Issue with php version - Only variables should be passed by reference in boost.module

PHP variable reference errors appear quite frequently in all versions of boost (in my experience) it depends on the php.ini file and the settings for error_reporting E_STRICT, E_WARNING.

Boost is hooked in to try and cache the output of drupal, some modules (or core components of drupal) start output then return or return nothing, so boost is hooked into passing nothing. There's nothing that can really be done as the error fires and throws before any analysis can be carried out. Ill try and illustrate.

function myFunc( $var ){

// never gets here because $var is not passed by reference

}

so we can't put anything in myFunc to tell us what is being called as the error has been thrown and the function aborted, plus backtracing only leads to a function in Drupal that we wouldn't be maintaining and that could produce valid output. One of the frequent triggers for this in the 7.x series is the httprl crawling mechanism on the status report page, the crawler is designed to be used by cron and produce no output to the browser and on the report page it does a diagnostic to see if it is locked which has no content but boost is hooked in afterwards (as it would need to be for a valid crawler) and so it always throws this error.

It's a very minor notification rather than a serious error that unfortunately is beyond the remit of boost to solve unless there was an additonal non referenced function put in in front of boost to check validity of the variable, but to my knowledge that cannot be done without referencing it and throwing an error - catch 22, though quite interesting.

Only if it is really bothering you :)

I'd recommend manually adding the patch as it doesn't say which version it's against and your error appears to indicate that the function exists twice so probably some lines have been inserted.

If running Apache then it would probably be more appropriate to set error_reporting in .htaccess as it's easier to switch from development to production, these pages may help with php_value in the file.

http://php.net/manual/en/configuration.changes.php

and

http://php.net/manual/en/errorfunc.configuration.php#ini.error-reporting