Right now there's a few points:
* Minimum php versions are all over the source code, putting it in DefaultSettings.php or Defines.php would make be a good start, that way all hardcoded uses of the versions after those are loaded can be centralized. However there are many php-versions compared before those are included as well ( all (web) entry points and other files parsed before the inclusion of DefaultSettings and/or Defines).
So a better solution would be to get those versions available right at the beginning of the web entry points.
Possible solutions:
1) Instead of putting the define() or $wg...= in DefaultSettings.php / Defines.php, create namethisfile.php and put them in there and include it in the all entry points.
This seems like a simple and quick solution but introduces yet another always-included file and puts them far away from other global variables and defines.
2) Put it in Defines.php * make it independant (ie. only defines(), nothing else, as the filename suggests) * and move it up the call stack
Things like inclusion of UtfNormalDefines could be put in the places where Defines.php is currenty included[1] and assignment of the $wgFeedClasses variable shouldn't be in Defines.php anyway.
3) Just put them in DefaultSettings.php and Defines.php and replace all uses with the globals where they are hardcoded and available. Any uses before this file is loaded (entry points) can hard code it
The third solution is basically what I was going to do, and can be safely done. But before I do so I'd like to know if the solutions that cover all scenarios are do-able.
-- Krinkle
[1] UtfNormalDefines.php may not have to be moved though, looks good on second thought. It's included everywhere anyway so it doesn't save load by loading it later or earlier.