From 7558bddcc9cf5ee14441304c2cfc7cffb566daba Mon Sep 17 00:00:00 2001
From: Jim Meyering <address@hidden>
Date: Wed, 22 Nov 2017 21:07:29 -0800
Subject: [PATCH] port elisp-compilation support to emacs-23.1 and newer

In May of 2017, Emacs' support for using the long-deprecated
byte-compile-dest-file function was removed, and that removal broke
automake's elisp-compiling rule for any .el file not in the current
directory.  In emacs-23.1 (July 2009) byte-compile-dest-file-function
became the recommended way to adjust the byte-compiler's destination.
We expect the removed functionality to be restored for Emacs-26,
albeit with dissuasive diagnostics warning about the imminent removal
of this functionality.  It may be removed in Emacs-27.
* lib/am/lisp.am (.el.elc): Use byte-compile-dest-file-function,
rather than byte-compile-dest-file.
* t/lisp-readonly-srcdir.sh: New file, to test for the above.
* t/list-of-tests.mk (handwritten_TESTS): Add it.
* NEWS (Bugs fixed): Mention this problem.
---
 NEWS                      |  5 +++++
 lib/am/lisp.am            |  2 +-
 t/lisp-readonly-srcdir.sh | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 t/list-of-tests.mk        |  1 +
 4 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 t/lisp-readonly-srcdir.sh

diff --git a/NEWS b/NEWS
index 04a285565..dd057b7b1 100644
--- a/NEWS
+++ b/NEWS
@@ -121,6 +121,11 @@ New in ?.?.?:
   - The time printed by 'mdate-sh' is now using the UTC time zone to support
     the reproducible build effort.  (automake bug#20314)

+  - The elisp byte-compilation rule now uses byte-compile-dest-file-function,
+    rather than byte-compile-dest-file, which was obsoleted in 2009. We expect
+    that Emacs-26 will continue to support the old function, but will complain
+    loudly, and that Emacs-27 will remove support for it altogether.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 New in 1.15.1:
diff --git a/lib/am/lisp.am b/lib/am/lisp.am
index 881bf3457..cacbc6feb 100644
--- a/lib/am/lisp.am
+++ b/lib/am/lisp.am
@@ -41,7 +41,7 @@ endif %?INSTALL%
 	  $(EMACS) --batch \
 	    $(AM_ELCFLAGS) $(ELCFLAGS) \
 	    $$am__subdir_includes -L $(builddir) -L $(srcdir) \
-	    --eval "(defun byte-compile-dest-file (f) \"address@hidden")" \
+	    --eval "(setq byte-compile-dest-file-function (lambda (_) \"address@hidden"))" \
 	    --eval "(unless (byte-compile-file \"$<\") (kill-emacs 1))"; \
 	else :; fi

diff --git a/t/lisp-readonly-srcdir.sh b/t/lisp-readonly-srcdir.sh
new file mode 100644
index 000000000..38b866404
--- /dev/null
+++ b/t/lisp-readonly-srcdir.sh
@@ -0,0 +1,46 @@
+#! /bin/sh
+# Copyright (C) 2017 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# Ensure that building elisp from a read-only srcdir works.
+
+required=emacs
+. test-init.sh
+
+cat > Makefile.am << 'EOF'
+lisp_LISP = am-one.el
+EOF
+
+cat >> configure.ac << 'EOF'
+AM_PATH_LISPDIR
+AC_OUTPUT
+EOF
+
+echo > am-one.el
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE --add-missing
+
+mkdir sub
+chmod a=rx .
+
+cd sub
+../configure
+$MAKE
+
+test -f am-one.elc
+
+:
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index b49a3ad0f..33e5adc49 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -655,6 +655,7 @@ t/lisp5.sh \
 t/lisp6.sh \
 t/lisp7.sh \
 t/lisp8.sh \
+t/lisp-readonly-srcdir.sh \
 t/lisp-loadpath.sh \
 t/lisp-subdir.sh \
 t/lisp-subdir2.sh \
-- 
2.14.1.729.g59c0ea183