@@ -1,5 +1,5 @@
 
-thread 'rustc' (63142030) panicked at compiler/rustc_mir_transform/src/coverage/query.rs:85:15:
+thread 'rustc' (63128998) panicked at compiler/rustc_mir_transform/src/coverage/query.rs:85:15:
 @@ (injected panic message)
 stack backtrace:
    0: __rustc::rust_begin_unwind
@@ -8,98 +8,96 @@
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/panicking.rs:80:14
    2: coverage_ids_info
              at ./compiler/rustc_mir_transform/src/coverage/query.rs:85:15
-   3: {closure#0}
-             at ./compiler/rustc_query_impl/src/plumbing.rs:296:9
-      [... omitted 22 frames ...]
-   4: query_get_at<rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::instance::InstanceKind, rustc_middle::query::erase::Erased<[u8; 8]>>>
+      [... omitted 20 frames ...]
+   3: query_get_at<rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::instance::InstanceKind, rustc_middle::query::erase::Erased<[u8; 8]>>>
              at ./compiler/rustc_middle/src/query/inner.rs:33:17
-   5: coverage_ids_info
+   4: coverage_ids_info
              at ./compiler/rustc_middle/src/query/plumbing.rs:414:31
-   6: coverage_ids_info
+   5: coverage_ids_info
              at ./compiler/rustc_middle/src/query/plumbing.rs:405:35
-   7: add_coverage
+   6: add_coverage
              at ./compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs:110:37
-   8: codegen_coverage<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+   7: codegen_coverage<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
              at ./compiler/rustc_codegen_ssa/src/mir/coverageinfo.rs:17:12
-   9: codegen_statement<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+   8: codegen_statement<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
              at ./compiler/rustc_codegen_ssa/src/mir/statement.rs:68:22
-  10: codegen_block<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+   9: codegen_block<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
              at ./compiler/rustc_codegen_ssa/src/mir/block.rs:1394:22
-  11: codegen_mir<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+  10: codegen_mir<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
              at ./compiler/rustc_codegen_ssa/src/mir/mod.rs:309:12
-  12: codegen_instance<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+  11: codegen_instance<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
              at ./compiler/rustc_codegen_ssa/src/base.rs:395:5
-  13: define<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+  12: define<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
              at ./compiler/rustc_codegen_ssa/src/mono_item.rs:49:21
-  14: module_codegen
+  13: module_codegen
              at ./compiler/rustc_codegen_llvm/src/base.rs:119:27
-  15: with_task<rustc_middle::dep_graph::DepsType, rustc_middle::ty::context::TyCtxt, rustc_span::symbol::Symbol, rustc_codegen_ssa::ModuleCodegen<rustc_codegen_llvm::ModuleLlvm>>
+  14: with_task<rustc_middle::dep_graph::DepsType, rustc_middle::ty::context::TyCtxt, rustc_span::symbol::Symbol, rustc_codegen_ssa::ModuleCodegen<rustc_codegen_llvm::ModuleLlvm>>
              at ./compiler/rustc_query_system/src/dep_graph/graph.rs:273:22
-  16: compile_codegen_unit
+  15: compile_codegen_unit
              at ./compiler/rustc_codegen_llvm/src/base.rs:65:37
-  17: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend>
+  16: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend>
              at ./compiler/rustc_codegen_ssa/src/base.rs:806:42
-  18: codegen_crate
+  17: codegen_crate
              at ./compiler/rustc_codegen_llvm/src/lib.rs:354:18
-  19: {closure#0}
+  18: {closure#0}
              at ./compiler/rustc_interface/src/passes.rs:1264:29
-  20: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
+  19: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
              at ./compiler/rustc_data_structures/src/profiling.rs:844:9
-  21: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
+  20: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
              at ./compiler/rustc_session/src/utils.rs:17:50
-  22: start_codegen
+  21: start_codegen
              at ./compiler/rustc_interface/src/passes.rs:1252:28
-  23: codegen_and_build_linker
+  22: codegen_and_build_linker
              at ./compiler/rustc_interface/src/queries.rs:33:43
-  24: {closure#2}
+  23: {closure#2}
              at ./compiler/rustc_driver_impl/src/lib.rs:391:18
-  25: {closure#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
+  24: {closure#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
              at ./compiler/rustc_interface/src/passes.rs:1018:27
-  26: {closure#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
+  25: {closure#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
              at ./compiler/rustc_middle/src/ty/context.rs:1643:37
-  27: {closure#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+  26: {closure#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
              at ./compiler/rustc_middle/src/ty/context/tls.rs:60:9
-  28: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+  27: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/thread/local.rs:513:12
-  29: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+  28: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/thread/local.rs:477:20
-  30: enter_context<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+  29: enter_context<rustc_middle::ty::context::{impl#20}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
