Context

A couple of time after adding some PHP code in iTop core, we saw that the setup cannot be launched anymore when using old PHP versions.

Some past examples :

• adding a finally block in \MetaModel::GetObjectWithArchive (commit 0adadeb in iTop 2.6.0) made iTop setup incompatible with PHP < 5.5.0
• adding constant visibility in ormLinkSet (commit b58a084 in iTop 2.8.0 dev version) broke setup for PHP < 7.1.0

Setup homepage error

Sample error when opening the setup with an incompatible PHP version :

🤯

We should instead display a clear message stating that the current PHP version is incompatible with iTop !

Risks

• This is something we don't test for now (we are aiming to do so but this is complicated as docker images with such old PHP version are hard to find/maintain !)
• Next major iTop version will update min PHP version from 5.6.0 to 7.1.3, and as this is directly configured in dev team PHPStorm's we will introduce more and more incompatible code in iTop core !

Proposition

This PR propose a lightweight setup index that will first check PHP version. This new index page includes the bare minimum files to avoid PHP parse errors.

If the test succeeds the setup is launched, without changing the browser's URL.
If not an error message is displayed.

Refactorings

Two new files were created, they are the only dependencies for the new setup/index.php :

• setup/setuputilslight.class.php
• setup/setupconst.class.php

The below constants/methods were moved/introduced :

• SetupUtils const for PHP / MySQL versions
• SetupUtils::CheckPhpVersion method and CheckResult object
• WebPage::PAGES_CHARSET
• \WebPageLight::EmbedSetupPageContent
• ITOP_* const that were defined in core/config.class.inc.php