handle var within catch of the same name (#1711)

The following code prints `1`:

var a = 1;
!function(){
  a = 4;
  try{
    throw 2;
  } catch (a) {
    var a = 3;
  }
}();
console.log(a);

fixes #1708

1 files changed, 19 insertions, 5 deletions

diff --git a/lib/scope.js b/lib/scope.js
index c2d0b552..025d4ca3 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -75,9 +75,16 @@ SymbolDef.prototype = {
         }
         else if (!this.mangled_name && !this.unmangleable(options)) {
             var s = this.scope;
-            if (!options.screw_ie8 && this.orig[0] instanceof AST_SymbolLambda)
+            var sym = this.orig[0];
+            if (!options.screw_ie8 && sym instanceof AST_SymbolLambda)
                 s = s.parent_scope;
-            this.mangled_name = s.next_mangled(options, this);
+            var def;
+            if (options.screw_ie8
+                && sym instanceof AST_SymbolCatch
+                && (def = s.parent_scope.find_variable(sym))) {
+                this.mangled_name = def.mangled_name || def.name;
+            } else
+                this.mangled_name = s.next_mangled(options, this);
             if (this.global && cache) {
                 cache.set(this.name, this.mangled_name);
             }
@@ -152,9 +159,16 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
             (node.scope = defun.parent_scope).def_function(node);
         }
         else if (node instanceof AST_SymbolVar
-                 || node instanceof AST_SymbolConst) {
+            || node instanceof AST_SymbolConst) {
             defun.def_variable(node);
-            if (defun !== scope) node.mark_enclosed(options);
+            if (defun !== scope) {
+                node.mark_enclosed(options);
+                var def = scope.find_variable(node);
+                if (node.thedef !== def) {
+                    node.thedef = def;
+                    node.reference(options);
+                }
+            }
         }
         else if (node instanceof AST_SymbolCatch) {
             scope.def_variable(node);
@@ -278,7 +292,7 @@ AST_Symbol.DEFMETHOD("mark_enclosed", function(options) {
     }
 });
 
-AST_SymbolRef.DEFMETHOD("reference", function(options) {
+AST_Symbol.DEFMETHOD("reference", function(options) {
     this.definition().references.push(this);
     this.mark_enclosed(options);
 });