Failed to normalize struct with generic const expression parameter as associated type

[zyansheep]

Code

// subcrate, lib.rs
#![feature(generic_const_exprs)]
#![feature(adt_const_params)]

#[derive(PartialEq, Eq)]
pub struct Const {}
impl Const {
	pub const fn func(self) -> usize { 1 }
}

pub struct Foo<const C: Const>
where
	[(); C.func()]: Sized
{}

pub trait Bar {
	type Associated;
	fn associated() -> Self::Associated;
}

impl<const C: Const> Bar for Foo<C>
where
	[(); C.func()]: Sized
{
	type Associated = [(); C.func()];
	fn associated() -> Self::Associated {
		[(); C.func()]
	}
}
// main.rs
use subcrate::*;

fn main() {
	<Foo::<{Const{}}> as Bar>::associated();
}

Meta

rustc --version --verbose:

rustc 1.60.0-nightly (bd3cb5256 2022-01-16)
binary: rustc
commit-hash: bd3cb52565faab2755ff1bdb54d88bc91f47b4b9
commit-date: 2022-01-16
host: x86_64-unknown-linux-gnu
release: 1.60.0-nightly
LLVM version: 13.0.0

Error output

error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:179:90: Failed to normalize <subcrate::Foo<C> as subcrate::Bar>::Associated, maybe try to call `try_normalize_erasing_regions` instead

thread 'rustc' panicked at 'Box<dyn Any>', compiler/rustc_errors/src/lib.rs:1169:9
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 1.60.0-nightly (bd3cb5256 2022-01-16) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
#0 [fn_abi_of_instance] computing call ABI of `<subcrate::Foo<subcrate::Const {  }> as subcrate::Bar>::associated`
end of query stack
error: could not compile `rust_cargo_rkyv_bug`

Backtrace

error: internal compiler error: compiler/rustc_middle/src/ty/normalize_erasing_regions.rs:179:90: Failed to normalize <subcrate::Foo<C> as subcrate::Bar>::Associated, maybe try to call `try_normalize_erasing_regions` instead

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::ty::util::fold_list::<rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder, &rustc_middle::ty::TyS, <&rustc_middle::ty::list::List<&rustc_middle::ty::TyS> as rustc_middle::ty::fold::TypeFoldable>::try_super_fold_with<rustc_middle::ty::normalize_erasing_regions::NormalizeAfterErasingRegionsFolder>::{closure#0}>
   8: rustc_middle::ty::layout::fn_abi_of_instance
   9: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::dep_node::DepKind>>::with_task::<rustc_middle::ty::context::TyCtxt, rustc_middle::ty::ParamEnvAnd<(rustc_middle::ty::instance::Instance, &rustc_middle::ty::list::List<&rustc_middle::ty::TyS>)>, core::result::Result<&rustc_target::abi::call::FnAbi<&rustc_middle::ty::TyS>, rustc_middle::ty::layout::FnAbiError>>
  10: rustc_data_structures::stack::ensure_sufficient_stack::<(core::result::Result<&rustc_target::abi::call::FnAbi<&rustc_middle::ty::TyS>, rustc_middle::ty::layout::FnAbiError>, rustc_query_system::dep_graph::graph::DepNodeIndex), rustc_query_system::query::plumbing::execute_job<rustc_query_impl::plumbing::QueryCtxt, rustc_middle::ty::ParamEnvAnd<(rustc_middle::ty::instance::Instance, &rustc_middle::ty::list::List<&rustc_middle::ty::TyS>)>, core::result::Result<&rustc_target::abi::call::FnAbi<&rustc_middle::ty::TyS>, rustc_middle::ty::layout::FnAbiError>>::{closure#3}>
  11: 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::ty::instance::Instance, &rustc_middle::ty::list::List<&rustc_middle::ty::TyS>)>, core::result::Result<&rustc_target::abi::call::FnAbi<&rustc_middle::ty::TyS>, rustc_middle::ty::layout::FnAbiError>>>
  12: <rustc_query_impl::Queries as rustc_middle::ty::query::QueryEngine>::fn_abi_of_instance
  13: rustc_codegen_ssa::mir::codegen_mir::<rustc_codegen_llvm::builder::Builder>
  14: rustc_codegen_llvm::base::compile_codegen_unit::module_codegen
  15: rustc_codegen_llvm::base::compile_codegen_unit
  16: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_llvm::LlvmCodegenBackend>
  17: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate
  18: <rustc_session::session::Session>::time::<alloc::boxed::Box<dyn core::any::Any>, rustc_interface::passes::start_codegen::{closure#0}>
  19: <rustc_interface::queries::Queries>::ongoing_codegen
  20: <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>>
  21: 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}>
  22: rustc_interface::interface::create_compiler_and_run::<core::result::Result<(), rustc_errors::ErrorReported>, rustc_driver::run_compiler::{closure#1}>
  23: <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 1.60.0-nightly (bd3cb5256 2022-01-16) running on x86_64-unknown-linux-gnu

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

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

query stack during panic:
#0 [fn_abi_of_instance] computing call ABI of `<subcrate::Foo<subcrate::Const {  }> as subcrate::Bar>::associated`
end of query stack
error: could not compile `rust_cargo_rkyv_bug`

One weird thing is that it only works if the offending code is in a subcrate, not in the main crate.
Example code is here: https://github.com/zyansheep/rust_const_rkyv_bug

[zyansheep]

I have reran the test on nightly with the most recent compiler:

rustc 1.66.0-nightly (a6b7274a4 2022-10-10)
binary: rustc
commit-hash: a6b7274a462829f8ef08a1ddcdcec7ac80dbf3e1
commit-date: 2022-10-10
host: x86_64-unknown-linux-gnu
release: 1.66.0-nightly
LLVM version: 15.0.2

and it seems to not error anymore.

Just in case it was a fluke, I went back to where I originally discovered the bug and everything seems to work just fine :)