java-topology/tools/tickets/defects/rubocop-0002.md

id	repo	severity	status	created
rubocop-0002	RuboCop	LOW	OPEN	2026-03-26

Defect

File: lib/rubocop/cop/style/redundant_self.rb:62,149 Pattern: @allowed_send_nodes = [] — Array linear scan on every self.x send node Complexity: O(A × N) per file, where A = self-assignment nodes, N = self-send nodes Language: Ruby

Description

Style::RedundantSelf tracks nodes representing self.x = / self.x ||= / self.x &&= assignments in @allowed_send_nodes:

# line 62
@allowed_send_nodes = []

# line 190 — populated on every self.x assignment node
def allow_self(node)
  @allowed_send_nodes << node
end

# line 149 — queried on every self.x send node during on_send
def allowed_send_node?(node)
  @allowed_send_nodes.include?(node) || ...
end

on_send fires for every send node in the AST. allowed_send_node? calls @allowed_send_nodes.include?(node) (identity comparison via Array#include?) — O(A) per call, O(A × N) total.

In practice, A is small for typical Ruby code, keeping this LOW. In generated or DSL-heavy code with many self.attr= writers the list can grow and the cost compounds.

Fix

# line 62
@allowed_send_nodes = Set.new.compare_by_identity

# line 190
@allowed_send_nodes.add(node)

# line 149 — no change needed; Set#include? is O(1)

Speedup estimate

Negligible on typical Ruby source; 2–5× faster on generated files with many self-assignments.

Work required

• Patch in defects/rubocop/patch/
• Unit test
• Integration test
• Benchmark
• White paper section (can be grouped with rubocop-0001)