cc-eval-when-compile

cc-eval-when-compile is a Lisp macro in `cc-defs.el'.

(cc-eval-when-compile &rest BODY)

Like `progn', but evaluates the body at compile time.
The result of the body appears to the compiler as a quoted constant.

This variant works around bugs in `eval-when-compile' in various
(X)Emacs versions. See cc-defs.el for details.