fix corner cases in `varify` (#4719)

1 files changed, 12 insertions, 9 deletions

diff --git a/lib/compress.js b/lib/compress.js
index e5e822af..7f642797 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -7723,7 +7723,10 @@ merge(Compressor.prototype, {
             var name = self.init.definitions[0].name;
             if ((name instanceof AST_Destructured || name instanceof AST_SymbolLet)
                 && !name.match_symbol(function(node) {
-                    if (node instanceof AST_SymbolDeclaration) return may_overlap(compressor, node.definition());
+                    if (node instanceof AST_SymbolDeclaration) {
+                        var def = node.definition();
+                        return !same_scope(def) || may_overlap(compressor, def);
+                    }
                 }, true)) {
                 self.init = to_var(self.init);
             }
@@ -8269,7 +8272,7 @@ merge(Compressor.prototype, {
     function can_varify(compressor, sym) {
         if (!sym.fixed_value()) return false;
         var def = sym.definition();
-        return is_safe_lexical(def) && !may_overlap(compressor, def);
+        return is_safe_lexical(def) && same_scope(def) && !may_overlap(compressor, def);
     }
 
     function varify(self, compressor) {
@@ -10214,6 +10217,13 @@ merge(Compressor.prototype, {
         } while (node = compressor.parent(level++));
     }
 
+    function same_scope(def) {
+        var scope = def.scope.resolve();
+        return all(def.references, function(ref) {
+            return scope === ref.scope.resolve();
+        });
+    }
+
     OPT(AST_SymbolRef, function(self, compressor) {
         if (!compressor.option("ie8")
             && is_undeclared_ref(self)
@@ -10380,13 +10390,6 @@ merge(Compressor.prototype, {
         }
         return self;
 
-        function same_scope(def) {
-            var scope = def.scope.resolve();
-            return all(def.references, function(ref) {
-                return scope === ref.scope.resolve();
-            });
-        }
-
         function has_symbol_ref(value) {
             var found;
             value.walk(new TreeWalker(function(node) {