enhance `arguments` (#4296)

1 files changed, 3 insertions, 2 deletions

diff --git a/lib/compress.js b/lib/compress.js
index e05b6f28..2a8ba8a0 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -9572,13 +9572,14 @@ merge(Compressor.prototype, {
             }
         }
         var parent = compressor.parent();
+        var assigned = is_lhs(compressor.self(), parent);
         var def, fn, fn_parent;
         if (compressor.option("arguments")
             && expr instanceof AST_SymbolRef
             && is_arguments(def = expr.definition())
             && prop instanceof AST_Number
             && (fn = expr.scope.resolve()) === find_lambda()
-            && fn.uses_arguments !== "d") {
+            && !(assigned && fn.uses_arguments === "d")) {
             var index = prop.value;
             if (parent instanceof AST_UnaryPrefix && parent.operator == "delete") {
                 if (!def.deleted) def.deleted = [];
@@ -9616,7 +9617,7 @@ merge(Compressor.prototype, {
                 return sym;
             }
         }
-        if (is_lhs(compressor.self(), parent)) return self;
+        if (assigned) return self;
         if (compressor.option("sequences")
             && parent.TYPE != "Call"
             && !(parent instanceof AST_ForIn && parent.init === self)) {