aclocal: tracing AC_CONFIG_MACRO_DIRS can work with older autoconf as well

This will allow our users to interact also with pre-2.70 autoconf without
need for the user to add ACLOCAL_AMFLAGS in Makefile.am.  For example,
before this change, in order to have aclocal look for macros in 'm4/dir1'
and 'm4/dir2' also when (say) autoconf 2.69 was used, our users would
have had to add something like:

    ACLOCAL_AMFLAGS = -I m4/dir1 -I m4/dir2

in Makefile.am, in addition to the

    AC_CONFIG_MACRO_DIRS([m4/dir1 m4/dir2])

in configure.ac.  Now, the AC_CONFIG_MACRO_DIRS call is enough.

See the long-winded discussion on automake bug#12845 for more details:
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=12845>

* aclocal.in ($ac_config_macro_dirs_fallback): New global variable,
contains m4 code to issue a fallback definition of AC_CONFIG_MACRO_DIRS
as an alias for the private macro _AM_CONFIG_MACRO_DIRS.
(trace_used_macros): Handle and trace that macro.  Do some code
reorganization and fix related botched indentation while at it.
(write_aclocal): Output '$ac_config_macro_dirs_fallback' early in
the generated aclocal.m4.
* t/aclocal-macrodirs.tap: Run unconditionally, even with older
autoconf.
* t/subpkg-macrodir.sh: Likewise.
* doc/automake.texi: Document only AC_CONFIG_MACRO_DIRS, rather
than AC_CONFIG_MACRO_DIR.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

diff --git a/aclocal.in b/aclocal.in
index d4e7000..1e56649 100644 (file)
--- a/aclocal.in
+++ b/aclocal.in
@@ -45,6 +45,16 @@ use File::Path ();
 
 # Some globals.
 
+# Support AC_CONFIG_MACRO_DIRS also with older autoconf.
+# FIXME: To be removed in Automake 1.14, once we can assume autoconf
+#        2.70 or later.
+# NOTE: This variable deliberately contain no newlines.
+my $ac_config_macro_dirs_fallback =
+  "m4_ifndef([AC_CONFIG_MACRO_DIRS], [" .
+    "m4_defun([_AM_CONFIG_MACRO_DIRS], [])" .
+    "m4_defun([AC_CONFIG_MACRO_DIRS], [_AM_CONFIG_MACRO_DIRS(\$@)])" .
+  "])";
+
 # We do not operate in threaded mode.
 $perl_threads = 0;
 
@@ -716,16 +726,23 @@ sub trace_used_macros ()
   my %files = map { $map{$_} => 1 } keys %macro_seen;
   %files = strip_redundant_includes %files;
 
-  my $traces = ($ENV{AUTOM4TE} || '@am_AUTOM4TE@');
-  $traces .= " --language Autoconf-without-aclocal-m4 ";
+  my $early_m4_code = "";
   # When AC_CONFIG_MACRO_DIRS is used, avoid possible spurious warnings
   # from autom4te about macros being "m4_require'd but not m4_defun'd";
   # for more background, see:
   # http://lists.gnu.org/archive/html/autoconf-patches/2012-11/msg00004.html
   # as well as autoconf commit 'v2.69-44-g1ed0548', "warn: allow aclocal
   # to silence m4_require warnings".
-  $traces = "echo 'm4_define([m4_require_silent_probe], [-])' | " .
-            "$traces - ";
+  $early_m4_code .= "m4_define([m4_require_silent_probe], [-])";
+  # Support AC_CONFIG_MACRO_DIRS also with older autoconf.
+  # FIXME: To be removed in Automake 1.14, once we can assume autoconf
+  #        2.70 or later.
+  $early_m4_code .= $ac_config_macro_dirs_fallback;
+
+  my $traces = ($ENV{AUTOM4TE} || '@am_AUTOM4TE@');
+  $traces .= " --language Autoconf-without-aclocal-m4 ";
+  $traces = "echo '$early_m4_code' | $traces - ";
+
   # All candidate files.
   $traces .= join (' ',
                   (map { "'$_'" }
@@ -738,11 +755,13 @@ sub trace_used_macros ()
                     'AC_DEFUN_ONCE',
                     'AU_DEFUN',
                     '_AM_AUTOCONF_VERSION',
-                    # FIXME: We still need to trace AC_CONFIG_MACRO_DIR
-                     # for compatibility with older autoconf.  Remove this
-                     # when we can assume Autoconf 2.70 or later.
+                    'AC_CONFIG_MACRO_DIR_TRACE',
+                     # FIXME: Tracing the next two macros is a hack for
+                     # compatibility with older autoconf.  Remove this in
+                     # Automake 1.14, when we can assume Autoconf 2.70 or
+                     # later.
                     'AC_CONFIG_MACRO_DIR',
-                    'AC_CONFIG_MACRO_DIR_TRACE')),
+                    '_AM_CONFIG_MACRO_DIRS')),
                   # Do not trace $1 for all other macros as we do
                   # not need it and it might contains harmful
                   # characters (like newlines).
@@ -776,18 +795,28 @@ sub trace_used_macros ()
         {
           push @ac_config_macro_dirs, $arg1;
         }
-    # FIXME: We still need to trace AC_CONFIG_MACRO_DIR
-    # for compatibility with older autoconf.  Remove this
-    # when we can assume Autoconf 2.70 or later.
-    elsif ($macro eq 'AC_CONFIG_MACRO_DIR')
+      # FIXME: We still need to trace AC_CONFIG_MACRO_DIR
+      # for compatibility with older autoconf.  Remove this
+      # once we can assume Autoconf 2.70 or later.
+      elsif ($macro eq 'AC_CONFIG_MACRO_DIR')
         {
           @ac_config_macro_dirs = ($arg1);
         }
+      # FIXME:This is an hack for compatibility with older autoconf.
+      # Remove this once we can assume Autoconf 2.70 or later.
+      elsif ($macro eq '_AM_CONFIG_MACRO_DIRS')
+        {
+           # Empty leading/trailing fields might be produced by split,
+           # hence the grep is really needed.
+           push @ac_config_macro_dirs, grep (/./, (split /\s+/, $arg1));
+        }
     }
 
