rust-lang / rust-lang/rust

ICE: `Failed to normalize &'{erased} mut Alias(Opaque`

Open
#141,850 1 comment 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

C-bug F-pin_ergonomics I-ICE S-has-mcve T-compiler
Dominant language
Rust
Stars
119k
Forks
16.1k
PR metrics pending

Description

auto-reduced (treereduce-rust):

//@compile-flags: --edition=2024
#![feature(pin_ergonomics)]
async fn a() {
    wrapper_call(handler, ()).await;
}
async fn wrapper_call<F, Args>(handler: F, args: Args) -> F::Output
where
    F: Handler<Args>,
{
    handler.call(args).await
}
async fn handler();
trait Handler<Args>: 'static {
    type Output;
    type Future: Future<Output = Self::Output>;
    fn call(&self, args: Args) -> Self::Future;
}
impl<Func, Fut> Handler() for Func
where
    Func: Fn() -> Fut + Clone + 'static,
    Fut: Future,
{
    type Output = Fut;
}

original:

#![feature(pin_ergonomics)]
async fn a() {
    wrapper_call(handler, ()).await;
}
async fn wrapper_call<F, Args>(handler: F, args: Args) -> F::Output
where
    F: Handler<Args>,
{
    handler.call(args).await
}
async fn handler();
trait Handler<Args>: 'static {
    type Output;
    type Future: Future<Output = Self::Output>;
    fn call(&self, args: Args) -> Self::Future;
}
impl<Func, Fut> Handler() for Func
where
    Func: Fn() -> Fut + Clone + 'static,
    Fut: Future,
{
    type Output = Fut;
}

Version information

rustc 1.89.0-nightly (13a454090 2025-06-01)
binary: rustc
commit-hash: 13a4540908d25642c0fa0ab726095cf57bbe6824
commit-date: 2025-06-01
host: x86_64-unknown-linux-gnu
release: 1.89.0-nightly
LLVM version: 20.1.5

Possibly related line of code:
https://github.com/rust-lang/rust/blob/13a4540908d25642c0fa0ab726095cf57bbe6824/compiler/rustc_middle/src/ty/normalize_erasing_regions.rs#L165-L177

Command:
/home/matthias/.rustup/toolchains/master/bin/rustc --edition=2024

Program output 

error: free function without a body
  --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:11:1
   |
11 | async fn handler();
   | ^^^^^^^^^^^^^^^^^^-
   |                   |
   |                   help: provide a definition for the function: `{ <body> }`

warning: the feature `pin_ergonomics` is incomplete and may not be safe to use and/or cause compiler crashes
 --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:1:12
  |
1 | #![feature(pin_ergonomics)]
  |            ^^^^^^^^^^^^^^
  |
  = note: see issue #130494 <https://github.com/rust-lang/rust/issues/130494> for more information
  = note: `#[warn(incomplete_features)]` on by default

error[E0601]: `main` function not found in crate `mvce`
  --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:23:2
   |
23 | }
   |  ^ consider adding a `main` function to `/tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs`

error[E0658]: parenthetical notation is only stable when used with `Fn`-family traits
  --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:17:17
   |
17 | impl<Func, Fut> Handler() for Func
   |                 ^^^^^^^^^
   |
   = note: see issue #29625 <https://github.com/rust-lang/rust/issues/29625> for more information
   = help: add `#![feature(unboxed_closures)]` to the crate attributes to enable
   = note: this compiler was built on 2025-06-01; consider upgrading it if it is out of date

error[E0229]: associated item constraints are not allowed here
  --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:17:17
   |
17 | impl<Func, Fut> Handler() for Func
   |                 ^^^^^^^^^ associated item constraint not allowed here
   |
help: parenthesized trait syntax expands to `Handler<(), Output=()>`
  --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:17:17
   |
17 | impl<Func, Fut> Handler() for Func
   |                 ^^^^^^^^^

