Module: Rigor::Inference::ScopeIndexer

Defined in:
lib/rigor/inference/scope_indexer.rb

Overview

Builds a per-node scope index for a Prism program by running ‘Rigor::Inference::StatementEvaluator` over the root and recording the entry scope visible at every node. Expression-interior nodes the evaluator does not specialise (call receivers, arguments, array/hash elements, …) inherit their nearest statement-y ancestor’s recorded scope, so a downstream caller that looks up the scope for any Prism node in the tree always gets the scope that was effectively visible at that point.

The CLI commands ‘rigor type-of` and `rigor type-scan` consume the index so that local-variable bindings established earlier in the program are visible to the typer when probing later nodes. Without the index, both commands would type every node under an empty scope and miss the constant-folding / dispatch precision that Slice 3 phase 2’s StatementEvaluator unlocks.

The returned object is an identity-comparing Hash:

“‘ruby index = Rigor::Inference::ScopeIndexer.index(program, default_scope: Scope.empty) index #=> the Rigor::Scope visible at that node “`

Nodes that are not part of the program subtree (e.g. synthesised virtual nodes that the caller looks up after the fact) yield the ‘default_scope`. The returned Hash is mutable in principle but callers MUST treat it as read-only; the indexer itself never exposes a way to update it past construction. rubocop:disable Metrics/ModuleLength

Constant Summary collapse

TOP_LEVEL_DEF_KEY =

v0.0.3 A — sentinel key under which ‘record_def_node` files DefNodes that live outside any class / module body (top-level helpers, `def`s nested inside DSL blocks like `RSpec.describe … do; def helper; end`). Looked up by `Scope#top_level_def_for` to give implicit-self calls priority over RBS dispatch when the file defines a same-named local method.

"<toplevel>"
MIXIN_CALL_NAMES = 
%i[include prepend].freeze
VISIBILITY_MODIFIERS = 
%i[public private protected].freeze

Class Method Summary collapse

Class Method Details

.apply_alias_def_nodes(root, accumulator) ⇒ Object

Post-pass over the ‘def_nodes` accumulator: for every `alias` declaration inside a class body, if the original method name maps to a `Prism::DefNode`, register the new name pointing to the same node so inter-procedural return-type inference works for the aliased name.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1243

def apply_alias_def_nodes(root, accumulator)
  alias_map = collect_class_alias_map(root, [], {})
  alias_map.each do |class_name, aliases|
    class_defs = accumulator[class_name]
    next unless class_defs

    aliases.each do |new_name, old_name|
      def_node = class_defs[old_name]
      next unless def_node.is_a?(Prism::DefNode)

      (accumulator[class_name] ||= {})[new_name] = def_node
    end
  end
end

.apply_named_visibility(args, qualified_prefix, visibility, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1206

def apply_named_visibility(args, qualified_prefix, visibility, accumulator)
  class_name = qualified_prefix.join("::")
  args.each do |arg|
    name = visibility_target_name(arg)
    next if name.nil?

    accumulator[class_name] ||= {}
    accumulator[class_name][name] = visibility
  end
end

.apply_visibility_call(call_node, qualified_prefix, current_visibility, accumulator) ⇒ Object

Recognises modifier calls on the implicit-self receiver inside a class body. Returns the (possibly updated) current visibility:

  • ‘private` / `public` / `protected` (no args) —switch the running default for subsequent defs.

  • ‘private :foo, :bar` — back-patch the named methods in the accumulator. Returns `current_visibility` unchanged because the running default does NOT change for this form.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1192

def apply_visibility_call(call_node, qualified_prefix, current_visibility, accumulator)
  return current_visibility unless call_node.receiver.nil?
  return current_visibility unless VISIBILITY_MODIFIERS.include?(call_node.name)
  return current_visibility if qualified_prefix.empty?

  args = call_node.arguments&.arguments || []
  if args.empty?
    call_node.name
  else
    apply_named_visibility(args, qualified_prefix, call_node.name, accumulator)
    current_visibility
  end
end

.build_class_cvar_index(root, default_scope) ⇒ Object

Slice 7 phase 6 — class-cvar pre-pass. Same shape as the ivar pre-pass but collects ‘Prism::ClassVariableWriteNode` writes inside ANY def body (instance or singleton) of the enclosing class, because Ruby cvars are shared across both facets. The resulting table is seeded into both instance and singleton method bodies through `Scope#class_cvars_for`.



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# File 'lib/rigor/inference/scope_indexer.rb', line 644

def build_class_cvar_index(root, default_scope)
  accumulator = {}
  walk_class_cvars(root, [], default_scope, accumulator)
  accumulator.transform_values(&:freeze).freeze
end

.build_class_ivar_index(root, default_scope) ⇒ Object

Slice 7 phase 2. Builds the class-level ivar accumulator by walking every ‘Prism::ClassNode` / `Prism::ModuleNode` body, descending into each nested `Prism::DefNode`, and typing every `Prism::InstanceVariableWriteNode` rvalue under a scope that carries the appropriate `self_type` for that def (singleton vs instance). The rvalue is typed with NO local bindings — the pre-pass lacks statement-level threading — so `@x = 1` records `Constant` but `@x = some_local + 1` records `Dynamic` (since `some_local` is unbound at pre-pass time). Multiple writes to the same ivar union via `Type::Combinator.union`.



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# File 'lib/rigor/inference/scope_indexer.rb', line 183

def build_class_ivar_index(root, default_scope)
  accumulator = {}
  mutated_ivars = {}
  read_before_write = {}
  init_writes = {}
  walk_class_ivars(root, [], default_scope, accumulator, mutated_ivars,
                   read_before_write, init_writes)
  widen_mutated_ivar_entries!(accumulator, mutated_ivars)
  contribute_read_before_write_nil!(accumulator, read_before_write, init_writes)
  accumulator.transform_values(&:freeze).freeze
end

.build_declaration_artifacts(root) ⇒ Object

Walks the program once for ‘Prism::ModuleNode` and `Prism::ClassNode`, recording the `Singleton` type for the outermost `constant_path` node of each declaration. Inner segments of a `class Foo::Bar::Baz` path remain real references (resolved through the ordinary lexical walk), so we annotate ONLY the topmost path node. Nested declarations contribute their fully qualified path: `class A::B; class C; …` produces `A::B` for the outer and `A::B::C` for the inner.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1427

def build_declaration_artifacts(root)
  identity_table = {}.compare_by_identity
  discovered = {}
  record_declarations(root, [], identity_table, discovered)
  [identity_table.freeze, discovered.freeze]
end

.build_discovered_def_nodes(root) ⇒ Object

v0.0.2 #5 — instance-side def-node recording. Walks class bodies the same way as ‘build_discovered_methods` but records the actual `Prism::DefNode` for each instance method so `ExpressionTyper` can re-type the body at the call site for inter-procedural return inference. Singleton methods and `define_method` calls are intentionally skipped: the inference path needs a statically introspectable body, and singleton dispatch has its own complications (Class / Module ancestry) the first-iteration rule does not yet model.



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# File 'lib/rigor/inference/scope_indexer.rb', line 946

def build_discovered_def_nodes(root)
  accumulator = {}
  walk_def_nodes(root, [], false, accumulator)
  apply_alias_def_nodes(root, accumulator)
  accumulator.transform_values(&:freeze).freeze
end

.build_discovered_includes(root) ⇒ Object

ADR-24 slice 2 — per-class/module table mapping a fully qualified user class or module to the list of module names it ‘include`s / `prepend`s, AS WRITTEN at the mixin call (`include Foo` / `include Foo::Bar`). Only constant arguments are recorded; dynamic mixins (`include some_method`) produce no entry. `prepend` is bucketed with `include` — both contribute instance methods to the ancestor chain. `extend` is NOT tracked (it adds singleton methods; ADR-24 slice 2 resolves the instance-side chain).



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# File 'lib/rigor/inference/scope_indexer.rb', line 1056

def build_discovered_includes(root)
  accumulator = {}
  walk_class_includes(root, [], nil, accumulator)
  accumulator.transform_values { |mods| mods.uniq.freeze }.freeze
end

.build_discovered_method_visibilities(root) ⇒ Object

v0.1.2 — per-class method-visibility table for the ‘def.method-visibility-mismatch` CheckRule.

Tracks two visibility-changing forms:

  • **Modifier blocks**: a bare ‘private` / `protected` / `public` call inside a class body switches the “current default” visibility for every subsequent `def` until another modifier flips it again.

