ICE when equating TAIT and RPIT in canonical queries #108498

aliemjay · 2023-02-26T16:42:17Z

Code

https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=ec86c1b56e1fe08951cf0dbb67ea7d7b

#![feature(type_alias_impl_trait)]

type Opaque = impl Sized;

fn get_rpit() -> impl Clone {}

fn query(_: impl FnOnce() -> Opaque) {}

fn test() -> Opaque {
    query(get_rpit);
    get_rpit()
}

While trying to prove the predicate <get_rpit as FnOnce>::Output == Opaque, we end up equating get_rpit::opaque#0 == Opaque::opaque#0. Because inside canonical queries we know nothing about the defining scope (DefiningAnchor::Bubble), we register the hidden type as get_rpit::opaque := Opaque::opaque instead of Opaque::opaque := get_rpit::opaque.

Cc @oli-obk.

Error output

Backtrace

warning: type alias `Opaque` is never used
 --> src/lib.rs:3:6
  |
3 | type Opaque = impl Sized;
  |      ^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: function `get_rpit` is never used
 --> src/lib.rs:5:4
  |
5 | fn get_rpit() -> impl Clone {}
  |    ^^^^^^^^

warning: function `query` is never used
 --> src/lib.rs:7:4
  |
7 | fn query(_: impl FnOnce() -> Opaque) {}
  |    ^^^^^

warning: function `test` is never used
 --> src/lib.rs:9:4
  |
9 | fn test() -> Opaque {
  |    ^^^^

error: internal compiler error: no errors encountered even though `delay_span_bug` issued

error: internal compiler error: VecMap([(OpaqueTypeKey { def_id: DefId(0:8 ~ playground[4e8e]::get_rpit::{opaque#0}), substs: [] }, OpaqueTypeDecl { hidden_type: OpaqueHiddenType { span: no-location (#0), ty: Opaque }, origin: FnReturn(DefId(0:4 ~ playground[4e8e]::get_rpit)) })])
  |
  = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
             1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &alloc::string::String>
             2: core::ptr::drop_in_place::<rustc_infer::infer::InferCtxt>
             3: <rustc_infer::infer::InferCtxtBuilder as rustc_trait_selection::infer::InferCtxtBuilderExt>::enter_canonical_trait_query::<rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::ProvePredicate>, (), rustc_traits::type_op::type_op_prove_predicate::{closure#0}>
             4: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_op_prove_predicate, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
             5: <rustc_middle::ty::ParamEnvAnd<rustc_middle::traits::query::type_op::ProvePredicate> as rustc_trait_selection::traits::query::type_op::TypeOp>::fully_perform
             6: <rustc_borrowck::type_check::TypeChecker>::normalize_and_prove_instantiated_predicates
             7: <rustc_borrowck::type_check::TypeVerifier as rustc_middle::mir::visit::Visitor>::visit_constant
             8: <rustc_borrowck::type_check::TypeVerifier as rustc_middle::mir::visit::Visitor>::visit_body
             9: rustc_borrowck::type_check::type_check
            10: rustc_borrowck::nll::compute_regions
            11: rustc_borrowck::do_mir_borrowck
            12: rustc_borrowck::mir_borrowck
            13: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
            14: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
            15: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>::check
            16: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_nested_item
            17: rustc_hir::intravisit::walk_mod::<rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>
            18: rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait
            19: rustc_hir_analysis::collect::type_of::type_of
            20: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
            21: rustc_hir_analysis::check::check::check_mod_item_types
            22: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
            23: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
            24: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
            25: rustc_hir_analysis::check_crate
            26: rustc_interface::passes::analysis
            27: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
            28: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
            29: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
            30: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorGuaranteed>>
            31: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
            32: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
            33: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            34: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/34e6673a0473e90ef01a18eb575392c9e3859747/library/alloc/src/boxed.rs:1988:9
            35: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/34e6673a0473e90ef01a18eb575392c9e3859747/library/alloc/src/boxed.rs:1988:9
            36: std::sys::unix::thread::Thread::new::thread_start
                       at /rustc/34e6673a0473e90ef01a18eb575392c9e3859747/library/std/src/sys/unix/thread.rs:108:17
            37: start_thread
            38: clone
          

