Performance Check Plugin

This is a phan plugin that looks for common micro-performance issues, while trying to be helpful instead of annoying.

In fact, all of the suggested fixes:

• Don't affect readability, or improve it
• Provide a proved performance gain

For now, it has a single config setting, to be added to phan's plugin_config setting: perf_check_echo. If true, issues will be echoed instead of emitted. This is an awful hack only intended to help while auditing the plugin in Wikimedia CI.

Requirements

• php >= 7.1.0
• Phan 2.1.0