From 7d295c594e1d100c9dcbdd89198eb3882856cfcb Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 4 Jun 2024 16:05:56 +0200
Subject: [PATCH] Make EvalState::srcToStore thread-safe

---
 src/libexpr/eval.cc | 8 ++++----
 src/libexpr/eval.hh | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 6a38bbe45..7dbb467e5 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -2415,10 +2415,10 @@ StorePath EvalState::copyPathToStore(NixStringContext & context, const SourcePat
     if (nix::isDerivation(path.path.abs()))
         error<EvalError>("file names are not allowed to end in '%1%'", drvExtension).debugThrow();
 
-    auto i = srcToStore.find(path);
+    auto dstPathCached = get(*srcToStore.lock(), path);
 
-    auto dstPath = i != srcToStore.end()
-        ? i->second
+    auto dstPath = dstPathCached
+        ? *dstPathCached
         : [&]() {
             auto dstPath = fetchToStore(
                 *store,
@@ -2429,7 +2429,7 @@ StorePath EvalState::copyPathToStore(NixStringContext & context, const SourcePat
                 nullptr,
                 repair);
             allowPath(dstPath);
-            srcToStore.insert_or_assign(path, dstPath);
+            srcToStore.lock()->try_emplace(path, dstPath);
             printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, store->printStorePath(dstPath));
             return dstPath;
         }();
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 06a687620..dac763268 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -306,7 +306,7 @@ private:
 
     /* Cache for calls to addToStore(); maps source paths to the store
        paths. */
-    std::map<SourcePath, StorePath> srcToStore;
+    Sync<std::map<SourcePath, StorePath>> srcToStore;
 
     /**
      * A cache from path names to parse trees.