Introduce LanguageTag::getBcp47MS() for writing MS malformed tags, tdf#83190

Change-Id: I1e2815b9ae60681c7cddc416cc05bf4c70dcc48a

i18nlangtag/source/languagetag/languagetag.cxx

@@ -2359,6 +2359,14 @@ LanguageTag & LanguageTag::makeFallback()
 }
 
 
+OUString LanguageTag::getBcp47MS() const
+{
+    if (getLanguageType() == LANGUAGE_SPANISH_DATED)
+        return "es-ES_tradnl";
+    return getBcp47();
+}
+
+
 bool LanguageTag::equals( const LanguageTag & rLanguageTag ) const
 {
     // If SYSTEM is not to be resolved or either both are SYSTEM or none, we

include/i18nlangtag/languagetag.hxx

@@ -120,6 +120,14 @@ public:
      */
     const OUString &                getBcp47( bool bResolveSystem = true ) const;
 
+    /** Obtain BCP 47 language tag, but with MS malformed exceptions.
+
+        To be used *only* in OOXML filter context.
+        For example, es-ES-u-co-trad is stored as es-ES_tradnl which is not a
+        valid BCP 47 language tag.
+     */
+    OUString                        getBcp47MS() const;
+
     /** Obtain language tag as Locale.
 
         As a convention, language tags that can not be expressed as "pure"