Amend 16660d12.

The previous commit introduced wrong behaviours for <>. The new code carefully escapes what needs to be escaped from LaTeX, using the now-standard XML tools (XMLStream).

autotests/export/xhtml/math_output_latex.lyx

@@ -100,7 +100,7 @@ The problem occurs when adding a label.
 \begin_layout Standard
 \begin_inset Formula 
 \begin{equation}
-x^{2}\label{eq:1}
+x^{2}<\log x\label{eq:1}
 \end{equation}
 
 \end_inset

autotests/export/xhtml/math_output_latex.xhtml

@@ -22,7 +22,7 @@ div.standard {
 <h1 class='title' id='magicparlabel-1'>Math formula output as raw LaTeX</h1>
 <div class='standard' id='magicparlabel-2'>The problem occurs when adding a label. https://www.lyx.org/trac/ticket/13048</div>
 
-<div class='standard' id='magicparlabel-3'><a id="eq_1" /><div class='math'><table class='mathtable'><tr><td class='math'>x^{2}</td><td>(1)</td></tr></table></div>
+<div class='standard' id='magicparlabel-3'><a id="eq_1" /><div class='math'><table class='mathtable'><tr><td class='math'>x^{2}<\log x</td><td>(1)</td></tr></table></div>
 </div>
 </body>
 </html>

src/insets/InsetLabel.cpp

@@ -380,6 +380,8 @@ void InsetLabel::docbook(XMLStream & xs, OutputParams const & runparams) const
 
 docstring InsetLabel::xhtml(XMLStream & xs, OutputParams const &) const
 {
+	// Print the label as an HTML anchor, so that an external link can point to this equation.
+	// (URL: FILE.html#EQ-ID.)
 	// FIXME XHTML
 	// Unfortunately, the name attribute has been deprecated, so we have to use
 	// id here to get the document to validate as XHTML 1.1. This will cause a

src/mathed/InsetMathHull.cpp

@@ -2574,35 +2574,56 @@ void InsetMathHull::mathmlize(MathMLStream & ms) const
 }
 
 
-void InsetMathHull::mathAsLatex(TeXMathStream & os) const
+docstring InsetMathHull::mathAsLatex() const
 {
-	MathEnsurer ensurer(os, false);
 	bool const havenumbers = haveNumbers();
 	bool const havetable = havenumbers || nrows() > 1 || ncols() > 1;
 
 	if (!havetable) {
+		odocstringstream ls;
+		otexrowstream ots(ls);
+		TeXMathStream os(ots, false, true, TeXMathStream::wsPreview);
+		ModeSpecifier specifier(os, MATH_MODE);
+		MathEnsurer ensurer(os, false);
+
 		os << cell(index(0, 0));
-		return;
+		return ls.str();
 	}
 
-	os << "<table class='mathtable'>";
+	odocstringstream ods;
+	XMLStream xs(ods);
+
+	xs << xml::StartTag("table", "class='mathtable'");
 	for (row_type row = 0; row < nrows(); ++row) {
-		os << "<tr>";
+		xs << xml::StartTag("tr");
 		for (col_type col = 0; col < ncols(); ++col) {
-			os << "<td class='math'>";
-			os << cell(index(row, col));
-			os << "</td>";
+			xs << xml::StartTag("td", "class='math'");
+
+			odocstringstream ls;
+			otexrowstream ots(ls);
+			TeXMathStream os(ots, false, true, TeXMathStream::wsPreview);
+			ModeSpecifier specifier(os, MATH_MODE);
+			MathEnsurer ensurer(os, false);
+
+			os << cell(index(0, 0));
+			// ls.str() contains a raw LaTeX string, which might require some encoding before being valid XML.
+			xs << ls.str();
+
+			xs << xml::EndTag("td");
 		}
 		if (havenumbers) {
-			os << "<td>";
+			xs << xml::StartTag("td");
 			docstring const & num = numbers_[row];
-			if (!num.empty())
-				os << '(' << num << ')';
-		    os << "</td>";
+			if (!num.empty()) {
+				xs << '(' << num << ')';
+			}
+			xs << xml::EndTag("td");
 		}
-		os << "</tr>";
+		xs << xml::EndTag("tr");
 	}
-	os << "</table>";
+	xs << xml::EndTag("table");
+
+	return ods.str();
 }
 
 
@@ -2703,7 +2724,7 @@ docstring InsetMathHull::xhtml(XMLStream & xs, OutputParams const & op) const
 			string const tag = (getType() == hullSimple) ? "span" : "div";
 			xs << xml::CR()
 			   << xml::StartTag(tag, "style = \"text-align: center;\"")
-			   << xml::CompTag("img", "src=\"" + filename + "\" alt=\"Mathematical Equation\"")
+			   << xml::CompTag("img", "src=\"" + filename + R"(" alt="Mathematical Equation")")
 			   << xml::EndTag(tag)
 			   << xml::CR();
 			success = true;
@@ -2716,12 +2737,8 @@ docstring InsetMathHull::xhtml(XMLStream & xs, OutputParams const & op) const
 	if (!success /* || mathtype != BufferParams::LaTeX */) {
 		// Unfortunately, we cannot use latexString() because we do not want
 		// $...$ or whatever.
-		odocstringstream ls;
-		otexrowstream ots(ls);
-		TeXMathStream wi(ots, false, true, TeXMathStream::wsPreview);
-		ModeSpecifier specifier(wi, MATH_MODE);
-		mathAsLatex(wi);
-		docstring const latex = ls.str();
+		// The returned value already has the correct escaping for HTML.
+		docstring const latex = mathAsLatex();
 
 		// class='math' allows for use of jsMath
 		// http://www.math.union.edu/~dpvc/jsMath/
@@ -2729,8 +2746,7 @@ docstring InsetMathHull::xhtml(XMLStream & xs, OutputParams const & op) const
 		// probably should allow for some kind of customization here
 		string const tag = (getType() == hullSimple) ? "span" : "div";
 		xs << xml::StartTag(tag, "class='math'")
-		   << XMLStream::ESCAPE_AND << latex // Don't escape <> tags: latex might contain them
-		   // (typically, when there is a label).
+		   << XMLStream::ESCAPE_NONE << latex // Don't escape anything: latex might contain XML.
 		   << xml::EndTag(tag)
 		   << xml::CR();
 	}

src/mathed/InsetMathHull.h

@@ -151,8 +151,8 @@ public:
 	void mathmlize(MathMLStream &) const override;
 	///
 	void htmlize(HtmlStream &) const override;
-	///
-	void mathAsLatex(TeXMathStream &) const;
+	/// Returns the hull as a LaTeX string for embedding in HTML or XML.
+	docstring mathAsLatex() const;
 	///
 	void toString(odocstream &) const override;
 	///