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java-topology/defects/efcore/patch/efcore-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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efcore diamond recursion scan — CLEAN

Scanned: 2026-03-29 Scope: diamond recursion / CWE-407 in migration dependency graph traversal

Files checked

  • src/Shared/Multigraph.cs — Kahn's algorithm (BFS topological sort) using Dictionary<TVertex, Dictionary<TVertex, object?>> for _successorMap and _predecessorMap. predecessorCounts is a Dictionary<TVertex, int>. All O(1) hash operations, no Array linear scans. Clean.
  • src/EFCore/Migrations/ — delegates to Multigraph. Clean.
  • src/EFCore.Relational/Metadata/Internal/Sequence.cs — IsCyclic is a sequence property (CYCLE/NO CYCLE SQL option), not graph cycle detection. Clean.

Verdict

CLEAN. All topology code uses Kahn's BFS with Dictionary-based O(1) lookups. No diamond recursion pattern. EFCore already has 3 previous defects (0001-0003) in different subsystems.