As of PHP 5 the error reporting
E_STRICT is available, with the
value 2048. When enabled, messages will be
issued to warn you about code usage which is deprecated or which
may not be future-proof.
E_ALLdoes not include
E_STRICT, so it's not enabled by default. You must explicitly set the error reporting level to include
E_STRICTin order to see these messages.
See Predefined Constants for more information.