fix `mangle` of `AST_SymbolLambda` under `ie8` (#2978)

fixes #2976

1 files changed, 5 insertions, 7 deletions

diff --git a/lib/scope.js b/lib/scope.js
index 9a8e25cc..baa3e8bd 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -74,17 +74,12 @@ SymbolDef.prototype = {
         var cache = options.cache && options.cache.props;
         if (this.global && cache && cache.has(this.name)) {
             this.mangled_name = cache.get(this.name);
-        }
-        else if (!this.mangled_name && !this.unmangleable(options)) {
-            var s = this.scope;
-            var sym = this.orig[0];
-            if (options.ie8 && sym instanceof AST_SymbolLambda)
-                s = s.parent_scope;
+        } else if (!this.mangled_name && !this.unmangleable(options)) {
             var def;
             if (def = this.redefined()) {
                 this.mangled_name = def.mangled_name || def.name;
             } else {
-                this.mangled_name = next_mangled_name(s, options, this);
+                this.mangled_name = next_mangled_name(this.scope, options, this);
             }
             if (this.global && cache) {
                 cache.set(this.name, this.mangled_name);
@@ -377,6 +372,9 @@ function next_mangled_name(scope, options, def) {
         holes.push(scope.cname);
     }
     scope.names_in_use[name] = true;
+    if (options.ie8 && def.orig[0] instanceof AST_SymbolLambda) {
+        names_in_use(scope.parent_scope, options)[name] = true;
+    }
     return name;
 }