* object.c (rb_mod_const_get): Fix constant missing exception class

  and message to maintain backwards compatibility. Constant search
  should start at Object when constant starts with '::'

* test/ruby/test_module.rb: test for fixes

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37494 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,11 @@
+Tue Nov  6 20:40:28 2012  Aaron Patterson <[email protected]>
+
+	* object.c (rb_mod_const_get): Fix constant missing exception class
+	  and message to maintain backwards compatibility. Constant search
+	  should start at Object when constant starts with '::'
+
+	* test/ruby/test_module.rb: test for fixes
+
 Tue Nov  6 16:50:00 2012  Masaki Matsushita  <[email protected]>
 
 	* lib/tempfile.rb (Tempfile#inspect): fix confusing #inspect.

object.c

@@ -1935,12 +1935,28 @@ rb_mod_const_get(int argc, VALUE *argv, VALUE mod)
     }
 
     pbeg = p = path;
+
+    if (!*p) {
+	rb_raise(rb_eNameError, "wrong constant name %s", path);
+    }
+
+    if (p[0] == ':' && p[1] == ':') {
+	mod = rb_cObject;
+	p += 2;
+	pbeg = p;
+    }
+
     while (*p) {
 	while (*p && *p != ':') p++;
+
+	if (pbeg == p) {
+	    rb_raise(rb_eNameError, "wrong constant name %s", path);
+	}
+
 	id = rb_intern3(pbeg, p-pbeg, enc);
 	if (p[0] == ':') {
 	    if (p[1] != ':') {
-              rb_raise(rb_eArgError, "undefined class/module %.*s", (int)(p-path), path);
+		rb_raise(rb_eNameError, "wrong constant name %s", path);
             }
 	    p += 2;
 	    pbeg = p;

test/ruby/test_module.rb

@@ -240,6 +240,24 @@ def test_const_defined?
     assert(!Math.const_defined?("IP"))
   end
 
+  def test_bad_constants
+    [
+      "#<Class:0x7b8b718b>",
+      ":Object",
+      "",
+      ":",
+    ].each do |name|
+      e = assert_raises(NameError) {
+        Object.const_get name
+      }
+      assert_equal("wrong constant name %s" % name, e.message)
+    end
+  end
+
+  def test_leading_colons
+    assert_equal Object, AClass.const_get('::Object')
+  end
+
   def test_const_get
     assert_equal(Math::PI, Math.const_get("PI"))
     assert_equal(Math::PI, Math.const_get(:PI))