From 5eebcf46fe05731f964818912e8debddb72a545c Mon Sep 17 00:00:00 2001
From: Bernardo Meurer Costa <beme@anthropic.com>
Date: Sat, 11 Oct 2025 19:34:58 +0000
Subject: [PATCH] refactor(libstore/find-cycles): remove unused hashPathMap
 parameter

The `hashPathMap` was being passed to `CycleEdgeScanSink` and stored as
a member variable, but was never actually used. The sink only needs the
hash strings for detection via `RefScanSink`, not the full `StorePath`
mapping.
---
 src/libstore/build/find-cycles.cc | 14 ++++----------
 src/libstore/build/find-cycles.hh |  3 +--
 2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/src/libstore/build/find-cycles.cc b/src/libstore/build/find-cycles.cc
index 4eb4a604d..d4562896c 100644
--- a/src/libstore/build/find-cycles.cc
+++ b/src/libstore/build/find-cycles.cc
@@ -15,10 +15,8 @@ namespace nix {
 // Hash length in characters (32 for base32-encoded sha256)
 static constexpr size_t refLength = StorePath::HashLen;
 
-CycleEdgeScanSink::CycleEdgeScanSink(
-    StringSet && hashes, std::map<std::string, StorePath> && backMap, std::string storeDir)
+CycleEdgeScanSink::CycleEdgeScanSink(StringSet && hashes, std::string storeDir)
     : RefScanSink(std::move(hashes))
-    , hashPathMap(std::move(backMap))
     , storeDir(std::move(storeDir))
 {
 }
@@ -62,7 +60,6 @@ StoreCycleEdgeVec && CycleEdgeScanSink::getEdges()
 void scanForCycleEdges(const Path & path, const StorePathSet & refs, StoreCycleEdgeVec & edges)
 {
     StringSet hashes;
-    std::map<std::string, StorePath> hashPathMap;
 
     // Extract the store directory from the path
     // Example: /run/user/1000/nix-test/store/abc-foo -> /run/user/1000/nix-test/store/
@@ -73,16 +70,13 @@ void scanForCycleEdges(const Path & path, const StorePathSet & refs, StoreCycleE
     debug("scanForCycleEdges: storePrefixPath = %s", storePrefixPath.string());
     debug("scanForCycleEdges: storePrefix = %s", storePrefix);
 
-    // Build map of hash -> StorePath and collect hashes to search for
+    // Collect hashes to search for
     for (auto & i : refs) {
-        std::string hashPart(i.hashPart());
-        auto inserted = hashPathMap.emplace(hashPart, i).second;
-        assert(inserted);
-        hashes.insert(hashPart);
+        hashes.insert(std::string(i.hashPart()));
     }
 
     // Create sink that reuses RefScanSink's hash-finding logic
-    CycleEdgeScanSink sink(std::move(hashes), std::move(hashPathMap), storePrefix);
+    CycleEdgeScanSink sink(std::move(hashes), storePrefix);
 
     // Walk the filesystem and scan files using the sink
     scanForCycleEdges2(path, sink);
diff --git a/src/libstore/build/find-cycles.hh b/src/libstore/build/find-cycles.hh
index dd38b1fea..ed773dcbe 100644
--- a/src/libstore/build/find-cycles.hh
+++ b/src/libstore/build/find-cycles.hh
@@ -35,7 +35,6 @@ typedef std::vector<StoreCycleEdge> StoreCycleEdgeVec;
 class CycleEdgeScanSink : public RefScanSink
 {
     std::string currentFilePath;
-    std::map<std::string, StorePath> hashPathMap;
     std::string storeDir;
 
     // Track hashes we've already recorded for current file
@@ -45,7 +44,7 @@ class CycleEdgeScanSink : public RefScanSink
 public:
     StoreCycleEdgeVec edges;
 
-    CycleEdgeScanSink(StringSet && hashes, std::map<std::string, StorePath> && backMap, std::string storeDir);
+    CycleEdgeScanSink(StringSet && hashes, std::string storeDir);
 
     /**
      * Set the current file path being scanned.