# HG changeset patch
# User John W. Eaton <jwe@octave.org>
# Date 1455123437 18000
# Node ID 7af5ca01ecaccbe19a8103a06bef62f8efddebee
# Parent  ffc9806bb30048658ced9820f3d76c3753c6710a
allow octave-config.h to be included unconditionally

* oct-conf-post.in.h (OCTAVE_AUTOCONFIG_H_INCLUDED): Rename from
OCTAVE_CONFIG_H_INCLUDED.
* mk-octave-config-h.sh: Protect contents of generated file with
OCTAVE_AUTOCONFIG_H_INCLUDED.
* oct-refcount.h: Simply include octave-config.h instead of checking
OCTAVE_CONFIG_H_INCLUDED.

diff -r ffc9806bb300 -r 7af5ca01ecac build-aux/mk-octave-config-h.sh
--- a/build-aux/mk-octave-config-h.sh	Wed Feb 10 11:46:14 2016 -0500
+++ b/build-aux/mk-octave-config-h.sh	Wed Feb 10 11:57:17 2016 -0500
@@ -18,6 +18,10 @@
 # along with Octave; see the file COPYING.  If not, see
 # <http://www.gnu.org/licenses/>.
 
+# Generate a header file that provides the public symbols from Octave's
+# autoconf-generated config.h file.  See the notes at the top of the
+# generated octave-config.h file for more details.
+
 if [ $# -ne 1 ]; then
   echo "usage: mk-octave-config-h.sh CONFIG-FILE" 1>&2
   exit 1
@@ -49,9 +53,45 @@
 
 */
 
+/*
+
+All Octave source files should begin with
+
+  #if defined (HAVE_CONFIG_H)
+  #  include <config.h>
+  #endif
+
+All public Octave header files should have the form
+
+  #if ! defined (INCLUSION_GUARD_SYMBOL)
+  #define INCLUSION_GUARD_SYMBOL 1
+
+  #include "octave-config.h"
+
+  // Contents of header file.
+
+  #endif
+
+In Octave source files, INCLUSION_GUARD_SYMBOL should have the form
+
+  octave_NAME_h
+
+with NAME formed from the header file name with '-' replaced by '_'.
+
+It is safe to include octave-config.h unconditionally since it will
+expand to an empty file if it is included after Octave's
+autoconf-generated config.h file.
+
+Users of Octave's libraries should not need to include octave-config.h
+since all of Octave's header files already include it.
+
+*/
+
 #if ! defined (octave_octave_config_h)
 #define octave_octave_config_h 1
 
+#if ! defined (OCTAVE_AUTOCONFIG_H_INCLUDED)
+
 #include <stdint.h>
 
 #if defined (__GNUC__)
@@ -175,4 +215,6 @@
 cat << EOF
 
 #endif
+
+#endif
 EOF
diff -r ffc9806bb300 -r 7af5ca01ecac liboctave/util/oct-refcount.h
--- a/liboctave/util/oct-refcount.h	Wed Feb 10 11:46:14 2016 -0500
+++ b/liboctave/util/oct-refcount.h	Wed Feb 10 11:57:17 2016 -0500
@@ -23,9 +23,7 @@
 #if ! defined (octave_oct_refcount_h)
 #define octave_oct_refcount_h 1
 
-#ifndef OCTAVE_CONFIG_INCLUDED
-#  error "The file <octave/config.h> must be included before oct-refcount.h."
-#endif
+#include "octave-config.h"
 
 #if defined (OCTAVE_ENABLE_ATOMIC_REFCOUNT) && (defined (_MSC_VER) || defined (__GNUC__))
 #  if defined (_MSC_VER)
diff -r ffc9806bb300 -r 7af5ca01ecac oct-conf-post.in.h
--- a/oct-conf-post.in.h	Wed Feb 10 11:46:14 2016 -0500
+++ b/oct-conf-post.in.h	Wed Feb 10 11:57:17 2016 -0500
@@ -185,5 +185,9 @@
 
 typedef OCTAVE_IDX_TYPE octave_idx_type;
 
-/* Tag indicating Octave config.h has been included */
-#define OCTAVE_CONFIG_INCLUDED 1
+/* Tag indicating Octave's autoconf-generated config.h has been
+   included.  This symbol is provided because autoconf-generated
+   config.h files do not define a multiple-inclusion guard.  See also
+   the notes at the top of the generated octave-config.h file.  */
+
+#define OCTAVE_AUTOCONFIG_H_INCLUDED 1