Is there a tool to analyze a set of PHP files and determine what the minimum PHP version number is that provides the functions used? For example, we have a number of servers, running 4.2.2, 4.3.1, etc. file_get_contents() is in 4.3 or better, so scripts using this function won't run on the 4.2.2 box.
On a similar note, is there a list or queryable DB anywhere that provides functions and the PHP version they first appeared in?