From c4f8c2103fd77e3a6666034c2ca19a5ef09fe68b Mon Sep 17 00:00:00 2001
From: Mihai Bazon <mihai@bazon.net>
Date: Fri, 21 Sep 2012 11:23:44 +0300
Subject: [PATCH] more on detecting side effects

---
 lib/compress.js | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/compress.js b/lib/compress.js
index 834cc388..89352c00 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -690,6 +690,13 @@ function Compressor(options, false_by_default) {
         def(AST_Constant, function(){ return false });
         def(AST_This, function(){ return false });
         def(AST_Function, function(){ return false });
+        def(AST_BlockStatement, function(){
+            for (var i = this.body.length; --i >= 0;) {
+                if (this.body[i].has_side_effects())
+                    return true;
+            }
+            return false;
+        });
 
         def(AST_SimpleStatement, function(){
             return this.body.has_side_effects();
@@ -707,7 +714,8 @@ function Compressor(options, false_by_default) {
         def(AST_Unary, function(){
             return this.operator == "delete"
                 || this.operator == "++"
-                || this.operator == "--";
+                || this.operator == "--"
+                || this.expression.has_side_effects();
         });
         def(AST_SymbolRef, function(){ return false });
         def(AST_Object, function(){
@@ -732,6 +740,10 @@ function Compressor(options, false_by_default) {
             return this.expression.has_side_effects()
                 || this.property.has_side_effects();
         });
+        def(AST_Seq, function(){
+            return this.car.has_side_effects()
+                || this.cdr.has_side_effects();
+        });
     })(function(node, func){
         node.DEFMETHOD("has_side_effects", func);
     });
-- 
2.34.1