Introduce "inherit" encoding for latex_language

This gets rid of the hardcoded latin1 encoding for verbatim. Instead,
verbatim now inherits the encoding from the context, which is what is
actually wanted here.

Fixes: #9012, #9258

lib/encodings

@@ -246,3 +246,9 @@ End
 # Pure 7bit ASCII encoding (partially hardcoded in LyX)
 Encoding ascii ascii "ASCII" ascii fixed none
 End
+
+# Semantic encodings
+
+# Inherit encoding of the context (used by verbatim)
+Encoding inherit inherit "" "" fixed none
+End

lib/languages

@@ -65,6 +65,8 @@
 # * Encoding is the default encoding used with TeX fonts.
 #   It is only used if Document > Settings > Language > Encoding
 #   is set to "Language Default" and "use non-TeX fonts" is FALSE.
+#   Encoding "inherit" means: keep encoding of the context (used by
+#   latex_language).
 # * InternalEncoding is used to tell LyX that babel internally sets a
 #   non-standard font encoding (such as hebrew to LHE or greek to LGR).
 #   If True, LyX cares for characters/macros that do not exist in
@@ -100,13 +102,13 @@ Language ignore
 	GuiName          "Ignore"
 	BabelName        ignore
 	PolyglossiaName  ignore
-	Encoding         iso8859-1
+	Encoding         inherit
 	LangCode         ignore
 End
 
 Language latex
 	GuiName          "LaTeX"
-	Encoding         iso8859-1
+	Encoding         inherit
 	LangCode         latex
 End
 

src/DocIterator.cpp

@@ -721,6 +721,17 @@ Encoding const * DocIterator::getEncoding() const
 	Text const & text = *sl.text();
 	Font font = text.getPar(sl.pit()).getFont(bp, sl.pos(),
 	                                          text.outerFont(sl.pit()));
+	Encoding const * enc = font.language()->encoding();
+	if (enc->name() == "inherit") {
+		size_t const n = depth();
+		for (size_t i = 0; i < n; ++i) {
+			Text const & otext = *slices_[i].text();
+			Font ofont = otext.getPar(slices_[i].pit()).getFont(bp, slices_[i].pos(),
+								  otext.outerFont(slices_[i].pit()));
+			if (ofont.language()->encoding()->name() != "inherit")
+				return ofont.language()->encoding();
+		}
+	}
 	return font.language()->encoding();
 }
 

src/Text.cpp

@@ -933,15 +933,12 @@ bool canInsertChar(Cursor const & cur, char_type c)
 		}
 	}
 
-	// Prevent to insert uncodable characters in verbatim and ERT
-	// (workaround for bug 9012)
-	// Don't do it for listings inset, since InsetListings::latex() tries
-	// to switch to a usable encoding which works in many cases (bug 9102).
-	if (par.isPassThru() && cur.inset().lyxCode() != LISTINGS_CODE &&
-	    cur.current_font.language()) {
-		Encoding const * e = cur.current_font.language()->encoding();
+	// Prevent to insert uncodable characters in verbatim and ERT.
+	// The encoding is inherited from the context here.
+	if (par.isPassThru() && cur.getEncoding()) {
+		Encoding const * e = cur.getEncoding();
 		if (!e->encodable(c)) {
-			cur.message(_("Character is uncodable in verbatim paragraphs."));
+			cur.message(_("Character is uncodable in this verbatim context."));
 			return false;
 		}
 	}

src/frontends/qt4/GuiDocument.cpp

@@ -1079,7 +1079,7 @@ GuiDocument::GuiDocument(GuiView & lv)
 	Encodings::const_iterator it = encodings.begin();
 	Encodings::const_iterator const end = encodings.end();
 	for (auto const & encvar : encodings) {
-		if (!encvar.unsafe())
+		if (!encvar.unsafe() && !encvar.guiName().empty())
 			encodinglist.append(qt_(encvar.guiName()));
 	}
 	encodinglist.sort();

src/output_latex.cpp

@@ -1530,7 +1530,7 @@ pair<bool, int> switchEncoding(odocstream & os, BufferParams const & bparams,
 	// * with useNonTeXFonts: "utf8plain",
 	// * with XeTeX and TeX fonts: "ascii" (inputenc fails),
 	// * with LuaTeX and TeX fonts: only one encoding accepted by luainputenc.
-	if (runparams.isFullUnicode())
+	if (runparams.isFullUnicode() || newEnc.name() == "inherit")
 		return make_pair(false, 0);
 
 	Encoding const & oldEnc = *runparams.encoding;