Cyclic dependency graph when parsing OPAQUE-KE v4.0.1

rust-analyzer version: rust-analyzer version: 0.3.2667-standalone (bacc5bbd30 2025-11-02)

rustc version: rustc 1.93.0-nightly (843f8ce2e 2025-11-07)

editor or extension: VSCode, extension version 0.3.2667

relevant settings: all empty

repository link (if public, optional): opaque-ke

code snippet to reproduce: Just add OPAQUE-KE v4.0.0 or v4.0.1 to Cargo.toml and you start to get the error. This does not happen if I downgrade rust-analyzer to the version 2025-08-25 v0.3.2593-standalone (6b2e677 2025-08-25). It starts appearing since 2025-10-27 (v0.3.2658).


thread 'Worker2' (3552474) panicked at /rust/deps/salsa-0.24.0/src/function/fetch.rs:271:21:
dependency graph cycle when querying generic_predicates_shim(Id(9d95)), set cycle_fn/cycle_initial to fixpoint iterate.
Query stack:
[
    infer_shim(Id(1457f)),
    trait_impls_in_deps_shim(Id(70d3)),
    trait_impls_in_crate_shim(Id(704d)),
    impl_trait_with_diagnostics_shim(Id(176ce)),
    impl_self_ty_with_diagnostics_shim(Id(176ce)),
    type_for_type_alias_with_diagnostics_shim(Id(a1cc)),
    generic_predicates_for_param_shim(Id(87035)),
    generic_predicates_shim(Id(9d95)),
    type_for_type_alias_with_diagnostics_shim(Id(a1cb)),
    generic_predicates_for_param_shim(Id(87036)),
]
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: <salsa::function::IngredientImpl<hir_ty::db::create_data_HirDatabase::create_data_HirDatabase_Configuration_>>::fetch_cold_cycle::{closure#0}
   3: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim::generic_predicates_shim_Configuration_>>::fetch_cold_cycle
   4: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim::generic_predicates_shim_Configuration_>>::fetch_cold_with_retry
   5: <_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim
   6: <hir_ty::next_solver::interner::DbInterner as ra_ap_rustc_type_ir::interner::Interner>::explicit_super_predicates_of
   7: ra_ap_rustc_type_ir::elaborate::supertrait_def_ids::<hir_ty::next_solver::interner::DbInterner>::{closure#0}
   8: <<_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim::generic_predicates_for_param_shim_Configuration_ as salsa::function::Configuration>::execute
   9: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim::generic_predicates_for_param_shim_Configuration_>>::execute
  10: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim::generic_predicates_for_param_shim_Configuration_>>::fetch_cold_with_retry
  11: <_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim
  12: <hir_ty::lower::path::PathLoweringContext>::select_associated_type
  13: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  14: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  15: hir_ty::lower::path::substs_from_args_and_bindings::<<hir_ty::lower::path::PathLoweringContext>::substs_from_args_and_bindings::LowererCtx>
  16: <hir_ty::lower::path::PathLoweringContext>::substs_from_path_segment
  17: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  18: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  19: <<_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim::type_for_type_alias_with_diagnostics_shim_Configuration_ as salsa::function::Configuration>::execute
  20: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim::type_for_type_alias_with_diagnostics_shim_Configuration_>>::execute
  21: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim::type_for_type_alias_with_diagnostics_shim_Configuration_>>::fetch_cold_with_retry
  22: <_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim
  23: hir_ty::lower::ty_query
  24: <hir_ty::lower::path::PathLoweringContext>::lower_path_inner
  25: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  26: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  27: <hir_ty::lower::TyLoweringContext>::lower_where_predicate
  28: hir_ty::lower::generic_predicates_filtered_by::<hir_ty::lower::generic_predicates_query::{closure#0}>
  29: <<_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim::generic_predicates_shim_Configuration_ as salsa::function::Configuration>::execute
  30: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim::generic_predicates_shim_Configuration_>>::execute
  31: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim::generic_predicates_shim_Configuration_>>::fetch_cold_with_retry
  32: <_ as hir_ty::db::HirDatabase>::generic_predicates::generic_predicates_shim
  33: <hir_ty::next_solver::interner::DbInterner as ra_ap_rustc_type_ir::interner::Interner>::explicit_super_predicates_of
  34: ra_ap_rustc_type_ir::elaborate::supertrait_def_ids::<hir_ty::next_solver::interner::DbInterner>::{closure#0}
  35: <<_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim::generic_predicates_for_param_shim_Configuration_ as salsa::function::Configuration>::execute
  36: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim::generic_predicates_for_param_shim_Configuration_>>::execute
  37: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim::generic_predicates_for_param_shim_Configuration_>>::fetch_cold_with_retry
  38: <_ as hir_ty::db::HirDatabase>::generic_predicates_for_param::generic_predicates_for_param_shim
  39: <hir_ty::lower::path::PathLoweringContext>::select_associated_type
  40: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  41: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  42: hir_ty::lower::path::substs_from_args_and_bindings::<<hir_ty::lower::path::PathLoweringContext>::substs_from_args_and_bindings::LowererCtx>
  43: <hir_ty::lower::path::PathLoweringContext>::substs_from_path_segment
  44: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  45: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  46: <<_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim::type_for_type_alias_with_diagnostics_shim_Configuration_ as salsa::function::Configuration>::execute
  47: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim::type_for_type_alias_with_diagnostics_shim_Configuration_>>::execute
  48: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim::type_for_type_alias_with_diagnostics_shim_Configuration_>>::fetch_cold_with_retry
  49: <_ as hir_ty::db::HirDatabase>::type_for_type_alias_with_diagnostics::type_for_type_alias_with_diagnostics_shim
  50: hir_ty::lower::ty_query
