From f7f8e5254e653b2f90892c16c84de6da82a30e43 Mon Sep 17 00:00:00 2001
From: Tim Van Holder <tim.van.holder@pandora.be>
Date: Wed, 20 Feb 2002 18:10:17 +0000
Subject: [PATCH] * m4/lispdir.m4: Redirect /dev/null to stdin when running
 $EMACS   to try and prevent a non-lisp emacs from starting in interactive  
 mode. * automake.texi: Document this change.

---
 ChangeLog     |  7 +++++++
 automake.texi | 11 +++++++++++
 m4/lispdir.m4 |  7 ++++++-
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 8c84bd53..9e92e16d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2002-02-20  Tim Van Holder  <tim.van.holder@pandora.be>
+
+	* m4/lispdir.m4: Redirect /dev/null to stdin when running $EMACS
+	to try and prevent a non-lisp emacs from starting in interactive
+	mode.
+	* automake.texi: Document this change.
+
 2002-02-19  Alexandre Duret-Lutz  <duret_g@epita.fr>
 
 	* automake.texi (Macros): Split into ...
diff --git a/automake.texi b/automake.texi
index 447b95a5..15e61c3a 100644
--- a/automake.texi
+++ b/automake.texi
@@ -1447,6 +1447,17 @@ or by passing a third non-empty argument to the obsolete form.
 @item AM_PATH_LISPDIR
 Searches for the program @code{emacs}, and, if found, sets the output
 variable @code{lispdir} to the full path to Emacs' site-lisp directory.
+
+Note that this test assumes the @code{emacs} found to be a version that
+supports Emacs Lisp (such as @sc{gnu} Emacs or XEmacs).  Other emacsen
+can cause this test to hang (some, like old versions of MicroEmacs,
+start up in interactive mode, requiring @samp{C-x C-c} to exit, which
+is hardly obvious for a non-emacs user).  In most cases, however, you
+should be able to use @samp{C-c} to kill the test.  In order to avoid
+problems, you can set @code{EMACS} to ``no'' in the environment, or
+use the @samp{--with-lispdir} option to @command{configure} to
+explictly set the correct path (if you're sure you have an @code{emacs}
+that supports Emacs Lisp.
 @cvindex AM_PATH_LISPDIR
 
 @item AM_PROG_AS
diff --git a/m4/lispdir.m4 b/m4/lispdir.m4
index 4d7b60d1..a790ad43 100644
--- a/m4/lispdir.m4
+++ b/m4/lispdir.m4
@@ -39,7 +39,12 @@ AC_DEFUN([AM_PATH_LISPDIR],
  if test $EMACS != "no"; then
    if test x${lispdir+set} != xset; then
      AC_CACHE_CHECK([where .elc files should go], [am_cv_lispdir],
-       [AC_RUN_LOG([$EMACS -batch -q -eval '(while load-path (princ (concat (car load-path) "\n")) (setq load-path (cdr load-path)))' >conftest.out])
+       [# If $EMACS isn't GNU Emacs or XEmacs, this can blow up pretty badly
+  # Some emacsen will start up in interactive mode, requiring C-x C-c to exit,
+  #  which is non-obvious for non-emacs users.
+  # Redirecting /dev/null should help a bit; pity we can't detect "broken"
+  #  emacsen earlier and avoid running this altogether.
+  AC_RUN_LOG([$EMACS -batch -q -eval '(while load-path (princ (concat (car load-path) "\n")) (setq load-path (cdr load-path)))' </dev/null >conftest.out])
         am_cv_lispdir=`sed -n \
        -e 's,/$,,' \
        -e '/.*\/lib\/\(x\?emacs\/site-lisp\)$/{s,,${libdir}/\1,;p;q;}' \
-- 
2.43.5