[Lldb-commits] [lldb] [lldb/DWARF] Fix type definition search with simple template names (PR #95905)

[Pavel Labath via lldb-commits]

================
@@ -3073,14 +3073,43 @@ SymbolFileDWARF::FindDefinitionTypeForDWARFDeclContext(const DWARFDIE &die) {
 
     // See comments below about -gsimple-template-names for why we attempt to
     // compute missing template parameter names.
-    ConstString template_params;
-    if (type_system) {
-      DWARFASTParser *dwarf_ast = type_system->GetDWARFParser();
-      if (dwarf_ast)
-        template_params = dwarf_ast->GetDIEClassTemplateParams(die);
+    std::vector<std::string> template_params;
+    DWARFDeclContext die_dwarf_decl_ctx;
+    DWARFASTParser *dwarf_ast = type_system ? type_system->GetDWARFParser() : nullptr;
+    for (DWARFDIE ctx_die = die; ctx_die && !isUnitType(ctx_die.Tag());
+         ctx_die = ctx_die.GetParentDeclContextDIE()) {
+      die_dwarf_decl_ctx.AppendDeclContext(ctx_die.Tag(), ctx_die.GetName());
+      template_params.push_back(
+          (ctx_die.IsStructUnionOrClass() && dwarf_ast)
+              ? dwarf_ast->GetDIEClassTemplateParams(ctx_die)
+              : "");
     }
+    const bool any_template_params = llvm::any_of(
+        template_params, [](llvm::StringRef p) { return !p.empty(); });
 
-    const DWARFDeclContext die_dwarf_decl_ctx = die.GetDWARFDeclContext();
+    auto die_matches = [&](DWARFDIE type_die) {
+      // Resolve the type if both have the same tag or {class, struct} tags.
+      const bool tag_matches =
+          type_die.Tag() == tag ||
+          (IsStructOrClassTag(type_die.Tag()) && IsStructOrClassTag(tag));
----------------
labath wrote:

> Yes, that's why I said "it matters for ast construction". I think it would nice to still print the type in the original way, which mostly comes up when someone (technically incorrectly) forward-declares something as `struct Foo`, but defines it as a class.
> 

I lost a sentence here.

It would be nice to print the types in the original way. We need the canonicalization to handle the cases where the forward declarations and definitions don't have matching tags.

https://github.com/llvm/llvm-project/pull/95905