  51: <hir_ty::lower::path::PathLoweringContext>::lower_path_inner
  52: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  53: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  54: <<hir_ty::lower::path::PathLoweringContext>::substs_from_args_and_bindings::LowererCtx as hir_ty::lower::path::GenericArgsLowerer>::provided_kind
  55: hir_ty::lower::path::substs_from_args_and_bindings::<<hir_ty::lower::path::PathLoweringContext>::substs_from_args_and_bindings::LowererCtx>
  56: <hir_ty::lower::path::PathLoweringContext>::substs_from_path_segment
  57: <hir_ty::lower::path::PathLoweringContext>::lower_path_inner
  58: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  59: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  60: <<hir_ty::lower::path::PathLoweringContext>::substs_from_args_and_bindings::LowererCtx as hir_ty::lower::path::GenericArgsLowerer>::provided_kind
  61: hir_ty::lower::path::substs_from_args_and_bindings::<<hir_ty::lower::path::PathLoweringContext>::substs_from_args_and_bindings::LowererCtx>
  62: <hir_ty::lower::path::PathLoweringContext>::substs_from_path_segment
  63: <hir_ty::lower::path::PathLoweringContext>::lower_path_inner
  64: <hir_ty::lower::path::PathLoweringContext>::lower_partly_resolved_path
  65: <hir_ty::lower::TyLoweringContext>::lower_ty_ext
  66: <<_ as hir_ty::db::HirDatabase>::impl_self_ty_with_diagnostics::impl_self_ty_with_diagnostics_shim::impl_self_ty_with_diagnostics_shim_Configuration_ as salsa::function::Configuration>::execute
  67: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::impl_self_ty_with_diagnostics::impl_self_ty_with_diagnostics_shim::impl_self_ty_with_diagnostics_shim_Configuration_>>::execute
  68: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::impl_self_ty_with_diagnostics::impl_self_ty_with_diagnostics_shim::impl_self_ty_with_diagnostics_shim_Configuration_>>::fetch_cold_with_retry
  69: <_ as hir_ty::db::HirDatabase>::impl_self_ty_with_diagnostics::impl_self_ty_with_diagnostics_shim
  70: <ide_db::RootDatabase as hir_ty::db::HirDatabase>::impl_self_ty
  71: <<_ as hir_ty::db::HirDatabase>::impl_trait_with_diagnostics::impl_trait_with_diagnostics_shim::impl_trait_with_diagnostics_shim_Configuration_ as salsa::function::Configuration>::execute
  72: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::impl_trait_with_diagnostics::impl_trait_with_diagnostics_shim::impl_trait_with_diagnostics_shim_Configuration_>>::execute
  73: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::impl_trait_with_diagnostics::impl_trait_with_diagnostics_shim::impl_trait_with_diagnostics_shim_Configuration_>>::fetch_cold_with_retry
  74: <_ as hir_ty::db::HirDatabase>::impl_trait_with_diagnostics::impl_trait_with_diagnostics_shim
  75: <ide_db::RootDatabase as hir_ty::db::HirDatabase>::impl_trait
  76: <hir_ty::method_resolution::TraitImpls>::collect_def_map
  77: <<_ as hir_ty::db::HirDatabase>::trait_impls_in_crate::trait_impls_in_crate_shim::trait_impls_in_crate_shim_Configuration_ as salsa::function::Configuration>::execute
  78: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::trait_impls_in_crate::trait_impls_in_crate_shim::trait_impls_in_crate_shim_Configuration_>>::execute
  79: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::trait_impls_in_crate::trait_impls_in_crate_shim::trait_impls_in_crate_shim_Configuration_>>::fetch_cold_with_retry
  80: <_ as hir_ty::db::HirDatabase>::trait_impls_in_crate::trait_impls_in_crate_shim
  81: <<_ as hir_ty::db::HirDatabase>::trait_impls_in_deps::trait_impls_in_deps_shim::trait_impls_in_deps_shim_Configuration_ as salsa::function::Configuration>::execute
  82: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::trait_impls_in_deps::trait_impls_in_deps_shim::trait_impls_in_deps_shim_Configuration_>>::execute
  83: <salsa::function::IngredientImpl<<_ as hir_ty::db::HirDatabase>::trait_impls_in_deps::trait_impls_in_deps_shim::trait_impls_in_deps_shim_Configuration_>>::fetch_cold_with_retry
  84: <_ as hir_ty::db::HirDatabase>::trait_impls_in_deps::trait_impls_in_deps_shim
  85: <ra_ap_rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<hir_ty::next_solver::solver::SolverContext, hir_ty::next_solver::interner::DbInterner>>::compute_trait_goal
  86: <ra_ap_rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<hir_ty::next_solver::solver::SolverContext, hir_ty::next_solver::interner::DbInterner>>::compute_goal
  87: <ra_ap_rustc_type_ir::search_graph::SearchGraph<ra_ap_rustc_next_trait_solver::solve::search_graph::SearchGraphDelegate<hir_ty::next_solver::solver::SolverContext>, hir_ty::next_solver::interner::DbInterner>>::evaluate_goal_in_task
  88: <ra_ap_rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<hir_ty::next_solver::solver::SolverContext, hir_ty::next_solver::interner::DbInterner>>::evaluate_goal_raw
  89: <ra_ap_rustc_next_trait_solver::solve::eval_ctxt::EvalCtxt<hir_ty::next_solver::solver::SolverContext, hir_ty::next_solver::interner::DbInterner>>::evaluate_goal
  90: <hir_ty::next_solver::solver::SolverContext as ra_ap_rustc_next_trait_solver::solve::eval_ctxt::SolverDelegateEvalExt>::evaluate_root_goal
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
query stacktrace:
   0: generic_predicates_for_param_shim(Id(87036)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   1: type_for_type_alias_with_diagnostics_shim(Id(a1cb)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   2: generic_predicates_shim(Id(9d95)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   3: generic_predicates_for_param_shim(Id(87035)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   4: type_for_type_alias_with_diagnostics_shim(Id(a1cc)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   5: impl_self_ty_with_diagnostics_shim(Id(176ce)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   6: impl_trait_with_diagnostics_shim(Id(176ce)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   7: trait_impls_in_crate_shim(Id(704d)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   8: trait_impls_in_deps_shim(Id(70d3)) -> (R20194, Durability::MEDIUM)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28
   9: infer_shim(Id(1457f)) -> (R20194, Durability::LOW)
             at src/tools/rust-analyzer/crates/hir-ty/src/db.rs:28

