[clang] [HLSL] Add ByteAddressBuffer definition to HLSLExternalSemaSource #113477 (PR #116699)

[Helena Kotas via cfe-commits]

================
@@ -1474,6 +1474,11 @@ DeclContext *DeclContext::getPrimaryContext() {
   case Decl::ObjCCategoryImpl:
     return this;
 
+  case Decl::CXXRecord:
+    if (auto *OPD = dyn_cast<CXXRecordDecl>(this))
+      if (auto *Def = OPD->getDefinition())
+        return Def;
+    return this;
   default:
----------------
hekota wrote:

Right, because the `TypeForDecl` is not set for `ByteAddressBuffer`. We need to make sure it gets set, otherwise the decl is not valid and it is going to bite us again someplace else.

We are creating the record in `BuiltinTypeDeclBuilder` constructor with `DelayTypeCreation` flag. For template classes the type gets created in `finalizeTemplateArgs` in the `ASTContext::getInjectedClassNameType` call, but that does not happed for non-template classes. We need to make sure it gets created and assigned, for example by adding `ASTContext::getTypeDeclType` call to the `BuiltinTypeDeclBuilder` destructor:

```
  ~BuiltinTypeDeclBuilder() {
    if (!Record->getTypeForDecl())
      Record->getASTContext().getTypeDeclType(Record,
                                              Record->getPreviousDecl());
    ... rest of the destructor code ....
  }

```

https://github.com/llvm/llvm-project/pull/116699