AM_PATH_LISPDIR sets EMACS to an invalid value

[Bruno Haible]

Hi,

Just got this bug report about GNU gettext:
================================================================
make[3]: Entering directory 
`/root/.local/share/Trash/files/gettext-0_2.14.5/gettext-tools/misc'
WARNING: Warnings can be ignored. :-)
if test "emacs" != no; then \
  set x; \
  list='start-po.el po-mode.el po-compat.el'; for p in $list; do \
    if test -f "$p"; then d=; else d="./"; fi; \
    set x "$@" "$d$p"; shift; \
  done; \
  shift; \
  EMACS="emacs" /bin/sh ../../build-aux/elisp-comp "$@" || exit 1; \
else : ; fi
emacs: error while loading shared libraries: libXaw3d.so.6: cannot open shared 
object file: No such file or directory
make[3]: *** [elc-stamp] Fehler 1
make[3]: Leaving directory 
`/root/.local/share/Trash/files/gettext-0_2.14.5/gettext-tools/misc'
make[2]: *** [all-recursive] Fehler 1
================================================================

The GNU gettext configure invokes AM_PROG_LISPDIR and then looks whether
"$EMACS" != no. It assumes that when "$EMACS" != no, $EMACS is an Emacs
command that can be used to compile Emacs Lisp files before installation.
(After all, installing *.el and *.elc files is the very purpose of
AM_PROG_LISPDIR.)

What happens here is that, for some reasons, the "emacs" executable exists
in $PATH but cannot be run. (Similar things happen when, for example,
you are on a HP-UX 10 machine and have an emacs built for HP-UX 11 in your
PATH. Seen it myself.)

Can the AM_PROG_LISPDIR test be extended to check whether the $EMACS
command is a valid Emacs (i.e. run    ($EMACS --help) > /dev/null 2&>1  )
and set EMACS=no if not?

Bruno