Revert "Fix bug #13069."

This reverts commit fafe3ea5d7.

config/qt.m4

@@ -28,10 +28,10 @@ AC_DEFUN([QT_CHECK_COMPILE],
 		qt_guilibs="'-lQtCore -lQtGui' '-lQtCore4 -lQtGui4'"
 		if test $USE_QT6 = "yes" ; then
 		    qt_corelibs="-lQt6Core"
-		    qt_guilibs="-lQt6Core -lQt6Concurrent -lQt6Gui -lQt6Svg -lQt6Xml -lQt6Widgets"
+		    qt_guilibs="-lQt6Core -lQt6Concurrent -lQt6Gui -lQt6Svg -lQt6Widgets"
 		else
 		    qt_corelibs="-lQt5Core"
-		    qt_guilibs="-lQt5Core -lQt5Concurrent -lQt5Gui -lQt5Svg -lQt5Xml -lQt5Widgets"
+		    qt_guilibs="-lQt5Core -lQt5Concurrent -lQt5Gui -lQt5Svg -lQt5Widgets"
 		fi
 		for libname in $qt_corelibs '-framework QtCore'
 		do
@@ -43,8 +43,8 @@ AC_DEFUN([QT_CHECK_COMPILE],
 		done
 		qt_cv_libname=
 		for libname in $qt_guilibs \
-		               '-framework QtCore -framework QtConcurrent -framework QtSvg -framework QtXml -framework QtWidgets -framework QtMacExtras -framework QtGui'\
+		               '-framework QtCore -framework QtConcurrent -framework QtSvg -framework QtWidgets -framework QtMacExtras -framework QtGui'\
-		               '-framework QtCore -framework QtConcurrent -framework QtSvg -framework QtSvgWidgets -framework QtXml -framework QtWidgets -framework QtGui'\
+		               '-framework QtCore -framework QtConcurrent -framework QtSvg -framework QtSvgWidgets -framework QtWidgets -framework QtGui'\
 		               '-framework QtCore -framework QtGui'
 		do
 			QT_TRY_LINK($libname)
@@ -264,7 +264,7 @@ AC_DEFUN([QT_DO_PKG_CONFIG],
 	  export PKG_CONFIG_PATH
 	fi
 	qt_corelibs="Qt5Core"
-	qt_guilibs="Qt5Core Qt5Concurrent Qt5Gui Qt5Svg Qt5Widgets Qt5Xml"
+	qt_guilibs="Qt5Core Qt5Concurrent Qt5Gui Qt5Svg Qt5Widgets"
 	lyx_use_x11extras=false
 	PKG_CHECK_EXISTS(Qt5X11Extras, [lyx_use_x11extras=true], [])
 	if $lyx_use_x11extras; then
@@ -339,7 +339,7 @@ AC_DEFUN([QT_DO_MANUAL_CONFIG],
 	QT_CORE_LDFLAGS=
 	if test -n "$qt_cv_includes"; then
 		QT_INCLUDES="-I$qt_cv_includes"
-		for i in Qt QtCore QtGui QtWidgets QtSvg QtConcurrent QtSvgWidgets QtXml QtMacExtras; do
+		for i in Qt QtCore QtGui QtWidgets QtSvg QtConcurrent QtSvgWidgets QtMacExtras; do
 			QT_INCLUDES="$QT_INCLUDES -I$qt_cv_includes/$i"
 			if test "$lyx_use_packaging" = "macosx" ; then
 				QT_INCLUDES="$QT_INCLUDES -I$qt_cv_libraries/${i}.framework/Headers"
@@ -435,7 +435,6 @@ qtHaveModule(concurrent)	{QT += concurrent} else {MISSING += concurrent}
 qtHaveModule(gui)		{QT += gui} else {MISSING += gui}
 qtHaveModule(gui-private)	{QT += gui-private} else {MISSING += gui-private}
 qtHaveModule(svg)		{QT += svg} else {MISSING += svg}
-qtHaveModule(xml)       	{QT += xml} else {MISSING += xml}
 qtHaveModule(widgets)		{QT += widgets} else {MISSING += widgets}
 EOF2
 	        if test "$qt_major" = 6; then

src/mathed/InsetMathBox.cpp

@@ -28,10 +28,6 @@
 #include <iostream>
 #include <ostream>
 
-#include <QtXml/QDomDocument>
-#include <QtXml/QDomElement>
-#include "support/qstring_helpers.h"
-
 using namespace lyx::support;
 