error[E0046]: not all trait items implemented, missing: `Future`, `call`
  --> /tmp/icemaker_global_tempdir.RuqRgdhmMFsu/rustc_testrunner_tmpdir_reporting.kFTDMkrcqGyG/mvce.rs:17:1
   |
14 |       type Future: Future<Output = Self::Output>;
   |       ------------------------------------------ `Future` from trait
15 |       fn call(&self, args: Args) -> Self::Future;
   |       ------------------------------------------- `call` from trait
16 |   }
17 | / impl<Func, Fut> Handler() for Func
18 | | where
19 | |     Func: Fn() -> Fut + Clone + 'static,
20 | |     Fut: Future,
   | |________________^ missing `Future`, `call` in implementation

error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13: Failed to normalize &'{erased} mut Alias(Opaque, AliasTy { args: [FnDef(DefId(0:11 ~ mvce[0140]::handler), []), ()], def_id: DefId(0:9 ~ mvce[0140]::wrapper_call::{opaque#0}), .. }) in typing_env=TypingEnv { typing_mode: PostAnalysis, param_env: ParamEnv { caller_bounds: [] } }, maybe try to call `try_normalize_erasing_regions` instead


thread 'rustc' panicked at compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:171:13:
Box<dyn Any>
stack backtrace:
   0:     0x7991cc6de703 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h1750895f43e843d4
   1:     0x7991cce03237 - core::fmt::write::h6b549521393450c4
   2:     0x7991cc6d4383 - std::io::Write::write_fmt::h56b183ab660d16eb
   3:     0x7991cc6de562 - std::sys::backtrace::BacktraceLock::print::h96fec1ee4eaf5d52
   4:     0x7991cc6e215a - std::panicking::default_hook::{{closure}}::h0272a1832c315d01
   5:     0x7991cc6e1cdf - std::panicking::default_hook::hbb92434c436b38d4
   6:     0x7991cb7fa5b3 - std[d5a5e8436f7bb80d]::panicking::update_hook::<alloc[84a9b4db4b1fd3b6]::boxed::Box<rustc_driver_impl[12f4e41c2796a3e6]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7991cc6e29d3 - std::panicking::rust_panic_with_hook::hdd99d03934c0d55d
   8:     0x7991cb8372d1 - std[d5a5e8436f7bb80d]::panicking::begin_panic::<rustc_errors[78ce2d78f255827f]::ExplicitBug>::{closure#0}
   9:     0x7991cb82bbc6 - std[d5a5e8436f7bb80d]::sys::backtrace::__rust_end_short_backtrace::<std[d5a5e8436f7bb80d]::panicking::begin_panic<rustc_errors[78ce2d78f255827f]::ExplicitBug>::{closure#0}, !>
  10:     0x7991cb82baab - std[d5a5e8436f7bb80d]::panicking::begin_panic::<rustc_errors[78ce2d78f255827f]::ExplicitBug>
  11:     0x7991cb840dc1 - <rustc_errors[78ce2d78f255827f]::diagnostic::BugAbort as rustc_errors[78ce2d78f255827f]::diagnostic::EmissionGuarantee>::emit_producing_guarantee
  12:     0x7991cbde238a - rustc_middle[c87150728fec5a49]::util::bug::opt_span_bug_fmt::<rustc_span[1b2e5f36c4767dc6]::span_encoding::Span>::{closure#0}
  13:     0x7991cbdc1dca - rustc_middle[c87150728fec5a49]::ty::context::tls::with_opt::<rustc_middle[c87150728fec5a49]::util::bug::opt_span_bug_fmt<rustc_span[1b2e5f36c4767dc6]::span_encoding::Span>::{closure#0}, !>::{closure#0}
  14:     0x7991cbdc1c3b - rustc_middle[c87150728fec5a49]::ty::context::tls::with_context_opt::<rustc_middle[c87150728fec5a49]::ty::context::tls::with_opt<rustc_middle[c87150728fec5a49]::util::bug::opt_span_bug_fmt<rustc_span[1b2e5f36c4767dc6]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
  15:     0x7991c8eaa280 - rustc_middle[c87150728fec5a49]::util::bug::bug_fmt
  16:     0x7991cd8b40ff - <rustc_middle[c87150728fec5a49]::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder as rustc_type_ir[c774dfba22605253]::fold::TypeFolder<rustc_middle[c87150728fec5a49]::ty::context::TyCtxt>>::fold_ty
