[ICE]: next solver: ` error performing operation: fully_perform` / `OpaqueTypeStorage`
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C-bug
F-type_alias_impl_trait
I-ICE
needs-triage
T-compiler
WG-trait-system-refactor
- Dominant language
- Rust
- Stars
- 119k
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Description
code:
//@compile-flags: -Znext-solver=globally
#![feature(type_alias_impl_trait)]
fn id2<'a, 'b>(s: (&'a str, &'b str)) -> (&'a str, &'b str) {
s
}
type Opaque<'a> = impl Sized + 'a;
#[define_opaque(Opaque)]
fn test() -> impl for<'a, 'b> Fn((&'a str, &'b str)) -> (Opaque<'a>, Opaque<'b>) {
id2
}
fn main() {}
Version information
rustc 1.99.0-nightly (be8e82435 2026-07-11)
binary: rustc
commit-hash: be8e82435eb04fbe75ed5286b52735366e160bed
commit-date: 2026-07-11
host: x86_64-unknown-linux-gnu
release: 1.99.0-nightly
LLVM version: 22.1.8
Command:
/home/matthias/.rustup/toolchains/master/bin/rustc -Zcrate-attr=feature(min_generic_const_args) -Znext-solver=globally
Program output
warning: function `id2` is never used
--> a.rs:2:4
|
2 | fn id2<'a, 'b>(s: (&'a str, &'b str)) -> (&'a str, &'b str) {
| ^^^
|
= note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
warning: type alias `Opaque` is never used
--> a.rs:5:6
|
5 | type Opaque<'a> = impl Sized + 'a;
| ^^^^^^
warning: function `test` is never used
--> a.rs:7:4
|
7 | fn test() -> impl for<'a, 'b> Fn((&'a str, &'b str)) -> (Opaque<'a>, Opaque<'b>) {
| ^^^^
warning: 3 warnings emitted
note: no errors encountered even though delayed bugs were created
note: those delayed bugs will now be shown as internal compiler errors
error: internal compiler error: error performing operation: query type op
--> a.rs:7:1
|
7 | fn test() -> impl for<'a, 'b> Fn((&'a str, &'b str)) -> (Opaque<'a>, Opaque<'b>) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: delayed at /rustc-dev/be8e82435eb04fbe75ed5286b52735366e160bed/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs:126:26
0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
4: <rustc_borrowck::type_check::free_region_relations::UniversalRegionRelationsBuilder>::add_implied_bounds
5: rustc_borrowck::type_check::type_check
6: <rustc_borrowck::root_cx::BorrowCheckRootCtxt>::do_mir_borrowck
7: rustc_borrowck::mir_borrowck
8: rustc_query_impl::query_impl::mir_borrowck::invoke_provider_fn::__rust_begin_short_backtrace
9: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
10: rustc_query_impl::query_impl::mir_borrowck::execute_query_non_incr::__rust_end_short_backtrace
11: <rustc_hir_analysis::collect::type_of::opaque::TaitConstraintLocator>::check
12: rustc_hir_analysis::collect::type_of::opaque::find_opaque_ty_constraints_for_tait
13: rustc_hir_analysis::collect::type_of::type_of_opaque.cold
14: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefIdCache<rustc_middle::query::erase::ErasedData<[u8; 8]>>, false>
15: rustc_query_impl::query_impl::type_of_opaque::execute_query_non_incr::__rust_end_short_backtrace
16: rustc_hir_analysis::collect::type_of::type_of
17: rustc_query_impl::query_impl::type_of::invoke_provider_fn::__rust_begin_short_backtrace
18: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefIdCache<rustc_middle::query::erase::ErasedData<[u8; 8]>>, false>
19: rustc_query_impl::query_impl::type_of::execute_query_non_incr::__rust_end_short_backtrace
20: rustc_hir_analysis::check::check::check_opaque
21: rustc_hir_analysis::check::check::check_item_type
22: rustc_hir_analysis::check::wfcheck::check_well_formed
23: rustc_query_impl::query_impl::check_well_formed::invoke_provider_fn::__rust_begin_short_backtrace
24: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 1]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
25: rustc_query_impl::query_impl::check_well_formed::execute_query_non_incr::__rust_end_short_backtrace
26: rustc_hir_analysis::check::wfcheck::check_type_wf
27: rustc_query_impl::query_impl::check_type_wf::invoke_provider_fn::__rust_begin_short_backtrace
28: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 1]>>, false>
29: rustc_query_impl::query_impl::check_type_wf::execute_query_non_incr::__rust_end_short_backtrace
30: rustc_hir_analysis::check_crate
31: rustc_interface::passes::analysis
32: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
33: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
34: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
35: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
36: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
37: <std::sys::thread::unix::Thread>::new::thread_start
