fix corner case in reduce_vars (#4950)

fixes #4949
2021-05-21 11:49:07 +01:00
parent 4a19575e74
commit de376c3d33
2 changed files with 26 additions and 3 deletions
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -580,9 +580,12 @@ merge(Compressor.prototype, {
        }

        function safe_to_assign(tw, def, declare) {
-            if (!(declare || all(def.orig, function(sym) {
-                return !(sym instanceof AST_SymbolConst);
-            }))) return false;
+            if (!declare) {
+                if (is_funarg(def) && def.scope.uses_arguments && !tw.has_directive("use strict")) return false;
+                if (!all(def.orig, function(sym) {
+                    return !(sym instanceof AST_SymbolConst);
+                })) return false;
+            }
            if (def.fixed === undefined) return declare || all(def.orig, function(sym) {
                return !(sym instanceof AST_SymbolLet);
            });