error: internal compiler error: broken MIR in DefId(0:6 ~ playground[4e8e]::test) (NoSolution): could not prove Binder(ProjectionPredicate(AliasTy { substs: [fn() -> impl std::clone::Clone {get_rpit}, ()], def_id: DefId(2:2923 ~ core[df15]::ops::function::FnOnce::Output) }, Term::Ty(Opaque)), [])
  |
  = note: delayed at    0: <rustc_errors::HandlerInner>::emit_diagnostic
             1: <rustc_errors::Handler>::delay_span_bug::<rustc_span::span_encoding::Span, &str>
             2: <rustc_borrowck::type_check::TypeChecker>::normalize_and_prove_instantiated_predicates
             3: <rustc_borrowck::type_check::TypeVerifier as rustc_middle::mir::visit::Visitor>::visit_constant
             4: <rustc_borrowck::type_check::TypeVerifier as rustc_middle::mir::visit::Visitor>::visit_body
             5: rustc_borrowck::type_check::type_check
             6: rustc_borrowck::nll::compute_regions
             7: rustc_borrowck::do_mir_borrowck
             8: rustc_borrowck::mir_borrowck
             9: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::mir_borrowck, rustc_query_impl::plumbing::QueryCtxt>
            10: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_borrowck
            11: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>::check
            12: <rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator as rustc_hir::intravisit::Visitor>::visit_nested_item
            13: rustc_hir::intravisit::walk_mod::<rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait::ConstraintLocator>
            14: rustc_hir_analysis::collect::type_of::find_opaque_ty_constraints_for_tait
            15: rustc_hir_analysis::collect::type_of::type_of
            16: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::type_of, rustc_query_impl::plumbing::QueryCtxt, rustc_middle::dep_graph::dep_node::DepKind>
            17: rustc_hir_analysis::check::check::check_mod_item_types
            18: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
            19: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_mod_item_types
            20: <rustc_middle::hir::map::Map>::for_each_module::<rustc_hir_analysis::check_crate::{closure#6}::{closure#0}>
            21: rustc_hir_analysis::check_crate
            22: rustc_interface::passes::analysis
            23: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
            24: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
            25: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}::{closure#4}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
            26: <rustc_interface::interface::Compiler>::enter::<rustc_driver_impl::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorGuaranteed>>
            27: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
            28: std::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
            29: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            30: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/34e6673a0473e90ef01a18eb575392c9e3859747/library/alloc/src/boxed.rs:1988:9
            31: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
                       at /rustc/34e6673a0473e90ef01a18eb575392c9e3859747/library/alloc/src/boxed.rs:1988:9
            32: std::sys::unix::thread::Thread::new::thread_start
                       at /rustc/34e6673a0473e90ef01a18eb575392c9e3859747/library/std/src/sys/unix/thread.rs:108:17
            33: start_thread
            34: clone
          

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: rustc 1.69.0-nightly (34e6673a0 2023-02-25) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib -C embed-bitcode=no -C codegen-units=1 -C debuginfo=2

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
end of query stack
warning: `playground` (lib) generated 4 warnings
error: could not compile `playground`; 4 warnings emitted

@rustbot label F-type_alias_impl_trait T-types

The text was updated successfully, but these errors were encountered:

compiler-errors · 2023-02-26T21:42:44Z

This would require some more design and stuff -- but I wonder if, when we relate an opaque with another opaque in a DefiningAnchor::Bubble scope, we should emit some other sort of opaque type constraint, like OpaqueEq(LHS, RHS), that isn't just LHS := RHS. Then when we instantiate it in some other infcx, we'll choose whether LHS := RHS or RHS := LHS depending on what the defining anchor of that one is.

oli-obk · 2023-02-28T08:24:21Z

yea, that was always the plan, but it seemed too niche to put the effort in for now

- rust-lang/rust#106238 - rust-lang/rust#107409 - rust-lang/rust#108339 - rust-lang/rust#108498 - rust-lang/rust#108683 - rust-lang/rust#108814 - rust-lang/rust#108832 - rust-lang/rust#109020

- rust-lang/rust#106238 - rust-lang/rust#107409 - rust-lang/rust#108399 - rust-lang/rust#108498 - rust-lang/rust#108683 - rust-lang/rust#108814 - rust-lang/rust#108832 - rust-lang/rust#109020

…ompiler-errors Bubble up opaque <eq> opaque operations instead of picking an order In case we are in `Bubble` mode (meaning every opaque type that is defined in the current crate is treated as if it were in its defining scope), we don't try to register an opaque type as the hidden type of another opaque type, but instead bubble up an obligation to equate them at the query caller site. Usually that means we have a `DefiningAnchor::Bind` and thus can reliably figure out whether an opaque type is in its defining scope. Where we can't, we'll error out, so the default is sound. With this change we start using `AliasTyEq` predicates in the old solver, too. fixes rust-lang/rust#108498 But also regresses `tests/ui/impl-trait/anon_scope_creep.rs`. Our use of `Bubble` for `check_opaque_type_well_formed` is going to keep biting us. r? `@lcnr` `@compiler-errors`

aliemjay · 2023-10-08T09:28:14Z

Reopened because the fix was incomplete. See #116530

Pass list of defineable opaque types into canonical queries based on rust-lang#121796 This eliminates `DefiningAnchor::Bubble` for good and brings the old solver closer to the new one wrt cycles and nested obligations. At that point the difference between `DefiningAnchor::Bind([])` and `DefiningAnchor::Error` was academic. We only used the difference for some sanity checks, which actually had to be worked around in places, so I just removed `DefiningAnchor` entirely and just stored the list of opaques that may be defined. fixes rust-lang#108498 * [ ] run crater

