Sometimes, you may wish to avoid showing a warning while a command is
running, and only show it only after the end of the command. You can
use the function delay-warning for this. Emacs automatically
delays any warnings emitted during the early stages of startup, and
shows them only after the init files are processed.
This function is the delayed counterpart to display-warning
(see Warning Basics), and it is called with the same arguments.
The warning message is queued into delayed-warnings-list.
The value of this variable is a list of warnings to be displayed after the current command has finished. Each element must be a list
(type message [level [buffer-name]])
with the same form, and the same meanings, as the argument list of
display-warning. Immediately after running
post-command-hook (see Command Loop Overview), the Emacs
command loop displays all the warnings specified by this variable,
then resets the variable to nil.
Programs which need to further customize the delayed warnings
mechanism can change the variable delayed-warnings-hook:
This is a normal hook which is run by the Emacs command loop, after
post-command-hook, in order to process and display delayed
warnings. Emacs also runs this hook during startup, after loading the
site-start and user init files (see Summary: Sequence of Actions at Startup), because
warnings emitted before that are automatically delayed.
Its default value is a list of two functions:
(collapse-delayed-warnings display-delayed-warnings)
The function collapse-delayed-warnings removes repeated entries
from delayed-warnings-list. The function
display-delayed-warnings calls display-warning on each
of the entries in delayed-warnings-list, in turn, and then sets
delayed-warnings-list to nil.