* Don't forget to apply the rewritten paths to the hash rewrite map

that's applied to the environment variables / command-line
  arguments.  Otherwise the builder will still use the unconsolidated
  paths.

src/libstore/build.cc

@@ -988,10 +988,27 @@ bool DerivationGoal::prepareBuild()
        different input closures might contain different paths from the
        *same* output path equivalence class.  We should pick one from
        each, and rewrite dependent paths. */
-    inputPaths = consolidatePaths(inputPaths, false);
+    Replacements replacements;
+    inputPaths = consolidatePaths(inputPaths, false, replacements);
 
+    HashRewrites rewrites2;
+    for (Replacements::iterator i = replacements.begin();
+         i != replacements.end(); ++i)
+    {
+        printMsg(lvlError, format("FOO %1% %2%")
+            % i->first % i->second);
+        printMsg(lvlError, format("HASH REWRITE %1% %2%")
+            % hashPartOf(i->first).toString() % hashPartOf(i->second).toString());
+        rewrites2[hashPartOf(i->first)] = hashPartOf(i->second);
+    }
+
+    for (HashRewrites::iterator i = rewrites.begin();
+         i != rewrites.end(); ++i)
+        rewrites[i->first] = PathHash(rewriteHashes(i->second.toString(), rewrites2));
+    
     /* !!! remove, debug only */
-    consolidatePaths(inputPaths, true);
+    Replacements dummy;
+    consolidatePaths(inputPaths, true, dummy);
     
     printMsg(lvlError, format("added input paths %1%") % showPaths(inputPaths)); /* !!! */
 

src/libstore/misc.cc

@@ -104,9 +104,12 @@ static void findBestRewrite(const ClassMap::const_iterator & pos,
 
 
 static Path maybeRewrite(const Path & path, const PathSet & selection,
-    const FinalClassMap & finalClassMap)
+    const FinalClassMap & finalClassMap,
+    Replacements & replacements)
 {
     assert(selection.find(path) != selection.end());
+
+    if (replacements.find(path) != replacements.end()) return replacements[path];
     
     PathSet references;
     queryReferences(noTxn, path, references);
@@ -131,7 +134,8 @@ static Path maybeRewrite(const Path & path, const PathSet & selection,
 
                 printMsg(lvlError, format("replacing with `%1%'") % j->second);
                 
-                Path newPath = maybeRewrite(j->second, selection, finalClassMap);
+                Path newPath = maybeRewrite(j->second, selection,
+                    finalClassMap, replacements);
                 if (*i != newPath)
                     rewrites[hashPartOf(*i)] = hashPartOf(newPath);
             }
@@ -148,11 +152,14 @@ static Path maybeRewrite(const Path & path, const PathSet & selection,
 
     printMsg(lvlError, format("rewrote `%1%' to `%2%'") % path % newPath);
 
+    replacements[path] = newPath;
+        
     return newPath;
 }
 
 
-PathSet consolidatePaths(const PathSet & paths, bool checkOnly)
+PathSet consolidatePaths(const PathSet & paths, bool checkOnly,
+    Replacements & replacements)
 {
     printMsg(lvlError, format("consolidating"));
     
@@ -199,9 +206,10 @@ PathSet consolidatePaths(const PathSet & paths, bool checkOnly)
                 finalClassMap[i->first] = *j;
 
     PathSet newPaths;
+    replacements.clear();
     for (PathSet::iterator i = bestSelection.begin();
          i != bestSelection.end(); ++i)
-        newPaths.insert(maybeRewrite(*i, bestSelection, finalClassMap));
+        newPaths.insert(maybeRewrite(*i, bestSelection, finalClassMap, replacements));
     
     return newPaths;
 }

src/libstore/misc.hh

@@ -33,7 +33,10 @@ Path findTrustedEqClassMember(const OutputEqClass & eqClass,
     const TrustId & trustId);
 
 
-PathSet consolidatePaths(const PathSet & paths, bool checkOnly);
+typedef map<Path, Path> Replacements;
+
+PathSet consolidatePaths(const PathSet & paths, bool checkOnly,
+    Replacements & replacements);
 
 
 #endif /* !__MISC_H */