On 4/25/21 3:32 PM, Daniel Mendler wrote:
> I attached a patch which adds grouping support to the completions 
> buffer. The completion table can specify a `group-function` via its 
> completion metadata.

I attached a revised patch with the following changes over the previous 
version:

1. Add a `completions-group` guard variable, to turn the grouping off. 
The setting is off by default.
2. Ensure that the original completion string is used in 
`choose-completion`. Attach the untransformed completion string to each 
completion string displayed in the *Completions* buffer.

You can try the patch with the following settings and execute 
`xref-find-references` for example (M-?).

(setq xref-show-xrefs-function
   #'xref-show-definitions-completing-read
   completions-group t
   completions-format 'one-column)

Daniel