GAT crash #98702

497e0bdf29873 · 2022-06-30T07:46:58Z

The compiler crashes with an internal error on the following MWE of a GAT workaround attempt to current const generics limitations, i.e., not being able to just do {N*N} (or rather pow(2, N) in my real code). There is no crash if T is fixed to some type, i.e, GATs are not needed, however, the idea would be to limit “trait bound bloat” by only having to repeat NodeLookup : NodeT<N> throughout the code without T and its trait bounds, etc..

Code

#![feature(generic_associated_types)]

struct Node<T, const N : usize, const P : usize> {
    data : [[T; N]; P]
}

trait NodeT<const N : usize> {
    type Node<T>;
}

struct NodeLookup;

macro_rules! impl_lookup {
    ($($n:literal)*) => { $(
        impl NodeT<$n> for NodeLookup {
            type Node<T> = Node<T, $n, {$n*$n}>;
        }
    )* }
}

impl_lookup!(1 2 3 4);

fn main() {
}

Error output

error: internal compiler error: /rustc/ddcbba036aee08f0709f98a92a342a278eae5c05/compiler/rustc_middle/src/ty/fold.rs:756:29: unexpected bound ty in binder: BoundTy { var: 0, kind: Param("T") }

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/ddcbba036aee08f0709f98a92a342a278eae5c05/compiler/rustc_errors/src/lib.rs:1391:9
stack backtrace:
   0:        0x10111ff18 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h094534642b0a9537
   1:        0x10116cab4 - core::fmt::write::he79b8cc7db6af844
   2:        0x101112f7c - std::io::Write::write_fmt::h9824dce6dc163d2c
   3:        0x101122b5c - std::panicking::default_hook::{{closure}}::h3cd2810b91c69805
   4:        0x1011228c4 - std::panicking::default_hook::hddba5976d502416b
   5:        0x1085cb5f4 - rustc_driver[f51bca0c71cdd034]::DEFAULT_HOOK::{closure#0}::{closure#0}
   6:        0x10112312c - std::panicking::rust_panic_with_hook::h94731f9d6cc315f3
   7:        0x10c0aa758 - std[ec5bd7e3f33f3027]::panicking::begin_panic::<rustc_errors[77f389aec993a0ef]::ExplicitBug>::{closure#0}
   8:        0x10c0a86cc - std[ec5bd7e3f33f3027]::sys_common::backtrace::__rust_end_short_backtrace::<std[ec5bd7e3f33f3027]::panicking::begin_panic<rustc_errors[77f389aec993a0ef]::ExplicitBug>::{closure#0}, !>
   9:        0x10c509f04 - std[ec5bd7e3f33f3027]::panicking::begin_panic::<rustc_errors[77f389aec993a0ef]::ExplicitBug>
  10:        0x10c00bc50 - std[ec5bd7e3f33f3027]::panic::panic_any::<rustc_errors[77f389aec993a0ef]::ExplicitBug>
  11:        0x10c0064d4 - <rustc_errors[77f389aec993a0ef]::HandlerInner>::bug::<&alloc[cde6e00f4e7b7126]::string::String>
  12:        0x10c0060a0 - <rustc_errors[77f389aec993a0ef]::Handler>::bug::<&alloc[cde6e00f4e7b7126]::string::String>
  13:        0x10c0be8b0 - rustc_middle[9331575e900b72f8]::ty::context::tls::with_opt::<rustc_middle[9331575e900b72f8]::util::bug::opt_span_bug_fmt<rustc_span[b8e5c2445f520dcd]::span_encoding::Span>::{closure#0}, ()>
  14:        0x10c0c0408 - rustc_middle[9331575e900b72f8]::util::bug::opt_span_bug_fmt::<rustc_span[b8e5c2445f520dcd]::span_encoding::Span>
  15:        0x10c50c650 - rustc_middle[9331575e900b72f8]::util::bug::bug_fmt
  16:        0x10be5ce1c - <rustc_middle[9331575e900b72f8]::ty::context::TyCtxt>::replace_late_bound_regions_uncached::<rustc_middle[9331575e900b72f8]::ty::PredicateKind, <rustc_middle[9331575e900b72f8]::ty::context::TyCtxt>::replace_late_bound_regions<rustc_middle[9331575e900b72f8]::ty::PredicateKind, <rustc_middle[9331575e900b72f8]::ty::context::TyCtxt>::anonymize_late_bound_regions<rustc_middle[9331575e900b72f8]::ty::PredicateKind>::{closure#0}>::{closure#0}>::{closure#0}
  17:        0x10c08da1c - <rustc_middle[9331575e900b72f8]::ty::fold::BoundVarReplacer as rustc_middle[9331575e900b72f8]::ty::fold::TypeFolder>::fold_ty