additional context:
   0: 
version: 1.93.0-nightly (843f8ce2 2025-11-07)
request: textDocument/semanticTokens/full/delta SemanticTokensDeltaParams {
    work_done_progress_params: WorkDoneProgressParams {
        work_done_token: None,
    },
    partial_result_params: PartialResultParams {
        partial_result_token: None,
    },
    text_document: TextDocumentIdentifier {
        uri: Url {
            scheme: "file",
            cannot_be_a_base: false,
            username: "",
            password: None,
            host: None,
            port: None,
            path: "/src/registration/signup.rs",
            query: None,
            fragment: None,
        },
    },
    previous_result_id: "1",
}

[Error - 7:04:49 AM] Request textDocument/semanticTokens/full/delta failed.
  Message: request handler panicked: dependency graph cycle when querying generic_predicates_shim(Id(9d95)), set cycle_fn/cycle_initial to fixpoint iterate.
Query stack:
[
    infer_shim(Id(1457f)),
    trait_impls_in_deps_shim(Id(70d3)),
    trait_impls_in_crate_shim(Id(704d)),
    impl_trait_with_diagnostics_shim(Id(176ce)),
    impl_self_ty_with_diagnostics_shim(Id(176ce)),
    type_for_type_alias_with_diagnostics_shim(Id(a1cc)),
    generic_predicates_for_param_shim(Id(87035)),
    generic_predicates_shim(Id(9d95)),
    type_for_type_alias_with_diagnostics_shim(Id(a1cb)),
    generic_predicates_for_param_shim(Id(87036)),
]
  Code: -32603

@rustbot

@rustbot claim

In commit 5038446, the GenericPredicates::query_with_diagnostics method was converted to a salsa tracked query but the cycle handler was not added during the conversion.

I met the same problem when I used rust-analyzer in neovim when parsing the same version of opaque-ke.

