Description:
------------
define()ing a constant with spaces, / signs, etc. doesn't throw an error (or warning).

i happened to try to create a constant with the name
'U/L DIR' and it worked. that's two illegal chars. since constant names like "2FOO" are checked and not allowed, shouldn't these also not be allowed?

sure doesn't satisfy "The name of a constant follows the same rules as any label in PHP." or the regexp [a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*

a name like that obviously can't be used (tried quotes and braces) but it works just fine with 'defined()', 'constant()' and shows up in get_defined_constants().

Reproduce code:
---------------
define('U/L DIR', 'myuploaddir');

if (defined('U/L DIR')) {  //true
     echo 'yup';
     echo constant('U/L DIR');
     print_r(get_defined_constants());
}

// all the lines above print 'myuploaddir' for 'U/L DIR'

Expected result:
----------------
E_ERROR since it's violates label rules (an E_WARNING at the least?)

Actual result:
--------------
spaces, etc. work just fine. (it shouldn't)