rust-lang / rust-lang/rust

ICE when implementing a generic trait + generic supertrait (and default values)

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C-bug F-adt_const_params F-generic_const_exprs I-ICE P-low S-bug-has-test T-compiler
Dominant language
Rust
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Description

Summary

The ICE occurs if

  • generic trait has a generic supertrait
  • trait and supertrait share the same generic
  • trait's and supertrait's generic defines a default value for the generic (can differ between trait and supertrait)
  • generic's default value is only defined in the trait definition, not in the implementation
  • "generic_const_expr" gate is enabled (even though it's functionality not used)

The ICE occurs as the trait is implemented for a type. The targeted type doesn't have to be the same as the generic one.

#![feature(adt_const_params)]
#![feature(generic_const_exprs)]

use core::marker::ConstParamTy;

// #[derive(ConstParamTy, PartialEq, Eq)]
// struct StructOrEnum;

#[derive(ConstParamTy, PartialEq, Eq)]
enum StructOrEnum {
    A,
}

trait TraitParent<const SMTH: StructOrEnum = { StructOrEnum::A }> {}

trait TraitChild<const SMTH: StructOrEnum = { StructOrEnum::A }>: TraitParent<SMTH> {}

impl TraitParent for StructOrEnum {}

// ICE occurs
impl TraitChild for StructOrEnum {}

// ICE does not occur
// impl TraitChild<{ StructOrEnum::A }> for StructOrEnum {}
Version
rustc 1.82.0-nightly (f167efad2 2024-08-24)
binary: rustc
commit-hash: f167efad2f51088d86180ee89177b3d7c9e7c2f5
commit-date: 2024-08-24
host: x86_64-unknown-linux-gnu
release: 1.82.0-nightly
LLVM version: 19.1.0
Error output
Backtrace 

stack backtrace:
 0: rust_begin_unwind
 1: core::panicking::panic_fmt
 2: <rustc_type_ir::binder::ArgFolder<rustc_middle::ty::context::TyCtxt>>::const_param_out_of_range
 3: <rustc_type_ir::binder::ArgFolder<rustc_middle::ty::context::TyCtxt> as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_const.llvm.11519418143500691559.cold
 4: <rustc_middle::ty::generics::GenericPredicates>::instantiate_into
 5: <rustc_trait_selection::traits::wf::WfPredicates>::nominal_obligations
 6: <rustc_trait_selection::traits::wf::WfPredicates as rustc_type_ir::visit::TypeVisitor<rustc_middle::ty::context::TyCtxt>>::visit_const
 7: <rustc_trait_selection::traits::fulfill::FulfillProcessor as rustc_data_structures::obligation_forest::ObligationProcessor>::process_obligation
 8: <rustc_data_structures::obligation_forest::ObligationForest<rustc_trait_selection::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection::traits::fulfill::FulfillProcessor>
 9: <rustc_trait_selection::traits::engine::ObligationCtxt<rustc_trait_selection::traits::FulfillmentError>>::assumed_wf_types_and_report_errors
10: rustc_hir_analysis::check::wfcheck::check_well_formed
    [... omitted 1 frame ...]
11: rustc_hir_analysis::check::wfcheck::check_mod_type_wf
    [... omitted 1 frame ...]
12: rustc_hir_analysis::check_crate
13: rustc_interface::passes::run_required_analyses
14: rustc_interface::passes::analysis
    [... omitted 1 frame ...]
15: rustc_interface::interface::run_compiler::<core::result::Result<(), rustc_span::ErrorGuaranteed>, rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}