  • **Named-argument form**: ‘private :foo, :bar` (or the same with `protected` / `public`) marks specific names already-recorded under the class. Symbol-only args are recognised; `private def foo; end` (the wrap-around form) is not yet — it would need tracking the def-call’s return-value visibility, which is a separate slice.

Top-level (no surrounding class) defs do not contribute — Ruby’s top-level visibility nuances (private at top-level marks the method on ‘Object`) are out of scope for v0.1.2.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1115

def build_discovered_method_visibilities(root)
  accumulator = {}
  walk_method_visibilities(root, [], false, :public, accumulator)
  accumulator.transform_values(&:freeze).freeze
end

.build_discovered_methods(root) ⇒ Object

Slice 7 phase 12 — in-source method discovery pre-pass. Walks every class/module body and records the methods introduced via ‘Prism::DefNode` (instance + singleton) and via recognised `define_method(:name) { … }` calls. The returned table maps qualified class name to a `Hash[Symbol, :instance | :singleton]`.



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# File 'lib/rigor/inference/scope_indexer.rb', line 793

def build_discovered_methods(root)
  accumulator = {}
  walk_methods(root, [], false, accumulator)
  accumulator.transform_values(&:freeze).freeze
end

.build_discovered_superclasses(root) ⇒ Object

ADR-24 slice 2 — per-class table mapping a fully qualified user class to its superclass name AS WRITTEN at the ‘class Foo < Bar` declaration. Only constant superclasses are recorded (`class Foo < Struct.new(…)` and other non-constant superclasses produce no entry). The as-written name is resolved to a qualified class at the call site against the subclass’s lexical nesting —see ‘ExpressionTyper#resolve_ancestor_class_name`.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1012

def build_discovered_superclasses(root)
  accumulator = {}
  walk_class_superclasses(root, [], accumulator)
  accumulator.freeze
end

.build_in_source_constants(root, default_scope) ⇒ Object

Slice 7 phase 9 — in-source constant value pre-pass. Walks the entire program (top-level AND inside class / module / def bodies) for ‘Prism::ConstantWriteNode` and `Prism::ConstantPathWriteNode`, types each rvalue, and accumulates by qualified name. Constants defined inside a class body are qualified with the surrounding class path; constants written via a path (`Foo::BAR = …`) use the rendered path as-is.



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# File 'lib/rigor/inference/scope_indexer.rb', line 730

def build_in_source_constants(root, default_scope)
  accumulator = {}
  walk_constant_writes(root, [], default_scope, accumulator)
  accumulator.freeze
end

.build_program_global_index(root, default_scope) ⇒ Object

Slice 7 phase 6 — program-global pre-pass. Globals are process-wide so the accumulator is a flat ‘Hash[Symbol, Type::t]` populated from every `Prism::GlobalVariableWriteNode` in the program (top-level AND inside method bodies). The same accumulator is seeded into every method body and the top-level scope.



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# File 'lib/rigor/inference/scope_indexer.rb', line 702

def build_program_global_index(root, default_scope)
  accumulator = {}
  gather_global_writes(root, default_scope, accumulator)
  accumulator.freeze
end

.class_new_call?(node) ⇒ Boolean

Recognises ‘Class.new`, `Class.new(super_class)`, and the block form `Class.new { … }`. Like `module_new_call?`, the block body is walked as the anonymous class’s body. The optional ‘super_class` positional is accepted but does NOT route through `ancestor` discovery in this slice — the synthesised class still answers method lookups via its own body’s defs, mirroring how ‘Struct.new` / `Data.define` are handled.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1538

def class_new_call?(node)
  meta_call_with_name?(node, :Class, :new)
end

.collect_class_alias_map(node, qualified_prefix, accumulator) ⇒ Object

Builds a map ‘=> {new_name_sym => old_name_sym}` by walking the tree for `AliasMethodNode` nodes inside class bodies.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1260

def collect_class_alias_map(node, qualified_prefix, accumulator)
  return accumulator unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      collect_class_alias_map(node.body, qualified_prefix + [name], accumulator) if node.body
      return accumulator
    end
  when Prism::SingletonClassNode
    return accumulator
  when Prism::AliasMethodNode
    record_alias_map_entry(node, qualified_prefix, accumulator)
    return accumulator
  end

  node.compact_child_nodes.each { |child| collect_class_alias_map(child, qualified_prefix, accumulator) }
  accumulator
end

.collect_class_body_ivar_writes(node, class_name, init_writes) ⇒ Object

Walks class-body level statements (i.e. NOT inside any nested DefNode / ClassNode / ModuleNode) and records every ‘@x = …` write target as a class-body init. Consumed by `contribute_read_before_write_nil!` to exempt ivars the author already knows might be nil (the `@x = nil` at class-body level is the canonical nullability acknowledgement; the instance @x is technically a separate store, but the pragmatic intent is unambiguous).



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# File 'lib/rigor/inference/scope_indexer.rb', line 427

def collect_class_body_ivar_writes(node, class_name, init_writes)
  return unless node.is_a?(Prism::Node)
  return if IVAR_BARRIER_NODES.any? { |klass| node.is_a?(klass) }

  if node.is_a?(Prism::InstanceVariableWriteNode) ||
     node.is_a?(Prism::InstanceVariableOrWriteNode) ||
     node.is_a?(Prism::InstanceVariableAndWriteNode) ||
     node.is_a?(Prism::InstanceVariableOperatorWriteNode)
    (init_writes[class_name] ||= Set.new) << node.name
  end

  node.compact_child_nodes.each do |child|
    collect_class_body_ivar_writes(child, class_name, init_writes)
  end
end

.collect_class_decls(node, qualified_prefix, accumulator) ⇒ Object

Class-only variant of ‘record_declarations` — descends into nested module bodies (so `module Foo; class Bar` registers `Foo::Bar`) but never registers the module itself in `accumulator`.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1399

def collect_class_decls(node, qualified_prefix, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode
    name = qualified_name_for(node.constant_path)
    if name
      full = (qualified_prefix + [name]).join("::")
      accumulator[full] = Type::Combinator.singleton_of(full)
      return collect_class_decls(node.body, qualified_prefix + [name], accumulator) if node.body
    end
  when Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    return collect_class_decls(node.body, qualified_prefix + [name], accumulator) if name && node.body
  end

  node.compact_child_nodes.each { |child| collect_class_decls(child, qualified_prefix, accumulator) }
end

.collect_def_cvar_writes(def_node, qualified_prefix, default_scope, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 671

def collect_def_cvar_writes(def_node, qualified_prefix, default_scope, accumulator)
  return if def_node.body.nil? || qualified_prefix.empty?

  class_name = qualified_prefix.join("::")
  body_scope = default_scope.with_self_type(Type::Combinator.nominal_of(class_name))
  gather_cvar_writes(def_node.body, body_scope, class_name, accumulator)
end

.collect_def_ivar_writes(def_node, qualified_prefix, default_scope, accumulator, mutated_ivars, read_before_write = nil, init_writes = nil) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 355

def collect_def_ivar_writes(def_node, qualified_prefix, default_scope, accumulator, mutated_ivars,
                            read_before_write = nil, init_writes = nil)
  return if def_node.body.nil? || qualified_prefix.empty?

  class_name = qualified_prefix.join("::")
  singleton = def_node.receiver.is_a?(Prism::SelfNode) ||
              def_receiver_targets_lexical_self?(def_node.receiver, qualified_prefix)
  self_type =
    if singleton
      Type::Combinator.singleton_of(class_name)
    else
      Type::Combinator.nominal_of(class_name)
    end
  body_scope = default_scope.with_self_type(self_type)

  gather_ivar_writes(def_node.body, body_scope, class_name, accumulator, EMPTY_GUARDED_IVARS, mutated_ivars)

  # B2.3 — collect per-method evidence for the read-before-
  # write nil contribution. The accumulator-level decision
  # ("is this ivar truly read-before-write across the
  # class lifetime?") is finalised at
  # `contribute_read_before_write_nil!` after the whole
  # class body has been walked, using `init_writes` as
  # the soundness gate (an ivar written in `initialize`
  # is initialised before any other method body runs).
  collect_read_before_write_evidence(def_node, class_name, read_before_write, init_writes)
end

.collect_defined_test_ivars(node, names) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 574

def collect_defined_test_ivars(node, names)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::DefinedNode
    target = node.value
    names << target.name if target.is_a?(Prism::InstanceVariableReadNode)
  when Prism::AndNode, Prism::OrNode
    collect_defined_test_ivars(node.left, names)
    collect_defined_test_ivars(node.right, names)
  end
end

.collect_nil_test_ivars(node, names) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 587

def collect_nil_test_ivars(node, names)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::CallNode
    receiver = node.receiver
    if receiver.is_a?(Prism::InstanceVariableReadNode) &&
       %i[nil? !].include?(node.name)
      names << receiver.name
    end
  when Prism::AndNode, Prism::OrNode
    collect_nil_test_ivars(node.left, names)
    collect_nil_test_ivars(node.right, names)
  end
end

.collect_read_before_write_evidence(def_node, class_name, read_before_write, init_writes) ⇒ Object

Walks the method body in AST (== execution) order tracking ivar names whose first reference is a read. The set is unioned into the class-wide ‘read_before_write` accumulator. For `initialize` def bodies, every write target is unioned into `init_writes` instead — used by the finalisation step to suppress nil contribution for ivars the constructor guarantees are initialised.



