From d56a5447f30688286c1fe19f3b51225f4b586b3e Mon Sep 17 00:00:00 2001
From: Juergen Spitzmueller <spitz@lyx.org>
Date: Sat, 16 Dec 2017 16:11:25 +0100
Subject: [PATCH] Consistent output of breakable/non-breakable dashes on all
 TeX engines.

Fixes: #10839
---
 src/LaTeXFeatures.cpp             |  3 +++
 src/Paragraph.cpp                 | 26 +++++++++++++++++++++-----
 src/frontends/qt4/GuiDocument.cpp |  5 ++---
 src/frontends/qt4/ui/FontUi.ui    |  4 ++--
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/src/LaTeXFeatures.cpp b/src/LaTeXFeatures.cpp
index 3f9eb67762..d4b0018b73 100644
--- a/src/LaTeXFeatures.cpp
+++ b/src/LaTeXFeatures.cpp
@@ -1318,6 +1318,9 @@ TexString LaTeXFeatures::getMacros() const
 		macros << getPreambleSnippets();
 	}
 
+	if (mustProvide("xetexdashbreakstate"))
+		macros << "\\XeTeXdashbreakstate 0" << '\n';
+
 	if (mustProvide("papersize")) {
 		if (runparams_.flavor == OutputParams::LATEX
 		    || runparams_.flavor == OutputParams::DVILUATEX)
diff --git a/src/Paragraph.cpp b/src/Paragraph.cpp
index 80bfe3decd..a6c72c310e 100644
--- a/src/Paragraph.cpp
+++ b/src/Paragraph.cpp
@@ -1289,7 +1289,10 @@ void Paragraph::Private::latexSpecialChar(otexstream & os,
 
 	case 0x2013:
 	case 0x2014:
-		if (bparams.use_dash_ligatures && !bparams.useNonTeXFonts) {
+		// XeTeX's dash behaviour is determined via a global setting
+		if (bparams.use_dash_ligatures
+		    && owner_->getFontSettings(bparams, i).fontInfo().family() != TYPEWRITER_FAMILY
+		    && (!bparams.useNonTeXFonts || runparams.flavor != OutputParams::XETEX)) {
 			if (c == 0x2013) {
 				// en-dash
 				os << "--";
@@ -1417,6 +1420,14 @@ bool Paragraph::Private::latexSpecialT3(char_type const c, otexstream & os,
 		os << "\\textvertline" << termcmd;
 		column += 14;
 		return true;
+	case 0x2013:
+		os << "\\textendash" << termcmd;
+		column += 12;
+		return true;
+	case 0x2014:
+		os << "\\textemdash" << termcmd;
+		column += 12;
+		return true;
 	default:
 		return false;
 	}
@@ -1425,11 +1436,11 @@ bool Paragraph::Private::latexSpecialT3(char_type const c, otexstream & os,
 
 void Paragraph::Private::validate(LaTeXFeatures & features) const
 {
+	Buffer const & buf = inset_owner_->buffer();
+	BufferParams const & bp = features.runparams().is_child
+		? buf.masterParams() : buf.params();
 	if (layout_->inpreamble && inset_owner_) {
 		bool const is_command = layout_->latextype == LATEX_COMMAND;
-		Buffer const & buf = inset_owner_->buffer();
-		BufferParams const & bp = features.runparams().is_child
-			? buf.masterParams() : buf.params();
 		Font f;
 		// Using a string stream here circumvents the encoding
 		// switching machinery of odocstream. Therefore the
@@ -1509,7 +1520,6 @@ void Paragraph::Private::validate(LaTeXFeatures & features) const
 	}
 
 	// then the contents
-	BufferParams const bp = features.buffer().masterParams();
 	for (pos_type i = 0; i < int(text_.size()) ; ++i) {
 		char_type c = text_[i];
 		if (c == 0x0022) {
@@ -1519,6 +1529,12 @@ void Paragraph::Private::validate(LaTeXFeatures & features) const
 				 || ((&owner_->getFontSettings(bp, i))->language()->internalFontEncoding()))
 				features.require("textquotedbl");
 		}
+		if (!bp.use_dash_ligatures
+		    && (c == 0x2013 || c == 0x2014)
+		    && bp.useNonTeXFonts
+		    && features.runparams().flavor == OutputParams::XETEX)
+			// XeTeX's dash behaviour is determined via a global setting
+			features.require("xetexdashbreakstate");
 		BufferEncodings::validate(c, features);
 	}
 }
diff --git a/src/frontends/qt4/GuiDocument.cpp b/src/frontends/qt4/GuiDocument.cpp
index b607231043..53cee98e04 100644
--- a/src/frontends/qt4/GuiDocument.cpp
+++ b/src/frontends/qt4/GuiDocument.cpp
@@ -2074,7 +2074,6 @@ void GuiDocument::updateFontOptions()
 				fontModule->fontsRomanCO->currentIndex()).toString();
 	fontModule->fontScCB->setEnabled(providesSC(font));
 	fontModule->fontOsfCB->setEnabled(providesOSF(font));
-	fontModule->dashesCB->setEnabled(tex_fonts);
 	updateMathFonts(font);
 }
 
@@ -3210,7 +3209,7 @@ void GuiDocument::applyView()
 		fromqstr(fontModule->cjkFontLE->text());
 
 	bp_.use_microtype = fontModule->microtypeCB->isChecked();
-	bp_.use_dash_ligatures = fontModule->dashesCB->isChecked();
+	bp_.use_dash_ligatures = !fontModule->dashesCB->isChecked();
 
 	bp_.fonts_sans_scale[nontexfonts] = fontModule->scaleSansSB->value();
 	bp_.fonts_sans_scale[!nontexfonts] = fontModule->font_sf_scale;
@@ -3745,7 +3744,7 @@ void GuiDocument::paramsToDialog()
 		fontModule->cjkFontLE->setText(QString());
 
 	fontModule->microtypeCB->setChecked(bp_.use_microtype);
-	fontModule->dashesCB->setChecked(bp_.use_dash_ligatures);
+	fontModule->dashesCB->setChecked(!bp_.use_dash_ligatures);
 
 	fontModule->fontScCB->setChecked(bp_.fonts_expert_sc);
 	fontModule->fontOsfCB->setChecked(bp_.fonts_old_figures);
diff --git a/src/frontends/qt4/ui/FontUi.ui b/src/frontends/qt4/ui/FontUi.ui
index f0b3fb7e8b..fc98c1b7eb 100644
--- a/src/frontends/qt4/ui/FontUi.ui
+++ b/src/frontends/qt4/ui/FontUi.ui
@@ -297,10 +297,10 @@
    <item row="11" column="1">
     <widget class="QCheckBox" name="dashesCB">
      <property name="toolTip">
-      <string>Use font ligatures -- and --- instead of \textendash and \textemdash for en- and em-dashes</string>
+      <string>By default, a line break can occur after en- and em-dashes and before em-dashes. Checking this box prevents that.</string>
      </property>
      <property name="text">
-      <string>Output en- and &amp;em-dashes as ligatures</string>
+      <string>Disallow l&amp;ine breaks at dashes</string>
      </property>
     </widget>
    </item>