fix AST_Scope.clone()

fixes #2799

lib/ast.js

@@ -308,6 +308,13 @@ var AST_Scope = DEFNODE("Scope", "variables functions uses_with uses_eval parent
         enclosed: "[SymbolDef*/S] a list of all symbol definitions that are accessed from this scope or any subscopes",
         cname: "[integer/S] current index for mangling variables (used internally by the mangler)",
     },
+    clone: function(deep) {
+        var node = this._clone(deep);
+        node.variables = this.variables.clone();
+        node.functions = this.functions.clone();
+        node.enclosed = this.enclosed.slice();
+        return node;
+    }
 }, AST_Block);
 
 var AST_Toplevel = DEFNODE("Toplevel", "globals", {

lib/utils.js

@@ -303,6 +303,13 @@ Dictionary.prototype = {
             ret.push(f(this._values[i], i.substr(1)));
         return ret;
     },
+    clone: function() {
+        var ret = new Dictionary();
+        for (var i in this._values)
+            ret._values[i] = this._values[i];
+        ret._size = this._size;
+        return ret;
+    },
     toObject: function() { return this._values }
 };
 Dictionary.fromObject = function(obj) {

test/compress/reduce_vars.js

@@ -5302,3 +5302,37 @@ issue_2774: {
     }
     expect_stdout: "undefined"
 }
+
+issue_2799: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            return f;
+            function f(n) {
+                function g(i) {
+                    return i && i + g(i - 1);
+                }
+                function h(j) {
+                    return g(j);
+                }
+                return h(n);
+            }
+        }()(5));
+    }
+    expect: {
+        console.log(function() {
+            return function(n) {
+                return function(j) {
+                    return function g(i) {
+                        return i && i + g(i - 1);
+                    }(j);
+                }(n);
+            }
+        }()(5));
+    }
+    expect_stdout: "15"
+}