https://wordpress.stackexchange.com/questions/tagged/functions
It's being used for both questions about a theme's functions.php file, as well as for generic usage regarding anything to do with PHP functions. This should be separated out into two tags, functions and functions.php, indicating the difference. Questions revolving about theme's functions.php files come up often enough to deserve their own tag.
Note that the function synonym should probably point to the functions tag.
function does point to functions.
functions.php points to functions at moment. It was created by hakre and I don't remember if I participated or saw the reasoning for it at the time.
I am not sure the functions tag wanted in a sense of PHP functions. Everything about PHP takes functions. You can't have code without functions.
Also I am not sure that functions.php is tag-worthy. There isn't much to it itself. Of course there are plenty things that go there, but file itself is not that complicated of a concept or source of many issues.
I am not against current setup but I see it has a weak spots in logic. Open to discussion and suggestions.
functions does make sense as "question about WordPress functions". Functions choice and usage in context of WordPress-specific is important (if not essential) topic. But then I don't see how to cleanly decouple these from functions.php, both are mashed together under functions thanks to synonym.
functions.php tag: Between functions.php, widgets and plugins, which is loaded first?, How often is functions.php loaded?, ... functions when talking about WordPress-specific functions might be better if called wp-functions. Currently I suggest breaking the synonym from functions.php to functions, and start using wp-functions. Those with courage can clean up the old functions tags.
Oct 7, 2011 at 7:12
wp-functions is confusing because of wp-* folders and wp-admin commonly used to describe admin area. It looks like core concept, but it wouldn't be.