Leo Butler <leo.butler@umanitoba.ca> writes:

> What is the name of the regexp used by xref-find-definitions to determine
> the identifier? I have looked in xref.el, but I don't see any way to do
> this.

Depending on the backend, it will call the method
xref-backend-identifier-at-point, that defaults to symbol-at-point, so
it doesn't use a regular expression in that sense.

> Leo
>
> PS:
>
>   M-. runs the command xref-find-definitions (found in global-map),
>   which is an autoloaded interactive compiled Lisp function in
>   ‘xref.el’.
>   
>   It is bound to M-., <menu-bar> <edit> <goto> <xref-find-def>.
>   
>   (xref-find-definitions IDENTIFIER)
>   
>     Probably introduced at or before Emacs version 25.1.
>   
>   Find the definition of the identifier at point.
>   With prefix argument or when there’s no identifier at point,
>   prompt for it.
>   
>   If sufficient information is available to determine a unique
>   definition for IDENTIFIER, display it in the selected window.
>   Otherwise, display the list of the possible definitions in a
>   buffer where the user can select from the list.
>   
>
>

-- 
	Philip K.