Should we enforce PHP 5.5/5.6 as a minimum ?

[tostinni]

Drupal 8 supports PHP 5.5.9 as a minimum version (see Drupal 8 PHP requirements), however in composer.json there is no PHP version which can led to conflicts when you upgrade some packages.

For example this issue Doctrine/Common 2.8 requires PHP ~7.1 expose this problem when working in a PHP 5.5/5.6 environment.
One solution proposed there is to add "platform": {"php": "5.6"} to composer.json.

Should we consider doing the same for drupal-composer ?

[pfrenssen]

I think adding the platform version this is a good idea. It can be confusing to people that are new to composer that it will use the PHP version of the machine that runs the update command as a minimum in the composer.lock file. If we put it in we will achieve two goals:

• Our users will end up with a build that actually works on an environment that meets the minimum requirements.
• We demonstrate the proper way to change the minimum PHP version in a way that best matches people's expectations.

[tostinni]

Sorry for the multiple commits, I was making some tests and fixing some typos.

I was thinking adding this directly to composer.json but it could be too restrictive to target PHP 5.5.9, so I added a FAQ section to README.md.

[webflo]

Thanks @tostinni