1 files changed, 11 insertions, 5 deletions
diff --git a/lib/compress.js b/lib/compress.js
index a3a4a63d..860eae11 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3369,9 +3369,10 @@ merge(Compressor.prototype, {
                 var elements = [];
                 for (var i = 0; i < this.elements.length; i++) {
                     var element = this.elements[i];
+                    if (element instanceof AST_Hole) continue;
                     var value = element._eval(compressor, ignore_side_effects, cached, depth);
                     if (element === value) return this;
-                    elements.push(value);
+                    elements[i] = value;
                 }
                 return elements;
             }
@@ -8446,7 +8447,8 @@ merge(Compressor.prototype, {
             var elements = expr.elements;
             var retValue = elements[index];
             if (safe_to_flatten(retValue, compressor)) {
-                var flatten = true;
+                var is_hole = retValue instanceof AST_Hole;
+                var flatten = !is_hole;
                 var values = [];
                 for (var i = elements.length; --i > index;) {
                     var value = elements[i].drop_side_effect_free(compressor);
@@ -8455,12 +8457,16 @@ merge(Compressor.prototype, {
                         if (flatten && value.has_side_effects(compressor)) flatten = false;
                     }
                 }
-                retValue = retValue instanceof AST_Hole ? make_node(AST_Undefined, retValue) : retValue;
                 if (!flatten) values.unshift(retValue);
                 while (--i >= 0) {
                     var value = elements[i].drop_side_effect_free(compressor);
-                    if (value) values.unshift(value);
-                    else index--;
+                    if (value) {
+                        values.unshift(value);
+                    } else if (is_hole) {
+                        values.unshift(make_node(AST_Hole, elements[i]));
+                    } else {
+                        index--;
+                    }
                 }
                 if (flatten) {
                     values.push(retValue);