What is this technique called?

parentheses-do-something-awesome.markdown

I was talking to a friend tonight about a particular flavor of syntax error in another language. It reminded me of the below behavior in PHP. I know there's a name for this technique/syntax/idiom, but I have no idea what that name is. Anyone?

$ php -a
Interactive shell

php > echo new DateTime()->format('Ymd');
PHP Parse error:  syntax error, unexpected '->' (T_OBJECT_OPERATOR), expecting ',' or ';' in php shell code on line 1

Parse error: syntax error, unexpected '->' (T_OBJECT_OPERATOR), expecting ',' or ';' in php shell code on line 1
php > echo (new DateTime())->format('Ymd');
20151030
php > exit

It's called "class member access on instantiation" and it was introduced in PHP 5.4. Thanks, @MethyleneGaming!