Extend a warnings accumulator with a non-fatal warning.
(warn [:type type]
[:fn fn] ;; defaults to __function__
[:acc warnings] ;; defaults to warnings
This macro builds a new, non-fatal warning w from the given
type, msg, args, and fn, then conses w onto the warnings accumulator acc.
See also fatal; it is identical except that it builds fatal
We make use of a few interfacing tricks:
- acc defaults to warnings because we often use warnings as
the name of the warnings accumulator we are working with. That is, as long as
your warnings accumulator is named warnings, you don't have to give an
- fn defaults to __function__. Macros like define often
bind this symbol to the name of the current function, so if you are using a
macro like this you don't have to give a fn argument. But you will need
to explicitly give a function name when using raw defun.
- We cons the new warning not onto acc, but instead onto
(vl-warninglist-fix acc). This ensures that code written using warn
can unconditionally produce vl-warninglist-ps, without needing to do