configure: check for qt private header availability

configure.ac

@@ -3971,6 +3971,7 @@ AS_IF([test "${enable_qt}" != "no"], [
 
       QT_PATH="$(eval $PKG_CONFIG --variable=exec_prefix Qt5Core)"
       QT_HOST_PATH="$(eval $PKG_CONFIG --variable=host_bins Qt5Core)"
+      QT_INCLUDE_DIRECTORY="$(eval $PKG_CONFIG --variable=includedir Qt5Core)"
       QT_VERSION="$(eval $PKG_CONFIG --modversion Qt5Gui)"
       AC_PATH_PROGS(MOC, [moc-qt5 moc], moc, ["${QT_HOST_PATH}" "${QT_PATH}/bin"])
       AC_PATH_PROGS(RCC, [rcc-qt5 rcc], rcc, ["${QT_HOST_PATH}" "${QT_PATH}/bin"])
@@ -3980,6 +3981,28 @@ AS_IF([test "${enable_qt}" != "no"], [
           AC_MSG_WARN([qmlcachegen not found])
       ])
 
+      dnl Check private headers avaibility
+      VLC_SAVE_FLAGS
+      CPPFLAGS="${CPPFLAGS} ${QT_CFLAGS}"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtCore/${QT_VERSION}"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtCore/${QT_VERSION}/QtCore"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtGui/${QT_VERSION}"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtGui/${QT_VERSION}/QtGui"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtQml/${QT_VERSION}"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtQml/${QT_VERSION}/QtQml"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtQuick/${QT_VERSION}"
+      CPPFLAGS="${CPPFLAGS} -I${QT_INCLUDE_DIRECTORY}/QtQuick/${QT_VERSION}/QtQuick"
+
+      AS_IF([test "${SYS}" != "mingw32"], [
+          CPPFLAGS="${CPPFLAGS} -fPIC"
+      ])
+
+      AC_LANG_PUSH([C++])
+      AC_CHECK_HEADERS([private/qquickitem_p.h private/qquickwindow_p.h],
+         [have_declarative_private="yes"], [])
+      AC_LANG_POP([C++])
+      VLC_RESTORE_FLAGS
+
       VLC_SAVE_FLAGS
       CPPFLAGS="${CPPFLAGS} ${QT_CFLAGS}"
       AC_COMPILE_IFELSE(
@@ -4044,10 +4067,12 @@ AS_IF([test "${enable_qt}" != "no"], [
   ALIASES="${ALIASES} qvlc"
 ])
 AC_SUBST([QT_VERSION])
+AC_SUBST([QT_INCLUDE_DIRECTORY])
 AM_CONDITIONAL([ENABLE_QT], [test "$enable_qt" != "no"])
 AM_CONDITIONAL([HAVE_QT5_X11], [test "${have_qt5_x11}" = "yes"])
 AM_CONDITIONAL([HAVE_QT5_WAYLAND], [test "${have_qt5_wayland}" = "yes"])
 AM_CONDITIONAL([HAVE_QT5_GTK], [test "${have_qt5_gtk}" = "yes"])
+AM_CONDITIONAL([HAVE_QT5_DECLARATIVE_PRIVATE], [test "${have_declarative_private}" = "yes"])
 
 dnl
 dnl detect kde4-config patch (used for kde solids).

modules/gui/qt/Makefile.am

@@ -81,6 +81,18 @@ endif
 if HAVE_QT5_GTK
 libqt_plugin_la_CPPFLAGS += -DQT5_HAS_GTK
 endif
+if HAVE_QT5_DECLARATIVE_PRIVATE
+libqt_plugin_la_CPPFLAGS += -DQT5_DECLARATIVE_PRIVATE \
+	-I$(QT_INCLUDE_DIRECTORY)/QtCore/$(QT_VERSION) \
+	-I$(QT_INCLUDE_DIRECTORY)/QtCore/$(QT_VERSION)/QtCore \
+	-I$(QT_INCLUDE_DIRECTORY)/QtGui/$(QT_VERSION) \
+	-I$(QT_INCLUDE_DIRECTORY)/QtGui/$(QT_VERSION)/QtGui \
+	-I$(QT_INCLUDE_DIRECTORY)/QtQml/$(QT_VERSION) \
+	-I$(QT_INCLUDE_DIRECTORY)/QtQml/$(QT_VERSION)/QtQml \
+	-I$(QT_INCLUDE_DIRECTORY)/QtQuick/$(QT_VERSION) \
+	-I$(QT_INCLUDE_DIRECTORY)/QtQuick/$(QT_VERSION)/QtQuick
+
+endif
 
 libqt_plugin_la_SOURCES = \
 	gui/qt/qt.cpp gui/qt/qt.hpp gui/qt/plugins.hpp \