fixing precedence order, so that you can nest range comprehensions

lib/coffee_script/grammar.y

@@ -32,7 +32,8 @@ prechigh
   left     '.'
   right    INDENT
   left     OUTDENT
-  right    THROW FOR IN WHILE WHEN NEW SUPER ELSE
+  right    WHEN IN
+  right    THROW FOR WHILE NEW SUPER ELSE
   left     UNLESS EXTENDS IF
   left     ASSIGN '||=' '&&='
   right    RETURN '=>'

lib/coffee_script/nodes.rb

@@ -360,10 +360,11 @@ module CoffeeScript
       write("#{idt}#{@from_var} = #{from_val};\n#{idt}#{@to_var} = #{to_val};\n#{idt}")
     end
 
-    def compile(o, fv)
-      vars     = "#{fv}=#{@from_var}"
-      compare  = "(#{@from_var} <= #{@to_var} ? #{fv} #{less_operator} #{@to_var} : #{fv} #{greater_operator} #{@to_var})"
-      incr     = "(#{@from_var} <= #{@to_var} ? #{fv} += 1 : #{fv} -= 1)"
+    def compile(o, idx=nil)
+      raise SyntaxError, "unexpected range literal" unless idx
+      vars     = "#{idx}=#{@from_var}"
+      compare  = "(#{@from_var} <= #{@to_var} ? #{idx} #{less_operator} #{@to_var} : #{idx} #{greater_operator} #{@to_var})"
+      incr     = "(#{@from_var} <= #{@to_var} ? #{idx} += 1 : #{idx} -= 1)"
       write("#{vars}; #{compare}; #{incr}")
     end
 

test/fixtures/execution/test_nested_comprehensions.coffee

@@ -0,0 +1,11 @@
+multi_liner:
+  for x in [3..5]
+    for y in [3..5]
+      [x, y]
+
+single_liner:
+  [x, y] for y in [3..5] for x in [3..5]
+
+print(multi_liner.length is single_liner.length)
+print(5 is multi_liner[2][2][1])
+print(5 is single_liner[2][2][1])