DWARFASTParserClang: Unify compilation unit language handling

[labath]

Summary

The function was not being consistent in how it retrieved the language
of the current compile unit. Sometimes it did so from the lldb CU
object, and sometimes from the DWARF die. This patch unifies the
handling on the latter. The reason for choosing the DWARF method is
because I'd eventually like to stop creating lldb CUs for dwarf type
units (and so this code needs to would need to work without them).

[labath]

source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

297

DWARFDIE::GetLanguage just fetches the (cached) language attribute from the parent DWARFUnit. The dwarf spec only speaks about this attribute in the context of top level DIEs.

source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

TypeSP DWARFASTParserClang::ParseTypeFromDWARF(const SymbolContext &sc,
   Declaration decl;
 
   Type::EncodingDataType encoding_data_type = Type::eEncodingIsUID;
   CompilerType clang_type;
   DWARFFormValue form_value;
 
   dw_attr_t attr;
   TypeSP type_sp;
+  LanguageType cu_language = die.GetLanguage();
   switch (tag) {
   case DW_TAG_typedef:
   case DW_TAG_base_type:
   case DW_TAG_pointer_type:
   case DW_TAG_reference_type:
   case DW_TAG_rvalue_reference_type:
   case DW_TAG_const_type:
   case DW_TAG_restrict_type:
if (!clang_type && (encoding_data_type == Type::eEncodingIsPointerUID ||
               }
 
               break;
             }
           }
         }
       }
 
-      bool translation_unit_is_objc =
-          (sc.comp_unit->GetLanguage() == eLanguageTypeObjC ||
-           sc.comp_unit->GetLanguage() == eLanguageTypeObjC_plus_plus);
-
-      if (translation_unit_is_objc) {
+      if (cu_language == eLanguageTypeObjC ||
+          cu_language == eLanguageTypeObjC_plus_plus) {
         if (type_name_cstr != nullptr) {
           static ConstString g_objc_type_name_id("id");
           static ConstString g_objc_type_name_Class("Class");
           static ConstString g_objc_type_name_selector("SEL");
 
           if (type_name_const_str == g_objc_type_name_id) {
             if (log)
               dwarf->GetObjectFile()->GetModule()->LogMessage(
case DW_TAG_class_type: {
     // variables in different blocks.
     std::unique_ptr<UniqueDWARFASTType> unique_ast_entry_up(
         new UniqueDWARFASTType());
 
     ConstString unique_typename(type_name_const_str);
     Declaration unique_decl(decl);
 
     if (type_name_const_str) {
-      LanguageType die_language = die.GetLanguage();
-      if (Language::LanguageIsCPlusPlus(die_language)) {
+      if (Language::LanguageIsCPlusPlus(cu_language)) {
         // For C++, we rely solely upon the one definition rule that says
         // only one thing can exist at a given decl context. We ignore the
         // file and line that things are declared on.
         std::string qualified_name;
         if (die.GetQualifiedName(qualified_name))
           unique_typename = ConstString(qualified_name);
         unique_decl.Clear();
       }
if (tag == DW_TAG_structure_type) {
       tag_decl_kind = clang::TTK_Union;
       default_accessibility = eAccessPublic;
     } else if (tag == DW_TAG_class_type) {
       tag_decl_kind = clang::TTK_Class;
       default_accessibility = eAccessPrivate;
     }
 
     if (byte_size && *byte_size == 0 && type_name_cstr && !die.HasChildren() &&
-        sc.comp_unit->GetLanguage() == eLanguageTypeObjC) {
+        cu_language == eLanguageTypeObjC) {
       // Work around an issue with clang at the moment where forward
       // declarations for objective C classes are emitted as:
       //  DW_TAG_structure_type [2]
       //  DW_AT_name( "ForwardObjcClass" )
       //  DW_AT_byte_size( 0x00 )
       //  DW_AT_decl_file( "..." )
       //  DW_AT_decl_line( 1 )
       //