preserve function identity in `reduce_vars` (#2451)

fixes #2450

1 files changed, 27 insertions, 18 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 274ab604..6354197d 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -324,9 +324,8 @@ merge(Compressor.prototype, {
                                     || value.is_constant_expression(node.scope);
                             } else {
                                 d.single_use = d.scope === node.scope
-                                    && loop_ids[d.id] === in_loop
                                     && value.is_constant_expression();
-                                }
+                            }
                         } else {
                             d.single_use = false;
                         }
@@ -384,6 +383,7 @@ merge(Compressor.prototype, {
                         d.fixed = false;
                     } else {
                         d.fixed = node;
+                        loop_ids[d.id] = in_loop;
                         mark(d, true);
                         if (ref_once(d)) {
                             d.single_use = d.scope === d.references[0].scope
@@ -577,7 +577,11 @@ merge(Compressor.prototype, {
         }
 
         function ref_once(def) {
-            return unused && !def.scope.uses_eval && !def.scope.uses_with && def.references.length == 1;
+            return unused
+                && !def.scope.uses_eval
+                && !def.scope.uses_with
+                && def.references.length == 1
+                && loop_ids[def.id] === in_loop;
         }
 
         function is_immutable(value) {
@@ -623,7 +627,8 @@ merge(Compressor.prototype, {
 
         function mark_escaped(d, node, value, level) {
             var parent = tw.parent(level);
-            if (value instanceof AST_Constant || value instanceof AST_Function) return;
+            if (value instanceof AST_Constant) return;
+            if (level > 0 && value instanceof AST_Function) return;
             if (parent instanceof AST_Assign && parent.operator == "=" && node === parent.right
                 || parent instanceof AST_Call && node !== parent.expression
                 || parent instanceof AST_Return && node === parent.value && node.scope !== d.scope
@@ -4216,6 +4221,17 @@ merge(Compressor.prototype, {
         return self;
     });
 
+    function recursive_ref(compressor, def) {
+        var node;
+        for (var i = 0; node = compressor.parent(i); i++) {
+            if (node instanceof AST_Lambda) {
+                var name = node.name;
+                if (name && name.definition() === def) break;
+            }
+        }
+        return node;
+    }
+
     OPT(AST_SymbolRef, function(self, compressor){
         var def = self.resolve_defines(compressor);
         if (def) {
@@ -4241,20 +4257,13 @@ merge(Compressor.prototype, {
             if (fixed instanceof AST_Defun) {
                 d.fixed = fixed = make_node(AST_Function, fixed, fixed);
             }
-            if (fixed && d.single_use) {
-                var recurse;
-                if (fixed instanceof AST_Function) {
-                    for (var i = 0; recurse = compressor.parent(i); i++) {
-                        if (recurse instanceof AST_Lambda) {
-                            var name = recurse.name;
-                            if (name && name.definition() === d) break;
-                        }
-                    }
-                }
-                if (!recurse) {
-                    var value = fixed.optimize(compressor);
-                    return value === fixed ? fixed.clone(true) : value;
-                }
+            if (fixed
+                && d.single_use
+                && !(fixed instanceof AST_Function
+                    && (d.escaped && d.scope !== self.scope
+                        || recursive_ref(compressor, d)))) {
+                var value = fixed.optimize(compressor);
+                return value === fixed ? fixed.clone(true) : value;
             }
             if (fixed && d.should_replace === undefined) {
                 var init;