Only word-ending colon separates new definition

When followed by non-space characters, rather it looks like a URL or a
path name on Windows.

lib/rdoc/parser/c.rb

@@ -938,10 +938,10 @@ def handle_constants(type, var_name, const_name, definition)
     # "/* definition: comment */" form.  The literal ':' and '\' characters
     # can be escaped with a backslash.
     if type.downcase == 'const' then
-      no_match, new_definition, new_comment = comment.text.split(/(\A.*):/)
+      if /\A(.+?)?:(?!\S)/ =~ comment.text
+        new_definition, new_comment = $1, $'
 
-      if no_match and no_match.empty? then
-        if new_definition.empty? then # Default to literal C definition
+        if !new_definition # Default to literal C definition
           new_definition = definition
         else
           new_definition = new_definition.gsub(/\\([\\:])/, '\1')

test/rdoc/test_rdoc_parser_c.rb

@@ -475,6 +475,9 @@ def test_do_constants
    /* TEST\:TEST: Checking to see if escaped colon works */
    rb_define_const(cFoo, "TEST", rb_str_new2("TEST:TEST"));
 
+   /* TEST: TEST:Checking to see if only word-ending colon works */
+   rb_define_const(cFoo, "TEST2", rb_str_new2("TEST:TEST"));
+
    /* \\: The file separator on MS Windows */
    rb_define_const(cFoo, "MSEPARATOR", rb_str_new2("\\"));
 
@@ -538,6 +541,9 @@ def test_do_constants
     assert_equal ['TEST', 'TEST:TEST',
                   'Checking to see if escaped colon works   '],
                  constants.shift
+    assert_equal ['TEST2', 'TEST',
+                  'TEST:Checking to see if only word-ending colon works   '],
+                 constants.shift
     assert_equal ['MSEPARATOR', '\\',
                   'The file separator on MS Windows   '],
                  constants.shift