Properly scope `catch` identifier when --screw-ie8

Fix #344

1 files changed, 16 insertions, 20 deletions

diff --git a/lib/scope.js b/lib/scope.js
index 49b04811..ed189d49 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -71,27 +71,28 @@ SymbolDef.prototype = {
     }
 };
 
-AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
-    // This does what ast_add_scope did in UglifyJS v1.
-    //
-    // Part of it could be done at parse time, but it would complicate
-    // the parser (and it's already kinda complex).  It's also worth
-    // having it separated because we might need to call it multiple
-    // times on the same tree.
+AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
+    options = defaults(options, {
+        screw_ie8: false
+    });
 
     // pass 1: setup scope chaining and handle definitions
     var self = this;
     var scope = self.parent_scope = null;
+    var defun = null;
     var nesting = 0;
     var tw = new TreeWalker(function(node, descend){
         if (node instanceof AST_Scope) {
             node.init_scope_vars(nesting);
             var save_scope = node.parent_scope = scope;
-            ++nesting;
+            var save_defun = defun;
+            if (!(node instanceof AST_Catch)) {
+                defun = node;
+            }
             scope = node;
-            descend();
+            ++nesting; descend(); --nesting;
             scope = save_scope;
-            --nesting;
+            defun = save_defun;
             return true;        // don't descend again in TreeWalker
         }
         if (node instanceof AST_Directive) {
@@ -108,7 +109,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
             node.scope = scope;
         }
         if (node instanceof AST_SymbolLambda) {
-            scope.def_function(node);
+            defun.def_function(node);
         }
         else if (node instanceof AST_SymbolDefun) {
             // Careful here, the scope where this should be defined is
@@ -116,22 +117,17 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
             // scope when we encounter the AST_Defun node (which is
             // instanceof AST_Scope) but we get to the symbol a bit
             // later.
-            (node.scope = scope.parent_scope).def_function(node);
+            (node.scope = defun.parent_scope).def_function(node);
         }
         else if (node instanceof AST_SymbolVar
                  || node instanceof AST_SymbolConst) {
-            var def = scope.def_variable(node);
+            var def = defun.def_variable(node);
             def.constant = node instanceof AST_SymbolConst;
             def.init = tw.parent().value;
         }
         else if (node instanceof AST_SymbolCatch) {
-            // XXX: this is wrong according to ECMA-262 (12.4).  the
-            // `catch` argument name should be visible only inside the
-            // catch block.  For a quick fix AST_Catch should inherit
-            // from AST_Scope.  Keeping it this way because of IE,
-            // which doesn't obey the standard. (it introduces the
-            // identifier in the enclosing scope)
-            scope.def_variable(node);
+            (options.screw_ie8 ? scope : defun)
+                .def_variable(node);
         }
     });
     self.walk(tw);