On the Viva64.com site they've posted the results of their own evaluation of PHP 7 in terms of both the source of the language itself and the libraries it makes use of.

Sometimes checking a project one more time can be quite amusing. It helps to see which errors were fixed, and which ones got into the code since the time it was last checked. My colleague has already written an article about PHP analysis. As there was a new version released, I decided to check the source code of the interpreter once again, and I wasn't disappointed - the project had a lot of interesting fragments to look at.

They start with a brief look at PHP 7 including when it was released, some of the features/functionality included and the tool they used to do the analysis. They talk about some of the difficulties in the analysis process and how the widespread user of macros tripped it up a bit. They includes some code examples from PHP's source and the warnings that their PVS-Studio returned. The post ends with a brief look at the third-party libraries PHP uses and the responsibility the project takes in including them.