Crate tsz_solver 

Query-Based Structural Solver

This module implements a declarative, query-based type solver architecture. It uses:

• Ena: For unification (Union-Find) in generic type inference
• Custom TypeData: Structural type representation with interning
• Cycle Detection: Coinductive semantics for recursive types

Key benefits:

• O(1) type equality via interning (TypeId comparison)
• Automatic cycle handling via coinductive semantics
• Lazy evaluation - only compute types that are queried

Re-exports

pub use operations::infer_generic_function;

pub use visitor::ConstAssertionVisitor;

pub use visitor::ObjectTypeKind;

pub use visitor::RecursiveTypeCollector;

pub use visitor::TypeCollectorVisitor;

pub use visitor::TypeKind;

pub use visitor::TypeKindVisitor;

pub use visitor::TypePredicateVisitor;

pub use visitor::TypeVisitor;

pub use visitor::application_id;

pub use visitor::array_element_type;

pub use visitor::bound_parameter_index;

pub use visitor::callable_shape_id;

pub use visitor::classify_object_type;

pub use visitor::collect_all_types;

pub use visitor::collect_enum_def_ids;

pub use visitor::collect_lazy_def_ids;

pub use visitor::collect_referenced_types;

pub use visitor::collect_type_queries;

pub use visitor::conditional_type_id;

pub use visitor::contains_error_type;

pub use visitor::contains_infer_types;

pub use visitor::contains_this_type;

pub use visitor::contains_type_matching;

pub use visitor::contains_type_parameters;

pub use visitor::enum_components;

pub use visitor::for_each_child;

pub use visitor::function_shape_id;

pub use visitor::index_access_parts;

pub use visitor::intersection_list_id;

pub use visitor::intrinsic_kind;

pub use visitor::is_array_type;

pub use visitor::is_conditional_type;

pub use visitor::is_empty_object_type;

pub use visitor::is_empty_object_type_db;

pub use visitor::is_enum_type;

pub use visitor::is_error_type;

pub use visitor::is_function_type;

pub use visitor::is_function_type_db;

pub use visitor::is_generic_application;

pub use visitor::is_index_access_type;

pub use visitor::is_intersection_type;

pub use visitor::is_literal_type;

pub use visitor::is_literal_type_db;

pub use visitor::is_mapped_type;

pub use visitor::is_module_namespace_type;

pub use visitor::is_module_namespace_type_db;

pub use visitor::is_object_like_type;

pub use visitor::is_object_like_type_db;

pub use visitor::is_primitive_type;

pub use visitor::is_template_literal_type;

pub use visitor::is_this_type;

pub use visitor::is_tuple_type;

pub use visitor::is_type_kind;

pub use visitor::is_type_parameter;

pub use visitor::is_type_reference;

pub use visitor::is_union_type;

pub use visitor::is_unit_type;

pub use visitor::keyof_inner_type;

pub use visitor::lazy_def_id;

pub use visitor::literal_number;

pub use visitor::literal_string;

pub use visitor::literal_value;

pub use visitor::mapped_type_id;

pub use visitor::module_namespace_symbol_ref;

pub use visitor::no_infer_inner_type;

pub use visitor::object_shape_id;

pub use visitor::object_with_index_shape_id;

pub use visitor::readonly_inner_type;

pub use visitor::recursive_index;

pub use visitor::ref_symbol;

pub use visitor::string_intrinsic_components;

pub use visitor::template_literal_id;

pub use visitor::test_type;

pub use visitor::tuple_list_id;

pub use visitor::type_param_info;

pub use visitor::type_query_symbol;

pub use visitor::union_list_id;

pub use visitor::unique_symbol_ref;

pub use visitor::walk_referenced_types;

pub use operations::AssignabilityChecker;

pub use operations::CallEvaluator;

pub use operations::CallResult;

pub use operations::MAX_CONSTRAINT_RECURSION_DEPTH;

pub use operations::get_contextual_signature_with_compat_checker;

pub use subtype::TypeEnvironment;

pub use subtype::TypeResolver;

pub use types::CallSignature;

pub use types::CallableShapeId;

pub use types::IntrinsicKind;

pub use types::LiteralValue;

pub use types::MappedModifier;

pub use types::ObjectShapeId;

pub use types::PropertyInfo;

pub use types::PropertyLookup;

pub use types::SymbolRef;

pub use types::TypeApplication;

