Compiler Error while trying to prototype a workaround for const methods in traits #116599
Description
Code
pub trait EvaluateConstMethods { type Trait: TraitWithConstMethods; /// **This block breaks** const DATA_3: Data3 = { <<<Self::Trait as TraitWithConstMethods>::Method2 as ConstFn<_, _>>::Body< <<Self::Trait as TraitWithConstMethods>::Method1 as ConstFn<_, _>>::Body<ContainsData1>, > as Contains<_>>::ITEM }; } pub trait TraitWithConstMethods { /// "const trait method" of signature `fn(Data1) -> Data2` type Method1: ConstFn<Data1, Data2>; /// "const trait method" of signature `fn(Data2) -> Data3` type Method2: ConstFn<Data2, Data3>; } /// A trait which tries to implement const methods in traits pub trait ConstFn<Arg, Ret> { type Body<T: Contains<Arg>>: Contains<Ret>; } /// A ZST which represents / "contains" a const value which can be pass to a [`ConstFn`] pub trait Contains<T> { const ITEM: T; } pub struct ContainsData1; impl Contains<Data1> for ContainsData1 { const ITEM: Data1 = Data1 {}; } // Arbitrary data pub struct Data1 {} pub struct Data2 {} pub struct Data3 {}Meta
rustc --version --verbose:
rustc 1.73.0 (cc66ad468 2023-10-03) binary: rustc commit-hash: cc66ad468955717ab92600c770da8c1601a4ff33 commit-date: 2023-10-03 host: x86_64-unknown-linux-gnu release: 1.73.0 LLVM version: 17.0.2 Also reproduced on the rust playground
Error output
error: internal compiler error: /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/compiler/rustc_infer/src/infer/nll_relate/mod.rs:483:21: unexpected inference var _ [...] query stack during panic: #0 [mir_borrowck] borrow-checking `EvaluateConstMethods::DATA_3` #1 [analysis] running analysis passes on this crate end of query stack Backtrace
error: internal compiler error: /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/compiler/rustc_infer/src/infer/nll_relate/mod.rs:483:21: unexpected inference var _ thread 'rustc' panicked at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/compiler/rustc_errors/src/lib.rs:1635:9: Box<dyn Any> stack backtrace: 0: 0x7f15ecee749c - std::backtrace_rs::backtrace::libunwind::trace::he43a6a3949163f8c at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5 1: 0x7f15ecee749c - std::backtrace_rs::backtrace::trace_unsynchronized::h50db52ca99f692e7 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5 2: 0x7f15ecee749c - std::sys_common::backtrace::_print_fmt::hd37d595f2ceb2d3c at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys_common/backtrace.rs:67:5 3: 0x7f15ecee749c - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h678bbcf9da6d7d75 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys_common/backtrace.rs:44:22 4: 0x7f15ecf4d3fc - core::fmt::rt::Argument::fmt::h3a159adc080a6fc9 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/fmt/rt.rs:138:9 5: 0x7f15ecf4d3fc - core::fmt::write::hb8eaf5a8e45a738e at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/fmt/mod.rs:1094:21 6: 0x7f15eceda12e - std::io::Write::write_fmt::h9663fe36b2ee08f9 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/io/mod.rs:1714:15 7: 0x7f15ecee7284 - std::sys_common::backtrace::_print::hcd4834796ee88ad2 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys_common/backtrace.rs:47:5 8: 0x7f15ecee7284 - std::sys_common::backtrace::print::h1360e9450e4f922a at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys_common/backtrace.rs:34:9 9: 0x7f15eceea193 - std::panicking::default_hook::{{closure}}::h2609fa95cd5ab1f4 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/panicking.rs:270:22 10: 0x7f15ecee9eac - std::panicking::default_hook::h6d75f5747cab6e8d at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/panicking.rs:290:9 11: 0x7f15ebd30a3e - <alloc[98253621d83cbf53]::boxed::Box<rustc_driver_impl[566d207f92c3d9d2]::install_ice_hook::{closure#0}> as core[d28c4e8d9c4eebaa]::ops::function::Fn<(&dyn for<'a, 'b> core[d28c4e8d9c4eebaa]::ops::function::Fn<(&'a