ICE: Generic traits of associated types of generic structs

[djkoloski]

Source: rkyv/rkyv#221

Code

lib.rs

pub trait Associate {
    type Associated;
}

pub struct Wrap<'a> {
    pub field: &'a i32,
}

pub trait Create<T> {
    fn create() -> Self;
}

pub fn oh_no<'a, T>()
where
    Wrap<'a>: Associate,
    <Wrap<'a> as Associate>::Associated: Create<T>,
{
    <Wrap<'a> as Associate>::Associated::create();
}

It is worth noting that this code should not compile.

Meta

This bug occurs in both beta and nightly.

rustc --version --verbose:

rustc 1.56.1 (59eed8a2a 2021-11-01)
binary: rustc
commit-hash: 59eed8a2aac0230a8b53e89d4e99d55912ba6b35
commit-date: 2021-11-01
host: x86_64-pc-windows-msvc
release: 1.56.1
LLVM version: 13.0.0

Error output

error: internal compiler error: compiler\rustc_traits\src\normalize_erasing_regions.rs:54:32: could not fully normalize `<Wrap as Associate>::Associated`

thread 'rustc' panicked at 'Box<dyn Any>', compiler\rustc_errors\src\lib.rs:1147:9
note: run with `RUST_BACKTRACE=1` environment variable to display a 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 1.56.1 (59eed8a2a 2021-11-01) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

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

query stack during panic:
#0 [normalize_generic_arg_after_erasing_regions] normalizing `<Wrap as Associate>::Associated`
#1 [mir_drops_elaborated_and_const_checked] elaborating drops for `oh_no`
end of query stack
error: could not compile `erase_repro`

Backtrace

error: internal compiler error: compiler\rustc_traits\src\normalize_erasing_regions.rs:54:32: could not fully normalize `<Wrap as Associate>::Associated`

