These variables are used by users to control what happens when a Lisp program reports a warning.
This user option specifies the minimum severity level that should be
shown immediately to the user, by popping the warnings buffer in some
window. The default is :warning, which means to show the
warning buffer for any warning severity except :debug. The
warnings of lower severity levels will still be written into the
warnings buffer, but the buffer will not be forced onto display.
This user option specifies the minimum severity level that should be
logged in the warnings buffer. Warnings of lower severity will be
completely ignored: not written to the warnings buffer and not
displayed. The default is :warning, which means to log
warnings of any severity except :debug.
This list specifies which warning types should not be displayed immediately when they occur. Each element of the list should be a list of symbols. If an element of this list has the same elements as the first elements in a warning type, then the warning of that type will not be shown on display by popping the warnings buffer in some window (the warning will still be logged in the warnings buffer).
For example, if the value of this variable is a list like this:
((foo) (bar subtype))
then warnings whose types are foo or (foo) or
(foo something) or (bar subtype other) will not
be shown to the user.
This list specifies which warning types should be ignored: not logged
in the warnings buffer and not shown to the user. The structure and
the matching of warning types are the same as for
warning-suppress-types above.
During startup, Emacs delays showing any warnings until after it
loads and processes the site-wide and user’s init files
(see Summary: Sequence of Actions at Startup). Let-binding (see Local Variables) the
values of these options around some code in your init files which
might emit a warning will therefore not work, because it will not be
in effect by the time the warning is actually processed. Thus, if you
want to suppress some warnings during startup, change the values of
the above options in your init file early enough, or put those
let-binding forms in your after-init-hook or
emacs-startup-hook functions. See The Init File.