fix corner cases in arrow functions & `rests` (#4667)

fixes #4666

1 files changed, 4 insertions, 3 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 325c0cd0..c3e315de 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -762,10 +762,11 @@ merge(Compressor.prototype, {
                     return arg || make_node(AST_Undefined, iife);
                 }, visit);
             });
-            if (fn.rest) scan_declaration(tw, compressor, fn.rest, compressor.option("rests") && function() {
-                return make_node(AST_Array, fn, {
+            var rest = fn.rest;
+            if (rest) scan_declaration(tw, compressor, rest, compressor.option("rests") && function() {
+                return fn.rest === rest ? make_node(AST_Array, fn, {
                     elements: iife.args.slice(fn.argnames.length),
-                });
+                }) : rest;
             }, visit);
             walk_lambda(fn, tw);
             var safe_ids = tw.safe_ids;