Subject: warn about misplaced or duplicated doc strings, `declare` or `interactive` forms
From: Mattias Engdegård <[email-masked]>
To: [email-masked]
Date: Sat, 11 Jun 2022 14:07:03 +0200
List-Id: <debbugs-submit.debbugs.gnu.org>

In function definitions, doc strings, `declare` and `interactive` forms are each optional but must appear in that order and duplications are not permitted. Many violations against these rules go undetected.

The attached patch adds checks to `defun` and `defmacro`. Violations result in compilation warnings but it could be changed into hard errors if desired. It also accepts `(:documentation EXPR)` as alternative to a doc string literal, which currently doesn't work i all cases.

Applying it reveals a handful of mistakes in the Emacs source tree, and in some external packages.