2 files changed, 26 insertions, 0 deletions
diff --git a/src/libcmd/built-path.cc b/src/libcmd/built-path.cc
index c6cc7fa9c..9a2dce806 100644
--- a/src/libcmd/built-path.cc
+++ b/src/libcmd/built-path.cc
@@ -58,6 +58,28 @@ StorePathSet BuiltPath::outPaths() const
     );
 }
 
+SingleDerivedPath::Built SingleBuiltPath::Built::discardOutputPath() const
+{
+    return SingleDerivedPath::Built {
+        .drvPath = make_ref<SingleDerivedPath>(drvPath->discardOutputPath()),
+        .output = output.first,
+    };
+}
+
+SingleDerivedPath SingleBuiltPath::discardOutputPath() const
+{
+    return std::visit(
+        overloaded{
+            [](const SingleBuiltPath::Opaque & p) -> SingleDerivedPath {
+                return p;
+            },
+            [](const SingleBuiltPath::Built & b) -> SingleDerivedPath {
+                return b.discardOutputPath();
+            },
+        }, raw()
+    );
+}
+
 nlohmann::json BuiltPath::Built::toJSON(const Store & store) const
 {
     nlohmann::json res;
diff --git a/src/libcmd/built-path.hh b/src/libcmd/built-path.hh
index 747bcc440..e677bc810 100644
--- a/src/libcmd/built-path.hh
+++ b/src/libcmd/built-path.hh
@@ -9,6 +9,8 @@ struct SingleBuiltPathBuilt {
     ref<SingleBuiltPath> drvPath;
     std::pair<std::string, StorePath> output;
 
+    SingleDerivedPathBuilt discardOutputPath() const;
+
     std::string to_string(const Store & store) const;
     static SingleBuiltPathBuilt parse(const Store & store, std::string_view, std::string_view);
     nlohmann::json toJSON(const Store & store) const;
@@ -34,6 +36,8 @@ struct SingleBuiltPath : _SingleBuiltPathRaw {
 
     StorePath outPath() const;
 
+    SingleDerivedPath discardOutputPath() const;
+
     static SingleBuiltPath parse(const Store & store, std::string_view);
     nlohmann::json toJSON(const Store & store) const;
 };