get emacs to automatically use biber instead of bibtex

AUCTeX uses bibtex as default bibliography processor. If one activates parsing of LaTeX documents setting the variable TeX-parse-self to t, in source files with an explicit \usepackage{biblatex} line AUCTeX prompts for biber or bibtex processor depending on the value of the variable LaTeX-biblatex-use-Biber, which defaults to t. But until version 11.87, AUCTeX isn't able to automatically choose the bibliography processor, which is set in a LaTeX document with the backend load option of the biblatex package.

Starting from version 11.88, to be released in the next weeks or few months, AUCTeX will look at biblatex load options to automatically choose between biber and bibtex. In this version, the variable LaTeX-biblatex-use-Biber will be removed since it will be no more needed.

Note that if \usepackage{biblatex} is written in different lines as, e.g.,

\usepackage[
  backend=biber,
  style=numeric,
  sorting=none
             ]
              {biblatex}

AUCTeX will not notice it and leaves LaTeX-biblatex-use-Biber false.