create-file-buffer is a compiled Lisp function in `files.el'.

(create-file-buffer FILENAME)

:around advice: `uniquify--create-file-buffer-advice'

Create a suitably named buffer for visiting FILENAME, and return it.
FILENAME (sans directory) is used unchanged if that name is free;
otherwise a string <2> or <3> or ... is appended to get an unused name.

Emacs treats buffers whose names begin with a space as internal buffers.
To avoid confusion when visiting a file whose name begins with a space,
this function prepends a "|" to the final result if necessary.