  17:     0x7991ce422973 - rustc_mir_transform[8ab4230bc871fcc6]::validate::validate_types
  18:     0x7991cdccf4ac - <rustc_mir_transform[8ab4230bc871fcc6]::validate::Validator as rustc_mir_transform[8ab4230bc871fcc6]::pass_manager::MirPass>::run_pass
  19:     0x7991cce109eb - rustc_mir_transform[8ab4230bc871fcc6]::run_optimization_passes
  20:     0x7991cdb3b9dc - rustc_mir_transform[8ab4230bc871fcc6]::optimized_mir
  21:     0x7991cdb3b19d - rustc_query_impl[22a781136fdb8532]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[22a781136fdb8532]::query_impl::optimized_mir::dynamic_query::{closure#2}::{closure#0}, rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 8usize]>>
  22:     0x7991cce25ae5 - rustc_query_system[58eb503a7502457a]::query::plumbing::try_execute_query::<rustc_query_impl[22a781136fdb8532]::DynamicConfig<rustc_query_system[58eb503a7502457a]::query::caches::DefIdCache<rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[22a781136fdb8532]::plumbing::QueryCtxt, false>
  23:     0x7991cce24f1b - rustc_query_impl[22a781136fdb8532]::query_impl::optimized_mir::get_query_non_incr::__rust_end_short_backtrace
  24:     0x7991ce21e068 - <rustc_middle[c87150728fec5a49]::ty::context::TyCtxt>::coroutine_layout
  25:     0x7991cd51b5ba - rustc_ty_utils[4b7a7000bd020946]::layout::layout_of_uncached
  26:     0x7991cd50b689 - rustc_ty_utils[4b7a7000bd020946]::layout::layout_of
  27:     0x7991cd50b5ea - rustc_query_impl[22a781136fdb8532]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[22a781136fdb8532]::query_impl::layout_of::dynamic_query::{closure#2}::{closure#0}, rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 16usize]>>
  28:     0x7991cd50a50f - rustc_query_system[58eb503a7502457a]::query::plumbing::try_execute_query::<rustc_query_impl[22a781136fdb8532]::DynamicConfig<rustc_query_system[58eb503a7502457a]::query::caches::DefaultCache<rustc_middle[c87150728fec5a49]::ty::PseudoCanonicalInput<rustc_middle[c87150728fec5a49]::ty::Ty>, rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 16usize]>>, false, true, false>, rustc_query_impl[22a781136fdb8532]::plumbing::QueryCtxt, false>
  29:     0x7991cd50a164 - rustc_query_impl[22a781136fdb8532]::query_impl::layout_of::get_query_non_incr::__rust_end_short_backtrace
  30:     0x7991cddd7cf6 - <rustc_mir_transform[8ab4230bc871fcc6]::known_panics_lint::KnownPanicsLint as rustc_mir_transform[8ab4230bc871fcc6]::pass_manager::MirLint>::run_lint
  31:     0x7991cce0b09c - rustc_mir_transform[8ab4230bc871fcc6]::run_analysis_to_runtime_passes
  32:     0x7991cd36f327 - rustc_mir_transform[8ab4230bc871fcc6]::mir_drops_elaborated_and_const_checked
  33:     0x7991cd36ece3 - rustc_query_impl[22a781136fdb8532]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[22a781136fdb8532]::query_impl::mir_drops_elaborated_and_const_checked::dynamic_query::{closure#2}::{closure#0}, rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 8usize]>>
  34:     0x7991ccfccd66 - rustc_query_system[58eb503a7502457a]::query::plumbing::try_execute_query::<rustc_query_impl[22a781136fdb8532]::DynamicConfig<rustc_data_structures[cdeb167cf83dddb5]::vec_cache::VecCache<rustc_span[1b2e5f36c4767dc6]::def_id::LocalDefId, rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 8usize]>, rustc_query_system[58eb503a7502457a]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[22a781136fdb8532]::plumbing::QueryCtxt, false>