core[d28c4e8d9c4eebaa]::panic::panic_info::PanicInfo<'b>,), Output = ()> + core[d28c4e8d9c4eebaa]::marker::Sync + core[d28c4e8d9c4eebaa]::marker::Send, &core[d28c4e8d9c4eebaa]::panic::panic_info::PanicInfo)>>::call 12: 0x7f15eceea9be - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h05249de742e1768e at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2021:9 13: 0x7f15eceea9be - std::panicking::rust_panic_with_hook::h57e78470c47c84de at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/panicking.rs:711:13 14: 0x7f15ec281521 - std[3759e478f3a6c4f2]::panicking::begin_panic::<rustc_errors[f3962fbeb8edb247]::ExplicitBug>::{closure#0} 15: 0x7f15ec27d206 - std[3759e478f3a6c4f2]::sys_common::backtrace::__rust_end_short_backtrace::<std[3759e478f3a6c4f2]::panicking::begin_panic<rustc_errors[f3962fbeb8edb247]::ExplicitBug>::{closure#0}, !> 16: 0x7f15ec2476c6 - std[3759e478f3a6c4f2]::panicking::begin_panic::<rustc_errors[f3962fbeb8edb247]::ExplicitBug> 17: 0x7f15ec254134 - <rustc_errors[f3962fbeb8edb247]::HandlerInner>::bug::<alloc[98253621d83cbf53]::string::String> 18: 0x7f15ec253fc6 - <rustc_errors[f3962fbeb8edb247]::Handler>::bug::<alloc[98253621d83cbf53]::string::String> 19: 0x7f15ec2fb5ac - rustc_middle[5935fdd60c99b3fe]::util::bug::opt_span_bug_fmt::<rustc_span[4c9f011e8b033119]::span_encoding::Span>::{closure#0} 20: 0x7f15ec2f9c5a - rustc_middle[5935fdd60c99b3fe]::ty::context::tls::with_opt::<rustc_middle[5935fdd60c99b3fe]::util::bug::opt_span_bug_fmt<rustc_span[4c9f011e8b033119]::span_encoding::Span>::{closure#0}, !>::{closure#0} 21: 0x7f15ec2f9c28 - rustc_middle[5935fdd60c99b3fe]::ty::context::tls::with_context_opt::<rustc_middle[5935fdd60c99b3fe]::ty::context::tls::with_opt<rustc_middle[5935fdd60c99b3fe]::util::bug::opt_span_bug_fmt<rustc_span[4c9f011e8b033119]::span_encoding::Span>::{closure#0}, !>::{closure#0}, !> 22: 0x7f15ea5fd1b0 - rustc_middle[5935fdd60c99b3fe]::util::bug::bug_fmt 23: 0x7f15eab04dd0 - <rustc_infer[2448fd35ed713fff]::infer::InferCtxt>::instantiate_nll_query_response_and_region_obligations::<()> 24: 0x7f15eaab5755 - <rustc_middle[5935fdd60c99b3fe]::ty::ParamEnvAnd<rustc_middle[5935fdd60c99b3fe]::traits::query::type_op::AscribeUserType> as rustc_trait_selection[48b7f7e13fbddf35]::traits::query::type_op::TypeOp>::fully_perform 25: 0x7f15eaab4f2a - <rustc_borrowck[29a4cdfbf3f92543]::type_check::TypeChecker>::ascribe_user_type 26: 0x7f15eaab1b16 - rustc_borrowck[29a4cdfbf3f92543]::type_check::type_check 27: 0x7f15eaa9ae2b - rustc_borrowck[29a4cdfbf3f92543]::nll::compute_regions 28: 0x7f15eaa82cff - rustc_borrowck[29a4cdfbf3f92543]::do_mir_borrowck 29: 0x7f15eaa81055 - rustc_borrowck[29a4cdfbf3f92543]::mir_borrowck 30: 0x7f15e9e53aae - rustc_query_impl[778daaabc67f3fff]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[778daaabc67f3fff]::query_impl::mir_borrowck::dynamic_query::{closure#2}::{closure#0}, rustc_middle[5935fdd60c99b3fe]::query::erase::Erased<[u8; 8usize]>> 31: 0x7f15e9e53a7e - <rustc_query_impl[778daaabc67f3fff]::query_impl::mir_borrowck::dynamic_query::{closure#2} as core[d28c4e8d9c4eebaa]::ops::function::FnOnce<(rustc_middle[5935fdd60c99b3fe]::ty::context::TyCtxt, rustc_span[4c9f011e8b033119]::def_id::LocalDefId)>>::call_once 32: 0x7f15ea3b71bf - rustc_query_system[e0e328d29a6e1c80]::query::plumbing::try_execute_query::<rustc_query_impl[778daaabc67f3fff]::DynamicConfig<rustc_query_system[e0e328d29a6e1c80]::query::caches::VecCache<rustc_span[4c9f011e8b033119]::def_id::LocalDefId, rustc_middle[5935fdd60c99b3fe]::query::erase::Erased<[u8; 8usize]>>, false, false, false>, rustc_query_impl[778daaabc67f3fff]::plumbing::QueryCtxt, true> 33: 0x7f15eb6a4dfe - rustc_query_impl[778daaabc67f3fff]::query_impl::mir_borrowck::get_query_incr::__rust_end_short_backtrace 34: 0x7f15eaeef031 - rustc_data_structures[29929b1a5d4d6700]::sync::par_for_each_in::<&[rustc_span[4c9f011e8b033119]::def_id::LocalDefId], <rustc_middle[5935fdd60c99b3fe]::hir::map::Map>::par_body_owners<rustc_interface[5bdd18de9f5858d8]::passes::analysis::{closure#1}::{closure#0}>::{closure#0}> 35: 0x7f15eaeeed4d - <rustc_session[f1e1083633086c54]::session::Session>::time::<(), rustc_interface[5bdd18de9f5858d8]::passes::analysis::{closure#1}> 36: 0x7f15eaeee4be - rustc_interface[5bdd18de9f5858d8]::passes::analysis 37: 0x7f15eb23670a - rustc_query_impl[778daaabc67f3fff]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[778daaabc67f3fff]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[5935fdd60c99b3fe]::query::erase::Erased<[u8; 1usize]>> 38: 0x7f15eb2366f9 - <rustc_query_impl[778daaabc67f3fff]::query_impl::analysis::dynamic_query::{closure#2} as core[d28c4e8d9c4eebaa]::ops::function::FnOnce<(rustc_middle[5935fdd60c99b3fe]::ty::context::TyCtxt, ())>>::call_once 39: 0x7f15eb51d898 - rustc_query_system[e0e328d29a6e1c80]::query::plumbing::try_execute_query::<rustc_query_impl[778daaabc67f3fff]::DynamicConfig<rustc_query_system[e0e328d29a6e1c80]::query::caches::SingleCache<rustc_middle[5935fdd60c99b3fe]::query::erase::Erased<[u8; 1usize]>>, false, false, false>, rustc_query_impl[778daaabc67f3fff]::plumbing::QueryCtxt, true> 40: 0x7f15eb51d3f4 - rustc_query_impl[778daaabc67f3fff]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace 41: 0x7f15eafe2973 - <rustc_interface[5bdd18de9f5858d8]::queries::QueryResult<&rustc_middle[5935fdd60c99b3fe]::ty::context::GlobalCtxt>>::enter::<core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>, rustc_driver_impl[566d207f92c3d9d2]::run_compiler::{closure#1}::{closure#2}::{closure#6}> 42: 0x7f15eafe194a - <rustc_interface[5bdd18de9f5858d8]::interface::Compiler>::enter::<rustc_driver_impl[566d207f92c3d9d2]::run_compiler::{closure#1}::{closure#2}, core[d28c4e8d9c4eebaa]::result::Result<core[d28c4e8d9c4eebaa]::option::Option<rustc_interface[5bdd18de9f5858d8]::queries::Linker>, rustc_span[4c9f011e8b033119]::ErrorGuaranteed>> 43: 0x7f15eafdec68 - std[3759e478f3a6c4f2]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[5bdd18de9f5858d8]::util::run_in_thread_pool_with_globals<rustc_interface[5bdd18de9f5858d8]::interface::run_compiler<core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>, rustc_driver_impl[566d207f92c3d9d2]::run_compiler::{closure#1}>::{closure#0}, core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>> 44: 0x7f15eafde3ee - <<std[3759e478f3a6c4f2]::thread::Builder>::spawn_unchecked_<rustc_interface[5bdd18de9f5858d8]::util::run_in_thread_pool_with_globals<rustc_interface[5bdd18de9f5858d8]::interface::run_compiler<core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>, rustc_driver_impl[566d207f92c3d9d2]::run_compiler::{closure#1}>::{closure#0}, core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[d28c4e8d9c4eebaa]::result::Result<(), rustc_span[4c9f011e8b033119]::ErrorGuaranteed>>::{closure#1} as core[d28c4e8d9c4eebaa]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0} 45: 0x7f15ecef5295 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::haadd4e5af2ab0d62 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9 46: 0x7f15ecef5295 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he4ba1fb09c16d807 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9 47: 0x7f15ecef5295 - std::sys::unix::thread::Thread::new::thread_start::he524ecf4b47bee95 at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/sys/unix/thread.rs:108:17 48: 0x7f15e8aaa9eb - <unknown> 49: 0x7f15e8b2e7cc - <unknown> 50: 0x0 - <unknown> 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 1.73.0 (cc66ad468 2023-10-03) running on x86_64-unknown-linux-gnu note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED] note: some of the compiler flags provided by cargo are hidden query stack during panic: #0 [mir_borrowck] borrow-checking `EvaluateConstMethods::DATA_3` #1 [analysis] running analysis passes on this crate end of query stack