fix corner case in `mangle` (#4961)

fixes #4960

1 files changed, 2 insertions, 3 deletions

diff --git a/lib/scope.js b/lib/scope.js
index 466ab8d6..c74c494a 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -70,9 +70,7 @@ SymbolDef.prototype = {
         } else if (!this.mangled_name && !this.unmangleable(options)) {
             var def = this.redefined();
             if (def) {
-                var name = def.mangled_name || def.name;
-                this.mangled_name = name;
-                names_in_use(this.scope, options)[name] = true;
+                this.mangled_name = def.mangled_name || def.name;
             } else {
                 this.mangled_name = next_mangled_name(this, options);
             }
@@ -683,6 +681,7 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
             redef = scope.def_variable(sym);
             scope.to_mangle.push(redef);
         } else if (redef.mangled_name) {
+            names_in_use(def.scope, options)[redef.mangled_name] = true;
             return false;
         }
         redefined.push(def);