New features
New global constants
Migrating from PHP 7.0.x to PHP 7.1.x
PHP Manual
New functions
Closure
Closure::fromCallable()
CURL
curl_multi_errno()
curl_share_errno()
curl_share_strerror()
SPL
is_iterable()
PCNTL
pcntl_async_signals()
New features
New global constants
Migrating from PHP 7.0.x to PHP 7.1.x
PHP Manual