thread 'rustc' panicked at 'Box<dyn Any>', compiler\rustc_errors\src\lib.rs:1147:9
stack backtrace:
   0:     0x7ffea42c7a9e - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h90fc78c6027cfe27
   1:     0x7ffea42f268a - core::fmt::write::h8afcb1031f89d60b
   2:     0x7ffea42bae08 - <std::io::IoSliceMut as core::fmt::Debug>::fmt::hb4b34c43836aedaf
   3:     0x7ffea42cb586 - std::panicking::take_hook::h8b2fe3f8f4cf4b43
   4:     0x7ffea42cb074 - std::panicking::take_hook::h8b2fe3f8f4cf4b43
   5:     0x7ffea486a525 - <serde_json::value::WriterFormatter as std::io::Write>::flush::hc1d196eaca04d7a8
   6:     0x7ffea42cbe99 - std::panicking::rust_panic_with_hook::h844a8dc19bbe524e
   7:     0x7ffea8e82430 - rustc_errors::diagnostic_builder::DiagnosticBuilder::code::h1645263d95f3b09a
   8:     0x7ffea8e823e9 - rustc_errors::diagnostic_builder::DiagnosticBuilder::code::h1645263d95f3b09a
   9:     0x7ffea9157ad1 - rustc_query_system::query::job::report_cycle::h12a555504324913c
  10:     0x7ffea8eb3080 - <rustc_errors::json::Diagnostic::from_errors_diagnostic::BufWriter as std::io::Write>::flush::hf0501cbec5358cf0
  11:     0x7ffea8ebad75 - rustc_errors::HandlerInner::emit_diagnostic::h728ec3ea46d2ed21
  12:     0x7ffea8eb8822 - rustc_errors::Handler::bug::h011b35fa3752efe1
  13:     0x7ffea8ba1ad7 - rustc_middle::ty::structural_impls::<impl core::fmt::Debug for rustc_middle::ty::closure::UpvarBorrow>::fmt::ha3dccab8f654b6b0
  14:     0x7ffea8b9fd90 - rustc_middle::ty::consts::valtree::ValTree::zst::hb53ec78846c4e3d7
  15:     0x7ffea8b9fd33 - rustc_middle::ty::consts::valtree::ValTree::zst::hb53ec78846c4e3d7
  16:     0x7ffea8ba1a09 - rustc_middle::ty::structural_impls::<impl core::fmt::Debug for rustc_middle::ty::closure::UpvarBorrow>::fmt::ha3dccab8f654b6b0
  17:     0x7ffea914e197 - rustc_middle::util::bug::bug_fmt::hb871ea62c9ba791a
  18:     0x7ffea7abf034 - <&chalk_ir::GenericArg<rustc_middle::traits::chalk::RustInterner> as rustc_traits::chalk::lowering::LowerInto<rustc_middle::ty::subst::GenericArg>>::lower_into::hac3acef454f06bed
  19:     0x7ffea7b9e463 - <rustc_traits::chalk::db::RustIrDatabase as chalk_ir::UnificationDatabase<rustc_middle::traits::chalk::RustInterner>>::adt_variance::he39df3eff3cd9e56
  20:     0x7ffea7ff8d0f - <rustc_span::def_id::DefIndex as rustc_query_impl::profiling_support::SpecIntoSelfProfilingString>::spec_to_self_profile_string::hbb4b4890437407bc
  21:     0x7ffea7fa23e3 - <rustc_span::def_id::DefIndex as rustc_query_impl::profiling_support::SpecIntoSelfProfilingString>::spec_to_self_profile_string::hbb4b4890437407bc
  22:     0x7ffea80d6f9f - rustc_metadata::rmeta::decoder::__ty_decoder_impl::<impl rustc_serialize::serialize::Decoder for rustc_metadata::rmeta::decoder::DecodeContext>::error::h95b02aeeaf1dc4be   
  23:     0x7ffea7c80a96 - <fixedbitset::FixedBitSet as core::fmt::Debug>::fmt::hedf20157683d04ae
  24:     0x7ffea8051deb - <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::try_mark_green::h02f98d8f46101c14
  25:     0x7ffea8c6e181 - rustc_middle::ty::flags::FlagComputation::for_unevaluated_const::hf9370068502c458d
  26:     0x7ffea8c6e3f6 - <rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder as rustc_middle::ty::fold::TypeFolder>::fold_ty::h97ea4149e1d91295
  27:     0x7ffea78bddcb - <rustc_mir::transform::dest_prop::CandidateAssignment as core::fmt::Debug>::fmt::h90783a921d19b6b1
  28:     0x7ffea790e94c - rustc_mir::dataflow::drop_flag_effects::on_all_children_bits::is_terminal_path::h8bbacca9de22ebf2
  29:     0x7ffea763202d - <rustc_mir::transform::elaborate_drops::ElaborateDrops as rustc_mir::transform::MirPass>::run_pass::h2d10c480fb5efb89
  30:     0x7ffea75d1033 - rustc_mir::transform::run_passes::h183bcfaf18b69333
  31:     0x7ffea75da478 - rustc_mir::transform::run_passes::h183bcfaf18b69333
  32:     0x7ffea75d9b00 - rustc_mir::transform::run_passes::h183bcfaf18b69333