Pass list of defineable opaque types into canonical queries This eliminates `DefiningAnchor::Bubble` for good and brings the old solver closer to the new one wrt cycles and nested obligations. At that point the difference between `DefiningAnchor::Bind([])` and `DefiningAnchor::Error` was academic. We only used the difference for some sanity checks, which actually had to be worked around in places, so I just removed `DefiningAnchor` entirely and just stored the list of opaques that may be defined. fixes rust-lang#108498 * [ ] run crater

…ompiler-errors Bubble up opaque <eq> opaque operations instead of picking an order In case we are in `Bubble` mode (meaning every opaque type that is defined in the current crate is treated as if it were in its defining scope), we don't try to register an opaque type as the hidden type of another opaque type, but instead bubble up an obligation to equate them at the query caller site. Usually that means we have a `DefiningAnchor::Bind` and thus can reliably figure out whether an opaque type is in its defining scope. Where we can't, we'll error out, so the default is sound. With this change we start using `AliasTyEq` predicates in the old solver, too. fixes rust-lang/rust#108498 But also regresses `tests/ui/impl-trait/anon_scope_creep.rs`. Our use of `Bubble` for `check_opaque_type_well_formed` is going to keep biting us. r? `@lcnr` `@compiler-errors`

aliemjay added C-bug Category: This is a bug. I-ICE Issue: The compiler panicked, giving an Internal Compilation Error (ICE) ❄️ T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Feb 26, 2023

rustbot added F-type_alias_impl_trait `#[feature(type_alias_impl_trait)]` T-types Relevant to the types team, which will review and decide on the PR/issue. labels Feb 26, 2023

aliemjay mentioned this issue Feb 26, 2023

ICE: assertion failed: self.scc_universes[scc] == ty::UniverseIndex::ROOT #108399

Closed

oli-obk self-assigned this Feb 28, 2023

oli-obk added this to type alias impl trait stabilization Feb 28, 2023

oli-obk moved this to Todo in type alias impl trait stabilization Feb 28, 2023

ritikmishra mentioned this issue Mar 12, 2023

Add some ICEs rust-lang/glacier#1525

Merged

rust-lang-glacier-bot added the glacier ICE tracked in rust-lang/glacier. label Mar 12, 2023

oli-obk added the fixed-by-next-solver Fixed by the next-generation trait solver, `-Znext-solver`. label Aug 7, 2023

oli-obk moved this from Todo to In Progress in type alias impl trait stabilization Aug 7, 2023

oli-obk mentioned this issue Aug 7, 2023

Bubble up opaque <eq> opaque operations instead of picking an order #114586

Merged

bors closed this as completed in e2b3676 Sep 11, 2023

github-project-automation bot moved this from In Progress to Done in type alias impl trait stabilization Sep 11, 2023

github-actions bot mentioned this issue Sep 12, 2023

ices/108498.rs: fixed with no errors rust-lang/glacier#1662

Merged

aliemjay reopened this Oct 8, 2023

matthiaskrgr mentioned this issue Oct 13, 2023

ICE: no errors encountered even though delay_span_bug issued (regression on 2023-10-12) #116684

Closed

aliemjay moved this from Done to Todo in type alias impl trait stabilization Oct 17, 2023

oli-obk mentioned this issue Mar 6, 2024

Pass list of defineable opaque types into canonical queries #122077

Merged

1 task

traviscross mentioned this issue Mar 19, 2024

Stabilize associated type position impl Trait (ATPIT) #120700

Open

3 tasks

bors closed this as completed in b234e44 Apr 9, 2024

github-project-automation bot moved this from Todo to Done in type alias impl trait stabilization Apr 9, 2024

matthiaskrgr mentioned this issue Apr 10, 2024

ICE: two delayed bugs: {OpaqueTypeKey { def_id: ...} and error performing ParamEnvAnd {...} #123707

Closed

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ICE when equating TAIT and RPIT in canonical queries #108498

ICE when equating TAIT and RPIT in canonical queries #108498

aliemjay commented Feb 26, 2023 •

edited

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compiler-errors commented Feb 26, 2023

oli-obk commented Feb 28, 2023

aliemjay commented Oct 8, 2023

ICE when equating TAIT and RPIT in canonical queries #108498

ICE when equating TAIT and RPIT in canonical queries #108498

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compiler-errors commented Feb 26, 2023

oli-obk commented Feb 28, 2023

aliemjay commented Oct 8, 2023

aliemjay commented Feb 26, 2023 •

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