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# File 'lib/rigor/inference/scope_indexer.rb', line 391

def collect_read_before_write_evidence(def_node, class_name, read_before_write, init_writes)
  return if read_before_write.nil? || init_writes.nil?

  seen_writes = Set.new
  read_first = Set.new
  detect_read_before_write(def_node.body, seen_writes, read_first)

  if def_node.name == :initialize
    init_set = (init_writes[class_name] ||= Set.new)
    seen_writes.each { |name| init_set << name }
    return
  end

  return if read_first.empty?

  rbw_set = (read_before_write[class_name] ||= Set.new)
  read_first.each { |name| rbw_set << name }
end

.collect_truthy_test_ivars(node, names) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 562

def collect_truthy_test_ivars(node, names)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::InstanceVariableReadNode
    names << node.name
  when Prism::AndNode, Prism::OrNode
    collect_truthy_test_ivars(node.left, names)
    collect_truthy_test_ivars(node.right, names)
  end
end

.contribute_read_before_write_nil!(accumulator, read_before_write, init_writes) ⇒ Object

B2.3 — finalize the read-before-write nil contribution. For each class, for each ivar where SOME method body observed a read-before-write AND no ‘initialize` write exists for that ivar, contribute `Constant` to the class-wide accumulator.

The ‘initialize` filter is the soundness gate: Ruby semantics guarantee `initialize` runs first (via `Class.new`), so a write there reaches every other method body’s read. Read-before-write in a non-init method is then NOT a nil-at-runtime case — it’s just AST-order coincidence. Without this filter a normal ‘def initialize; @x = … end` / `def use; @x.foo end` class would have `@x` widened with nil, producing FPs at every `@x.foo` call.



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# File 'lib/rigor/inference/scope_indexer.rb', line 210

def contribute_read_before_write_nil!(accumulator, read_before_write, init_writes)
  nil_t = Type::Combinator.constant_of(nil)
  read_before_write.each do |class_name, ivar_set|
    init_set = init_writes[class_name] || EMPTY_GUARDED_IVARS
    per_class = accumulator[class_name]
    next if per_class.nil?

    ivar_set.each do |ivar_name|
      # Soundness gates (in order):
      # (1) `initialize` writes the ivar → it's set
      #     before any other method runs, so the
      #     read-before-write in a sibling method is
      #     NOT a runtime nil case.
      # (2) The accumulator has NO entry for the ivar
      #     → some write was deliberately skipped (the
      #     falsey-default `@x = nil unless @x` slice's
      #     no-seed behaviour). Adding nil here would
      #     defeat that skip and re-introduce the
      #     `Constant[nil]` FP the skip silenced.
      next if init_set.include?(ivar_name)
      next unless per_class.key?(ivar_name)

      existing = per_class[ivar_name]
      per_class[ivar_name] = Type::Combinator.union(existing, nil_t)
    end
  end
end

.data_define_call?(node) ⇒ Boolean

Recognises ‘Data.define(*Symbol)` and `Data.define(*Symbol) do … end` at constant-write rvalue position. The receiver MUST be the bare `Data` constant (or `::Data`); other receivers (a local variable, a method call return) are rejected because their identity is not statically known.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1491

def data_define_call?(node)
  return false unless node.is_a?(Prism::CallNode)
  return false unless node.name == :define
  return false unless meta_constant_receiver?(node.receiver, :Data)

  args = node.arguments&.arguments || []
  args.all?(Prism::SymbolNode)
end

.def_receiver_targets_lexical_self?(receiver, qualified_prefix) ⇒ Boolean

Only ‘Prism::ConstantReadNode` is observed in real Ruby —Prism mis-parses `def C::P.method` as `def C.P` (Ruby itself rejects the form as a SyntaxError). The ConstantPathNode branch stays defensive in case Prism’s grammar widens.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 919

def def_receiver_targets_lexical_self?(receiver, qualified_prefix)
  return false if qualified_prefix.empty?

  case receiver
  when Prism::ConstantReadNode
    receiver.name.to_s == qualified_prefix.last
  when Prism::ConstantPathNode
    rendered = render_constant_path(receiver)
    return false unless rendered

    path = rendered.split("::")
    qualified_prefix.last(path.length) == path
  else
    false
  end
end

.def_singleton?(def_node, qualified_prefix, in_singleton_class) ⇒ Boolean

‘def Foo.bar` inside `module Foo` (or `def Meta.init` inside `module Meta`) is semantically equivalent to `def self.bar`: at the def-site, the runtime value of the constant `Foo` is the module itself (== `self`). Recognise the form so the method registers as singleton on the enclosing class.

The cross-class form ‘def Bar.baz` inside `module Foo` —where the receiver names a constant other than the enclosing class — is not supported at this slice; falls through to `:instance` (current behaviour) rather than silently re-routing the registration.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 909

def def_singleton?(def_node, qualified_prefix, in_singleton_class)
  return true if def_node.receiver.is_a?(Prism::SelfNode) || in_singleton_class

  def_receiver_targets_lexical_self?(def_node.receiver, qualified_prefix)
end

.detect_read_before_write(node, seen_writes, read_first) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 443

def detect_read_before_write(node, seen_writes, read_first)
  return unless node.is_a?(Prism::Node)
  return if IVAR_BARRIER_NODES.any? { |klass| node.is_a?(klass) }

  read_first << node.name if node.is_a?(Prism::InstanceVariableReadNode) && !seen_writes.include?(node.name)

  # Descend BEFORE recording a write — `@x = @x + 1`'s
  # RHS is an `InstanceVariableReadNode` that runs before
  # the write is committed; the read is therefore
  # read-before-write semantically. Prism's
  # `compact_child_nodes` returns the value child before
  # the lvalue target, matching this order.
  node.compact_child_nodes.each do |c|
    detect_read_before_write(c, seen_writes, read_first)
  end

  seen_writes << node.name if IVAR_WRITE_NODES.any? { |klass| node.is_a?(klass) }
end

.discovered_classes_for_paths(paths, buffer: nil) ⇒ Hash{String => Rigor::Type::Singleton}

Walks every file in ‘paths` (each path is parsed once with `Prism.parse_file`) and returns the unioned project-wide `discovered_classes` Hash: `=> Singleton`. Used by `Analysis::Runner` to seed each file’s ‘default_scope.discovered_classes` so that lexical constant lookup in one file resolves a `class Foo` declared in a sibling file. Per-file collisions are last-write-wins (matches the existing in-file merge semantics). Parse failures fail-soft to an empty contribution. The `buffer` argument, when present, redirects reads for the bound logical path to the buffer’s physical path so editor-mode pre-passes see the in-flight bytes.

**Modules are intentionally excluded** from the project-wide seed: a ‘module M; module_function; def x; end; end` body, when surfaced as `singleton(M)` to the dispatcher, falls through to `Kernel#x` (or any Module ancestor method) when the project’s per-file ‘discovered_methods` doesn’t know ‘M.x` — leading to surprising types like `Kernel.select → Array`. Until cross-file `discovered_methods` follows the same project-wide seed, registering modules here would introduce regressions in modules-with-module_function idioms that previously resolved to `Dynamic`. Class declarations are safe because per-file `discovered_methods` already tracks `def self.x` / `def x` instance and singleton methods consistently.

Parameters:

Returns:



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# File 'lib/rigor/inference/scope_indexer.rb', line 1342

def discovered_classes_for_paths(paths, buffer: nil)
  accumulator = {}
  paths.each do |path|
    physical = buffer ? buffer.resolve(path) : path
    source = File.read(physical)
    root = Prism.parse(source, filepath: path).value
    collect_class_decls(root, [], accumulator)
  rescue StandardError
    # Skip files that fail to parse or read; the per-file
    # analyzer surfaces the parse error separately.
    next
  end
  accumulator.freeze
end

.discovered_def_index_for_paths(paths, buffer: nil) ⇒ Hash{Symbol => Hash}

ADR-24 slice 2 — cross-file companion to ‘discovered_classes_for_paths`. Walks every project file once and returns both the merged `discovered_def_nodes` table (a class reopened across files has its method tables merged) and the merged class -> superclass-name map. The engine consults these so an implicit-self call inside a subclass resolves against a superclass `def` declared in a sibling file (`Mastodon::CLI::Accounts` calling a helper defined in `Mastodon::CLI::Base`).

