From d1cefb2c9bbc29e61797e9027229dc5cf559953c Mon Sep 17 00:00:00 2001
From: David Greenspan <dgreenspan@alum.mit.edu>
Date: Wed, 28 Jan 2015 14:18:21 -0800
Subject: [PATCH] Improve cost function

It's still not really correct to do it this way, but it passes the
existing tests now.

In particular, we now prioritize making top-level dependencies
newer over making indirect dependencies older.  However, this
approach is flawed because we only visit the packages in the
original solution, before optimization.  We should assign a cost
to every package version that might be chosen, and let the solver
shift things around arbitrarily.
---
 packages/constraint-solver/constraint-solver.js | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/packages/constraint-solver/constraint-solver.js b/packages/constraint-solver/constraint-solver.js
index 32d2b65961..58dc4e5cb0 100644
--- a/packages/constraint-solver/constraint-solver.js
+++ b/packages/constraint-solver/constraint-solver.js
@@ -167,7 +167,17 @@ var newResolveWithInput = function (input, _nudge) {
           }
           return false;
         });
-      } else {
+      }
+    }
+  });
+  _.each(solution.getTrueVars(), function (x) {
+    if (x.indexOf(' ') >= 0) {
+      var pv = CS.PackageAndVersion.fromString(x);
+      var package = pv.package;
+      var version = pv.version;
+      var otherVersions = cache.getPackageVersions(package); // sorted
+
+      if (! _.has(rootDeps, package)) {
         // try to make older
         otherVersions = _.clone(otherVersions);
         otherVersions.reverse();