Notice on non existing array key (on a boolean)

Hi all, I'd expect the following code to throw a notice/warning: $x = true; $y = $x['foo']; It executes completely silently. $y is NULL afterwards, which is expected, since the right hand side of the assignment is undefined. If $x was an array (e.g. empty array), a E_NOTICE would be emitted. Can anyone shed a light on this behaviour? If accessing non existing array keys is worth a notice, shouldn't accessing an array index on a non array be worth a notice as well (maybe even a warning)? The other way round emits a warning (i.e. writing to an array key on a non array): $x = true; $x['foo'] = 'bar'; Warning: Cannot use a scalar value as an array ... Thanks for any insight, greetings Nico