Parameters:

Returns:

  • (Hash{Symbol => Hash}) —

    ‘{ def_nodes:, superclasses: }`



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# File 'lib/rigor/inference/scope_indexer.rb', line 1371

def discovered_def_index_for_paths(paths, buffer: nil)
  def_nodes = {}
  superclasses = {}
  includes = {}
  paths.each do |path|
    physical = buffer ? buffer.resolve(path) : path
    root = Prism.parse(File.read(physical), filepath: path).value
    build_discovered_def_nodes(root).each do |class_name, methods|
      (def_nodes[class_name] ||= {}).merge!(methods)
    end
    superclasses.merge!(build_discovered_superclasses(root))
    build_discovered_includes(root).each do |class_name, mods|
      includes[class_name] = ((includes[class_name] || []) + mods).uniq
    end
  rescue StandardError
    # Skip files that fail to parse or read; the per-file
    # analyzer surfaces the parse error separately.
    next
  end
  def_nodes.each_value(&:freeze)
  includes.each_value(&:freeze)
  { def_nodes: def_nodes.freeze, superclasses: superclasses.freeze, includes: includes.freeze }
end

.falsey_constant?(type) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 633

def falsey_constant?(type)
  type.is_a?(Type::Constant) && (type.value.nil? || type.value == false)
end

.gather_cvar_writes(node, scope, class_name, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 679

def gather_cvar_writes(node, scope, class_name, accumulator)
  return unless node.is_a?(Prism::Node)

  record_cvar_write(node, scope, class_name, accumulator) if node.is_a?(Prism::ClassVariableWriteNode)
  return if IVAR_BARRIER_NODES.any? { |klass| node.is_a?(klass) }

  node.compact_child_nodes.each { |c| gather_cvar_writes(c, scope, class_name, accumulator) }
end

.gather_global_writes(node, scope, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 708

def gather_global_writes(node, scope, accumulator)
  return unless node.is_a?(Prism::Node)

  record_global_write(node, scope, accumulator) if node.is_a?(Prism::GlobalVariableWriteNode)
  node.compact_child_nodes.each { |c| gather_global_writes(c, scope, accumulator) }
end

.gather_ivar_writes(node, scope, class_name, accumulator, guarded_ivars = EMPTY_GUARDED_IVARS, mutated_ivars = nil) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 468

def gather_ivar_writes(node, scope, class_name, accumulator, guarded_ivars = EMPTY_GUARDED_IVARS,
                       mutated_ivars = nil)
  return unless node.is_a?(Prism::Node)

  if node.is_a?(Prism::InstanceVariableWriteNode)
    record_ivar_write(node, scope, class_name, accumulator,
                      guarded: guarded_ivars.include?(node.name))
  end
  record_ivar_mutator_call(node, class_name, mutated_ivars) if mutated_ivars && node.is_a?(Prism::CallNode)

  # Don't recurse into nested defs, classes, or modules; their
  # ivars belong to their own enclosing class.
  return if IVAR_BARRIER_NODES.any? { |klass| node.is_a?(klass) }

  if node.is_a?(Prism::IfNode) || node.is_a?(Prism::UnlessNode)
    walk_conditional_ivar_writes(node, scope, class_name, accumulator, guarded_ivars, mutated_ivars)
    return
  end

  node.compact_child_nodes.each do |c|
    gather_ivar_writes(c, scope, class_name, accumulator, guarded_ivars, mutated_ivars)
  end
end

.index(root, default_scope:) ⇒ Hash{Prism::Node => Rigor::Scope}

Build the scope index for a Prism program subtree.

Parameters:

  • root (Prism::Node) —

    usually a ‘Prism::ProgramNode`, but any subtree the caller wants the indexer to walk works.

  • default_scope (Rigor::Scope) —

    the scope used for the root, and the fallback returned for any Prism node not contained in ‘root`’s subtree.

Returns:

  • (Hash{Prism::Node => Rigor::Scope}) —

    identity-comparing table whose default value is ‘default_scope`.



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# File 'lib/rigor/inference/scope_indexer.rb', line 54

def index(root, default_scope:) # rubocop:disable Metrics/AbcSize
  # Slice A-declarations. Build the declaration overrides
  # first so every scope handed to the StatementEvaluator
  # already carries the table; structural sharing through
  # `Scope#with_local` / `#with_fact` / `#with_self_type`
  # propagates it across every derived scope.
  declared_types, discovered_classes = build_declaration_artifacts(root)
  # Merge the indexer's findings on top of whatever the
  # base scope already carries so callers that seed
  # cross-file class knowledge (e.g. the ADR-14
  # `SigGen::ObservationCollector` pre-walking project
  # `lib/` before scanning `spec/`) keep their seeds
  # alongside the per-file declarations the indexer
  # itself discovers. Indexer-found entries win on
  # collision — same-file declarations are the most
  # specific authority.
  merged_classes = default_scope.discovered_classes.merge(discovered_classes)
  seeded_scope = default_scope
                 .with_declared_types(declared_types)
                 .with_discovered_classes(merged_classes)

  # Slice 7 phase 2. Pre-pass over every class/module body
  # to collect the per-class ivar accumulator. Seeded after
  # declared_types so the rvalue typer in the pre-pass can
  # see declaration overrides.
  class_ivars = build_class_ivar_index(root, seeded_scope)
  seeded_scope = seeded_scope.with_class_ivars(class_ivars)

  # Slice 7 phase 6. Same pre-pass shape for cvars (per
  # class) and globals (program-wide). Globals are also
  # materialised into the top-level scope's `globals` map
  # so reads at the top level (and in CLI probes that do
  # not enter a method body) observe the precise type
  # without consulting the accumulator on every lookup.
  class_cvars = build_class_cvar_index(root, seeded_scope)
  seeded_scope = seeded_scope.with_class_cvars(class_cvars)
  program_globals = build_program_global_index(root, seeded_scope)
  seeded_scope = seeded_scope.with_program_globals(program_globals)
  program_globals.each { |name, type| seeded_scope = seeded_scope.with_global(name, type) }

  # Slice 7 phase 9. In-source constant value tracking.
  # Walks every ConstantWriteNode/ConstantPathWriteNode in
  # the program and types its rvalue under a scope that
  # carries the surrounding qualified prefix as
  # `self_type`, so the rvalue typer sees in-class
  # references resolve correctly. Multiple writes to the
  # same qualified name union via `Type::Combinator.union`.
  in_source_constants = build_in_source_constants(root, seeded_scope)
  seeded_scope = seeded_scope.with_in_source_constants(in_source_constants)

  # Slice 7 phase 12. In-source method discovery. Walks
  # every class/module body for `Prism::DefNode` and
  # recognised `define_method` calls and records the
  # introduced method names. `rigor check` consults the
  # table to suppress false positives for methods the
  # user has defined but no RBS sig describes.
  discovered_methods = build_discovered_methods(root)
  seeded_scope = seeded_scope.with_discovered_methods(discovered_methods)

  # v0.0.2 #5 + ADR-24 slice 2 — record per-instance-method
  # def nodes, the class -> superclass map, and the
  # class/module -> included-modules map, each merged under
  # the cross-file pre-pass seed (see below).
  seeded_scope = merge_project_method_indexes(seeded_scope, default_scope, root)

  # v0.1.2 — per-class table of method visibilities
  # (`:public` / `:private` / `:protected`). The
  # `def.method-visibility-mismatch` CheckRule consults
  # the table to flag explicit-non-self calls to a
  # private user method.
  discovered_method_visibilities = build_discovered_method_visibilities(root)
  seeded_scope = seeded_scope.with_discovered_method_visibilities(discovered_method_visibilities)

  table = {}.compare_by_identity
  table.default = seeded_scope

  # Last-visit-wins, not first: when `StatementEvaluator`
  # internally re-evaluates a subtree (notably `eval_begin`'s
  # retry-edge widening pass), the LATER visit carries the
  # corrected entry scope (e.g. a `tries` widened to
  # `Nominal[Integer]` after the rescue body's `tries += 1;
  # retry` is observed). The diagnostic layer reads
  # `table[node]` to type predicates; the second pass's
  # entry is the one that reflects all flow-derived
  # rebinds, so it MUST overwrite the first.
  on_enter = ->(node, scope) { table[node] = scope }
  StatementEvaluator.new(scope: seeded_scope, on_enter: on_enter).evaluate(root)

  propagate(root, table, seeded_scope)
  table
end

.literal_method_name(node) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1304

def literal_method_name(node)
  return nil unless node.is_a?(Prism::SymbolNode) || node.is_a?(Prism::StringNode)

  node.unescaped&.to_sym
end

.merge_project_method_indexes(seeded_scope, default_scope, root) ⇒ Object

v0.0.2 #5 + ADR-24 slice 2 — seeds the three project-method indexes onto ‘seeded_scope`: the per-instance-method def-node table, the class -> superclass map, and the class/module -> included-modules map. Each per-file table is merged UNDER the cross-file `discovered_def_index_for_paths` seed carried on `default_scope` — same-file declarations win per entry, the cross-file seed supplies sibling-file ancestors.



