[LyX/master] Do not switch listings to singlebyte encoding with pLateX/Japanese

[Juergen Spitzmueller]

commit dd6340cfcca284074becccdf7fa2a23263ad0db6
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Tue Nov 17 10:28:10 2015 +0100

    Do not switch listings to singlebyte encoding with pLateX/Japanese
    
    Also improve Listings warning about uncodable characters
    if the encoding has been switched by LyX.
    
    Fixes: #8439

diff --git a/src/insets/InsetListings.cpp b/src/insets/InsetListings.cpp
index 566636d..ac31d28 100644
--- a/src/insets/InsetListings.cpp
+++ b/src/insets/InsetListings.cpp
@@ -122,13 +122,16 @@ void InsetListings::latex(otexstream & os, OutputParams 
const & runparams) const
 
        bool encoding_switched = false;
        Encoding const * const save_enc = runparams.encoding;
-
-       if (!runparams.isFullUnicode()
-           && !runparams.encoding->hasFixedWidth()) {
-               // We need to switch to a singlebyte encoding, since the
-               // listings package cannot deal with multi-byte-encoded
-               // glyphs (not needed with full-unicode aware backends
-               // such as XeTeX).
+       // The listings package cannot deal with multi-byte-encoded
+       // glyphs, except if full-unicode aware backends
+       // such as XeTeX or LuaTeX are used, and with pLaTeX.
+       bool const multibyte_possible = runparams.isFullUnicode()
+           || (buffer().params().bufferFormat() == "platex"
+               && runparams.encoding->package() == Encoding::japanese);
+
+       if (!multibyte_possible && !runparams.encoding->hasFixedWidth()) {
+               // We need to switch to a singlebyte encoding, due to
+               // the restrictions of the listings package (see above).
                // This needs to be consistent with
                // LaTeXFeatures::getTClassI18nPreamble().
                Language const * const outer_language =
@@ -242,10 +245,20 @@ void InsetListings::latex(otexstream & os, OutputParams 
const & runparams) const
        if (!uncodable.empty() && !runparams.silent) {
                // issue a warning about omitted characters
                // FIXME: should be passed to the error dialog
-               frontend::Alert::warning(_("Uncodable characters in listings 
inset"),
-                       bformat(_("The following characters in one of the 
program listings are\n"
-                                 "not representable in the current encoding 
and have been omitted:\n%1$s."),
-                       uncodable));
+               if (!multibyte_possible && !runparams.encoding->hasFixedWidth())
+                       frontend::Alert::warning(_("Uncodable characters in 
listings inset"),
+                               bformat(_("The following characters in one of 
the program listings are\n"
+                                         "not representable in the current 
encoding and have been omitted:\n%1$s.\n"
+                                         "This is due to a restriction of the 
listings package, which does\n"
+                                         "not support your encoding '%2$s'.\n"
+                                         "Toggling 'Use non-TeX fonts' in 
Document > Settings...\n"
+                                         "might help."),
+                               uncodable, _(runparams.encoding->guiName())));
+               else
+                       frontend::Alert::warning(_("Uncodable characters in 
listings inset"),
+                               bformat(_("The following characters in one of 
the program listings are\n"
+                                         "not representable in the current 
encoding and have been omitted:\n%1$s."),
+                               uncodable));
        }
 }