Re: [Emacs-diffs] emacs-25 f8208b6: Document the user-level features of the Xref package

[Ken Brown <kbrown@cornell.edu>]

I have a couple of suggestions, based on my experience when I tried to 
use Xref for the first time.

First, paragraph b of the Xref info node talks about etags, with a 
reference to the subnode on creating tags tables.  It would have helped 
me if there had been a further sentence saying that a user has to give 
the command M-x visit-tags-table before Xref will use etags as the 
backend.  This sentence would be accompanied by a reference to the 
subnode on selecting a tags table.  That node is currently listed in the 
Menu, but it's not obvious (or at least wasn't obvious to me) what the 
relevance was, especially since the description of that node refers to 
*visiting* a tags table rather than telling Xref to using one.

Second, I suggest that Xref should offer to use etags as the backend 
when a TAGS file exists in the current directory.

I had the following experience in my first attempt to use Xref:

After reading the Xref node and glancing at the "Creating Tags Tables" 
node, I remembered that there was a 'tags' target in the top level 
Makefile of the emacs tree, so I gave the command 'make tags' to create 
the TAGS files.  Then I visited a C file in the src directory and tried 
'M-.' on an identifier.  The result was the error message 'Symbol’s 
function definition is void: etags--xref-backend'.  I didn't know what 
to do with that message, so I went back to the Xref node to see if it 
would tell me how to tell Xref to use etags as backend.  It didn't, but 
I finally tried M-x visit-tags-table, and it worked.

Ken