aclocal: fix for more-than-once specified directories

Related to automake bug#13514.

Do not consider directories for extra m4 files multiple times in
'aclocal'.  Doing so caused problems on older packages that specify

    configure.ac:  AC_CONFIG_MACRO_DIRS([m4])
    Makefile.am:   ACLOCAL_AMFLAGS = -I m4

if the 'm4' directory does not exist when aclocal is called the first
time by autoreconf.

See:
<http://lists.gnu.org/archive/html/bug-automake/2013-01/msg00115.html>

* aclocal.in (scan_m4_files): Remove duplicates in @user_includes.
* t/aclocal-macrodir.tap: Extend.
* t/aclocal-macrodirs.tap: Likewise.

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

3 files changed, 52 insertions, 2 deletions

diff --git a/aclocal.in b/aclocal.in
index e65b0ab2d..d68ea3365 100644
--- a/aclocal.in
+++ b/aclocal.in
@@ -432,6 +432,16 @@ sub scan_m4_files ()
 
   if (@user_includes)
     {
+      # Don't explore the same directory multiple times.  This is here not
+      # only for speedup purposes.  We need this when the user has e.g.
+      # specified 'ACLOCAL_AMFLAGS = -I m4' and has also set
+      # AC_CONFIG_MACRO_DIR[S]([m4]) in configure.ac.  This makes the 'm4'
+      # directory to occur twice here and fail on the second call to
+      # scan_m4_dirs([m4]) when the 'm4' directory doesn't exist.
+      # TODO: Shouldn't there be rather a check in scan_m4_dirs for
+      #       @user_includes[0]?
+      @user_includes = uniq @user_includes;
+
       # Don't complain if the first user directory doesn't exist, in case
       # we need to create it later (can happen if '--install' was given).
       scan_m4_dirs (FT_USER,
diff --git a/t/aclocal-macrodir.tap b/t/aclocal-macrodir.tap
index a480c4cd4..051fdb517 100755
--- a/t/aclocal-macrodir.tap
+++ b/t/aclocal-macrodir.tap
@@ -20,7 +20,7 @@
 am_create_testdir=empty
 . test-init.sh
 
-plan_ 6
+plan_ 7
 
 ocwd=$(pwd) || fatal_ "getting current working directory"
 ACLOCAL_PATH=; unset ACLOCAL_PATH
@@ -181,6 +181,26 @@ test_end
 
 #---------------------------------------------------------------------------
 
+test_begin "AC_CONFIG_MACRO_DIR([not-exist]) and ACLOCAL_AMFLAGS = -I not-exist"
+
+cat > configure.ac << 'END'
+AC_INIT([oops], [1.0])
+AC_CONFIG_MACRO_DIR([not-exist])
+END
+
+cat > Makefile.am << 'END'
+ACLOCAL_AMFLAGS = -I not-exist
+END
+
+$ACLOCAL -Wno-error 2>stderr \
+  && cat stderr >&2 \
+  && test $(grep -c "couldn't open directory 'not-exist'" stderr) -eq 1 \
+  || r='not ok'
+
+test_end
+
+#---------------------------------------------------------------------------
+
 # Avoid spurious failures with pre-2.70 autoconf.
 # FIXME: remove this in automake 1.14, once we require Autoconf 2.70.
 if echo 'AC_INIT AC_CONFIG_MACRO_DIRS' | $AUTOCONF -o/dev/null -; then
diff --git a/t/aclocal-macrodirs.tap b/t/aclocal-macrodirs.tap
index c0bb0acee..0deae7236 100755
--- a/t/aclocal-macrodirs.tap
+++ b/t/aclocal-macrodirs.tap
@@ -20,7 +20,7 @@
 am_create_testdir=empty
 . test-init.sh
 
-plan_ 14
+plan_ 15
 
 ocwd=$(pwd) || fatal_ "getting current working directory"
 ACLOCAL_PATH=; unset ACLOCAL_PATH
@@ -381,6 +381,26 @@ test_end
 
 #---------------------------------------------------------------------------
 
+test_begin "AC_CONFIG_MACRO_DIRS([not-exist]) and ACLOCAL_AMFLAGS = -I not-exist"
+
+cat > configure.ac << 'END'
+AC_INIT([oops], [1.0])
+AC_CONFIG_MACRO_DIRS([not-exist])
+END
+
+cat > Makefile.am << 'END'
+ACLOCAL_AMFLAGS = -I not-exist
+END
+
+$ACLOCAL -Wno-error 2>stderr \
+  && cat stderr >&2 \
+  && test $(grep -c "couldn't open directory 'not-exist'" stderr) -eq 1 \
+  || r='not ok'
+
+test_end
+
+#---------------------------------------------------------------------------
+
 # Avoid spurious failures with pre-2.70 autoconf.
 # FIXME: remove this in automake 1.14, once we require Autoconf 2.70.
 if echo 'AC_INIT AC_CONFIG_MACRO_DIRS' | $AUTOCONF -o/dev/null -; then