[AUCTeX] AucTeX activation of latex-mode

[Julien Cubizolles]

I recently noticed a change in AucTeX behaviour (maybe triggered by an
update or some tinkering of my .emacs) regarding the activation of
latex-mode.

Before, every .tex file was opened in latex-mode (not tex-mode), now
files opened at emacs startup (by the workgroups package for instance)
are opened in tex-mode. However, subsequent .tex files are opened in
latex-mode.

While investigating this problem, I realized that I don't understand how
the choice between tex-mode and latex-mode is made. According to (info
"(emacs) Choosing Modes"), the default for a .tex file should be set to
*tex-mode* by auto-mode-alist with the rule ("\\.[tT]e[xX]\\'"
*. tex-mode). So AucTeX must somehow overrule this behaviour to choose
latex-mode. I couldn't find the relevant part in (info "AucTeX").

So the question is : how do I configure Emacs/AucTeX to activate
latex-mode for every .tex file ? I guess I could play with
auto-mode-alist but it used to work without any modification to this
variable.

Thanks for your help.