Context managers

[arnaud-lb]

RFC: https://wiki.php.net/rfc/context-managers

This implements with() / context managers mostly as syntax sugar.

One opcode is added as it reduces the generated code size considerably. This avoids generating code for:

if (!$__mgr instanceof ContextManager) {
    $type_name = is_object($__mgr) ? get_class($__mgr) : gettype($__mgr);
    $message = "with() expression must be of type ContextManager, $type_name given";
    throw new TypeError($message);
}

TODO:

• resource support
• non-var on the rhs of as