Get rid of QPA_XCB define

Since the platform is selected at run time (e.g. xcb vs. Wayland), it
is not a good idea to decide at compile time what code is run. Another
example is on macOS, where having xcb libraries available will lead to
lauching the Xquartz whenever LyX is running.

With this patch, things are separated:
- the code is run when run-time platform is "xcb".
- the support code is compiled in when xcb header and libraries are
  available.

The cmake code is courtesy of Kornel Benko.

Fixes ticket #13086.

(cherry picked from commit 18c310a8cf)
(cherry picked from commit f1fddd86ef)
(cherry picked from commit 3bc4554e57)
(cherry picked from commit 8c14748e78)

CMakeLists.txt

@@ -805,7 +805,6 @@ if(LYX_USE_QT MATCHES "QT6|QT5")
 			Qt5_wrap_ui(${ARGN})
 		endmacro()
 	endif()
-	# set QPA_XCB if QT uses X11
 	find_package(${QtVal}Core CONFIG REQUIRED)
 	if (${QtVal}Core_FOUND)
 		find_package(${QtVal}Widgets CONFIG REQUIRED)
@@ -1188,6 +1187,13 @@ get_data_destination(dest_data)
 list(APPEND tmp_vi "  LyX files dir:           ${CMAKE_INSTALL_PREFIX}/${dest_data}")
 string(REPLACE ";" "\\n" VERSION_INFO "${tmp_vi}")
 
+# the result XCB_LIBRARY will be used in src/CMakeLists.txt and also in configuring config.h
+find_library(XCB_LIBRARY NAMES xcb)
+if (XCB_LIBRARY)
+  set(HAVE_LIBXCB 1 CACHE BOOL "" FORCE)
+else()
+  set(HAVE_LIBXCB 0 CACHE BOOL "" FORCE)
+endif()
 configure_file(${LYX_CMAKE_DIR}/config.h.cmake ${TOP_BINARY_DIR}/config.h)
 unset(opts)
 unset(tmp_vi)

config/qt.m4

@@ -214,31 +214,15 @@ AC_DEFUN([QT_DO_IT_ALL],
 	     fi;;
 	esac
 
+	dnl Specific support for X11 will be built if these are available
+	AC_CHECK_HEADERS([xcb/xcb.h])
+	AC_CHECK_LIB([xcb], [xcb_send_event])
 
 	save_CPPFLAGS=$CPPFLAGS
 	CPPFLAGS="$save_CPPFLAGS $QT_CORE_INCLUDES"
 	AC_CHECK_HEADER(QtGui/qtgui-config.h,
 	  [lyx_qt_config=QtGui/qtgui-config.h],
 	  [lyx_qt_config=qconfig.h])
-	AC_MSG_CHECKING([whether Qt uses the X Window system])
-	if test x$USE_QT6 = xyes ; then
-	  dnl FIXME: Check whether defining QPA_XCB makes sense with Qt6
-	  AC_PREPROC_IFELSE([AC_LANG_SOURCE([
-	    [#include <$lyx_qt_config>]
-	    [#if !defined(QT_FEATURE_xcb) || QT_FEATURE_xcb < 0]
-	    [#error Fail]
-	    [#endif]])],
-	    [AC_MSG_RESULT(yes)
-	     AC_DEFINE(QPA_XCB, 1, [Define if Qt uses the X Window System])],
-	    [AC_MSG_RESULT(no)])
-	else
-	  AC_EGREP_CPP(xcb,
-	    [#include <$lyx_qt_config>
-	    QT_QPA_DEFAULT_PLATFORM_NAME],
-	    [AC_MSG_RESULT(yes)
-	     AC_DEFINE(QPA_XCB, 1, [Define if Qt uses the X Window System])],
-	    [AC_MSG_RESULT(no)])
-	fi
 	CPPFLAGS=$save_CPPFLAGS
 
 	QT_FIND_TOOL([QT_MOC], [moc])

development/cmake/ConfigureChecks.cmake

@@ -28,7 +28,7 @@ test_big_endian(WORDS_BIGENDIAN)
 set(Include_Defines)
 foreach(_h_file aspell.h aspell/aspell.h limits.h locale.h
 	stdlib.h sys/stat.h sys/time.h sys/types.h sys/utime.h
-	sys/socket.h unistd.h inttypes.h utime.h string.h argz.h)
+	sys/socket.h unistd.h inttypes.h utime.h string.h argz.h xcb/xcb.h)
 	string(REGEX REPLACE "[/\\.]" "_" _hf ${_h_file})
 	string(TOUPPER ${_hf} _HF)
 	check_include_files(${_h_file} HAVE_${_HF})
@@ -275,7 +275,6 @@ else()
   endif()
 endif()
 
