* load.c (rb_provide_feature): clarify error message for frozen

$LOADED_FEATURES.  based on a patch from Run Paint Run Run at
  [ruby-core:31913].

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@29135 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Sun Aug 29 12:51:33 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* load.c (rb_provide_feature): clarify error message for frozen
+	  $LOADED_FEATURES.  based on a patch from Run Paint Run Run at
+	  [ruby-core:31913].
+
 Sun Aug 29 12:19:58 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* load.c (load_failed): should honor encoding.  [ruby-core:31915]

load.c

@@ -250,6 +250,10 @@ rb_feature_provided(const char *feature, const char **loading)
 static void
 rb_provide_feature(VALUE feature)
 {
+    if (OBJ_FROZEN(get_loaded_features())) {
+	rb_raise(rb_eRuntimeError,
+		 "$LOADED_FEATURES is frozen; cannot append feature");
+    }
     rb_ary_push(get_loaded_features(), feature);
 }
 

test/ruby/test_require.rb

@@ -310,4 +310,11 @@ class TestRequire < Test::Unit::TestCase
       }
     }
   end
+
+  def test_frozen_loaded_features
+    bug3756 = '[ruby-core:31913]'
+    assert_in_out_err(['-e', '$LOADED_FEATURES.freeze; require "ostruct"'], "",
+                      [], /\$LOADED_FEATURES is frozen; cannot append feature \(RuntimeError\)$/,
+                      bug3756)
+  end
 end