From 408a7bfac1f4282ff6647696dfbc7988eed3a2ca Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <eelco.dolstra@logicblox.com>
Date: Mon, 26 Nov 2012 17:39:09 +0100
Subject: nix-instantiate: Fix read-only evaluation

---
 src/nix-instantiate/nix-instantiate.cc | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

(limited to 'src/nix-instantiate')

diff --git a/src/nix-instantiate/nix-instantiate.cc b/src/nix-instantiate/nix-instantiate.cc
index a5053c32376d..53cd711895ff 100644
--- a/src/nix-instantiate/nix-instantiate.cc
+++ b/src/nix-instantiate/nix-instantiate.cc
@@ -62,16 +62,9 @@ void processExpr(EvalState & state, const Strings & attrPaths,
                     Path drvPath = i->queryDrvPath(state);
 
                     /* What output do we want? */
-                    Path outPath = i->queryOutPath(state);
-                    Derivation drv = derivationFromPath(*store, drvPath);
-                    string outputName;
-                    foreach (DerivationOutputs::iterator, i, drv.outputs)
-                        if (i->second.path == outPath) {
-                            outputName = i->first;
-                            break;
-                        }
+                    string outputName = i->queryOutputName(state);
                     if (outputName == "")
-                        throw Error(format("derivation `%1%' does not have an output `%2%'") % drvPath % outPath);
+                        throw Error(format("derivation `%1%' lacks an `outputName' attribute ") % drvPath);
 
                     if (gcRoot == "")
                         printGCWarning();
-- 
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