-lSyntax check only (lint)
-l performs a static syntax check. The code is never actually executed. And in your code there are no syntax errors.
The gibberish at the end of your file is considered a constant (since it's a valid name for a constant) and undefined constants evaluate to their string representation (and cause an E_NOTICE). Since it's the last statement in the file the missing semicolon also does not result in a syntax error.
Since PHP is a dynamic language an undefined constant cannot be detected without executing the code -
define() is just a normal function after all.