  33:     0x7ffea7ff8eaf - <rustc_span::def_id::DefIndex as rustc_query_impl::profiling_support::SpecIntoSelfProfilingString>::spec_to_self_profile_string::hbb4b4890437407bc
  34:     0x7ffea7fa5623 - <rustc_span::def_id::DefIndex as rustc_query_impl::profiling_support::SpecIntoSelfProfilingString>::spec_to_self_profile_string::hbb4b4890437407bc
  35:     0x7ffea80d801d - rustc_metadata::rmeta::decoder::__ty_decoder_impl::<impl rustc_serialize::serialize::Decoder for rustc_metadata::rmeta::decoder::DecodeContext>::error::h95b02aeeaf1dc4be   
  36:     0x7ffea7cd468a - <fixedbitset::FixedBitSet as core::fmt::Debug>::fmt::hedf20157683d04ae
  37:     0x7ffea8046d59 - <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::try_mark_green::h02f98d8f46101c14
  38:     0x7ffea75dafe9 - rustc_mir::transform::run_passes::h183bcfaf18b69333
  39:     0x7ffea7ff38ef - <rustc_span::def_id::DefIndex as rustc_query_impl::profiling_support::SpecIntoSelfProfilingString>::spec_to_self_profile_string::hbb4b4890437407bc
  40:     0x7ffea7f92511 - <rustc_span::def_id::DefIndex as rustc_query_impl::profiling_support::SpecIntoSelfProfilingString>::spec_to_self_profile_string::hbb4b4890437407bc
  41:     0x7ffea80d34de - rustc_metadata::rmeta::decoder::__ty_decoder_impl::<impl rustc_serialize::serialize::Decoder for rustc_metadata::rmeta::decoder::DecodeContext>::error::h95b02aeeaf1dc4be   
  42:     0x7ffea7da1403 - <fixedbitset::FixedBitSet as core::fmt::Debug>::fmt::hedf20157683d04ae
  43:     0x7ffea7cbaf39 - <fixedbitset::FixedBitSet as core::fmt::Debug>::fmt::hedf20157683d04ae
  44:     0x7ffea8047200 - <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::try_mark_green::h02f98d8f46101c14
  45:     0x7ffea8371ec9 - <rustc_metadata::rmeta::encoder::EncodeContext as rustc_middle::ty::codec::TyEncoder>::encode_alloc_id::h1def24179fdbee6d
  46:     0x7ffea838f396 - <rustc_metadata::rmeta::encoder::ImplVisitor as rustc_hir::itemlikevisit::ItemLikeVisitor>::visit_item::h69098d911b1ad348
  47:     0x7ffea83f1505 - <rustc_metadata::rmeta::decoder::DecodeContext as rustc_middle::ty::codec::TyDecoder>::decode_alloc_id::h7b90eba30f514af9
  48:     0x7ffea84cbcf2 - rustc_metadata::rmeta::decoder::cstore_impl::<impl rustc_middle::middle::cstore::CrateStore for rustc_metadata::creader::CStore>::encode_metadata::h7bc78bca2f8068cf        
  49:     0x7ffea8bebaa4 - rustc_middle::ty::context::TyCtxt::encode_metadata::h5ddfe09d2e3d95b9
  50:     0x7ffea49b3c8c - rustc_interface::queries::Queries::ongoing_codegen::h81f3e17d2f79ca80
  51:     0x7ffea48bf413 - regex_syntax::hir::Error::pattern::h26de5cae1e560f3c
  52:     0x7ffea48897b5 - rustc_driver::pretty::print_after_hir_lowering::h8daab7168b9a121b
  53:     0x7ffea48c14c7 - regex_syntax::hir::Error::pattern::h26de5cae1e560f3c
  54:     0x7ffea488dfc0 - <tracing_subscriber::util::TryInitError as core::fmt::Display>::fmt::h6e9774f2c0dd7eb3
  55:     0x7ffea488a248 - rustc_driver::pretty::print_after_hir_lowering::h8daab7168b9a121b
  56:     0x7ffea487e67d - <rustc_driver::Compilation as core::fmt::Debug>::fmt::ha388fa55e25fcec9
  57:     0x7ffea42da1cc - std::sys::windows::thread::Thread::new::h5ab92c811b2297f5
  58:     0x7fff0f967034 - BaseThreadInitThunk
  59:     0x7fff10822651 - RtlUserThreadStart

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 1.56.1 (59eed8a2a 2021-11-01) running on x86_64-pc-windows-msvc

note: compiler flags: -C embed-bitcode=no -C debuginfo=2 -C incremental --crate-type lib

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

query stack during panic:
#0 [normalize_generic_arg_after_erasing_regions] normalizing `<Wrap as Associate>::Associated`
#1 [mir_drops_elaborated_and_const_checked] elaborating drops for `oh_no`
#2 [optimized_mir] optimizing MIR for `oh_no`
end of query stack
error: could not compile `erase_repro`

[Alexendoo]

No longer ICEs since #91462