# HG changeset patch
# User Markus Mützel <markus.muetzel@gmx.de>
# Date 1639772853 -3600
# Node ID e0e22183ffcaeed5ef7e1fc119ea2abf01176499
# Parent  838e73617671e8fd0f9f6b1bb3979c958d7fdda0
Restore building with visibility flags for Windows.

* configure.ac: Windows uses a dllexport/dllimport mechanism instead of
visibility attributes. Don't deactivate visibility flags on that platform if
HAVE_VISIBILITY is 0 (which it will always be).
* build-aux/mk-octave-config-h.sh: Add missing flag to octave-config.h.

diff -r 838e73617671 -r e0e22183ffca build-aux/mk-octave-config-h.sh
--- a/build-aux/mk-octave-config-h.sh	Fri Dec 17 19:13:04 2021 +0100
+++ b/build-aux/mk-octave-config-h.sh	Fri Dec 17 21:27:33 2021 +0100
@@ -181,6 +181,13 @@
 #    define octave_unused_parameter(param) (void) param;
 #  endif
 
+/* Defined to 1 if Octave libraries were built with visibility flags */
+EOF
+
+$SED -n 's/#\(\(undef\|define\) OCTAVE_ENABLE_LIB_VISIBILITY_FLAGS.*$\)/#  \1/p' $config_h_file
+
+cat << EOF
+
 #  if defined (OCTAVE_ENABLE_LIB_VISIBILITY_FLAGS)
 #    if defined (_WIN32) || defined (__CYGWIN__)
 #      if defined (__GNUC__)
diff -r 838e73617671 -r e0e22183ffca configure.ac
--- a/configure.ac	Fri Dec 17 19:13:04 2021 +0100
+++ b/configure.ac	Fri Dec 17 21:27:33 2021 +0100
@@ -2665,10 +2665,17 @@
      *) AC_MSG_ERROR([bad value $enableval for --enable-lib-visibility-flags]) ;;
    esac])
 
-if test $ENABLE_LIB_VISIBILITY_FLAGS = yes && test $HAVE_VISIBILITY = 0; then
-  AC_MSG_NOTICE([cannot build with visibility flags on this platform])
-  ENABLE_LIB_VISIBILITY_FLAGS=no
-fi
+case $host_os in
+  msdosmsvc | mingw* | cygwin*)
+    # Assume that symbol export is working on that platform
+  ;;
+  *)
+    if test $ENABLE_LIB_VISIBILITY_FLAGS = yes && test $HAVE_VISIBILITY = 0; then
+      AC_MSG_NOTICE([cannot build with visibility flags on this platform])
+      ENABLE_LIB_VISIBILITY_FLAGS=no
+    fi
+  ;;
+esac
 
 if test $ENABLE_LIB_VISIBILITY_FLAGS = yes; then
   AC_DEFINE(OCTAVE_ENABLE_LIB_VISIBILITY_FLAGS, 1,