Fixing Issue #904. Destructuring parameters need to reserve their variable names as if they were true parameters.

lib/nodes.js

@@ -1034,10 +1034,11 @@
   }();
   exports.Assign = Assign = function() {
     __extends(Assign, Base);
-    function Assign(variable, value, context) {
+    function Assign(variable, value, context, options) {
       this.variable = variable;
       this.value = value;
       this.context = context;
+      this.param = options && options.param;
     }
     Assign.prototype.METHOD_DEF = /^(?:(\S+)\.prototype\.|\S+?)?\b([$A-Za-z_][$\w]*)$/;
     Assign.prototype.children = ['variable', 'value'];
@@ -1075,7 +1076,11 @@
         throw SyntaxError("\"" + (this.variable.compile(o)) + "\" cannot be assigned.");
       }
       if (!(this.context || isValue && (this.variable.namespaced || this.variable.hasProperties()))) {
-        o.scope.find(name);
+        if (this.param) {
+          o.scope.add(name, 'var');
+        } else {
+          o.scope.find(name);
+        }
       }
       val = name + (" " + (this.context || '=') + " ") + val;
       if (o.level <= LEVEL_LIST) {
@@ -1152,7 +1157,9 @@
           }
           val = new Value(new Literal(vvar), [new (acc ? Access : Index)(idx)]);
         }
-        assigns.push(new Assign(obj, val).compile(o, LEVEL_TOP));
+        assigns.push(new Assign(obj, val, null, {
+          param: this.param
+        }).compile(o, LEVEL_TOP));
       }
       if (!top) {
         assigns.push(vvar);
@@ -1246,7 +1253,9 @@
           if (param.value) {
             val = new Op('?', ref, param.value);
           }
-          exprs.push(new Assign(new Value(param.name), val, '='));
+          exprs.push(new Assign(new Value(param.name), val, '=', {
+            param: true
+          }));
         } else {
           ref = param;
           if (param.value) {

src/nodes.coffee

@@ -832,7 +832,8 @@ exports.Class = class Class extends Base
 # The **Assign** is used to assign a local variable to value, or to set the
 # property of an object -- including within object literals.
 exports.Assign = class Assign extends Base
-  constructor: (@variable, @value, @context) ->
+  constructor: (@variable, @value, @context, options) ->
+    @param = options and options.param
 
   # Matchers for detecting class/method names
   METHOD_DEF: /^(?:(\S+)\.prototype\.|\S+?)?\b([$A-Za-z_][$\w]*)$/
@@ -862,8 +863,11 @@ exports.Assign = class Assign extends Base
     return "#{name}: #{val}" if @context is 'object'
     unless @variable.isAssignable()
       throw SyntaxError "\"#{ @variable.compile o }\" cannot be assigned."
-    o.scope.find name unless @context or
-      isValue and (@variable.namespaced or @variable.hasProperties())
+    unless @context or isValue and (@variable.namespaced or @variable.hasProperties())
+      if @param
+        o.scope.add name, 'var'
+      else
+        o.scope.find name
     val = name + " #{ @context or '=' } " + val
     if o.level <= LEVEL_LIST then val else "(#{val})"
 
@@ -932,7 +936,7 @@ exports.Assign = class Assign extends Base
         else
           acc = isObject and IDENTIFIER.test idx.unwrap().value or 0
         val = new Value new Literal(vvar), [new (if acc then Access else Index) idx]
-      assigns.push new Assign(obj, val).compile o, LEVEL_TOP
+      assigns.push new Assign(obj, val, null, param: @param).compile o, LEVEL_TOP
     assigns.push vvar unless top
     code = assigns.join ', '
     if o.level < LEVEL_LIST then code else "(#{code})"
@@ -1000,7 +1004,7 @@ exports.Code = class Code extends Base
       if param.isComplex()
         val = ref = param.asReference o
         val = new Op '?', ref, param.value if param.value
-        exprs.push new Assign new Value(param.name), val, '='
+        exprs.push new Assign new Value(param.name), val, '=', param: yes
       else
         ref = param
         if param.value

test/test_functions.coffee

@@ -366,4 +366,14 @@ class Foo
 
 new Foo().bar([101]...)
 
-eq x, 101
+eq x, 101
+
+
+# Issue #904: Destructuring function arguments with same-named variables in scope.
+key for key, value of a: 1
+f = ([key, value]) ->
+  key + value
+
+eq f([10, 11]), 21
+eq key, 'a'
+eq value, 1