error: internal compiler error: compiler/rustc_middle/src/middle/region.rs:377:32: no enclosing scope for id 6

[DutchGhost]

Code

struct Bug<A = [(); (let a = (), 1).1]> {
    a: A   
}

fn main() {
    
}

Meta

rustc --version --verbose:

rustc 1.58.0 (02072b482 2022-01-11)
rustc 1.59.0-beta.1 (7c0b25092 2022-01-13)
rustc 1.60.0-nightly (22e491ac7 2022-01-13)

Error output

error: internal compiler error: compiler/rustc_middle/src/middle/region.rs:377:32: no enclosing scope for id 6

Backtrace

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1169:9
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
   2: <rustc_errors::HandlerInner>::bug
   3: <rustc_errors::Handler>::bug
   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::middle::region::ScopeTree>::var_scope
   8: <rustc_mir_build::build::Builder>::bind_and_guard_matched_candidate
   9: <rustc_mir_build::build::Builder>::bind_pattern
  10: <rustc_mir_build::build::Builder>::lower_let_expr
  11: <rustc_mir_build::build::Builder>::in_if_then_scope::<<rustc_mir_build::build::Builder>::expr_into_dest::{closure#1}>
  12: <rustc_mir_build::build::Builder>::expr_into_dest
  13: <rustc_mir_build::build::Builder>::as_temp_inner
  14: <rustc_mir_build::build::Builder>::as_operand
  15: <rustc_mir_build::build::Builder>::as_operand
  16: <alloc::vec::Vec<rustc_middle::mir::Operand> as alloc::vec::spec_from_iter::SpecFromIter<rustc_middle::mir::Operand, core::iter::adapters::map::Map<core::iter::adapters::copied::Copied<core::slice::iter::Iter<rustc_middle::thir::ExprId>>, <rustc_mir_build::build::Builder>::as_rvalue::{closure#2}>>>::from_iter
  17: <rustc_mir_build::build::Builder>::as_rvalue
  18: <rustc_mir_build::build::Builder>::expr_into_dest
  19: <rustc_mir_build::build::Builder>::as_temp_inner
  20: <rustc_mir_build::build::Builder>::expr_as_place
  21: <rustc_mir_build::build::Builder>::expr_as_place
  22: <rustc_mir_build::build::Builder>::expr_as_place
  23: <rustc_mir_build::build::Builder>::expr_into_dest
  24: <rustc_mir_build::build::Builder>::in_scope::<<rustc_mir_build::build::Builder>::expr_into_dest::{closure#0}::{closure#0}, ()>
  25: <rustc_mir_build::build::Builder>::expr_into_dest
  26: <rustc_mir_build::build::Builder>::in_scope::<<rustc_mir_build::build::Builder>::expr_into_dest::{closure#0}::{closure#0}, ()>
  27: <rustc_mir_build::build::Builder>::expr_into_dest
  28: rustc_mir_build::build::construct_const
  29: <rustc_infer::infer::InferCtxtBuilder>::enter::<rustc_middle::mir::Body, rustc_mir_build::build::mir_build::{closure#1}>
  30: rustc_mir_build::build::mir_built
  31: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::WithOptConstParam<rustc_span::def_id::LocalDefId>, &rustc_data_structures::steal::Steal<rustc_middle::mir::Body>>>
  32: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_built
  33: rustc_mir_transform::check_unsafety::unsafety_check_result
  34: <rustc_mir_transform::check_unsafety::provide::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::LocalDefId)>>::call_once
  35: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, &rustc_middle::mir::query::UnsafetyCheckResult>>
  36: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::unsafety_check_result
  37: rustc_mir_transform::mir_const
  38: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::WithOptConstParam<rustc_span::def_id::LocalDefId>, &rustc_data_structures::steal::Steal<rustc_middle::mir::Body>>>
  39: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::mir_const
  40: rustc_mir_transform::mir_const_qualif
  41: <rustc_mir_transform::provide::{closure#0} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, rustc_span::def_id::DefId)>>::call_once
  42: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::DefId, rustc_middle::mir::query::ConstQualifs>>
  43: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::mir_const_qualif, rustc_query_impl::plumbing::QueryCtxt>
  44: rustc_const_eval::const_eval::eval_queries::eval_to_allocation_raw_provider
  45: rustc_query_system::query::plumbing::get_query::<rustc_query_impl::queries::eval_to_allocation_raw, rustc_query_impl::plumbing::QueryCtxt>
  46: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::eval_to_allocation_raw
  47: rustc_const_eval::const_eval::eval_queries::eval_to_const_value_raw_provider
  48: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::ParamEnvAnd<rustc_middle::mir::interpret::GlobalId>, core::result::Result<rustc_middle::mir::interpret::value::ConstValue, rustc_middle::mir::interpret::error::ErrorHandled>>>
  49: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::eval_to_const_value_raw
  50: rustc_const_eval::const_eval::eval_queries::eval_to_const_value_raw_provider
  51: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_middle::ty::ParamEnvAnd<rustc_middle::mir::interpret::GlobalId>, core::result::Result<rustc_middle::mir::interpret::value::ConstValue, rustc_middle::mir::interpret::error::ErrorHandled>>>
  52: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::eval_to_const_value_raw
  53: <rustc_middle::ty::context::TyCtxt>::const_eval_global_id
  54: <rustc_middle::ty::context::TyCtxt>::const_eval_resolve
  55: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_const
  56: <&rustc_middle::ty::TyS as rustc_middle::ty::fold::TypeFoldable>::super_fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  57: <rustc_trait_selection::traits::project::AssocTypeNormalizer as rustc_middle::ty::fold::TypeFolder>::fold_ty
  58: <&rustc_middle::ty::list::List<rustc_middle::ty::subst::GenericArg> as rustc_middle::ty::fold::TypeFoldable>::fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  59: <rustc_middle::ty::PredicateKind as rustc_middle::ty::fold::TypeFoldable>::fold_with::<rustc_trait_selection::traits::project::AssocTypeNormalizer>
  60: <rustc_trait_selection::traits::project::AssocTypeNormalizer>::fold::<rustc_middle::ty::Predicate>
  61: rustc_trait_selection::traits::project::normalize::<rustc_middle::ty::Predicate>
  62: <rustc_infer::infer::InferCtxt as rustc_trait_selection::infer::InferCtxtExt>::partially_normalize_associated_types_in::<rustc_middle::ty::Predicate>
  63: rustc_typeck::check::wfcheck::check_where_clauses
  64: <rustc_infer::infer::InferCtxtBuilder>::enter::<(), <rustc_typeck::check::inherited::InheritedBuilder>::enter<<rustc_typeck::check::wfcheck::CheckWfFcxBuilder>::with_fcx<rustc_typeck::check::wfcheck::check_type_defn<rustc_typeck::check::wfcheck::check_item_well_formed::{closure#2}>::{closure#0}>::{closure#0}, ()>::{closure#0}>
  65: rustc_typeck::check::wfcheck::check_item_well_formed
  66: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<rustc_span::def_id::LocalDefId, ()>>
  67: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::check_item_well_formed
  68: <core::panic::unwind_safe::AssertUnwindSafe<rustc_data_structures::sync::par_for_each_in<&alloc::vec::Vec<core::option::Option<rustc_hir::hir::OwnerInfo>>, <rustc_middle::hir::map::Map>::par_visit_all_item_likes<rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor>::{closure#0}>::{closure#0}::{closure#0}> as core::ops::function::FnOnce<()>>::call_once
  69: rustc_data_structures::sync::par_for_each_in::<&alloc::vec::Vec<core::option::Option<rustc_hir::hir::OwnerInfo>>, <rustc_middle::hir::map::Map>::par_visit_all_item_likes<rustc_typeck::check::wfcheck::CheckTypeWellFormedVisitor>::{closure#0}>
  70: <rustc_session::session::Session>::track_errors::<rustc_typeck::check_crate::{closure#5}, ()>
  71: rustc_typeck::check_crate
  72: rustc_interface::passes::analysis
  73: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::plumbing::QueryCtxt, rustc_query_system::query::caches::DefaultCache<(), core::result::Result<(), rustc_errors::ErrorReported>>>
  74: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::analysis
  75: <rustc_interface::passes::QueryContext>::enter::<rustc_driver::run_compiler::{closure#1}::{closure#2}::{closure#3}, core::result::Result<(), rustc_errors::ErrorReported>>
  76: <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::ErrorReported>>
  77: rustc_span::with_source_map::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_interface::interface::create_compiler_and_run<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#1}>
  78: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::setup_callbacks_and_run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>::{closure#0}::{closure#0}, core::result::Result<(), rustc_errors::ErrorReported>>
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 1.58.0 (02072b482 2022-01-11) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
#0 [mir_built] building MIR for `Bug::{constant#0}`
#1 [unsafety_check_result] unsafety-checking `Bug::{constant#0}`
#2 [mir_const] processing MIR for `Bug::{constant#0}`
#3 [mir_const_qualif] const checking `Bug::{constant#0}`
#4 [eval_to_allocation_raw] const-evaluating + checking `Bug::{constant#0}`
#5 [eval_to_const_value_raw] simplifying constant for the type system `Bug::{constant#0}`
#6 [eval_to_const_value_raw] simplifying constant for the type system `Bug::{constant#0}`
#7 [check_item_well_formed] checking that `Bug` is well-formed
#8 [analysis] running analysis passes on this crate
end of query stack
For more information about this error, try `rustc --explain E0658`.
error: could not compile `playground` due to 2 previous er

