[lldb][NFCI] Redefine dw_attr_t typedef with llvm::dwarf::Attribute

Similar to dw_form_t, dw_attr_t is typedef'd to be a uint16_t. LLVM
defines their type `llvm::dwarf::Attribute` as an enum backed by a
uint16_t. Switching to the LLVM type buys us type checking and the
requirement of explicit casts.

Differential Revision: https://reviews.llvm.org/D150299

Author: bulbazord

lldb/include/lldb/Core/dwarf.h

@@ -21,7 +21,7 @@ namespace dwarf {
 }
 }
 
-typedef uint16_t dw_attr_t;
+typedef llvm::dwarf::Attribute dw_attr_t;
 typedef llvm::dwarf::Form dw_form_t;
 typedef llvm::dwarf::Tag dw_tag_t;
 typedef uint64_t dw_addr_t; // Dwarf address define that must be big enough for

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -274,6 +274,8 @@ ParsedDWARFTypeAttributes::ParsedDWARFTypeAttributes(const DWARFDIE &die) {
     if (!attributes.ExtractFormValueAtIndex(i, form_value))
       continue;
     switch (attr) {
+    default:
+      break;
     case DW_AT_abstract_origin:
       abstract_origin = form_value;
       break;

lldb/source/Plugins/SymbolFile/DWARF/DWARFAbbreviationDeclaration.cpp

@@ -40,7 +40,7 @@ DWARFAbbreviationDeclaration::extract(const DWARFDataExtractor &data,
   m_has_children = data.GetU8(offset_ptr);
 
   while (data.ValidOffset(*offset_ptr)) {
-    dw_attr_t attr = data.GetULEB128(offset_ptr);
+    auto attr = static_cast<dw_attr_t>(data.GetULEB128(offset_ptr));
     auto form = static_cast<dw_form_t>(data.GetULEB128(offset_ptr));
 
     // This is the last attribute for this abbrev decl, but there may still be

lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp

@@ -391,6 +391,8 @@ void DWARFUnit::AddUnitDIE(const DWARFDebugInfoEntry &cu_die) {
     if (!attributes.ExtractFormValueAtIndex(i, form_value))
       continue;
     switch (attr) {
+    default:
+      break;
     case DW_AT_loclists_base:
       SetLoclistsBase(form_value.Unsigned());
       break;

lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp

@@ -239,6 +239,8 @@ void ManualDWARFIndex::IndexUnitImpl(DWARFUnit &unit,
         dw_attr_t attr = attributes.AttributeAtIndex(i);
         DWARFFormValue form_value;
         switch (attr) {
+        default:
+          break;
         case DW_AT_name:
           if (attributes.ExtractFormValueAtIndex(i, form_value))
             name = form_value.AsCString();