  18:        0x10be40f88 - <&rustc_middle[9331575e900b72f8]::ty::list::List<rustc_middle[9331575e900b72f8]::ty::subst::GenericArg> as rustc_middle[9331575e900b72f8]::ty::fold::TypeFoldable>::try_fold_with::<rustc_middle[9331575e900b72f8]::ty::fold::BoundVarReplacer>
  19:        0x10be7082c - <rustc_middle[9331575e900b72f8]::ty::PredicateKind as rustc_middle[9331575e900b72f8]::ty::fold::TypeFoldable>::fold_with::<rustc_middle[9331575e900b72f8]::ty::fold::BoundVarReplacer>
  20:        0x10be582cc - <rustc_middle[9331575e900b72f8]::ty::context::TyCtxt>::anonymize_late_bound_regions::<rustc_middle[9331575e900b72f8]::ty::PredicateKind>
  21:        0x10bdfe5f0 - <rustc_middle[9331575e900b72f8]::ty::erase_regions::RegionEraserVisitor as rustc_middle[9331575e900b72f8]::ty::fold::FallibleTypeFolder>::try_fold_binder::<rustc_middle[9331575e900b72f8]::ty::PredicateKind>
  22:        0x10be3effc - <&rustc_middle[9331575e900b72f8]::ty::list::List<rustc_middle[9331575e900b72f8]::ty::Predicate> as rustc_middle[9331575e900b72f8]::ty::fold::TypeFoldable>::try_fold_with::<rustc_middle[9331575e900b72f8]::ty::erase_regions::RegionEraserVisitor>
  23:        0x10bdbf7f4 - <rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer as rustc_middle[9331575e900b72f8]::ty::fold::TypeFolder>::fold_const
  24:        0x10be44734 - <&rustc_middle[9331575e900b72f8]::ty::list::List<rustc_middle[9331575e900b72f8]::ty::subst::GenericArg> as rustc_middle[9331575e900b72f8]::ty::fold::TypeFoldable>::try_fold_with::<rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer>
  25:        0x10be71208 - <rustc_middle[9331575e900b72f8]::ty::Ty as rustc_middle[9331575e900b72f8]::ty::fold::TypeSuperFoldable>::super_fold_with::<rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer>
  26:        0x10bdbb148 - <rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer as rustc_middle[9331575e900b72f8]::ty::fold::TypeFolder>::fold_ty
  27:        0x10bdc04dc - rustc_trait_selection[b4f82a16548071ea]::traits::project::opt_normalize_projection_type
  28:        0x10bdbbd54 - rustc_trait_selection[b4f82a16548071ea]::traits::project::normalize_projection_type
  29:        0x10bdbaf18 - <rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer as rustc_middle[9331575e900b72f8]::ty::fold::TypeFolder>::fold_ty
  30:        0x10ab6613c - <&rustc_middle[9331575e900b72f8]::ty::list::List<rustc_middle[9331575e900b72f8]::ty::subst::GenericArg> as rustc_middle[9331575e900b72f8]::ty::fold::TypeFoldable>::try_fold_with::<rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer>
  31:        0x10abe2fe8 - <rustc_middle[9331575e900b72f8]::ty::PredicateKind as rustc_middle[9331575e900b72f8]::ty::fold::TypeFoldable>::try_fold_with::<rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer>
  32:        0x10abf0724 - <rustc_middle[9331575e900b72f8]::ty::Predicate as rustc_middle[9331575e900b72f8]::ty::fold::TypeSuperFoldable>::super_fold_with::<rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer>
  33:        0x10ac5a1f4 - <rustc_trait_selection[b4f82a16548071ea]::traits::project::AssocTypeNormalizer>::fold::<rustc_middle[9331575e900b72f8]::ty::Predicate>
  34:        0x10ac5e55c - rustc_trait_selection[b4f82a16548071ea]::traits::project::normalize::<rustc_middle[9331575e900b72f8]::ty::Predicate>
  35:        0x10abb0a68 - <rustc_infer[45d40a8feb40e3fa]::infer::InferCtxtBuilder>::enter::<core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>, rustc_typeck[67235f765db4edde]::check::compare_method::check_type_bounds::{closure#2}>
  36:        0x10ac2b1f4 - rustc_typeck[67235f765db4edde]::check::compare_method::check_type_bounds
  37:        0x10ac20290 - rustc_typeck[67235f765db4edde]::check::compare_method::compare_ty_impl
  38:        0x10aac793c - rustc_typeck[67235f765db4edde]::check::check::check_item_type
  39:        0x10aacaca0 - rustc_typeck[67235f765db4edde]::check::check::check_mod_item_types