 namespace lyx {
@@ -66,10 +62,6 @@ namespace {
 void splitAndWrapInMText(MathMLStream & ms, MathData const & cell,
 						 const std::string & attributes)
 {
-        // The goal of this function is to take an XML fragment and wrap
-        // anything that is outside of any tag in <mtext></mtext> tags,
-        // then wrap the whole thing in an <mrow></mrow> tag with attributes
-
 	// First, generate the inset into a string of its own.
 	docstring inset_contents;
 	{
@@ -82,46 +74,53 @@ void splitAndWrapInMText(MathMLStream & ms, MathData const & cell,
 		inset_contents = ostmp.str();
 	}
 
-        // We use the QT XML library. It's easier if we deal with an XML "document"
+	// No tags are allowed within <m:mtext>: split the string if there are tags.
-        // rather than "fragment", so we wrap it in a fake root node (which we will
+	std::vector<docstring> parts;
-        // remove at the end).
+	while (true) {
-        docstring inset_contents_xml = "<root>" + inset_contents + "</root>";
+		std::size_t angle_pos = inset_contents.find('<');
+		if (angle_pos == docstring::npos)
+			break;
 
-        // Parse the XML into a DOM
+		// String structure:
-        QDomDocument xml;
+		// - prefix: pure text, no tag
-        xml.setContent(toqstr(inset_contents_xml));
+		// - tag to split: something like <m:mn>1</m:mn> or more complicated
+		//   (like nested tags), with or without name space
+		// - rest to be taken care of in the next iteration
 
-        QDomElement docElem = xml.documentElement();
+		// Push the part before the tag.
+		parts.emplace_back(inset_contents.substr(0, angle_pos));
+		inset_contents = inset_contents.substr(angle_pos);
+		// Now, inset_contents starts with the tag to isolate, so that
+		//     inset_contents[0] == '<'
 
-        // Iterate through the children of our fake root element.
+		// Push the tag, up to its end. Process: find the tag name (either
-        QDomNode n = docElem.firstChild();
+		// before > or the first attribute of the tag), then the matching end
-        while (!n.isNull()) {
+		// tag, then proceed with pushing.
-			// try to convert the child into a text element
+		const std::size_t tag_name_end =
-			// (i.e. some text that is outside of an XML tag)
+				std::min(inset_contents.find(' ', 1), inset_contents.find('>', 1));
-            QDomText text = n.toText();
+		const std::size_t tag_name_length = tag_name_end - 1;
-            if (!text.isNull()) {
+		const docstring tag_name = inset_contents.substr(1, tag_name_length);
-				// if the result is not null, then the child was indeed
-				// bare text, so we need to wrap it in mtext tags
-				// make an mtext element
-                QDomElement wrapper = xml.createElement(toqstr(ms.namespacedTag("mtext")));
-				// put the mtext element in the document right before the text
-                docElem.insertBefore(wrapper,n);
-                // move the text node inside the mtext element (this has the side
-                // effect of removing it from where it was as a child of the root)
-				wrapper.appendChild(n);
-                n = wrapper.nextSibling();
-            } else {
-				// if the text is null, then we have something besides a text
-				// element (i.e. a tag), so we don't need to do anything and just
-				// move onto the next child
-                n = n.nextSibling();
-            }
-        }
 
-        ms << MTag("mrow", attributes);
+		const std::size_t end_tag_start =
-        docstring interior = qstring_to_ucs4(xml.toString(-1));
+				inset_contents.find(tag_name, tag_name_end + 1);
-        ms << interior.substr(6,interior.length()-13); // chop off the initial <root> and final </root> tags
+		const std::size_t end_tag = inset_contents.find('>', end_tag_start);
-        ms << ETag("mrow");
+
+		parts.emplace_back(inset_contents.substr(0, end_tag + 1));
+		inset_contents = inset_contents.substr(end_tag + 1);
+	}
+	parts.emplace_back(inset_contents);
+
+	// Finally, output the complete inset: escape the test in <m:mtext>, leave
+	// the other tags untouched.
+	ms << MTag("mrow", attributes);
+	for (std::size_t i = 0; i < parts.size(); i += 2) {
+		ms << MTag("mtext")
+		   << parts[i]
+		   << ETag("mtext");
+		if (parts.size() > i + 1)
+			ms << parts[i + 1];
+	}
+	ms << ETag("mrow");
 }
 }