fixes #2333: fix prohibition of duplicate object properties

src/helpers.coffee

@@ -54,3 +54,8 @@ exports.del = (obj, key) ->
 
 # Gets the last item of an array(-like) object.
 exports.last = (array, back) -> array[array.length - (back or 0) - 1]
+
+# Typical Array::any
+exports.any = (array, fn) ->
+  return true for e in array when fn e
+  false

src/nodes.coffee

@@ -7,7 +7,7 @@
 {RESERVED, STRICT_PROSCRIBED} = require './lexer'
 
 # Import the helpers we plan to use.
-{compact, flatten, extend, merge, del, starts, ends, last} = require './helpers'
+{any, compact, flatten, extend, merge, del, starts, ends, last} = require './helpers'
 
 exports.extend = extend  # for parser
 
@@ -806,7 +806,17 @@ exports.Obj = class Obj extends Base
       prop = prop.variable if prop.isComplex()
       if prop?
         propName = prop.unwrapAll().value.toString()
-        if propName in propNames
+        isDuplicate = (x) ->
+          p0 = propName[0]
+          x0 = x[0]
+          propName is x or +propName is +x or
+          if p0 is "'" and x0 is '"' or p0 is '"' and x0 is "'"
+            eval(x) is eval(propName)
+          else if p0 is "'" then propName is "'#{x}'"
+          else if p0 is '"' then propName is "\"#{x}\""
+          else if x0 is "'" then x is "'#{propName}'"
+          else if x0 is '"' then x is "\"#{propName}\""
+        if any propNames, isDuplicate
           throw SyntaxError "multiple object literal properties named \"#{propName}\""
         propNames.push propName
     return (if @front then '({})' else '{}') unless props.length

test/strict.coffee

@@ -57,9 +57,17 @@ test "octal escape sequences prohibited", ->
 
 
 test "duplicate property definitions in object literals are prohibited", ->
-  strict 'o = {x:1,x:1}'
+  strict 'o = {x:1, x:1}'
   strict 'x = 1; o = {x, x: 2}'
 
+test "#2333: more duplicate property prohibitions", ->
+  strict '{a:0, "a":0}'
+  strict "{'a':0, a:0}"
+  strict '{\'a\':0, "a":0}'
+  strict '{0:0, 0x0:0}'
+  strict 'a = 0; {a, "a":0}'
+  strictOk '{"a":0, "\'a\'":0}'
+
 test "duplicate formal parameters are prohibited", ->
   nonce = {}