js optimizer fix, and remove assigns to undefined in library

2 files changed, 12 insertions, 1 deletions

diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index bc993eae..5aeee636 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -160,7 +160,6 @@ function unGlobalize(ast) {
 // This pass assumes that unGlobalize has been run, so undefined
 // is now explicit.
 function removeAssignsToUndefined(ast) {
-  // TODO: in vars too
   traverse(ast, function(node, type) {
     if (type == 'assign' && jsonCompare(node[3], ['unary-prefix', 'void', ['num', 0]])) {
       return emptyNode();
@@ -173,6 +172,17 @@ function removeAssignsToUndefined(ast) {
       });
     }
   });
+  // cleanup (|x = y = void 0| leaves |x = ;| right now)
+  var modified = true;
+  while (modified) {
+    modified = false;
+    traverse(ast, function(node, type) {
+      if (type == 'assign' && jsonCompare(node[3], emptyNode())) {
+        modified = true;
+        return emptyNode();
+      }
+    });
+  }
 }
 
 // Main
diff --git a/tools/test-js-optimizer.js b/tools/test-js-optimizer.js
index 042f4cf9..05e574f9 100644
--- a/tools/test-js-optimizer.js
+++ b/tools/test-js-optimizer.js
@@ -7,6 +7,7 @@ function abc() {
   var fleefl;
   cheez = 10;
   fleefl = x;
+  fleefl = cheez = x;
   var waka = x, flake = x, marfoosh = x;
   var waka2 = 5, flake2 = x, marfoosh2 = x;
   var waka3 = x, flake3 = 5, marfoosh3 = x;