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java-topology/defects/sqlalchemy/patch/sqlalchemy-diamond-recursion-CLEAN.md
russell@unturf.com 3986d8dc50 diamond hunt: godot-0009/0010 + meson-0002 + typeorm-0004/0005 + ts-0003; count 629→635 
New diamond recursion defects (O(2^D) → O(N)):
- godot-0009: Font::_is_cyclic no visited set — CJK fallback diamond, 2648x at F=4,D=8
- godot-0010: Font::_update_rids_fb no visited set — duplicate RIDs + O(N^2) hot path
- meson-0002: get_internal_static_libraries_recurse link_whole guard missing — 132x at D=10
- typescript-0003: hasBaseType inner check() no visited set — 1024x at D=10; hot on instanceof

New O(N²) defects:
- typeorm-0004: SubjectTopologicalSorter Array.indexOf dedup — 200x at N=400
- typeorm-0005: DepGraph.createDFS result.indexOf + addDependency edge dedup — 300x at N=600

CLEAN confirmed (diamond recursion sweep): bazel, cargo, cmake, composer, dgl, diesel,
doctrine-orm, efcore, helm, mybatis, networkx-deeper, ninja, npm-arborist, peewee, pip,
rubygems, seaorm, sqlalchemy, swift

UNDF: 571→578 assigned; MOAD count: 629→635
2026-03-29 16:52:04 -04:00

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sqlalchemy diamond recursion scan — CLEAN

Scanned: 2026-03-29 Scope: diamond recursion / CWE-407 in topological sort

Files checked

  • lib/sqlalchemy/util/topological.py:sort_as_subsets() — Kahn's algorithm using todo_set (a set) and edges (a defaultdict(set)). todo_set.isdisjoint(edges[node]) is O(min(|todo_set|, |edges[node]|)) using set intersection. Clean.
  • lib/sqlalchemy/util/topological.py:find_cycles() — iterative DFS using a stack and todo set; no recursion, no unbounded revisits. Clean.
  • lib/sqlalchemy/orm/dependency.py — delegates to topological module above. Clean.

Verdict

CLEAN. Topological sort is iterative Kahn's algorithm with set-based membership throughout. find_cycles is an iterative DFS with a proper todo set.