ICE 

thread 'rustc' panicked at /rustc/f167efad2f51088d86180ee89177b3d7c9e7c2f5/compiler/rustc_type_ir/src/binder.rs:739:9:
const parameter `SMTH/#1` (SMTH/#1/1) out of range when instantiating args=[StructOrEnum]
stack backtrace:
 0:     0x7044d54c4ea5 - std::backtrace::Backtrace::create::h60f0872d50b7947d
 1:     0x7044d39d1ec5 - std::backtrace::Backtrace::force_capture::h5f5782d9f084b444
 2:     0x7044d2b602ae - std[6e15924ca43b8509]::panicking::update_hook::<alloc[74339d1d9b201e21]::boxed::Box<rustc_driver_impl[d6b1c5b97f2d776c]::install_ice_hook::{closure#0}>>::{closure#0}
 3:     0x7044d39e9d37 - std::panicking::rust_panic_with_hook::h48ec1454fab3e9d6
 4:     0x7044d39e99f7 - std::panicking::begin_panic_handler::{{closure}}::hdfdc79a140009172
 5:     0x7044d39e71f9 - std::sys::backtrace::__rust_end_short_backtrace::h5e9ef3624d34a08c
 6:     0x7044d39e96c4 - rust_begin_unwind
 7:     0x7044d0b9f263 - core::panicking::panic_fmt::h5c7dda2686e962d9
 8:     0x7044d30f2bb9 - <rustc_type_ir[a178b1c04a843a22]::binder::ArgFolder<rustc_middle[715031de33b6a9f]::ty::context::TyCtxt>>::const_param_out_of_range
 9:     0x7044d55da828 - <rustc_type_ir[a178b1c04a843a22]::binder::ArgFolder<rustc_middle[715031de33b6a9f]::ty::context::TyCtxt> as rustc_type_ir[a178b1c04a843a22]::fold::TypeFolder<rustc_middle[715031de33b6a9f]::ty::context::TyCtxt>>::fold_const.llvm.11519418143500691559.cold
10:     0x7044d423268c - <rustc_middle[715031de33b6a9f]::ty::generics::GenericPredicates>::instantiate_into
11:     0x7044d422f5a3 - <rustc_trait_selection[76948cd8c7a47ffa]::traits::wf::WfPredicates>::nominal_obligations
12:     0x7044d4c88362 - <rustc_trait_selection[76948cd8c7a47ffa]::traits::wf::WfPredicates as rustc_type_ir[a178b1c04a843a22]::visit::TypeVisitor<rustc_middle[715031de33b6a9f]::ty::context::TyCtxt>>::visit_const
13:     0x7044d08b4bdf - <rustc_trait_selection[76948cd8c7a47ffa]::traits::fulfill::FulfillProcessor as rustc_data_structures[34dac5edc44e011b]::obligation_forest::ObligationProcessor>::process_obligation
14:     0x7044d44178c1 - <rustc_data_structures[34dac5edc44e011b]::obligation_forest::ObligationForest<rustc_trait_selection[76948cd8c7a47ffa]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[76948cd8c7a47ffa]::traits::fulfill::FulfillProcessor>
15:     0x7044d440a8c3 - <rustc_trait_selection[76948cd8c7a47ffa]::traits::engine::ObligationCtxt<rustc_trait_selection[76948cd8c7a47ffa]::traits::FulfillmentError>>::assumed_wf_types_and_report_errors
16:     0x7044d17183ca - rustc_hir_analysis[2f099064b091af30]::check::wfcheck::check_well_formed
17:     0x7044d45a6d27 - rustc_query_impl[7a841671113bb270]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7a841671113bb270]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[715031de33b6a9f]::query::erase::Erased<[u8; 1usize]>>
18:     0x7044d45aa4ea - rustc_query_system[77a41dfa2d87d677]::query::plumbing::try_execute_query::<rustc_query_impl[7a841671113bb270]::DynamicConfig<rustc_query_system[77a41dfa2d87d677]::query::caches::VecCache<rustc_hir[9a201f138b4d1b5]::hir_id::OwnerId, rustc_middle[715031de33b6a9f]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[7a841671113bb270]::plumbing::QueryCtxt, true>
19:     0x7044d45a9ef8 - rustc_query_impl[7a841671113bb270]::query_impl::check_well_formed::get_query_incr::__rust_end_short_backtrace
20:     0x7044d45a7acb - rustc_hir_analysis[2f099064b091af30]::check::wfcheck::check_mod_type_wf
21:     0x7044d45a7909 - rustc_query_impl[7a841671113bb270]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7a841671113bb270]::query_impl::check_mod_type_wf::dynamic_query::{closure#2}::{closure#0}, rustc_middle[715031de33b6a9f]::query::erase::Erased<[u8; 1usize]>>
22:     0x7044d508fbcc - rustc_query_system[77a41dfa2d87d677]::query::plumbing::try_execute_query::<rustc_query_impl[7a841671113bb270]::DynamicConfig<rustc_query_system[77a41dfa2d87d677]::query::caches::DefaultCache<rustc_span[641b1e127128c80]::def_id::LocalModDefId, rustc_middle[715031de33b6a9f]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[7a841671113bb270]::plumbing::QueryCtxt, true>