@ChayimFriedman2

OK, I have a minimal standalone repro.

trait VCipherSuite {}

trait CipherSuite
where
    OprfHash<Self>: Hash,
{
}

type Bar<CS: CipherSuite> = <CS::Baz as VCipherSuite>::Hash;

type OprfHash<CS: CipherSuite> = <CS::Baz as VCipherSuite>::Hash;

impl<CS: CipherSuite> Foo<CS> {
    fn seal() {}
}

Put this in a lib.rs and run rust-analyzer analysis-stats . to get the error:

thread 'main' (13941245) panicked at /Users/wilfred/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/salsa-0.24.0/src/function/fetch.rs:271:21:
dependency graph cycle when querying GenericPredicates < 'db >::query_with_diagnostics_(Id(7d96)), set cycle_fn/cycle_initial to fixpoint iterate.
Query stack:
[
    InferenceResult < 'db >::for_body_(Id(1500b)),
    trait_environment_shim(Id(1500b)),
    GenericPredicates < 'db >::query_with_diagnostics_(Id(7d96)),
    type_for_type_alias_with_diagnostics_shim(Id(81c4)),
    generic_predicates_for_param(Id(20011)),
    trait_signature_with_source_map_shim(Id(7d95)),
    VariantFields::firewall_(Id(840a)),
    VariantFields::query_(Id(840a)),
    VariantFields::firewall_(Id(8749)),
    VariantFields::query_(Id(8749)),
]
stack backtrace:
   0: __rustc::rust_begin_unwind
   1: core::panicking::panic_fmt
   2: salsa::function::fetch::<impl salsa::function::IngredientImpl<C>>::fetch_cold_cycle::{{closure}}
   3: salsa::function::fetch::<impl salsa::function::IngredientImpl<C>>::fetch_cold_cycle
   4: salsa::function::fetch::<impl salsa::function::IngredientImpl<C>>::fetch_cold_with_retry
   5: salsa::function::fetch::<impl salsa::function::IngredientImpl<C>>::fetch
   6: std::thread::local::LocalKey<T>::with
   7: <hir_ty::next_solver::interner::DbInterner as ra_ap_rustc_type_ir::interner::Interner>::explicit_super_predicates_of
...

I'm not sure if this is a lowering issue (as suggested by @ChayimFriedman2 on #21117) or a salsa issue.

Woah, thanks! I don't believe this can be a Salsa issue, and this likely is a lowering problem, as rustc does not cycle on this code.

@Aditya-PS-05

@Aditya-PS-05, are you still interested in this?

The reason for the cycle is these lines:

rust-analyzer/crates/hir-ty/src/lower.rs

Lines 1569 to 1573 in 34fd9f6

    
           rustc_type_ir::elaborate::supertrait_def_ids(interner, tr.into()).any(|tr| { 
        
               tr.0.trait_items(db).items.iter().any(|(name, item)| { 
        
                   matches!(item, AssocItemId::TypeAliasId(_)) && name == assoc_name 
        
               }) 
        
           })

supertrait_def_ids() calls explicit_super_predicates_of() which calls GenericPredicates::query(), something not allowed in generic_predicates_for_params(). In rustc this is good since explicit_super_predicates_of() is its own query which only lowers generic parameters on Self; what we need to do is to call generic_predicates_for_params() on Self (unless we're computing it) and get the supertraits from there instead.

I was wrong to say that we do not need cycle handlers, but not completely wrong: we need them, because erroneous code can still trigger a cycle. Code that compiles with rustc, however, should never trigger a cycle.

Is the only workaround for this to downgrade rust-analyzer? I've tried several things but it practically makes this crate unusable for me, which sucks since it seems to be the only actively maintained choice for my project. It wouldn't be too big of an issue if it was self contained but it affects the projects that use it and causes issues with cargo workspaces.

Fix lowering with supertrait predicates

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Cyclic dependency graph when parsing OPAQUE-KE v4.0.1 #21006

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	rustc_type_ir::elaborate::supertrait_def_ids(interner, tr.into()).any(\|tr\| {
	tr.0.trait_items(db).items.iter().any(\|(name, item)\| {
	matches!(item, AssocItemId::TypeAliasId(_)) && name == assoc_name
	})
	})

Cyclic dependency graph when parsing OPAQUE-KE v4.0.1 #21006

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Aditya-PS-05 commented on Nov 23, 2025

Aditya-PS-05 commented on Nov 23, 2025

zincentimeter commented on Dec 15, 2025

Wilfred commented on Dec 17, 2025

ChayimFriedman2 commented on Dec 17, 2025

ChayimFriedman2 commented on Dec 17, 2025

ChayimFriedman2 commented on Dec 17, 2025

ChayimFriedman2 commented on Dec 24, 2025

giddyos commented on Dec 25, 2025

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