              at ./compiler/rustc_middle/src/ty/context/tls.rs:57:9
-  31: enter<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
+  30: enter<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
              at ./compiler/rustc_middle/src/ty/context.rs:1643:9
-  32: create_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
+  31: create_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
              at ./compiler/rustc_middle/src/ty/context.rs:1850:13
-  33: {closure#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
+  32: {closure#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
              at ./compiler/rustc_interface/src/passes.rs:985:9
-  34: call_once<rustc_interface::passes::create_and_enter_global_ctxt::{closure_env#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, (&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2})>
+  33: call_once<rustc_interface::passes::create_and_enter_global_ctxt::{closure_env#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, (&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2})>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/ops/function.rs:250:5
-  35: call_once<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), dyn core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), Output=core::option::Option<rustc_interface::queries::Linker>>, alloc::alloc::Global>
+  34: call_once<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), dyn core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}), Output=core::option::Option<rustc_interface::queries::Linker>>, alloc::alloc::Global>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/alloc/src/boxed.rs:2206:9
-  36: create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
+  35: create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
              at ./compiler/rustc_interface/src/passes.rs:1026:5
-  37: {closure#0}
+  36: {closure#0}
              at ./compiler/rustc_driver_impl/src/lib.rs:348:22
-  38: {closure#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
+  37: {closure#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
              at ./compiler/rustc_interface/src/interface.rs:532:80
-  39: call_once<(), rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>
+  38: call_once<(), rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/core/src/panic/unwind_safe.rs:274:9
-  40: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
+  39: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:581:40
-  41: catch_unwind<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>>
+  40: catch_unwind<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panicking.rs:544:19
-  42: catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
+  41: catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
              at /rustc/9b1f8ff42d110b0ca138116745be921df5dc97e7/library/std/src/panic.rs:359:14
-  43: {closure#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
+  42: {closure#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
              at ./compiler/rustc_interface/src/interface.rs:532:23
-  44: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>
+  43: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>
              at ./compiler/rustc_interface/src/util.rs:204:17
-  45: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
+  44: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
              at ./compiler/rustc_interface/src/util.rs:158:24
-  46: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
+  45: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
              at /Users/stuart/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/scoped-tls-1.0.1/src/lib.rs:137:9
-  47: create_session_globals_then<(), rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>>
+  46: create_session_globals_then<(), rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>>
              at ./compiler/rustc_span/src/lib.rs:142:21
-  48: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
+  47: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
              at ./compiler/rustc_interface/src/util.rs:154:17
 note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
 
@@ -109,7 +107,7 @@
 
 note: please make sure that you have updated to the latest nightly
 
-note: please attach the file at `/Users/stuart/Dev/rust/rust/rustc-ice-2026-01-29T04_21_17-77558.txt` to your bug report
+note: please attach the file at `/Users/stuart/Dev/rust/rust/rustc-ice-2026-01-29T04_19_21-75821.txt` to your bug report
 
 note: rustc 1.95.0-dev running on aarch64-apple-darwin

Zalathar · 2026-01-29T06:37:01Z

Properly testing stack traces is quite tricky, because they're very sensitive to platform and build configuration.

rust-bors · 2026-01-29T20:41:28Z

☔ The latest upstream changes (presumably #151835) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot assigned fee1-dead Jan 27, 2026

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

Auto merge of #151739 - Zalathar:short-backtrace, r=<try>

21dc8d7

Use fewer intermediate functions for short backtraces in queries

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jan 27, 2026

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fee1-dead added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 28, 2026

Zalathar force-pushed the short-backtrace branch from bd2e5db to 30e75b0 Compare January 29, 2026 03:49

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

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