How to get rid of those warnings about byte-compile-dest-file-function

BLUF: Add

--eval '(require (quote bytecomp))'

to AM_ELCFLAGS to get rid of those

Warning (bytecomp): Changing ‘byte-compile-dest-file’ is obsolete (as of 23.2);

when compiling Elisp with Automake.

Dunno if anyone out there is using Automake with an Elisp project, but if you are, you may have been plagued by a once-per-file warning like the following:

Warning (bytecomp): Changing ‘byte-compile-dest-file’ is obsolete (as of 23.2);

This is because Automake (at least as late as 1.16.5) produces make rules like:

if test '/opt/emacsen/current/bin/emacs' != no; then \
  am__dir=. am__subdir_includes=''; \
  case indie-org-rss.elc in */*) \
    am__dir=`echo 'indie-org-rss.elc' | sed 's,/[^/]*$,,'`; \
    am__subdir_includes="-L $am__dir -L ./$am__dir"; \
  esac; \
  test -d "$am__dir" || /bin/mkdir -p "$am__dir" || exit 1; \
  /opt/emacsen/current/bin/emacs --batch \
    -L contrib --eval '(require (quote bytecomp))'  \
    $am__subdir_includes -L . -L . \
    --eval '(if (boundp (quote byte-compile-dest-file-function)) (setq byte-compile-dest-file-function (lambda (_) "indie-org-rss.elc")) (
defun byte-compile-dest-file (_) "indie-org-rss.elc") )' \
    -f batch-byte-compile 'indie-org-rss.el'; \
else :; fi

This is the salient bit:

(if (boundp (quote byte-compile-dest-file-function))
    (setq byte-compile-dest-file-function (lambda (_) "indie-org-rss.elc"))
  (defun byte-compile-dest-file (_) "indie-org-rss.elc"))

This trips over the following code in bytecomp.el:

;; Sadly automake relies on this misfeature up to at least version 1.15.1.
(if (fboundp 'byte-compile-dest-file)
    (or (featurep 'bytecomp)
        (display-warning 'bytecomp (format-message "\
Changing `byte-compile-dest-file' is obsolete (as of 23.2);
set `byte-compile-dest-file-function' instead.")))
(defun byte-compile-dest-file (filename)
  ;; ...
  )

I wondered why byte-compile-dest-file wasn't defined; turns out, it's defined in the bytecomp package. Adding --eval '(require (quote bytecomp))' to AM_ELCFLAGS ensures it's defined before compilation.

Unwound Stack