fix corner case in `merge_vars` (#4151)

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 883345b6..517f29fd 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4331,7 +4331,7 @@ merge(Compressor.prototype, {
 
     AST_Scope.DEFMETHOD("merge_variables", function(compressor) {
         if (!compressor.option("merge_vars")) return;
-        var self = this, segment = {};
+        var self = this, segment = {}, root;
         var first = [], last = [], index = 0;
         var declarations = new Dictionary();
         var references = Object.create(null);
@@ -4414,10 +4414,8 @@ merge(Compressor.prototype, {
             if (node instanceof AST_Scope) {
                 push();
                 segment.block = node;
-                if (node instanceof AST_Lambda && node.name) {
-                    if (node !== self) segment.loop = true;
-                    references[node.name.definition().id] = false;
-                }
+                if (node === self) root = segment;
+                if (node instanceof AST_Lambda && node.name) references[node.name.definition().id] = false;
                 descend();
                 pop();
                 return true;
@@ -4563,7 +4561,8 @@ merge(Compressor.prototype, {
                         definition: def,
                     });
                 }
-                refs.start = self;
+                if (segment.block !== self) return references[def.id] = false;
+                refs.start = root;
             }
             prev[def.id] = last.length;
             last.push({