drop assignments to constant expressions only (#2839)

fixes #2838
2018-01-23 02:49:54 +08:00
parent 5e2cd07d6f
commit ec4202590d
2 changed files with 31 additions and 2 deletions
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3469,8 +3469,10 @@ merge(Compressor.prototype, {
            while (left instanceof AST_PropAccess) {
                left = left.expression;
            }
-            if (left instanceof AST_Symbol) return this;
-            return this.right.drop_side_effect_free(compressor);
+            if (left.is_constant_expression(compressor.find_parent(AST_Scope))) {
+                return this.right.drop_side_effect_free(compressor);
+            }
+            return this;
        });
        def(AST_Conditional, function(compressor){
            var consequent = this.consequent.drop_side_effect_free(compressor);