23:     0x7044d509089b - rustc_query_impl[7a841671113bb270]::query_impl::check_mod_type_wf::get_query_incr::__rust_end_short_backtrace
24:     0x7044d473c34d - rustc_hir_analysis[2f099064b091af30]::check_crate
25:     0x7044d4739abf - rustc_interface[eb6eb7ed9ab023cb]::passes::run_required_analyses
26:     0x7044d4d59c9e - rustc_interface[eb6eb7ed9ab023cb]::passes::analysis
27:     0x7044d4d59c71 - rustc_query_impl[7a841671113bb270]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[7a841671113bb270]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[715031de33b6a9f]::query::erase::Erased<[u8; 1usize]>>
28:     0x7044d520d90d - rustc_query_system[77a41dfa2d87d677]::query::plumbing::try_execute_query::<rustc_query_impl[7a841671113bb270]::DynamicConfig<rustc_query_system[77a41dfa2d87d677]::query::caches::SingleCache<rustc_middle[715031de33b6a9f]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[7a841671113bb270]::plumbing::QueryCtxt, true>
29:     0x7044d520d5ba - rustc_query_impl[7a841671113bb270]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
30:     0x7044d4ff43aa - rustc_interface[eb6eb7ed9ab023cb]::interface::run_compiler::<core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>, rustc_driver_impl[d6b1c5b97f2d776c]::run_compiler::{closure#0}>::{closure#1}
31:     0x7044d506f390 - std[6e15924ca43b8509]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[eb6eb7ed9ab023cb]::util::run_in_thread_with_globals<rustc_interface[eb6eb7ed9ab023cb]::util::run_in_thread_pool_with_globals<rustc_interface[eb6eb7ed9ab023cb]::interface::run_compiler<core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>, rustc_driver_impl[d6b1c5b97f2d776c]::run_compiler::{closure#0}>::{closure#1}, core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>>::{closure#0}, core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>>
32:     0x7044d506f9fa - <<std[6e15924ca43b8509]::thread::Builder>::spawn_unchecked_<rustc_interface[eb6eb7ed9ab023cb]::util::run_in_thread_with_globals<rustc_interface[eb6eb7ed9ab023cb]::util::run_in_thread_pool_with_globals<rustc_interface[eb6eb7ed9ab023cb]::interface::run_compiler<core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>, rustc_driver_impl[d6b1c5b97f2d776c]::run_compiler::{closure#0}>::{closure#1}, core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>>::{closure#0}, core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[f2f627d3c87d2691]::result::Result<(), rustc_span[641b1e127128c80]::ErrorGuaranteed>>::{closure#1} as core[f2f627d3c87d2691]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
33:     0x7044d506fd6b - std::sys::pal::unix::thread::Thread::new::thread_start::h5ac727470998e7f2
34:     0x7044d680d39d - <unknown>
35:     0x7044d689249c - <unknown>
36:                0x0 - <unknown>


rustc version: 1.82.0-nightly (f167efad2 2024-08-24)
platform: x86_64-unknown-linux-gnu

query stack during panic:
#0 [check_well_formed] checking that `<impl at src/lib.rs:21:1: 21:33>` is well-formed
rust-lang/rust-clippy#1 [check_mod_type_wf] checking that types are well-formed in top-level module
rust-lang/rust-clippy#2 [analysis] running analysis passes on this crate
end of query stack

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Research direction

Reproduce the ICE with the Rust example and enabled adt_const_params and generic_const_exprs features. Start at compiler/rustc_type_ir/src/binder.rs:739 and the rustc_hir_analysis check/wfcheck path named in the backtrace. Done means the generic trait implementation no longer causes an internal compiler error for this case.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
compilers
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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