1 files changed, 10 insertions, 0 deletions
diff --git a/src/libstore/realisation.hh b/src/libstore/realisation.hh
index fa53fc487..9429c7004 100644
--- a/src/libstore/realisation.hh
+++ b/src/libstore/realisation.hh
@@ -96,4 +96,14 @@ struct RealisedPath {
     GENERATE_CMP(RealisedPath, me->raw);
 };
 
+class MissingRealisation : public Error
+{
+public:
+    MissingRealisation(DrvOutput & outputId)
+        : Error( "cannot operate on an output of the "
+                "unbuilt derivation '%s'",
+                outputId.to_string())
+    {}
+};
+
 }