erb.rb: shadow by keys

* lib/erb.rb (ERB#new_toplevel): shadow already defined local
  variables by block local variabes, not to overwrite them.
  [ruby-core:84390] [Bug #14215]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61411 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

lib/erb.rb

@@ -889,7 +889,7 @@ class ERB
   # Render a template on a new toplevel binding with local variables specified
   # by a Hash object.
   def result_with_hash(hash)
-    b = new_toplevel
+    b = new_toplevel(hash.keys)
     hash.each_pair do |key, value|
       b.local_variable_set(key, value)
     end
@@ -900,8 +900,15 @@ class ERB
   # Returns a new binding each time *near* TOPLEVEL_BINDING for runs that do
   # not specify a binding.
 
-  def new_toplevel
-    TOPLEVEL_BINDING.dup
+  def new_toplevel(vars = nil)
+    b = TOPLEVEL_BINDING
+    if vars
+      vars = vars.select {|v| b.local_variable_defined?(v)}
+      unless vars.empty?
+        return b.eval("tap {|;#{vars.join(',')}| break binding}")
+      end
+    end
+    b.dup
   end
   private :new_toplevel
 

test/erb/test_erb.rb

@@ -611,6 +611,10 @@ EOS
     erb = @erb.new("<%= foo %>")
     erb.result_with_hash(foo: "1")
     assert_equal(false, TOPLEVEL_BINDING.local_variable_defined?(:foo))
+    TOPLEVEL_BINDING.eval 'template2 = "two"'
+    erb = @erb.new("<%= template2 %>")
+    erb.result_with_hash(template2: "TWO")
+    assert_equal "two", TOPLEVEL_BINDING.local_variable_get("template2")
   end
 
   # This depends on the behavior that #local_variable_set raises TypeError by invalid key.