38: <unknown>
39: <unknown>
--> a.rs:7:1
|
7 | fn test() -> impl for<'a, 'b> Fn((&'a str, &'b str)) -> (Opaque<'a>, Opaque<'b>) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: internal compiler error: error performing operation: query type op
--> a.rs:7:1
|
7 | fn test() -> impl for<'a, 'b> Fn((&'a str, &'b str)) -> (Opaque<'a>, Opaque<'b>) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: delayed at /rustc-dev/be8e82435eb04fbe75ed5286b52735366e160bed/compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs:126:26
0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
2: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
4: <rustc_borrowck::BorrowckInferCtxt>::fully_perform::<rustc_middle::traits::query::type_op::DeeplyNormalize<rustc_middle::ty::Ty>>
5: rustc_borrowck::type_check::type_check
6: <rustc_borrowck::root_cx::BorrowCheckRootCtxt>::do_mir_borrowck
7: rustc_borrowck::mir_borrowck
8: rustc_query_impl::query_impl::mir_borrowck::invoke_provider_fn::__rust_begin_short_backtrace
9: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 8]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
10: rustc_query_impl::query_impl::mir_borrowck::execute_query_non_incr::__rust_end_short_backtrace
11: <rustc_hir_analysis::collect::type_of::opaque::TaitConstraintLocator>::check
12: rustc_hir_analysis::collect::type_of::opaque::find_opaque_ty_constraints_for_tait
13: rustc_hir_analysis::collect::type_of::type_of_opaque.cold
14: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefIdCache<rustc_middle::query::erase::ErasedData<[u8; 8]>>, false>
15: rustc_query_impl::query_impl::type_of_opaque::execute_query_non_incr::__rust_end_short_backtrace
16: rustc_hir_analysis::collect::type_of::type_of
17: rustc_query_impl::query_impl::type_of::invoke_provider_fn::__rust_begin_short_backtrace
18: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::DefIdCache<rustc_middle::query::erase::ErasedData<[u8; 8]>>, false>
19: rustc_query_impl::query_impl::type_of::execute_query_non_incr::__rust_end_short_backtrace
20: rustc_hir_analysis::check::check::check_opaque
21: rustc_hir_analysis::check::check::check_item_type
22: rustc_hir_analysis::check::wfcheck::check_well_formed
23: rustc_query_impl::query_impl::check_well_formed::invoke_provider_fn::__rust_begin_short_backtrace
24: rustc_query_impl::execution::try_execute_query::<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::ErasedData<[u8; 1]>, rustc_middle::dep_graph::graph::DepNodeIndex>, false>
25: rustc_query_impl::query_impl::check_well_formed::execute_query_non_incr::__rust_end_short_backtrace
26: rustc_hir_analysis::check::wfcheck::check_type_wf
27: rustc_query_impl::query_impl::check_type_wf::invoke_provider_fn::__rust_begin_short_backtrace
28: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 1]>>, false>
29: rustc_query_impl::query_impl::check_type_wf::execute_query_non_incr::__rust_end_short_backtrace
30: rustc_hir_analysis::check_crate
31: rustc_interface::passes::analysis
32: rustc_query_impl::execution::try_execute_query::<rustc_middle::query::caches::SingleCache<rustc_middle::query::erase::ErasedData<[u8; 0]>>, false>
33: rustc_query_impl::query_impl::analysis::execute_query_non_incr::__rust_end_short_backtrace
34: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
35: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
36: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
37: <std::sys::thread::unix::Thread>::new::thread_start
38: <unknown>
39: <unknown>
--> a.rs:7:1
|
7 | fn test() -> impl for<'a, 'b> Fn((&'a str, &'b str)) -> (Opaque<'a>, Opaque<'b>) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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 `/tmp/nextsolv/rustc-ice-2026-07-12T07_23_35-3812194.txt` to your bug report
note: rustc 1.99.0-nightly (be8e82435 2026-07-11) running on x86_64-unknown-linux-gnu
note: compiler flags: -Z next-solver=globally
query stack during panic:
end of query stack
@rustbot label +F-type_alias_impl_trait +WG-trait-system-refactor
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the ICE with the supplied a.rs and -Znext-solver=globally command. Start at compiler/rustc_trait_selection/src/traits/query/type_op/custom.rs:126, then follow the borrow-checking type_check and fully_perform frames in the report. Done means this opaque-type example no longer produces an internal compiler error and has regression coverage.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Active
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100