[Lldb-commits] [lldb] [LLDB][NativePDB] Use typedef compiler type for typedef types (PR #156250)

[via lldb-commits]

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@@ -2045,14 +2045,17 @@ TypeSP SymbolFileNativePDB::CreateTypedef(PdbGlobalSymId id) {
   if (!ts)
     return nullptr;
 
-  ts->GetNativePDBParser()->GetOrCreateTypedefDecl(id);
+  auto *typedef_decl = ts->GetNativePDBParser()->GetOrCreateTypedefDecl(id);
+
+  CompilerType ct = target_type->GetForwardCompilerType();
+  if (auto *clang = llvm::dyn_cast_or_null<TypeSystemClang>(ts.get()))
+    ct = clang->GetType(clang->getASTContext().getTypeDeclType(typedef_decl));
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Nerixyz wrote:


> What use does `GetOrCreateType` have here? If that's not the thing that creates the correct `TypedefType`? Or in other words, could you elaborate on how this fixes the issue?

Ah, I left out the confusing/unintuitive part:

Currently, in the PDBs produced by both MSVC and LLVM, type aliases are _not_ in the "type system" (TPI stream/`LF_*` records; https://redirect.github.com/llvm/llvm-project/pull/153936 attempts to change this in LLVM).

`GetOrCreateType` looks in the PDB type stream TPI. The typedefs we currently have are from `S_UDT` records in the globals stream, so they're represented as "symbols" and `GetOrCreateType` would not be able to create the type.
Because of this, they're handled differently. 

---

> Does that mean we create two different typedefs?

No, `clang::ASTContext::getTypeDeclType` will use [`TypeForDecl`](https://github.com/llvm/llvm-project/blob/91f4db77b07368b47d32eb4d384fda2b2e5c9617/clang/include/clang/AST/Decl.h#L3517-L3521) to get back to the type.


https://github.com/llvm/llvm-project/pull/156250