bug#17871: 24.4.50; (elisp) `Core Advising Primitives': interactive spec as function?

[Drew Adams <drew.adams@oracle.com>]

This node says this:

  One exception: if the interactive
  spec of FUNCTION is a function (rather than an expression or a
  string), then the interactive spec of the combined function will
  be a call to that function with as sole argument the interactive
  spec of the original function.

I'm unfamiliar with an interactive spec (i.e., the SPEC in
(interactive SPEC) being a function, rather than an expression or
a string.  I cannot find anything else in the manual that refers to
this possibility.  Please document this feature.  Or if it is in
fact documented already, please cross-reference that location from
this node.

(If SPEC cannot be a function, which has been my understanding,
then please correct the statement that it can be.)


In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-06-17 on ODIEONE
Bzr revision: 117359 monnier@iro.umontreal.ca-20140617193358-2t1nl1te9gc2mqrx
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''