[compiler-errors]

I was just looking at the parsing code for const generic exprs..

@rustbot claim

[compiler-errors]

actually, so this isn't related to incorrectly parsing let, since we're parsing let in expr position to allow if-let chains.. -- this is due to const eval lowering to MIR and the fact that const generic parameters have no enclosing scope. Adding { } around the generic args works, but I don't know where exactly to hack in a scope for these params.

@rustbot release-assignment
@rustbot label A-const-eval A-mir

[matthiaskrgr]

Maybe fixing this also fixes rust-lang/rust-clippy#8245 🙂

[ouz-a]

This gives an error without ICE in 1.55 https://godbolt.org/z/fP1xMx8f3

[jyn514]

Adding { } around the generic args works, but I don't know where exactly to hack in a scope for these params.

It was unclear to me - I think @compiler-errors meant that changing (let a = (), 1).1 to {(let a = (), 1).1} gives a compile error instead of an ICE. So the proper fix here is probably to add delay_span_bug somewhere instead of panicking.

[ouz-a]

Adding { } around the generic args works, but I don't know where exactly to hack in a scope for these params.

It was unclear to me - I think @compiler-errors meant that changing (let a = (), 1).1 to {(let a = (), 1).1} gives a compile error instead of an ICE. So the proper fix here is probably to add delay_span_bug somewhere instead of panicking.

Then this should be easy.
@rustbot claim