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# File 'lib/rigor/inference/scope_indexer.rb', line 154

def merge_project_method_indexes(seeded_scope, default_scope, root)
  def_nodes = default_scope.discovered_def_nodes.merge(
    build_discovered_def_nodes(root)
  ) { |_class, cross_file, per_file| cross_file.merge(per_file) }
  superclasses = default_scope.discovered_superclasses.merge(
    build_discovered_superclasses(root)
  )
  includes = default_scope.discovered_includes.merge(
    build_discovered_includes(root)
  ) { |_class, cross_file, per_file| (cross_file + per_file).uniq }

  seeded_scope
    .with_discovered_def_nodes(def_nodes)
    .with_discovered_superclasses(superclasses)
    .with_discovered_includes(includes)
end

.meta_call_with_name?(node, receiver_name, method_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1542

def meta_call_with_name?(node, receiver_name, method_name)
  return false unless node.is_a?(Prism::CallNode)
  return false unless node.name == method_name

  meta_constant_receiver?(node.receiver, receiver_name)
end

.meta_constant_receiver?(node, expected_name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1553

def meta_constant_receiver?(node, expected_name)
  case node
  when Prism::ConstantReadNode
    node.name == expected_name
  when Prism::ConstantPathNode
    node.parent.nil? && node.name == expected_name
  end
end

.meta_new_block_body(node) ⇒ Object

v0.1.2 — when a ‘Const = Data.define(*sym) do … end` / `Const = Struct.new(*sym) do … end` constant write carries a block, the block body holds method overrides whose canonical class is `Const`. Survey item (e) extended the recognition to `Const = Module.new do … end` and `Const = Class.new(?super) do … end` — the ADR-16 Tier A “block-as-method” idiom at constant-write position. Returns the block body node (a `Prism::StatementsNode`) when the rvalue matches; nil otherwise. Used by `walk_methods` / `walk_def_nodes` to push `Const` onto the qualified prefix before recursing.



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# File 'lib/rigor/inference/scope_indexer.rb', line 876

def meta_new_block_body(node)
  return nil unless node.is_a?(Prism::ConstantWriteNode)

  rvalue = node.value
  return nil unless data_define_call?(rvalue) ||
                    struct_new_call?(rvalue) ||
                    module_new_call?(rvalue) ||
                    class_new_call?(rvalue)

  rvalue.block&.body
end

.meta_new_constant_type(node, full) ⇒ Object

Survey item (e): when the rvalue is a recognised ‘Module.new do … end` / `Class.new do … end` / `Struct.new(*sym) do … end` / `Data.define(*sym) do … end` form, type the named constant as `Singleton` so the discovered-method table registered under `full` becomes reachable through singleton-side dispatch (`Const.[]=` etc.). Returns nil for non-meta-new rvalues so the caller falls back to the default `body_scope.type_of(node.value)` shape.



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# File 'lib/rigor/inference/scope_indexer.rb', line 781

def meta_new_constant_type(node, full)
  return nil unless meta_new_block_body(node)

  Type::Combinator.singleton_of(full)
end

.module_new_call?(node) ⇒ Boolean

Recognises ‘Module.new` and `Module.new(&block)` / `Module.new do … end` at constant-write rvalue position. The block body is the anonymous module’s ‘module_eval` body; defs inside it bind methods on the named constant (`Const = Module.new do …; def foo; …; end; end`). Arguments are NOT inspected because `Module.new` accepts no positionals — Ruby raises ArgumentError if any are passed — so a malformed call falls through the walker without affecting analysis.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1526

def module_new_call?(node)
  meta_call_with_name?(node, :Module, :new)
end

.propagate(node, table, parent_scope) ⇒ Object

Walks ‘node`’s subtree DFS and fills in scope entries for every Prism node the StatementEvaluator did not visit (i.e. expression- interior nodes like the receiver/args of a CallNode). Those nodes inherit their nearest recorded ancestor’s scope.

‘IfNode` / `UnlessNode` are special-cased: the truthy and falsey branches each get their predicate’s narrowed scope before recursing. This handles expression-position conditionals (e.g. ‘cache = if cond; t; else; e; end` and conditionals nested as call arguments) which are typed by ExpressionTyper without going through `eval_if`’s narrowing path.



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# File 'lib/rigor/inference/scope_indexer.rb', line 1592

def propagate(node, table, parent_scope)
  return unless node.is_a?(Prism::Node)

  current_scope =
    if table.key?(node)
      table[node]
    else
      table[node] = parent_scope
      parent_scope
    end

  case node
  when Prism::IfNode
    propagate_if_branches(node, table, current_scope)
  when Prism::UnlessNode
    propagate_unless_branches(node, table, current_scope)
  else
    node.compact_child_nodes.each { |child| propagate(child, table, current_scope) }
  end
end

.propagate_if_branches(node, table, current_scope) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1613

def propagate_if_branches(node, table, current_scope)
  truthy_scope, falsey_scope = Narrowing.predicate_scopes(node.predicate, current_scope)
  propagate(node.predicate, table, current_scope) if node.predicate
  propagate(node.statements, table, truthy_scope) if node.statements
  propagate(node.subsequent, table, falsey_scope) if node.subsequent
end

.propagate_unless_branches(node, table, current_scope) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1620

def propagate_unless_branches(node, table, current_scope)
  truthy_scope, falsey_scope = Narrowing.predicate_scopes(node.predicate, current_scope)
  propagate(node.predicate, table, current_scope) if node.predicate
  propagate(node.statements, table, falsey_scope) if node.statements
  propagate(node.else_clause, table, truthy_scope) if node.else_clause
end

.qualified_name_for(constant_path_node) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1562

def qualified_name_for(constant_path_node)
  case constant_path_node
  when Prism::ConstantReadNode
    constant_path_node.name.to_s
  when Prism::ConstantPathNode
    render_constant_path(constant_path_node)
  end
end

.record_alias_map_entry(alias_node, qualified_prefix, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1281

def record_alias_map_entry(alias_node, qualified_prefix, accumulator)
  return if qualified_prefix.empty?
  return unless alias_node.new_name.is_a?(Prism::SymbolNode) && alias_node.old_name.is_a?(Prism::SymbolNode)

  class_name = qualified_prefix.join("::")
  new_name = alias_node.new_name.unescaped.to_sym
  old_name = alias_node.old_name.unescaped.to_sym
  (accumulator[class_name] ||= {})[new_name] = old_name
end

.record_alias_method(alias_node, qualified_prefix, in_singleton_class, accumulator) ⇒ Object

Registers the alias name in the ‘discovered_methods` table so `undefined-method` diagnostics are not emitted for calls to the aliased name. The kind mirrors the surrounding class context (instance inside a regular class body, singleton inside `class << self`).



