Subject: undocumented option to pass a "lexical environment" to eval

From: Glenn Morris <[email-masked]>
Date: Mon, 09 Sep 2013 20:24:33 -0400

Package: emacs
Version: 24.3.50

I wondered how the changes in
http://lists.gnu.org/archive/html/emacs-diffs/2013-09/msg00072.html
could possibly work.

Turns out `eval' has a completely undocumented behaviour:

(eval 'foo t)
  -> (void-variable foo)

(eval 'foo '((foo . 99)))
  -> 99

Added in
http://lists.gnu.org/archive/html/emacs-diffs/2013-02/msg00317.html

Not mentioned in NEWS, doc-string, anywhere, AFAICS.