Delayed Warnings

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 variable delayed-warnings-list for this.

— Variable: 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 (see Warning Basics). Immediately after running post-command-hook (see Command Overview), the Emacs command loop displays all the warnings specified by this variable, then resets it to nil.

Programs which need to further customize the delayed warnings mechanism can change the variable delayed-warnings-hook:

— 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.
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.

39.5.4 Delayed Warnings