From: Karl Berry <karl@freefriends.org>
Date: Sun, 5 Jan 2020 01:06:40 +0000 (-0800)
Subject: automake: Support byte compilation in older Emacsen
X-Git-Tag: v1.16.2~18
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b87f297426c2d79494b707d0fecddaff2b6eaefd;p=thirdparty%2Fautomake.git

automake: Support byte compilation in older Emacsen

* lib/am/lisp.am (am__emacs_byte_compile_setup) [FIRST]: define
new make variable, to use byte-compile-dest-file-function if
available, else byte-compile-dest-file.
(.el.elc): use it.
* t/lisp-loadpath.sh: skip test if emacs version is <= 23,
since their -L ordering is backwards.
* NEWS: update.
---

diff --git a/NEWS b/NEWS
index 8c5bf5702..8dc53207b 100644
--- a/NEWS
+++ b/NEWS
@@ -87,6 +87,9 @@ New in ?.?.?:
   - The automake test txinfo-vtexi4.sh no longer fails when localtime
     and UTC cross a day boundary.
 
+  - Emacsen older than version 25, which require use of
+    byte-compile-dest-file, are supported again.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 New in 1.16.1:
diff --git a/lib/am/lisp.am b/lib/am/lisp.am
index 02383eb1e..705181ca1 100644
--- a/lib/am/lisp.am
+++ b/lib/am/lisp.am
@@ -41,10 +41,29 @@ endif %?INSTALL%
 	  $(EMACS) --batch \
 	    $(AM_ELCFLAGS) $(ELCFLAGS) \
 	    $$am__subdir_includes -L $(builddir) -L $(srcdir) \
-	    --eval '(setq byte-compile-dest-file-function (lambda (_) "$@"))' \
+	    --eval '$(am__emacs_byte_compile_setup)' \
 	    -f batch-byte-compile '$<'; \
 	else :; fi
 
+if %?FIRST%
+## In Automake 1.16, byte compilation was changed to use
+## byte-compile-dest-file-function, but that doesn't exist in Emacs
+## versions earlier than 25, which are still widespread (likely
+## permanently). There's no harm in supporting the older versions, which
+## require defining the byte-compile-file defun, so do so.
+## Otherwise, various of our lisp-related tests fail with the older
+## Emacsen, since they would try to byte-compile into a read-only srcdir.
+##
+## This is used, single-quoted, in the shell sequence above.
+## So use (quote) instead of another single quote in the Lisp.
+##
+am__emacs_byte_compile_setup = \
+  (if (boundp (quote byte-compile-dest-file-function)) \
+    (setq byte-compile-dest-file-function (lambda (_) "$@")) \
+    (defun byte-compile-dest-file (_) "$@") \
+  )
+## Just to be clear: that "$@" above is an Elisp string of the make target.
+endif %?FIRST%
 
 ## ------------ ##
 ## Installing.  ##
diff --git a/t/lisp-loadpath.sh b/t/lisp-loadpath.sh
index 312498845..37bec19d6 100644
--- a/t/lisp-loadpath.sh
+++ b/t/lisp-loadpath.sh
@@ -20,6 +20,23 @@
 required=emacs
 . test-init.sh
 
+# The story here is that at least in Emacs 21, -L foo -L bar ends up
+# with bar before foo in load-path. The invocation in the .el.elc rule
+# in lisp.am correctly uses -L $(builddir) -L $(srcdir), and thus the
+# test below ends up failing. So skip the test on such old Emacs; no
+# need to work around in the code.
+#
+# At least as of Emacs 24, -L foo -L bar preserves command line order,
+# so foo is before bar in load-path, and all is well.
+#
+# Situation with Emacs 22 and 23 is unknown, so play it safe and skip
+# the test for them too.
+#
+emacs_major=$(${EMACS-emacs} --version | sed -e 's/.* //;s/\..*$//;1q')
+if test -z "$emacs_major" || test "$emacs_major" -le 23; then
+  exit 77
+fi
+
 cat >> configure.ac << 'END'
 AM_PATH_LISPDIR
 AC_OUTPUT