pub use types::TypeApplicationId;

pub use types::TypeData;

pub use types::TypeId;

pub use types::TypeListId;

pub use types::Visibility;

pub use types::is_compiler_managed_type;

pub use types::CallableShape;

pub use types::ConditionalType;

pub use types::FunctionShape;

pub use types::FunctionShapeId;

pub use types::IndexSignature;

pub use types::MappedType;

pub use types::MappedTypeId;

pub use types::ObjectFlags;

pub use types::ObjectShape;

pub use types::OrderedFloat;

pub use types::ParamInfo;

pub use types::RelationCacheKey;

pub use types::TemplateSpan;

pub use types::TupleElement;

pub use types::TupleListId;

pub use types::TypeParamInfo;

pub use types::TypePredicate;

pub use types::TypePredicateTarget;

pub use binary_ops::*;

pub use canonicalize::*;

pub use compat::*;

pub use compound_assignment::*;

pub use def::*;

pub use element_access::*;

pub use freshness::*;

pub use inheritance::*;

pub use judge::*;

pub use objects::*;

pub use relation_queries::*;

pub use sound::*;

pub use unsoundness_audit::*;

pub use variance::*;

pub use widening::*;

Modules

binary_ops

Binary operation type evaluation.

canonicalize

Canonicalization for structural type identity (Task #32: Graph Isomorphism)

compat

TypeScript compatibility layer for assignability rules.

compound_assignment

def

Definition identifiers and storage for the solver.

element_access

evaluate_rules

Type evaluation rules organized by type category.

expression_ops

Expression type computation operations.

freshness

Freshness helpers for object literal excess property checking.

inheritance

Inheritance Graph Solver

judge

The Judge: Query-based type algebra engine.

objects

Property collection and merging for intersection types.

operations

Type operations and expression evaluation.

operations_generics

Generic type instantiation validation.

operations_iterators

Iterator and async iterator type extraction.

operations_property

Property access resolution (PropertyAccessEvaluator) for resolving property access on types (obj.prop, obj[“key”], etc.).

recursion

Unified recursion guard for cycle detection, depth limiting, and iteration bounding in recursive type computations.

relation_queries

Unified relation query entrypoints.

sound

Sound Mode: Strict type checking beyond TypeScript’s defaults.

tracer

Tracer-based subtype checking.

type_queries

Type Query Functions

type_queries_classifiers

Additional type query classifiers.

type_queries_data

Type Content Queries and Data Extraction Helpers

type_queries_extended

Extended Type Query Functions

type_queries_flow

Control Flow and Advanced Type Classification Queries

type_resolver

Type resolution trait and environment.

types

Type representation for the structural solver.

unsoundness_audit

TypeScript Unsoundness Catalog Implementation Audit

utils

Shared utility functions for the solver module.

variance

Variance calculation for type parameters.

visitor

Type Visitor Pattern

widening

Type widening operations for literal types.

Structs

AnyPropagationRules

Rules for any propagation in type checking.

ApplicationEvaluator

Evaluator for generic type applications.

ClassTypeBuilder

Builder for constructing class instance types.

ConstraintSet

Constraint set for an inference variable. Tracks both lower bounds (L <: α) and upper bounds (α <: U).

ContextualTypeContext

Context for contextual typing. Holds the expected type and provides methods to extract type information.

DiagnosticBuilder

Builder for creating type error diagnostics.

DiagnosticCollector

A diagnostic collector that accumulates diagnostics with source tracking.

DiscriminantInfo

Result of finding discriminant properties in a union.

FlowFacts

Flow facts that represent the state of variables at a specific program point.

FlowTypeEvaluator

Flow type evaluator that integrates flow analysis with the solver.

IndexSignatureResolver

Resolver for index signature queries on types.

InferenceCandidate

A candidate type for an inference variable.

InferenceContext

Type inference context for a single function call or expression.

InferenceInfo

Value stored for each inference variable root.

InferenceVar

An inference variable representing an unknown type. These are created when instantiating generic functions.

NarrowingCache

Narrowing context for type guards and control flow analysis. Shared across multiple narrowing contexts to persist resolution results.

NarrowingContext

Narrowing context for type guards and control flow analysis.

NarrowingResult

Result of a narrowing operation.

ObjectLiteralBuilder

Builder for constructing object literal types.

PendingDiagnostic

A pending diagnostic that hasn’t been rendered yet.