  40:        0x10b386704 - rustc_query_system[e247dafbc3a4ff98]::query::plumbing::try_execute_query::<rustc_query_impl[90b84e005b379a12]::plumbing::QueryCtxt, rustc_query_system[e247dafbc3a4ff98]::query::caches::DefaultCache<rustc_span[b8e5c2445f520dcd]::def_id::LocalDefId, ()>>
  41:        0x10b42c6a0 - rustc_query_system[e247dafbc3a4ff98]::query::plumbing::get_query::<rustc_query_impl[90b84e005b379a12]::queries::check_mod_item_types, rustc_query_impl[90b84e005b379a12]::plumbing::QueryCtxt>
  42:        0x10abdb8c8 - <rustc_session[24b5e5485ce21942]::session::Session>::time::<(), rustc_typeck[67235f765db4edde]::check_crate::{closure#6}>
  43:        0x10ab8dfc4 - rustc_typeck[67235f765db4edde]::check_crate
  44:        0x108656888 - rustc_interface[5cb818030c646550]::passes::analysis
  45:        0x10b3b96f8 - rustc_query_system[e247dafbc3a4ff98]::query::plumbing::try_execute_query::<rustc_query_impl[90b84e005b379a12]::plumbing::QueryCtxt, rustc_query_system[e247dafbc3a4ff98]::query::caches::DefaultCache<(), core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>>
  46:        0x10b457934 - rustc_query_system[e247dafbc3a4ff98]::query::plumbing::get_query::<rustc_query_impl[90b84e005b379a12]::queries::analysis, rustc_query_impl[90b84e005b379a12]::plumbing::QueryCtxt>
  47:        0x10858d7e8 - <rustc_interface[5cb818030c646550]::passes::QueryContext>::enter::<rustc_driver[f51bca0c71cdd034]::run_compiler::{closure#1}::{closure#2}::{closure#3}, core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>
  48:        0x1085717a4 - <rustc_interface[5cb818030c646550]::interface::Compiler>::enter::<rustc_driver[f51bca0c71cdd034]::run_compiler::{closure#1}::{closure#2}, core[c82fdd3b01836480]::result::Result<core[c82fdd3b01836480]::option::Option<rustc_interface[5cb818030c646550]::queries::Linker>, rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>
  49:        0x1085bd41c - rustc_span[b8e5c2445f520dcd]::with_source_map::<core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>, rustc_interface[5cb818030c646550]::interface::create_compiler_and_run<core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>, rustc_driver[f51bca0c71cdd034]::run_compiler::{closure#1}>::{closure#1}>
  50:        0x108571f9c - <scoped_tls[c0f860eaab270d6e]::ScopedKey<rustc_span[b8e5c2445f520dcd]::SessionGlobals>>::set::<rustc_interface[5cb818030c646550]::interface::run_compiler<core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>, rustc_driver[f51bca0c71cdd034]::run_compiler::{closure#1}>::{closure#0}, core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>
  51:        0x10858fdd8 - std[ec5bd7e3f33f3027]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[5cb818030c646550]::util::run_in_thread_pool_with_globals<rustc_interface[5cb818030c646550]::interface::run_compiler<core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>, rustc_driver[f51bca0c71cdd034]::run_compiler::{closure#1}>::{closure#0}, core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>::{closure#0}, core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>
  52:        0x1085904a4 - <<std[ec5bd7e3f33f3027]::thread::Builder>::spawn_unchecked_<rustc_interface[5cb818030c646550]::util::run_in_thread_pool_with_globals<rustc_interface[5cb818030c646550]::interface::run_compiler<core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>, rustc_driver[f51bca0c71cdd034]::run_compiler::{closure#1}>::{closure#0}, core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>::{closure#0}, core[c82fdd3b01836480]::result::Result<(), rustc_errors[77f389aec993a0ef]::ErrorGuaranteed>>::{closure#1} as core[c82fdd3b01836480]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  53:        0x10112b58c - std::sys::unix::thread::Thread::new::thread_start::h46c89a4ac1d16d95
  54:        0x1a242226c - __pthread_deallocate