   # FIXME: in Autoconf >= 2.70, AC_CONFIG_MACRO_DIR calls
   # AC_CONFIG_MACRO_DIR_TRACE behind the scenes, which could
   # leave unwanted duplicates in @ac_config_macro_dirs.
+  # Remove this in Automake 1.14, when we'll stop tracing
+  # AC_CONFIG_MACRO_DIR explicitly.
   @ac_config_macro_dirs = uniq @ac_config_macro_dirs;
 
   $tracefh->close;
@@ -915,6 +944,7 @@ $output";
 # even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 # PARTICULAR PURPOSE.
 
+$ac_config_macro_dirs_fallback
 $output";
 
   # We try not to update $output_file unless necessary, because

diff --git a/doc/automake.texi b/doc/automake.texi
index 0118a21..c0b1abf 100644 (file)
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -3605,10 +3605,10 @@ will be almost impossible to share macros between packages.
 The second possibility, which we do recommend, is to write each macro
 in its own file and gather all these files in a directory.  This
 directory is usually called @file{m4/}.  Then it's enough to update
-@file{configure.ac} by adding a proper call to @code{AC_CONFIG_MACRO_DIR}:
+@file{configure.ac} by adding a proper call to @code{AC_CONFIG_MACRO_DIRS}:
 
 @example
-AC_CONFIG_MACRO_DIR([m4])
+AC_CONFIG_MACRO_DIRS([m4])
 @end example
 
 @command{aclocal} will then take care of automatically adding @file{m4/}
@@ -3731,7 +3731,7 @@ MyPackage uses an @file{m4/} directory to store local macros as
 explained in @ref{Local Macros}, and has
 
 @example
-AC_CONFIG_MACRO_DIR([m4])
+AC_CONFIG_MACRO_DIRS([m4])
 @end example
 
 @noindent

diff --git a/t/aclocal-macrodirs.tap b/t/aclocal-macrodirs.tap
index 28abb7c..0b6886b 100755 (executable)
--- a/t/aclocal-macrodirs.tap
+++ b/t/aclocal-macrodirs.tap
@@ -20,12 +20,6 @@
 am_create_testdir=empty
 . test-init.sh
 
-{ $AUTOCONF -o /dev/null - <<END
-    AC_INIT([x], [0])
-    AC_CONFIG_MACRO_DIRS([.])
-END
-} || skip_all_ "autoconf doesn't define the AC_CONFIG_MACRO_DIRS macro"
-
 plan_ 14
 
 ocwd=$(pwd) || fatal_ "getting current working directory"

diff --git a/t/subpkg-macrodir.sh b/t/subpkg-macrodir.sh
index 275af0d..a16f42b 100755 (executable)
--- a/t/subpkg-macrodir.sh
+++ b/t/subpkg-macrodir.sh
@@ -19,12 +19,6 @@
 
 . test-init.sh
 
-{ $AUTOCONF -o /dev/null - <<END
-    AC_INIT([x], [0])
-    AC_CONFIG_MACRO_DIRS([.])
-END
-} || skip_ "autoconf doesn't define the AC_CONFIG_MACRO_DIRS macro"
-
 cat > configure.ac <<'END'
 AC_INIT([super], [1.0])
 AM_INIT_AUTOMAKE