  35:     0x7991ccfcc589 - rustc_query_impl[22a781136fdb8532]::query_impl::mir_drops_elaborated_and_const_checked::get_query_non_incr::__rust_end_short_backtrace
  36:     0x7991ccfc74dc - rustc_interface[2437496f2585cb44]::passes::run_required_analyses
  37:     0x7991cdb4f81e - rustc_interface[2437496f2585cb44]::passes::analysis
  38:     0x7991cdb4f7f3 - rustc_query_impl[22a781136fdb8532]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[22a781136fdb8532]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 0usize]>>
  39:     0x7991cdb526ce - rustc_query_system[58eb503a7502457a]::query::plumbing::try_execute_query::<rustc_query_impl[22a781136fdb8532]::DynamicConfig<rustc_query_system[58eb503a7502457a]::query::caches::SingleCache<rustc_middle[c87150728fec5a49]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[22a781136fdb8532]::plumbing::QueryCtxt, false>
  40:     0x7991cdb522b6 - rustc_query_impl[22a781136fdb8532]::query_impl::analysis::get_query_non_incr::__rust_end_short_backtrace
  41:     0x7991ce08edff - rustc_interface[2437496f2585cb44]::passes::create_and_enter_global_ctxt::<core[8a55f9a5e0f462be]::option::Option<rustc_interface[2437496f2585cb44]::queries::Linker>, rustc_driver_impl[12f4e41c2796a3e6]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  42:     0x7991ce08188c - rustc_interface[2437496f2585cb44]::interface::run_compiler::<(), rustc_driver_impl[12f4e41c2796a3e6]::run_compiler::{closure#0}>::{closure#1}
  43:     0x7991ce031448 - std[d5a5e8436f7bb80d]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[2437496f2585cb44]::util::run_in_thread_with_globals<rustc_interface[2437496f2585cb44]::util::run_in_thread_pool_with_globals<rustc_interface[2437496f2585cb44]::interface::run_compiler<(), rustc_driver_impl[12f4e41c2796a3e6]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  44:     0x7991ce031130 - <<std[d5a5e8436f7bb80d]::thread::Builder>::spawn_unchecked_<rustc_interface[2437496f2585cb44]::util::run_in_thread_with_globals<rustc_interface[2437496f2585cb44]::util::run_in_thread_pool_with_globals<rustc_interface[2437496f2585cb44]::interface::run_compiler<(), rustc_driver_impl[12f4e41c2796a3e6]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[8a55f9a5e0f462be]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  45:     0x7991ce02f77d - std::sys::pal::unix::thread::Thread::new::thread_start::h7d76966977b816fa
  46:     0x7991c7aa57eb - <unknown>
  47:     0x7991c7b2918c - <unknown>
  48:                0x0 - <unknown>

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: rustc 1.89.0-nightly (13a454090 2025-06-01) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z dump-mir-dir=dir

query stack during panic:
#0 [optimized_mir] optimizing MIR for `a::{closure#0}`
#1 [layout_of] computing layout of `{async fn body of a()}`
#2 [mir_drops_elaborated_and_const_checked] elaborating drops for `a`
#3 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to 6 previous errors; 1 warning emitted

Some errors have detailed explanations: E0046, E0229, E0601, E0658.
For more information about an error, try `rustc --explain E0046`.

@rustbot label +F-pin_ergonomics

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the ICE with the reduced a.rs program and the provided rustc --edition=2024 command. Read compiler/rustc_middle/src/ty/normalize_erasing_regions.rs around lines 165-177, then follow the MIR validation path shown in the backtrace. Done means this input no longer causes an internal compiler error or panic.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.