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# File 'lib/rigor/inference/scope_indexer.rb', line 1228

def record_alias_method(alias_node, qualified_prefix, in_singleton_class, accumulator)
  return if qualified_prefix.empty?
  return unless alias_node.new_name.is_a?(Prism::SymbolNode)

  class_name = qualified_prefix.join("::")
  new_name = alias_node.new_name.unescaped.to_sym
  kind = in_singleton_class ? :singleton : :instance
  (accumulator[class_name] ||= {})[new_name] = kind
end

.record_class_or_module?(node, qualified_prefix, identity_table, discovered) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1449

def record_class_or_module?(node, qualified_prefix, identity_table, discovered)
  name = qualified_name_for(node.constant_path)
  return false unless name

  full = (qualified_prefix + [name]).join("::")
  singleton = Type::Combinator.singleton_of(full)
  identity_table[node.constant_path] = singleton
  discovered[full] = singleton
  child_prefix = qualified_prefix + [name]
  record_declarations(node.body, child_prefix, identity_table, discovered) if node.body
  true
end

.record_constant_write(node, qualified_prefix, default_scope, accumulator, base_name) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 761

def record_constant_write(node, qualified_prefix, default_scope, accumulator, base_name)
  full = qualified_prefix.empty? ? base_name : "#{qualified_prefix.join('::')}::#{base_name}"
  body_scope = default_scope
  unless qualified_prefix.empty?
    body_scope = body_scope.with_self_type(Type::Combinator.singleton_of(qualified_prefix.join("::")))
  end
  rvalue_type = meta_new_constant_type(node, full) || body_scope.type_of(node.value)
  existing = accumulator[full]
  accumulator[full] = existing ? Type::Combinator.union(existing, rvalue_type) : rvalue_type
end

.record_cvar_write(node, scope, class_name, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 688

def record_cvar_write(node, scope, class_name, accumulator)
  rvalue_type = scope.type_of(node.value)
  accumulator[class_name] ||= {}
  existing = accumulator[class_name][node.name]
  accumulator[class_name][node.name] =
    existing ? Type::Combinator.union(existing, rvalue_type) : rvalue_type
end

.record_declarations(node, qualified_prefix, identity_table, discovered) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1434

def record_declarations(node, qualified_prefix, identity_table, discovered)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ModuleNode, Prism::ClassNode
    return if record_class_or_module?(node, qualified_prefix, identity_table, discovered)
  when Prism::ConstantWriteNode
    return if record_meta_new_constant?(node, qualified_prefix, identity_table, discovered)
  end

  node.compact_child_nodes.each do |child|
    record_declarations(child, qualified_prefix, identity_table, discovered)
  end
end

.record_def_method(def_node, qualified_prefix, in_singleton_class, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 888

def record_def_method(def_node, qualified_prefix, in_singleton_class, accumulator)
  return if qualified_prefix.empty?

  class_name = qualified_prefix.join("::")
  singleton = def_singleton?(def_node, qualified_prefix, in_singleton_class)
  kind = singleton ? :singleton : :instance
  accumulator[class_name] ||= {}
  accumulator[class_name][def_node.name] = kind
end

.record_def_node(def_node, qualified_prefix, in_singleton_class, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 996

def record_def_node(def_node, qualified_prefix, in_singleton_class, accumulator)
  return if def_singleton?(def_node, qualified_prefix, in_singleton_class)

  class_name = qualified_prefix.empty? ? TOP_LEVEL_DEF_KEY : qualified_prefix.join("::")
  accumulator[class_name] ||= {}
  accumulator[class_name][def_node.name] = def_node
end

.record_def_visibility(def_node, qualified_prefix, in_singleton_class, current_visibility, accumulator) ⇒ Object

rubocop:enable Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity, Metrics/AbcSize



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# File 'lib/rigor/inference/scope_indexer.rb', line 1173

def record_def_visibility(def_node, qualified_prefix, in_singleton_class, current_visibility, accumulator)
  return if def_node.receiver.is_a?(Prism::SelfNode) || in_singleton_class
  return if qualified_prefix.empty?

  class_name = qualified_prefix.join("::")
  accumulator[class_name] ||= {}
  accumulator[class_name][def_node.name] = current_visibility
end

.record_define_method(call_node, qualified_prefix, in_singleton_class, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1291

def record_define_method(call_node, qualified_prefix, in_singleton_class, accumulator)
  return if qualified_prefix.empty?
  return if call_node.arguments.nil? || call_node.arguments.arguments.empty?

  first_arg = call_node.arguments.arguments.first
  method_name = literal_method_name(first_arg)
  return if method_name.nil?

  class_name = qualified_prefix.join("::")
  accumulator[class_name] ||= {}
  accumulator[class_name][method_name] = in_singleton_class ? :singleton : :instance
end

.record_global_write(node, scope, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 715

def record_global_write(node, scope, accumulator)
  rvalue_type = scope.type_of(node.value)
  existing = accumulator[node.name]
  accumulator[node.name] =
    existing ? Type::Combinator.union(existing, rvalue_type) : rvalue_type
end

.record_ivar_mutator_call(node, class_name, mutated_ivars) ⇒ Object

Records ‘@ivar.<method>(…)` calls whose method is in `MutationWidening::ARRAY_MUTATORS` or `HASH_MUTATORS`. The class-ivar pre-pass uses the resulting set to widen the post-collected accumulator entries (see widen_mutated_ivar_entries!). Always-safe to over- collect: any name that the widening primitive declines is ignored at finalization.



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# File 'lib/rigor/inference/scope_indexer.rb', line 499

def record_ivar_mutator_call(node, class_name, mutated_ivars)
  receiver = node.receiver
  return unless receiver.is_a?(Prism::InstanceVariableReadNode)
  return unless MutationWidening::ARRAY_MUTATORS.include?(node.name) ||
                MutationWidening::HASH_MUTATORS.include?(node.name)

  per_class = (mutated_ivars[class_name] ||= {})
  per_ivar = (per_class[receiver.name] ||= Set.new)
  per_ivar << node.name
end

.record_ivar_write(node, scope, class_name, accumulator, guarded: false) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 603

def record_ivar_write(node, scope, class_name, accumulator, guarded: false)
  rvalue_type = scope.type_of(node.value)

  # `@x = nil unless @x` / `@y = false unless @y` —
  # follow-up to the polarity-aware defensive-init guard
  # fix (ROADMAP § Future cycles — "Defensive ivar-init
  # with nil / false rvalue"). When the rvalue is itself a
  # falsey Constant, `union(rvalue, Constant[nil])`
  # collapses (for `nil`) or doesn't widen the type's
  # truthiness profile (for `false`) — the predicate
  # `unless @x` then folds to a single `Constant[nil]` /
  # `Constant[false]` and the
  # `flow.always-truthy-condition` / `-always-falsey-`
  # rule false-fires on the no-op-but-documented-default
  # idiom. Skip the seed contribution for this write
  # (matches the existing skip for `@x ||= v`, which the
  # pre-pass also does not seed). Other writes to the
  # same ivar still contribute; the falsey-default write
  # carries no useful precision the predicate hasn't
  # already given us. See tdiary-core HEAD `ee40c2b`
  # `lib/tdiary/configuration.rb:157` for the worked site.
  return if guarded && falsey_constant?(rvalue_type)

  rvalue_type = Type::Combinator.union(rvalue_type, Type::Combinator.constant_of(nil)) if guarded
  accumulator[class_name] ||= {}
  existing = accumulator[class_name][node.name]
  accumulator[class_name][node.name] =
    existing ? Type::Combinator.union(existing, rvalue_type) : rvalue_type
end

.record_meta_new_constant?(node, qualified_prefix, identity_table, discovered) ⇒ Boolean

Recognises class-creating meta calls at constant-write rvalue position and registers ‘Const` (qualified by the surrounding class/module path) as a discovered class. `Const.new(…)` then resolves to a fresh `Nominal` via `meta_new`, instead of the un-narrowed `Dynamic` returned by the default `Class#new` envelope.

Two recognised meta forms:

  • ‘Const = Data.define(*Symbol) [do … end]`

  • ‘Const = Struct.new(*Symbol [, keyword_init: …]) [do … end]`

The block body, if present, is recursed into so any nested class/module declarations in the override block (rare but legal) still feed the discovered table.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1477

def record_meta_new_constant?(node, qualified_prefix, identity_table, discovered)
  return false unless data_define_call?(node.value) || struct_new_call?(node.value)

  full = (qualified_prefix + [node.name.to_s]).join("::")
  discovered[full] = Type::Combinator.singleton_of(full)
  record_declarations(node.value, qualified_prefix, identity_table, discovered)
  true
end

.record_mixin_call(node, current_class, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1082

def record_mixin_call(node, current_class, accumulator)
  return unless current_class && node.receiver.nil?
  return unless MIXIN_CALL_NAMES.include?(node.name)

  node.arguments&.arguments&.each do |arg|
    mod = qualified_name_for(arg)
    (accumulator[current_class] ||= []) << mod if mod
  end
end

.render_constant_path(node) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1571

def render_constant_path(node)
  prefix =
    case node.parent
    when Prism::ConstantReadNode then "#{node.parent.name}::"
    when Prism::ConstantPathNode then "#{render_constant_path(node.parent)}::"
    else ""
    end
  "#{prefix}#{node.name}"
end

.singleton_class_prefix(node, qualified_prefix) ⇒ Object

Resolves a ‘class << X` body’s qualified prefix.