-set(QPA_XCB)
 set(HAVE_QT5_X11_EXTRAS)
 set(HAVE_QT6_X11_EXTRAS)
 if (LYX_USE_QT MATCHES "QT5|QT6")
@@ -312,10 +311,6 @@ if (LYX_USE_QT MATCHES "QT5|QT6")
       }
       "
       QT_USES_X11)
-    if(QT_USES_X11 AND NOT LYX_USE_QT MATCHES "QT6")
-      set(QPA_XCB ${QT_USES_X11})
-      message(STATUS "Found QPA_XCB = ${QPA_XCB}")
-    endif()
   endif()
 
   if (${QtVal}X11Extras_FOUND)

development/cmake/config.h.cmake

@@ -64,9 +64,6 @@
 
 #cmakedefine Z_PREFIX 1
 
-// Defined if QT=QT5 uses X11
-#cmakedefine QPA_XCB 1
-
 // Define if you have the Qt5X11Extras module
 #cmakedefine HAVE_QT5_X11_EXTRAS 1
 
@@ -91,10 +88,13 @@ ${Include_used_spellchecker}
 // Define to 1 if enchant is version 2.x at least
 #cmakedefine HAVE_ENCHANT2 1
 
-#endif // config.h guard
+// Define to 1 if have xcb library
+#cmakedefine HAVE_LIBXCB ${HAVE_LIBXCB}
 
 #define MYTHES_H_LOCATION <${MYTHES_DIR}/mythes.hxx>
 
+#endif // config.h guard
+
 // Unguarded cleanup of global namespace:
 
 #ifdef ColorMode

src/CMakeLists.txt

@@ -148,7 +148,6 @@ if(QT_USES_X11)
   find_package(X11 REQUIRED)
   target_link_libraries(${_lyx} ${X11_X11_LIB}) # we need it because we use XSendEvent
   if(HAVE_QT5_X11_EXTRAS)
-    find_library(XCB_LIBRARY NAMES xcb)
     if (XCB_LIBRARY MATCHES "NOTFOUND")
       message(FATAL_ERROR "Need xcb library to use with QT5_X11_EXTRAS")
     endif()

src/frontends/qt/GuiApplication.cpp

@@ -121,7 +121,7 @@
 #include <QThreadPool>
 #include <QWidget>
 
-#if defined(QPA_XCB)
+#ifdef HAVE_XCB_XCB_H
 #include <xcb/xcb.h>
 #ifdef HAVE_QT5_X11_EXTRAS
 #include <QtX11Extras/QX11Info>
@@ -1157,10 +1157,14 @@ GuiApplication::GuiApplication(int & argc, char ** argv)
 	// Install Qt native translator for GUI elements.
 	installTranslator(&d->qt_trans_);
 
-#ifdef QPA_XCB
+	if (platformName() == "xcb") {
+#if defined(HAVE_XCB_XCB_H) && defined(HAVE_LIBXCB)
 		// Enable reception of XCB events.
 		installNativeEventFilter(this);
+#else
+		LYXERR0("Warning: X11 support is incomplete in this LyX binary.");
 #endif
+	}
 
 	// FIXME: quitOnLastWindowClosed is true by default. We should have a
 	// lyxrc setting for this in order to let the application stay resident.
@@ -1181,13 +1185,13 @@ GuiApplication::GuiApplication(int & argc, char ** argv)
 			this, SLOT(onApplicationStateChanged(Qt::ApplicationState)));
 #endif
 
-#if defined(QPA_XCB)
+	if (platformName() == "xcb") {
 		// doubleClickInterval() is 400 ms on X11 which is just too long.
 		// On Windows and Mac OS X, the operating system's value is used.
 		// On Microsoft Windows, calling this function sets the double
 		// click interval for all applications. So we don't!
 		QApplication::setDoubleClickInterval(300);
-#endif
+	}
 
 	connect(this, SIGNAL(lastWindowClosed()), this, SLOT(onLastWindowClosed()));
 
@@ -3477,7 +3481,7 @@ bool GuiApplication::longOperationStarted() {
 //
 // X11 specific stuff goes here...
 
-#if defined(QPA_XCB)
+#if defined(HAVE_XCB_XCB_H) && defined(HAVE_LIBXCB)
 bool GuiApplication::nativeEventFilter(const QByteArray & eventType,
 				       void * message, QINTPTR *)
 {

src/frontends/qt/GuiApplication.h

@@ -20,7 +20,7 @@
 
 #include <QApplication>
 #include <QList>
-#ifdef QPA_XCB
+#if defined(HAVE_XCB_XCB_H) && defined(HAVE_LIBXCB)
 #include <QAbstractNativeEventFilter>
 #endif
 
@@ -53,7 +53,7 @@ There should be only one instance of this class. No Qt object
 initialisation should be done before the instantiation of this class.
 */
 class GuiApplication : public QApplication, public Application
-#ifdef QPA_XCB
+#if defined(HAVE_XCB_XCB_H) && defined(HAVE_LIBXCB)
 		     , public QAbstractNativeEventFilter
 #endif
 {
@@ -120,7 +120,7 @@ public:
 	//@{
 	bool notify(QObject * receiver, QEvent * event) override;
 	void commitData(QSessionManager & sm);
-#if defined(QPA_XCB)
+#if defined(HAVE_XCB_XCB_H) && defined(HAVE_LIBXCB)
 #if (QT_VERSION < 0x060000)
 #define QINTPTR long
 #else

status.24x

@@ -59,6 +59,9 @@ What's new
 
 - Make -geometry command-line option work on all platforms.
 
+- Fix macOS bug, where XQuartz application would be launched for no
+  reason (bug #13086).
+
 
 * DOCUMENTATION AND LOCALIZATION