Get --enable-gcc-warnings to work after touching configure.ac.

Preserve ACLOCAL_PATH in later builds, so that by default it has
the same value as it did in the first build after initial checkout.
* Makefile.in (ACLOCAL_PATH): New macro.
($(srcdir)/aclocal.m4): Use it.
* configure.ac (ACLOCAL_PATH): AC_SUBST it.
* autogen.sh (env_space): New var.
Tell user what variables, if any, to pass to 'configure'.

4 files changed, 19 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index 61df7093527..a93a93c8f29 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2014-05-03  Paul Eggert  <eggert@cs.ucla.edu>
 
+        Get --enable-gcc-warnings to work after touching configure.ac.
+        Preserve ACLOCAL_PATH in later builds, so that by default it has
+        the same value as it did in the first build after initial checkout.
+        * Makefile.in (ACLOCAL_PATH): New macro.
+        ($(srcdir)/aclocal.m4): Use it.
+        * configure.ac (ACLOCAL_PATH): AC_SUBST it.
+        * autogen.sh (env_space): New var.
+        Tell user what variables, if any, to pass to 'configure'.
+
         Get --enable-gcc-warnings working again.
         The recent changes to configure.ac removed the transliteration of
         -I to -isystem in CFLAGS, which is needed for --enable-gcc-warnings.
diff --git a/Makefile.in b/Makefile.in
index 2eda8c365da..ffee1ec131d 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -425,9 +425,10 @@ AUTOCONF_INPUTS = $(srcdir)/configure.ac $(srcdir)/aclocal.m4
 $(srcdir)/configure: $(AUTOCONF_INPUTS)
         cd ${srcdir} && autoconf
 
+ACLOCAL_PATH = @ACLOCAL_PATH@
 ACLOCAL_INPUTS = $(srcdir)/configure.ac $(srcdir)/m4/gnulib-comp.m4
 $(srcdir)/aclocal.m4: $(ACLOCAL_INPUTS)
-        cd $(srcdir) && aclocal -I m4
+        cd $(srcdir) && ACLOCAL_PATH='$(ACLOCAL_PATH)' aclocal -I m4
 
 AUTOMAKE_INPUTS = $(srcdir)/aclocal.m4 $(srcdir)/lib/Makefile.am \
   $(srcdir)/lib/gnulib.mk
diff --git a/autogen.sh b/autogen.sh
index c2a2c7af04f..b7804548cec 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -210,6 +210,7 @@ fi
 # find the pkg.m4 that is installed in the standard location.
 echo "Checking for pkg.m4..."
 AUTORECONF_ENV=
+env_space=
 ac_dir=`aclocal --print-ac-dir` && test -r "$ac_dir/pkg.m4" || {
   oIFS=$IFS
   IFS=:
@@ -225,7 +226,8 @@ ac_dir=`aclocal --print-ac-dir` && test -r "$ac_dir/pkg.m4" || {
           ?*) ACLOCAL_PATH=$ACLOCAL_PATH:$ac_dir;;
         esac
         export ACLOCAL_PATH
-        AUTORECONF_ENV="ACLOCAL_PATH='$ACLOCAL_PATH' "
+        AUTORECONF_ENV="ACLOCAL_PATH='$ACLOCAL_PATH'"
+        env_space=' '
         break
       fi
     fi
@@ -244,7 +246,7 @@ EOF
 echo ok
 
 echo 'Your system has the required tools.'
-echo "Running \"${AUTORECONF_ENV}autoreconf -fi -I m4\" ..."
+echo "Running \"$AUTORECONF_ENV${env_space}autoreconf -fi -I m4\" ..."
 
 
 ## Let autoreconf figure out what, if anything, needs doing.
@@ -255,7 +257,7 @@ autoreconf -fi -I m4 || exit $?
 ## cause 'make' to needlessly run 'autoheader'.
 echo timestamp > src/stamp-h.in || exit
 
-echo "You can now run \`./configure'."
+echo "You can now run \`./configure$env_space$AUTORECONF_ENV'."
 
 exit 0
 
diff --git a/configure.ac b/configure.ac
index 74ea10dd5cd..7545e14e15d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -295,6 +295,9 @@ otherwise for the first of `gfile' or `inotify' that is usable.])
 dnl http://lists.gnu.org/archive/html/emacs-devel/2008-04/msg01844.html
 OPTION_DEFAULT_ON([makeinfo],[don't require makeinfo for building manuals])
 
+## This might be a 'configure' arg, e.g., autogen.sh might set it.
+AC_SUBST([ACLOCAL_PATH])
+
 ## Makefile.in needs the cache file name.
 AC_SUBST(cache_file)