Several extensions are not listed in composer requirements

[dktapps]

When installing phpDocumentor2 using Composer, everything seems to be fine until trying to run it.
My PHP build is stripped-back (built with --disable-all and only specific extensions enabled to reduce build size), and does not have several extensions that phpDocumentor expects to be present but does not declare in composer.json.

According to a PhpStorm scan of the project on the develop branch, the missing dependencies are:

• ext-dom
• ext-simplexml
• ext-libxml
• ext-xsl
• ext-zlib

There may be other dependencies on other branches that I have not checked.

Expected Behavior

Installing phpDocumentor2 with my PHP setup should fail because ext-dom, ext-simplexml and ext-libxml are not found in my PHP build

Actual Behavior

phpDocumentor2 installs successfully and crashes when trying to run.

Steps to Reproduce the Problem

1. Compile PHP with any of the listed XML extensions missing (simplexml is the first problem I encountered)
2. Install phpDocumentor in a project
3. Try to generate documentation and watch it crash.

Your environment

• Version used: 2.9
• Install method: composer install phpdocumentor/phpdocumentor
• php version: 7.2.13
• Operating system and version (e.g. Ubuntu 16.04, Windows 7): Windows 10

[jaapio]

Thanks for your report, we are working currently on a new version of phpdocumentor, which does have the listed requirements.
Due limited time we don't give this issue priority over the new version.

[mvriel]

While reviewing this issue and the composer.json of v3 I noticed some of your suggestions were missing. I have resolved this for v3, because of limited resources we are not able to backport many of these improvements to v2.x. Because of this limitation, I am going to close this item as the issue is resolved in v3.

If you have more suggestions like these we would love to hear more!