- `class << self` keeps `qualified_prefix` (the enclosing class).
- `class << Foo` inside `class Foo` collapses to the same prefix
  (semantically `class << self`).
- `class << Foo` not nested in `class Foo` returns `[Foo]`
  so methods defined inside register on Foo's singleton.
- Any other expression (variable, method call) returns nil
  so the walker falls through and skips the body.



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# File 'lib/rigor/inference/scope_indexer.rb', line 848

def singleton_class_prefix(node, qualified_prefix)
  case node.expression
  when Prism::SelfNode
    qualified_prefix
  when Prism::ConstantReadNode, Prism::ConstantPathNode
    rendered = qualified_name_for(node.expression)
    return nil unless rendered

    if !qualified_prefix.empty? && qualified_prefix.last == rendered
      qualified_prefix
    else
      rendered.split("::")
    end
  end
end

.struct_new_call?(node) ⇒ Boolean

Recognises ‘Struct.new(*Symbol)` and `Struct.new(*Symbol, keyword_init: <expr>)` at constant-write rvalue position. A trailing `KeywordHashNode` (the `keyword_init: …` form) is accepted but does not contribute to member discovery; every other argument MUST be a `Prism::SymbolNode`. At least one Symbol member is required —`Struct.new()` is a degenerate form callers don’t typically use.

Returns:

  • (Boolean) 


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# File 'lib/rigor/inference/scope_indexer.rb', line 1507

def struct_new_call?(node)
  return false unless meta_call_with_name?(node, :Struct, :new)

  args = node.arguments&.arguments || []
  positional = struct_new_positionals(args)
  return false if positional.nil? || positional.empty?

  positional.all?(Prism::SymbolNode)
end

.struct_new_positionals(args) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1549

def struct_new_positionals(args)
  args.last.is_a?(Prism::KeywordHashNode) ? args[0..-2] : args
end

.then_body_guarded_ivars(node) ⇒ Object

Returns the set of ivar names that, in the THEN body of this conditional, are statically known to be in a nil / unset state — i.e. the body really IS the defensive-init half of the idiom. Conservative on purpose: only the shapes that idiomatically express “the ivar is missing” qualify.

For ‘unless P; body; end`, body runs when `P` is falsey:

- `P = @x` (or `@x && other` / `@x || other`)            → @x is falsey
- `P = defined?(@x)`                                     → @x is undefined

For ‘if P; body; …`, body runs when `P` is truthy:

- `P = @x.nil?`                                          → @x is nil
- `P = !@x` / `not @x`                                   → @x is falsey



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# File 'lib/rigor/inference/scope_indexer.rb', line 551

def then_body_guarded_ivars(node)
  names = Set.new
  if node.is_a?(Prism::UnlessNode)
    collect_truthy_test_ivars(node.predicate, names)
    collect_defined_test_ivars(node.predicate, names)
  else
    collect_nil_test_ivars(node.predicate, names)
  end
  names
end

.visibility_target_name(arg) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1217

def visibility_target_name(arg)
  return arg.unescaped.to_sym if arg.is_a?(Prism::SymbolNode) || arg.is_a?(Prism::StringNode)

  nil
end

.walk_class_cvars(node, qualified_prefix, default_scope, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 650

def walk_class_cvars(node, qualified_prefix, default_scope, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      child_prefix = qualified_prefix + [name]
      walk_class_cvars(node.body, child_prefix, default_scope, accumulator) if node.body
      return
    end
  when Prism::DefNode
    collect_def_cvar_writes(node, qualified_prefix, default_scope, accumulator)
    return
  end

  node.compact_child_nodes.each do |child|
    walk_class_cvars(child, qualified_prefix, default_scope, accumulator)
  end
end

.walk_class_includes(node, qualified_prefix, current_class, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1062

def walk_class_includes(node, qualified_prefix, current_class, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      full = (qualified_prefix + [name]).join("::")
      walk_class_includes(node.body, qualified_prefix + [name], full, accumulator) if node.body
      return
    end
  when Prism::CallNode
    record_mixin_call(node, current_class, accumulator)
  end

  node.compact_child_nodes.each do |child|
    walk_class_includes(child, qualified_prefix, current_class, accumulator)
  end
end

.walk_class_ivars(node, qualified_prefix, default_scope, accumulator, mutated_ivars, read_before_write = nil, init_writes = nil) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 312

def walk_class_ivars(node, qualified_prefix, default_scope, accumulator, mutated_ivars,
                     read_before_write = nil, init_writes = nil)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      child_prefix = qualified_prefix + [name]
      if node.body
        # Class-body level `@x = nil` writes don't
        # initialise instance ivars at runtime (the
        # class's own singleton ivars and the instance's
        # ivars are separate stores), but they signal
        # "the author KNOWS @x could be nil" and extend
        # the B2.3 soundness gate: an ivar with a
        # class-body write is exempted from the
        # read-before-write nil contribution because the
        # seed already reflects the author's acknowledged
        # nullability via the def-body writes' union.
        # Without this exemption, code that explicitly
        # `@x = nil`s at class-body level then writes
        # `@x = SomeClass.new` inside an instance method
        # gains an unjustified nil widening at every
        # read.
        collect_class_body_ivar_writes(node.body, child_prefix.join("::"), init_writes) if init_writes
        walk_class_ivars(node.body, child_prefix, default_scope, accumulator,
                         mutated_ivars, read_before_write, init_writes)
      end
      return
    end
  when Prism::DefNode
    collect_def_ivar_writes(node, qualified_prefix, default_scope, accumulator,
                            mutated_ivars, read_before_write, init_writes)
    return
  end

  node.compact_child_nodes.each do |child|
    walk_class_ivars(child, qualified_prefix, default_scope, accumulator,
                     mutated_ivars, read_before_write, init_writes)
  end
end

.walk_class_superclasses(node, qualified_prefix, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 1018

def walk_class_superclasses(node, qualified_prefix, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode
    name = qualified_name_for(node.constant_path)
    if name
      full = (qualified_prefix + [name]).join("::")
      superclass = node.superclass && qualified_name_for(node.superclass)
      accumulator[full] = superclass if superclass
      walk_class_superclasses(node.body, qualified_prefix + [name], accumulator) if node.body
      return
    end
  when Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      walk_class_superclasses(node.body, qualified_prefix + [name], accumulator) if node.body
      return
    end
  end

  node.compact_child_nodes.each do |child|
    walk_class_superclasses(child, qualified_prefix, accumulator)
  end
end

.walk_conditional_ivar_writes(node, scope, class_name, accumulator, guarded_ivars, mutated_ivars = nil) ⇒ Object

Walk an ‘IfNode` / `UnlessNode` so writes inside the THEN body that look like defensive ivar initialisation gain a `nil` union in the seeded type. Without this, `@x = v unless @x` records `Constant` for `@x`, then the predicate folds to that same constant and `flow.always-truthy-condition` fires against a working program. Mirrors the existing skip for `@x ||= v` (`Prism::InstanceVariableOrWriteNode`, which the pre-pass does not seed at all).

Polarity-aware on purpose: only the THEN body picks up the guard. The ELSE branch of ‘if @x; …; else; @x = init; end` would otherwise be marked too — but that pattern (write @x in the else of `if @x`) is a separate idiom whose surrounding reads of `@x` would then surface a nil-receiver FP. The ELSE branch is left ungarded so those reads continue to type as they did before this fix.



