Identify the open tag file

Question

I have set :set tags=./tags;$HOME to do an "upward search" for a tags file. How do I find out what file has actually been loaded?

Answer 1

Reading :help 'tags' and scrolling a little bit down finds the following sentence:

The tagfiles() function can be used to get a list of the file names
actually used.

Accordingly, :echo tagfiles() will show the name(s) of found tagfile(s).

An easy way to test this is in any of Vim's help files. It will pick up the helptags in <whatever>/doc/tags.

Answer 2

echo findfile("tags", "./;$HOME") appears to work, but it is slightly different syntax and redoes the search.