Encountered anon const with inference variable args but no error reported

[joonazan]

Backtrace

            0: std::backtrace::Backtrace::create
             1: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             2: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             3: <rustc_span::ErrorGuaranteed as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
             4: <rustc_errors::DiagCtxtHandle>::delayed_bug::<&str>
             5: rustc_trait_selection::traits::try_evaluate_const
             6: <rustc_trait_selection::traits::normalize::AssocTypeNormalizer as rustc_type_ir::fold::TypeFolder<rustc_middle::ty::context::TyCtxt>>::fold_const
             7: <&rustc_middle::ty::list::RawList<(), rustc_middle::ty::generic_args::GenericArg> as rustc_type_ir::fold::TypeFoldable<rustc_middle::ty::context::TyCtxt>>::try_fold_with::<rustc_trait_selection::traits::normalize::AssocTypeNormalizer>
             8: <rustc_middle::ty::Ty as rustc_type_ir::fold::TypeSuperFoldable<rustc_middle::ty::context::TyCtxt>>::try_super_fold_with::<rustc_trait_selection::traits::normalize::AssocTypeNormalizer>
             9: <rustc_infer::infer::at::At as rustc_trait_selection::traits::normalize::NormalizeExt>::normalize::<rustc_middle::ty::Ty>
            10: <rustc_hir_typeck::fn_ctxt::FnCtxt>::normalize::<rustc_middle::ty::Ty>
            11: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_struct_fields
            12: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_kind
            13: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
            14: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_decl
            15: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_block
            16: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_expr_with_expectation_and_args
            17: <rustc_hir_typeck::fn_ctxt::FnCtxt>::check_return_or_body_tail
            18: rustc_hir_typeck::check::check_fn
            19: rustc_hir_typeck::typeck_with_inspect::{closure#0}
            20: rustc_hir_typeck::typeck
            21: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::typeck::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 8]>>
            22: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_data_structures::vec_cache::VecCache<rustc_span::def_id::LocalDefId, rustc_middle::query::erase::Erased<[u8; 8]>, rustc_query_system::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
            23: rustc_query_impl::query_impl::typeck::get_query_incr::__rust_end_short_backtrace
            24: <rustc_middle::ty::context::TyCtxt>::par_hir_body_owners::<rustc_hir_analysis::check_crate::{closure#3}>::{closure#0}
            25: rustc_hir_analysis::check_crate
            26: rustc_interface::passes::run_required_analyses
            27: rustc_interface::passes::analysis
            28: rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>
            29: rustc_query_system::query::plumbing::try_execute_query::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt, true>
            30: rustc_query_impl::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
            31: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>
            32: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}
            33: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            34: <<std::thread::Builder>::spawn_unchecked_<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            35: std::sys::pal::unix::thread::Thread::new::thread_start
            36: __pthread_cond_wait

rustc-ice-2025-05-06T12_15_48-6382.txt

[lqd]

Could you please add the code that reproduces the error?

The nightly used is quite old btw. Maybe this has been fixed already on more recent ones.

[joonazan]

The code is rather big so I'm afraid it isn't very useful. Also, the compilation is started via a fuzzing script and I haven't been able to find out where that gets its Rust version. So all in all not a very good test case.

May be the same issue as #134044

[shamatar]

There were quite a few ICEs lately when type alias was used where even min_const_generics constant was substituted into concrete, but non-literal (basically another "const X: usize = ...") constant, and const generics feature was enabled