Fix a long-standing FIXME by resetting only the counter for top-level

sectioning when we see an appendix. This fixes bug #8271, whose root
cause was the fact that we were resetting all the counters inside ERT.

Conflicts:
	src/TextClass.h

src/Buffer.cpp

@@ -4145,9 +4145,11 @@ void Buffer::Impl::setLabel(ParIterator & it, UpdateType utype) const
 	Counters & counters = textclass.counters();
 
 	if (par.params().startOfAppendix()) {
-		// FIXME: only the counter corresponding to toplevel
-		// sectioning should be reset
-		counters.reset();
+		// We want to reset the counter corresponding to toplevel sectioning
+		Layout const & lay = textclass.getTOCLayout();
+		docstring const cnt = lay.counter;
+		if (!cnt.empty())
+			counters.reset(cnt);
 		counters.appendix(true);
 	}
 	par.params().appendix(counters.appendix());

src/TextClass.cpp

@@ -1387,27 +1387,32 @@ bool DocumentClass::hasTocLevels() const
 }
 
 
+Layout const & DocumentClass::getTOCLayout() const
+{
+	// we're going to look for the layout with the minimum toclevel
+	TextClass::LayoutList::const_iterator lit = begin();
+	TextClass::LayoutList::const_iterator const len = end();
+	int minlevel = 1000;
+	Layout const * lay = NULL;
+	for (; lit != len; ++lit) {
+		int const level = lit->toclevel;
+		// we don't want Part
+		if (level == Layout::NOT_IN_TOC || level < 0 || level >= minlevel)
+			continue;
+		lay = &*lit;
+		minlevel = level;
+	}
+	if (lay)
+		return *lay;
+	// hmm. that is very odd, so we'll do our best.
+	return operator[](defaultLayoutName());
+}
+
+
 Layout const & DocumentClass::htmlTOCLayout() const
 {
 	if (html_toc_section_.empty()) {
-		// we're going to look for the layout with the minimum toclevel
-		TextClass::LayoutList::const_iterator lit = begin();
-		TextClass::LayoutList::const_iterator const len = end();
-		int minlevel = 1000;
-		Layout const * lay = NULL;
-		for (; lit != len; ++lit) {
-			int const level = lit->toclevel;
-			// we don't want Part
-			if (level == Layout::NOT_IN_TOC || level < 0 || level >= minlevel)
-				continue;
-			lay = &*lit;
-			minlevel = level;
-		}
-		if (lay)
-			html_toc_section_ = lay->name();
-		else
-			// hmm. that is very odd, so we'll do our best
-			html_toc_section_ = defaultLayoutName();
+		html_toc_section_ = getTOCLayout().name();
 	}
 	return operator[](html_toc_section_);
 }

src/TextClass.h

@@ -397,6 +397,8 @@ public:
 	docstring const & preamble() const { return preamble_; }
 	///
 	docstring const & htmlpreamble() const { return htmlpreamble_; }
+	///
+	Layout const & getTOCLayout() const;
 	/// the paragraph style to use for TOCs, Bibliography, etc
 	/// we will attempt to calculate this if it was not given
 	Layout const & htmlTOCLayout() const;

src/output_xhtml.cpp

@@ -947,11 +947,15 @@ void xhtmlParagraphs(Text const & text,
 	while (bpit < epit) {
 		ParagraphList::const_iterator par = paragraphs.constIterator(bpit);
 		if (par->params().startOfAppendix()) {
-			// FIXME: only the counter corresponding to toplevel
-			// sectioning should be reset
-			Counters & cnts = buf.masterBuffer()->params().documentClass().counters();
-			cnts.reset();
-			cnts.appendix(true);
+			// We want to reset the counter corresponding to toplevel sectioning
+			Layout const & lay =
+				buf.masterBuffer()->params().documentClass().getTOCLayout();
+			docstring const cnt = lay.counter;
+			if (!cnt.empty()) {
+				Counters & cnts =
+					buf.masterBuffer()->params().documentClass().counters();
+				cnts.reset(cnt);
+			}
 		}
 		Layout const & style = par->layout();
 		ParagraphList::const_iterator const lastpar = par;

status.20x

@@ -41,6 +41,8 @@ What's new
 
 * USER INTERFACE
 
+- Reset only the top-level counter when starting the appendix.
+
 - Show backends, not formats, in View>Source (bug #7652).
 
 - Allow native LyX format to be shown in View>Source.
@@ -66,6 +68,8 @@ What's new
 
 * DOCUMENT INPUT/OUTPUT
 
+- Fix assertion when start of appendix is in ERT (bug 8271).
+
 - Do not output empty language switch commands (bug 8216).
 
 - When using Turkish language, use the xkeyval package to avoid