simplify logic

add tests

lib/compress.js

@@ -277,12 +277,6 @@ merge(Compressor.prototype, {
                         d.fixed = false;
                     }
                 }
-                if (node instanceof AST_Lambda) {
-                    node.variables.get("arguments").fixed = null;
-                    node.argnames.forEach(function(arg) {
-                        arg.definition().fixed = null;
-                    });
-                }
                 if (node instanceof AST_Defun) {
                     var d = node.name.definition();
                     if (!toplevel && d.global || is_safe(d)) {
@@ -364,7 +358,7 @@ merge(Compressor.prototype, {
         function is_safe(def) {
             for (var i = safe_ids.length, id = def.id; --i >= 0;) {
                 if (safe_ids[i][id]) {
-                    if (def.fixed === null) {
+                    if (def.fixed == null) {
                         var orig = def.orig[0];
                         if (orig instanceof AST_SymbolFunarg || orig.name == "arguments") return false;
                         def.fixed = make_node(AST_Undefined, orig);

test/compress/reduce_vars.js

@@ -1823,3 +1823,34 @@ redefine_farg_3: {
     }
     expect_stdout: "object number undefined"
 }
+
+delay_def: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            return a;
+            var a;
+        }
+        function g() {
+            return a;
+            var a = 1;
+        }
+        console.log(f(), g());
+    }
+    expect: {
+        function f() {
+            return a;
+            var a;
+        }
+        function g() {
+            return a;
+            var a = 1;
+        }
+        console.log(f(), g());
+    }
+    expect_stdout: true
+}