[Lldb-commits] [lldb] [lldb][DWARF] Delay struct/class/union definition DIE searching when parsing declaration DIEs. (PR #90663)

[Zequan Wu via lldb-commits]

================
@@ -1667,13 +1791,40 @@ DWARFASTParserClang::ParseStructureLikeDIE(const SymbolContext &sc,
     }
 
     if (dwarf->GetUniqueDWARFASTTypeMap().Find(
-            unique_typename, die, unique_decl, attrs.byte_size.value_or(-1),
-            *unique_ast_entry_up)) {
+            unique_typename, die, unique_decl, byte_size,
+            attrs.is_forward_declaration, *unique_ast_entry_up)) {
       type_sp = unique_ast_entry_up->m_type_sp;
       if (type_sp) {
         dwarf->GetDIEToType()[die.GetDIE()] = type_sp.get();
         LinkDeclContextToDIE(
             GetCachedClangDeclContextForDIE(unique_ast_entry_up->m_die), die);
+        if (!attrs.is_forward_declaration) {
+          // If the DIE being parsed in this function is a definition and the
+          // entry in the map is a declaration, then we need to update the entry
+          // to point to the definition DIE.
+          if (unique_ast_entry_up->m_is_forward_declaration) {
+            unique_ast_entry_up->m_die = die;
+            unique_ast_entry_up->m_byte_size = byte_size;
+            unique_ast_entry_up->m_declaration = unique_decl;
+            unique_ast_entry_up->m_is_forward_declaration = false;
+            // Need to update Type ID to refer to the definition DIE. because
+            // it's used in ParseSubroutine to determine if we need to copy cxx
+            // method types from a declaration DIE to this definition DIE.
+            type_sp->SetID(die.GetID());
+            clang_type = type_sp->GetForwardCompilerType();
+            if (attrs.class_language != eLanguageTypeObjC &&
+                attrs.class_language != eLanguageTypeObjC_plus_plus)
+              TypeSystemClang::StartTagDeclarationDefinition(clang_type);
+
+            CompilerType compiler_type_no_qualifiers =
+                ClangUtil::RemoveFastQualifiers(clang_type);
+            auto result = dwarf->GetForwardDeclCompilerTypeToDIE().try_emplace(
----------------
ZequanWu wrote:

It doesn't compile, because the value of the map is a DIERef, which doesn't have zero-argument constructor (can only constructed with 1 or 3 arguments). DIERef is a reference to a parsed DIE, so adding a zero-argument constructor for it doesn't quite make sense.

https://github.com/llvm/llvm-project/pull/90663