PendingDiagnosticBuilder

Builder for creating lazy pending diagnostics.

QueryCache

Query database wrapper with basic caching.

RelationCacheStats

SourceLocation

Tracks source locations for AST nodes during type checking.

SourceSpan

A source location span.

SpannedDiagnosticBuilder

A diagnostic builder that automatically attaches source spans.

SubtypeChecker

Subtype checking context. Maintains the “seen” set for cycle detection.

TypeEvaluator

Type evaluator for meta-types.

TypeFactory

TypeFormatter

Context for generating type strings.

TypeInstantiator

Instantiator for applying type substitutions.

TypeInterner

Type interning table with lock-free concurrent access.

TypeSubstitution

A substitution map from type parameter names to concrete types.

Enums

AnyPropagationMode

Controls how any is treated during subtype checks.

ApparentMemberKind

ApplicationResult

Result of application type evaluation.

ConditionalResult

Result of conditional type evaluation

ConstraintConflict

Conflict detected between constraints on an inference variable.

DiagnosticArg

Argument for a diagnostic message template.

DiagnosticSeverity

Diagnostic severity level.

IndexKind

Distinguishes between string and numeric index signatures.

InferenceError

Inference error

RelationCacheProbe

SubtypeFailureReason

Detailed reason for a subtype check failure.

SubtypeResult

Result of a subtype check

TypeGuard

AST-agnostic representation of a type narrowing condition.

TypeofKind

The result of a typeof expression, restricted to the 8 standard JavaScript types.

Constants

ARRAY_METHODS_RETURN_ANY

Array methods that return any (used for apparent type computation).

ARRAY_METHODS_RETURN_BOOLEAN

Array methods that return boolean.

ARRAY_METHODS_RETURN_NUMBER

Array methods that return number.

ARRAY_METHODS_RETURN_STRING

Array methods that return string.

ARRAY_METHODS_RETURN_VOID

Array methods that return void.

MAX_CONSTRAINT_ITERATIONS

Maximum iterations for constraint strengthening loops to prevent infinite loops.

MAX_INSTANTIATION_DEPTH

Maximum depth for recursive type instantiation.

MAX_TYPE_RECURSION_DEPTH

Maximum recursion depth for type containment checks.

MAX_VISITING_SET_SIZE

Maximum number of unique types to track in the visiting set. Prevents unbounded memory growth in pathological cases.

Traits

QueryDatabase

Query layer for higher-level solver operations.

TypeDatabase

Query interface for the solver.

Functions

apparent_object_member_kind

apparent_primitive_member_kind

apparent_primitive_members

apply_contextual_type

Apply contextual type to infer a more specific type.

are_types_structurally_identical

Check if two types are structurally identical using De Bruijn indices for cycles.

can_be_nullish

Check if a type can be nullish (contains null/undefined/void).

evaluate_conditional

Convenience function for evaluating conditional types

evaluate_index_access

Convenience function for evaluating index access types

evaluate_index_access_with_options

Convenience function for evaluating index access types with options.

evaluate_keyof

Convenience function for evaluating keyof types

evaluate_mapped

Convenience function for evaluating mapped types

evaluate_type

Convenience function for full type evaluation

find_discriminants

Convenience function for finding discriminants.

instantiate_type

Convenience function for instantiating a type with a substitution.

is_definitely_nullish

Check if a type is definitely nullish (only null/undefined/void).

is_nullish_type

Check if a type is nullish (null/undefined/void or union containing them).

is_subtype_of

Convenience function for one-off subtype checks (without resolver)

narrow_by_discriminant

Convenience function for narrowing by discriminant.

narrow_by_typeof

Convenience function for typeof narrowing.

remove_definitely_falsy_types

Remove types that are definitely falsy from a union, without narrowing non-falsy types. This matches TypeScript’s removeDefinitelyFalsyTypes: removes null, undefined, void, false, 0, "", 0n but keeps boolean, string, number, bigint, and object types unchanged.

remove_nullish

Remove nullish parts of a type (non-null assertion).

split_nullish_type

Split a type into its non-nullish part and its nullish cause.

substitute_this_type

Substitute ThisType with a concrete type throughout a type.

type_contains_nullish

Check if a type (possibly a union) contains null or undefined.

type_contains_undefined

Check if a type contains undefined (or void).

would_create_inheritance_cycle

Detects if adding a parent to a child would create a cycle in the inheritance graph.