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# File 'lib/rigor/inference/scope_indexer.rb', line 526

def walk_conditional_ivar_writes(node, scope, class_name, accumulator, guarded_ivars, mutated_ivars = nil)
  then_guards = then_body_guarded_ivars(node)
  then_guarded = then_guards.empty? ? guarded_ivars : (guarded_ivars | then_guards)

  gather_ivar_writes(node.predicate, scope, class_name, accumulator, guarded_ivars, mutated_ivars)
  if node.statements
    gather_ivar_writes(node.statements, scope, class_name, accumulator, then_guarded, mutated_ivars)
  end
  branch = node.is_a?(Prism::IfNode) ? node.subsequent : node.else_clause
  gather_ivar_writes(branch, scope, class_name, accumulator, guarded_ivars, mutated_ivars) if branch
end

.walk_constant_writes(node, qualified_prefix, default_scope, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 736

def walk_constant_writes(node, qualified_prefix, default_scope, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      child_prefix = qualified_prefix + [name]
      walk_constant_writes(node.body, child_prefix, default_scope, accumulator) if node.body
      return
    end
  when Prism::ConstantWriteNode
    record_constant_write(node, qualified_prefix, default_scope, accumulator, node.name.to_s)
    return
  when Prism::ConstantPathWriteNode
    full = qualified_name_for(node.target)
    record_constant_write(node, [], default_scope, accumulator, full) if full
    return
  end

  node.compact_child_nodes.each do |child|
    walk_constant_writes(child, qualified_prefix, default_scope, accumulator)
  end
end

.walk_def_nodes(node, qualified_prefix, in_singleton_class, accumulator) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 953

def walk_def_nodes(node, qualified_prefix, in_singleton_class, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      child_prefix = qualified_prefix + [name]
      walk_def_nodes(node.body, child_prefix, false, accumulator) if node.body
      return
    end
  when Prism::SingletonClassNode
    if node.body
      singleton_prefix = singleton_class_prefix(node, qualified_prefix)
      if singleton_prefix
        walk_def_nodes(node.body, singleton_prefix, true, accumulator)
        return
      end
    end
  when Prism::ConstantWriteNode
    if meta_new_block_body(node)
      child_prefix = qualified_prefix + [node.name.to_s]
      walk_def_nodes(meta_new_block_body(node), child_prefix, false, accumulator)
      return
    end
  when Prism::DefNode
    record_def_node(node, qualified_prefix, in_singleton_class, accumulator)
    return
  end

  node.compact_child_nodes.each do |child|
    walk_def_nodes(child, qualified_prefix, in_singleton_class, accumulator)
  end
end

.walk_method_visibilities(node, qualified_prefix, in_singleton_class, current_visibility, accumulator) ⇒ Object

rubocop:disable Metrics/CyclomaticComplexity, Metrics/MethodLength, Metrics/PerceivedComplexity, Metrics/AbcSize



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# File 'lib/rigor/inference/scope_indexer.rb', line 1122

def walk_method_visibilities(node, qualified_prefix, in_singleton_class, current_visibility, accumulator)
  return current_visibility unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      child_prefix = qualified_prefix + [name]
      walk_method_visibilities(node.body, child_prefix, false, :public, accumulator) if node.body
      return current_visibility
    end
  when Prism::SingletonClassNode
    if node.body
      singleton_prefix = singleton_class_prefix(node, qualified_prefix)
      if singleton_prefix
        walk_method_visibilities(node.body, singleton_prefix, true, :public, accumulator)
        return current_visibility
      end
    end
  when Prism::ConstantWriteNode
    if meta_new_block_body(node)
      child_prefix = qualified_prefix + [node.name.to_s]
      walk_method_visibilities(meta_new_block_body(node), child_prefix, false, :public, accumulator)
      return current_visibility
    end
  when Prism::DefNode
    record_def_visibility(node, qualified_prefix, in_singleton_class, current_visibility, accumulator)
    return current_visibility
  when Prism::CallNode
    updated = apply_visibility_call(node, qualified_prefix, current_visibility, accumulator)
    return updated unless updated.equal?(current_visibility)
  end

  # Statement-position StatementsNode preserves
  # left-to-right visibility flow; everything else
  # recurses with the entry visibility unchanged.
  if node.is_a?(Prism::StatementsNode)
    local_visibility = current_visibility
    node.compact_child_nodes.each do |child|
      local_visibility = walk_method_visibilities(child, qualified_prefix, in_singleton_class,
                                                  local_visibility, accumulator)
    end
  else
    node.compact_child_nodes.each do |child|
      walk_method_visibilities(child, qualified_prefix, in_singleton_class, current_visibility, accumulator)
    end
  end
  current_visibility
end

.walk_methods(node, qualified_prefix, in_singleton_class, accumulator) ⇒ Object

rubocop:disable Metrics/CyclomaticComplexity, Metrics/MethodLength



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# File 'lib/rigor/inference/scope_indexer.rb', line 800

def walk_methods(node, qualified_prefix, in_singleton_class, accumulator)
  return unless node.is_a?(Prism::Node)

  case node
  when Prism::ClassNode, Prism::ModuleNode
    name = qualified_name_for(node.constant_path)
    if name
      child_prefix = qualified_prefix + [name]
      walk_methods(node.body, child_prefix, false, accumulator) if node.body
      return
    end
  when Prism::SingletonClassNode
    if node.body
      singleton_prefix = singleton_class_prefix(node, qualified_prefix)
      if singleton_prefix
        walk_methods(node.body, singleton_prefix, true, accumulator)
        return
      end
    end
  when Prism::ConstantWriteNode
    if meta_new_block_body(node)
      child_prefix = qualified_prefix + [node.name.to_s]
      walk_methods(meta_new_block_body(node), child_prefix, false, accumulator)
      return
    end
  when Prism::DefNode
    record_def_method(node, qualified_prefix, in_singleton_class, accumulator)
    return
  when Prism::AliasMethodNode
    record_alias_method(node, qualified_prefix, in_singleton_class, accumulator)
    return
  when Prism::CallNode
    record_define_method(node, qualified_prefix, in_singleton_class, accumulator) if node.name == :define_method
  end

  node.compact_child_nodes.each do |child|
    walk_methods(child, qualified_prefix, in_singleton_class, accumulator)
  end
end

.widen_member_for_observed_mutators(member, observed_methods) ⇒ Object 



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# File 'lib/rigor/inference/scope_indexer.rb', line 296

def widen_member_for_observed_mutators(member, observed_methods)
  case member
  when Type::Tuple
    return member unless observed_methods.any? { |m| MutationWidening::ARRAY_MUTATORS.include?(m) }

    Type::Combinator.nominal_of("Array", type_args: [Type::Combinator.untyped])
  when Type::HashShape
    return member unless observed_methods.any? { |m| MutationWidening::HASH_MUTATORS.include?(m) }

    Type::Combinator.nominal_of("Hash",
                                type_args: [Type::Combinator.untyped, Type::Combinator.untyped])
  else
    member
  end
end

.widen_mutated_ivar_entries!(accumulator, mutated_ivars) ⇒ Object

Walks the post-collected accumulator and widens any Tuple / HashShape entry for an ivar that observed a mutator call anywhere in the same class body. The mutation evidence comes from ‘gather_ivar_writes` recording every `@ivar.<method>(…)` call whose method is in `MutationWidening::ARRAY_MUTATORS` or `HASH_MUTATORS`.

The widening uses ‘MutationWidening.widen_for_mutator` —the same primitive `Inference::StatementEvaluator#eval_call` applies for per-method-body widening on a local / ivar receiver. The class-level pass extends that primitive’s reach so a ‘Tuple`-seeded ivar in `initialize` is observed as `Nominal` at the entry of every OTHER method body in the class — closing the cross-method gap noted in ROADMAP § Future cycles / Type-language / engine (“Tuple / HashShape widening for ivar-seeded literals after mutation”; Redmine 6.1.2 `Redmine::Views::Builders::Structure` is the canonical worked site).

Always-safe: the widening can only LOSE precision; the underlying nominal (‘Array` / `Hash`) and the element union are preserved.



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# File 'lib/rigor/inference/scope_indexer.rb', line 261

def widen_mutated_ivar_entries!(accumulator, mutated_ivars)
  accumulator.each do |class_name, ivars|
    observed = mutated_ivars[class_name]
    next if observed.nil? || observed.empty?

    ivars.each do |ivar_name, type|
      methods = observed[ivar_name]
      next if methods.nil? || methods.empty?

      ivars[ivar_name] = widen_type_for_observed_mutators(type, methods)
    end
  end
end

.widen_type_for_observed_mutators(type, observed_methods) ⇒ Object

Walks a class-ivar accumulator entry (which may be a ‘Union` of multiple write rvalues) and widens any `Tuple` or `HashShape` member whose corresponding mutator family was observed against the ivar somewhere in the class. Class-level widening is more aggressive than the per-method-body `MutationWidening` primitive: it widens both the SHAPE carrier (Tuple → Array, HashShape → Hash) AND the element types to `Dynamic`. The justification — once any method mutates the ivar, its post-mutation contents are statically unknown across method boundaries, so preserving the seed-write’s element precision would be an unsound over-claim (e.g. ‘@struct = [{}]; somewhere: `Constant`).



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# File 'lib/rigor/inference/scope_indexer.rb', line 290

def widen_type_for_observed_mutators(type, observed_methods)
  members = type.is_a?(Type::Union) ? type.members : [type]
  widened = members.map { |m| widen_member_for_observed_mutators(m, observed_methods) }
  Type::Combinator.union(*widened)
end