libxml_disable_entity_loader

In PHP 8.0 and later, PHP uses libxml versions from 2.9.0, libxml_disable_entity_loader is deprecated.
so it is now safe to remove all `libxml_disable_entity_loader` calls on php8

if you want Backwards Compatibility

use this snippet

if (\PHP_VERSION_ID < 80000) {
    libxml_disable_entity_loader(true);
}

If is called 
libxml_disable_entity_loader(true);

, it causes that new SoapClient(.) fails with

SOAP-ERROR: Parsing WSDL: Couldn't load from 'D:\path/dm_operations.wsdl' : failed to load external entity "D:\path/dm_operations.wsdl

because this wsdl imports a xsd as an another external file.
Tested on php 7.1.12, win x64.

There is an extra \ should be deleted before PHP_VERSION_ID in the code which suconghou posted 2 years ago.

if (PHP_VERSION_ID < 80000) {
    libxml_disable_entity_loader(true);
}

Be mindful that this also disables url loading in simplexml_load_file() and likely other libxml based functions that deal with URLs

Using this function you can prevent a vulnerable to Local and Remote File Inclusion attacks.

You'll see it in an example where I load and validate the following string:

<!DOCTYPE scan [<!ENTITY test SYSTEM "php://filter/read=convert.base64-encode/resource=/etc/passwd">]>
<scan>&test;</scan>

One way to prevent that the file in given back is to set this value to 0.
Please take a closer look at the release of symfony 2.0.11

This also seems to have an impact on <xsl:import /> statements if this is applied when loading XSLT for the XSLTProcessor class.