Fix algorithm for finding localized files

Now we search in priority with the GUI language, and then the
language(s) specified in the LANGUAGES environment variable.
Preoviously, the GUI language would only be considered when
LANGUAGES was not set (which was a bug).

Take this opportunity to remove old compatibility code from 2007.

(cherry picked from commit e203bf519b)

src/support/filetools.cpp

@@ -357,25 +357,20 @@ FileName const libFileSearch(string const & dir, string const & name,
 FileName const i18nLibFileSearch(string const & dir, string const & name,
 		  string const & ext)
 {
-	/* The highest priority value is the `LANGUAGE' environment
+	// if the LANGUAGE variable is set, use it as a fallback for searching for files.
-	   variable. But we don't use the value if the currently
-	   selected locale is the C locale. This is a GNU extension.
-
-	   Otherwise, w use a trick to guess what support/gettext.has done:
-	   each po file is able to tell us its name. (JMarc)
-	*/
-
 	string lang = getGuiMessages().language();
 	string const language = getEnv("LANGUAGE");
-	if (!lang.empty() && !language.empty())
+	if (!language.empty())
-		lang = language;
+		lang += ":" + language;
 
-	string l;
+	for (auto const & l : getVectorFromString(lang, ":")) {
-	lang = split(lang, l, ':');
-	while (!l.empty()) {
 		FileName tmp;
 		// First try with the full name
-		tmp = libFileSearch(addPath(dir, l), name, ext);
+		// `en' files are not in a subdirectory
+		if (l == "en")
+			tmp = libFileSearch(dir, name, ext);
+		else
+			tmp = libFileSearch(addPath(dir, l), name, ext);
 		if (!tmp.empty())
 			return tmp;
 
@@ -386,18 +381,6 @@ FileName const i18nLibFileSearch(string const & dir, string const & name,
 			if (!tmp.empty())
 				return tmp;
 		}
-
-#if 1
-		// For compatibility, to be removed later (JMarc)
-		tmp = libFileSearch(dir, token(l, '_', 0) + '_' + name,
-				    ext);
-		if (!tmp.empty()) {
-			lyxerr << "i18nLibFileSearch: File `" << tmp
-			       << "' has been found by the old method" <<endl;
-			return tmp;
-		}
-#endif
-		lang = split(lang, l, ':');
 	}
 
 	return libFileSearch(dir, name, ext);

status.23x

@@ -144,6 +144,9 @@ What's new
 
 - Expand environment variables when modifying the PATH prefix.
 
+- Fix language of Help documents when LyX UI language is different from
+  OS UI language.
+
 
 
 * INTERNALS