note: 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: rustc 1.64.0-nightly (ddcbba036 2022-06-29) running on aarch64-apple-darwin

query stack during panic:
#0 [check_mod_item_types] checking item types in top-level module
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

Backtrace

$ RUST_BACKTRACE=1 rustc crash.rs 
error: internal compiler error: /rustc/ddcbba036aee08f0709f98a92a342a278eae5c05/compiler/rustc_middle/src/ty/fold.rs:756:29: unexpected bound ty in binder: BoundTy { var: 0, kind: Param("T") }

thread 'rustc' panicked at 'Box<dyn Any>', /rustc/ddcbba036aee08f0709f98a92a342a278eae5c05/compiler/rustc_errors/src/lib.rs:1391:9
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
   2: <rustc_errors::HandlerInner>::bug::<&alloc::string::String>
   3: <rustc_errors::Handler>::bug::<&alloc::string::String>
   4: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, ()>
   5: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>
   6: rustc_middle::util::bug::bug_fmt
   7: <rustc_middle::ty::context::TyCtxt>::replace_late_bound_regions_uncached::<rustc_middle::ty::PredicateKind, <rustc_middle::ty::context::TyCtxt>::replace_late_bound_regions<rustc_middle::ty::PredicateKind, <rustc_middle::ty::context::TyCtxt>::anonymize_late_bound_regions<rustc_middle::ty::PredicateKind>::{closure#0}>::{closure#0}>::{closure#0}
   8: <rustc_middle::ty::fold::BoundVarReplacer as rustc_middle::ty::fold::TypeFolder>::fold_ty
   9: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::try_fold_with::<rustc_middle::ty::fold::BoundVarReplacer>
  10: <rustc_middle::ty::PredicateKind as rustc_middle::ty::fold::TypeFoldable>::fold_with::<rustc_middle::ty::fold::BoundVarReplacer>
  11: <rustc_middle::ty::context::TyCtxt>::anonymize_late_bound_regions::<rustc_middle::ty::PredicateKind>
  12: <rustc_middle::ty::erase_regions::RegionEraserVisitor as rustc_middle::ty::fold::FallibleTypeFolder>::try_fold_binder::<rustc_middle::ty::PredicateKind>
  13: <&rustc_middle::ty::list::List<rustc_middle::ty::Predicate> as rustc_middle::ty::fold::TypeFoldable>::try_fold_with::<rustc_middle::ty::erase_regions::RegionEraserVisitor>
  14: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_const
  15: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::try_fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  16: <rustc_middle::ty::Ty as rustc_middle::ty::fold::TypeSuperFoldable>::super_fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  17: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_ty
  18: rustc_trait_selection::traits::project::opt_normalize_projection_type
  19: rustc_trait_selection::traits::project::normalize_projection_type
  20: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_ty
  21: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::try_fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  22: <rustc_middle::ty::PredicateKind as rustc_middle::ty::fold::TypeFoldable>::try_fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  23: <rustc_middle::ty::Predicate as rustc_middle::ty::fold::TypeSuperFoldable>::super_fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  24: <rustc_trait_selection::traits::project::AssocTypeNormalizer>::fold::<rustc_middle::ty::Predicate>
  25: rustc_trait_selection::traits::project::normalize::<rustc_middle::ty::Predicate>
  26: <rustc_infer::infer::InferCtxtBuilder>::enter::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_typeck::check::compare_method::check_type_bounds::{closure#2}>
  27: rustc_typeck::check::compare_method::check_type_bounds
  28: rustc_typeck::check::compare_method::compare_ty_impl
  29: rustc_typeck::check::check::check_item_type
  30: rustc_typeck::check::check::check_mod_item_types
  31: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, ()>>
  32: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::check_mod_item_types, rustc_query_impl::plumbing::QueryCtxt>
  33: <rustc_session::session::Session>::time::<(), rustc_typeck::check_crate::{closure#6}>
  34: rustc_typeck::check_crate
  35: rustc_interface::passes::analysis
  36: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), core::result::Result<(), rustc_errors::ErrorGuaranteed>>>
  37: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::analysis, rustc_query_impl::plumbing::QueryCtxt>
  38: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
  39: <rustc_interface::interface::Compiler>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}, core::result::Result<core::option::Option<rustc_interface::queries::Linker>, rustc_errors::ErrorGuaranteed>>
  40: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
  41: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorGuaranteed>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorGuaranteed>>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

note: 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: rustc 1.64.0-nightly (ddcbba036 2022-06-29) running on aarch64-apple-darwin

query stack during panic:
#0 [check_mod_item_types] checking item types in top-level module
#1 [analysis] running analysis passes on this crate
end of query stack
error: aborting due to previous error

