Module: Rigor::Inference::ClosureEscapeAnalyzer

Defined in:

lib/rigor/inference/closure_escape_analyzer.rb

Overview

Slice 6 phase C sub-phase 3a — closure-escape classification.

Given a ‘(receiver_type, method_name)` pair representing a block-accepting call, this analyzer answers one question: does the receiver’s method invoke its block **immediately and synchronously**, without retaining the block past the call?

The answer is one of three outcomes:

• ‘:non_escaping` — the block is proven to be invoked immediately, zero or more times, and is NOT retained past the call. The receiver does not store the block in an instance variable, return it as a value, or schedule it for later invocation. Outer-local narrowing facts that survive the block body MAY safely survive the call.

• ‘:escaping` — the block is proven to be retained past the call (stored, returned, or invoked asynchronously). Outer narrowing facts on locals the block can rebind MUST be dropped at the call boundary.

• ‘:unknown` — the analyzer cannot prove either edge. Callers MUST treat `:unknown` as conservatively as `:escaping` for the purposes of fact retention; the distinction exists so diagnostics and later RBS-Extended effect plumbing can tell “deliberately conservative” apart from “declared escape”.

## Catalogue

Sub-phase 3a is RBS-blind: it ships a hardcoded catalogue keyed by Ruby class name. A future sub-phase will replace this with an ‘RBS::Extended` call-timing effect read from method signatures. The catalogue therefore covers ONLY the core-and-stdlib surface where immediate invocation is part of the documented contract:

• ‘Array`, `Hash`, `Range`, `Integer`, `Enumerator::Lazy` iteration methods (`each`, `map`, `select`, `reject`, `flat_map`, `find`/`detect`, `any?`, `all?`, `none?`, `one?`, `count`, `inject`/`reduce`, `each_with_index`, `each_with_object`, `min_by`, `max_by`, `sort_by`, `partition`, `group_by`, `tally`, `sum`, `take_while`, `drop_while`, `chunk_while`, `slice_when`, `zip`, `collect`, `collect_concat`, `filter`, `filter_map`).

• ‘Hash`-only iteration: `each_pair`, `each_key`, `each_value`, `transform_keys`, `transform_values`.

• ‘Integer#times`, `Integer#upto`, `Integer#downto`, `Range#each`, `Range#step`.

• ‘Object#tap`, `Object#then`, `Object#yield_self`.

• Tuple/HashShape carriers map to Array/Hash for catalogue lookup so a literal ‘[1, 2, 3].each { … }` is recognised.

Anything outside the catalogue resolves to ‘:unknown`. The catalogue is intentionally narrow: adding entries requires confirming, by reading the method’s stdlib documentation, that the block is not retained. False positives in this catalogue would silently weaken the soundness of fact retention in later sub-phases.

The analyzer is a pure query. It MUST NOT mutate the receiver type or scope, MUST NOT raise on unrecognised inputs, and MUST be deterministic for a given input.

Constant Summary

OBJECT_NON_ESCAPING =

%i[tap then yield_self].freeze

ENUMERABLE_NON_ESCAPING =

%i[
  each map collect flat_map collect_concat
  select filter reject filter_map
  find detect find_index find_all
  any? all? none? one? count tally sum
  inject reduce
  each_with_index each_with_object
  min_by max_by sort_by minmax_by
  partition group_by chunk chunk_while slice_when slice_before slice_after
  take_while drop_while
  zip
].freeze

ARRAY_EXTRA =

%i[each_index].freeze

HASH_EXTRA =

%i[
  each_pair each_key each_value
  transform_keys transform_values
  delete_if keep_if
  any? all? none? one?
].freeze

RANGE_EXTRA =

%i[step].freeze

INTEGER_EXTRA =

%i[times upto downto].freeze

NON_ESCAPING =

{
  "Array" => (ENUMERABLE_NON_ESCAPING + ARRAY_EXTRA).freeze,
  "Hash" => (ENUMERABLE_NON_ESCAPING + HASH_EXTRA).freeze,
  "Range" => (ENUMERABLE_NON_ESCAPING + RANGE_EXTRA).freeze,
  "Set" => ENUMERABLE_NON_ESCAPING,
  "Integer" => INTEGER_EXTRA,
  "Enumerator" => ENUMERABLE_NON_ESCAPING,
  "Enumerator::Lazy" => ENUMERABLE_NON_ESCAPING
}.freeze

ESCAPING =

Methods that are documented to retain the block past the call. The block is stored or scheduled, so outer narrowing facts on writeable captured locals cannot survive.

{
  "Module" => %i[define_method].freeze,
  "Class" => %i[define_method].freeze,
  "Thread" => %i[new start fork].freeze,
  "Fiber" => %i[new].freeze,
  "Proc" => %i[new].freeze
}.freeze

Class Method Summary

• .classify(receiver_type:, method_name:, environment: nil) ⇒ Symbol

  One of ‘:non_escaping`, `:escaping`, `:unknown`.

Class Method Details

.classify(receiver_type:, method_name:, environment: nil) ⇒ Symbol

Returns one of ‘:non_escaping`, `:escaping`, `:unknown`.

Parameters:

• receiver_type (Rigor::Type, nil)
• method_name (Symbol)
• environment (Rigor::Environment, nil) (defaults to: nil) —

  reserved for the future sub-phase that consults ‘RBS::Extended` call-timing effects; sub-phase 3a ignores it.

Returns:

• (Symbol) —

  one of ‘:non_escaping`, `:escaping`, `:unknown`.

# File 'lib/rigor/inference/closure_escape_analyzer.rb', line 77

def classify(receiver_type:, method_name:, environment: nil) # rubocop:disable Lint/UnusedMethodArgument
  return :unknown if receiver_type.nil?

  class_name = receiver_class_name(receiver_type)
  return :unknown if class_name.nil?

  method_sym = method_name.to_sym
  return :non_escaping if non_escaping?(class_name, method_sym)
  return :escaping if escaping?(class_name, method_sym)

  :unknown
end