Generic/LowerCaseConstant: improve performance

[jrfnl]

Description

Generic/LowerCaseConstant: add tests with functions which don't create scope

Generic/LowerCaseConstant: improve performance

I noticed a PHPCS run on a particular code base being quite slow. Running the Performance report from PR suizlabs/PHP_CodeSniffer#3810 / #60 showed the Generic.PHP.LowerCaseConstant sniff being the slowest sniff taking 27 seconds on a total sniff run time of 87 seconds (with a few hundred sniffs being run).

A closer look at the sniff pointed to the "skip type declarations for typed properties" part of the sniff as the culprit - in combination with the code base in question having a lot of array properties containing large arrays with mostly true/false/null values.

Every single one of those true/false/null values would trigger a condition check and then a check whether the token was in the property value, causing lots of token walking for those long arrays.

This PR should fix that by changing the logic for skipping over the property type declaration.

Instead of checking for each true/false/null whether it is a property type (or value), the sniff now listens to all property modifier keywords and skips over the type declaration from there, meaning that true/false/null found within property values will no longer need to do a conditions check/"am I a value or a type?" check.

For this particular code base, with this change, the sniff run time goes down from 27 seconds to 0.102 seconds.

Includes additional tests for the "property type skipping" code to verify it works correctly, but also that it won't cause issues with too much/the wrong things being skipped.

Note: an additional performance boost could be gained by not recording metrics and bowing out early for any true/false/null which are already lowercase, but that would change the functionality of the sniff.

Suggested changelog entry

• Performance improvement for the Generic.PHP.LowerCaseConstant sniff