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

Rageking8 · 2022-06-30T08:30:47Z

@rustbot label +requires-nightly

rust-lang/rust#98702

voidc · 2022-07-01T10:27:59Z

Minimized:

#![feature(generic_associated_types)]

trait Foo {
    type Assoc<T>;
}

impl Foo for () {
    type Assoc<T> = [T; 2*2];
}

Playground

jackh726 · 2022-07-02T03:54:10Z

Caused by this change: https://github.com/rust-lang/rust/pull/97648/files#diff-79cd877dd2dfb44945f291684ef33b7d715853b694fcaa153e0d849712e9439cR770

jackh726 · 2022-07-02T03:54:31Z

@lcnr ^

jackh726 · 2022-07-02T04:16:58Z

The problem is we end up with for<T> <() as Foo>::Assoc<T> = [T; 2*2] in the param_env.

When folding consts, we eval them (here:

rust/compiler/rustc_trait_selection/src/traits/project.rs

Line 618 in 9a6fa4f

constant.eval(self.selcx.tcx(), self.param_env)

)

try_eval_inner calls erase_regions here:

rust/compiler/rustc_middle/src/ty/consts/kind.rs

Line 187 in 9a6fa4f

.erase_regions(param_env)

Part of erasing regions is anonymizing late-bound regions (here:

rust/compiler/rustc_middle/src/ty/erase_regions.rs

Line 51 in 9a6fa4f

let u = self.tcx.anonymize_late_bound_regions(t);

)

In anonymize_late_bound_regions (

rust/compiler/rustc_middle/src/ty/fold.rs

Line 920 in 9a6fa4f

    
               pub fn anonymize_late_bound_regions<T>(self, sig: Binder<'tcx, T>) -> Binder<'tcx, T>

), we delegate to replace_late_bound_regions, which returns T instead of Binder<T>, which "makes sense" if we assume that there are no bound tys or consts.

It's a bit of a tug of war game between wanting to catch unexpected bound tys/consts, and "delegating" bound variable binding higher up. Probably the right thing to do for now would be to revert the bound variable handling to just not panic if we encounter bound tys or consts.

lcnr · 2022-07-04T12:08:07Z

Part of erasing regions is anonymizing late-bound regions here

I guess alternatively, just anonymize all bound variables at this point? don't think regions should be special, going to try that

497e0bdf29873 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 Jun 30, 2022

rustbot added the requires-nightly This issue requires a nightly compiler in some way. label Jun 30, 2022

matthiaskrgr added a commit to matthiaskrgr/glacier that referenced this issue Jun 30, 2022

add 1 ice

03f241b

rust-lang/rust#98702

matthiaskrgr mentioned this issue Jun 30, 2022

add 1 ice rust-lang/glacier#1328

Merged

rust-lang-glacier-bot added the glacier ICE tracked in rust-lang/glacier. label Jun 30, 2022

BoxyUwU added the F-generic_associated_types `#![feature(generic_associated_types)]` a.k.a. GATs label Jul 1, 2022

jackh726 mentioned this issue Jul 7, 2022

GAT + Generic Const Exprs causes "unexpected bound ty in binder: BoundTy" #99029

Closed

lcnr mentioned this issue Jul 25, 2022

anonymize all bound vars, not just regions #99730

Merged

bors closed this as completed in 211637d Jul 30, 2022

github-actions bot mentioned this issue Jul 31, 2022

ices/98702.rs: fixed with no errors rust-lang/glacier#1366

Merged

fmease added the A-GATs Area: Generic associated types (GATs) label Nov 2, 2024

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

GAT crash #98702

GAT crash #98702

497e0bdf29873 commented Jun 30, 2022

Rageking8 commented Jun 30, 2022

voidc commented Jul 1, 2022

jackh726 commented Jul 2, 2022

jackh726 commented Jul 2, 2022

jackh726 commented Jul 2, 2022

lcnr commented Jul 4, 2022

GAT crash #98702

GAT crash #98702

Comments

497e0bdf29873 commented Jun 30, 2022

Code

Meta

Error output

Rageking8 commented Jun 30, 2022

voidc commented Jul 1, 2022

jackh726 commented Jul 2, 2022

jackh726 commented Jul 2, 2022

jackh726 commented Jul 2, 2022

lcnr commented Jul 4, 2022