martong added inline comments.
================
Comment at: lldb/source/Symbol/StdModuleHandler.cpp:242
+ // Instantiate the template.
+ found_decl = ClassTemplateSpecializationDecl::Create(
+ m_sema->getASTContext(),
----------------
teemperor wrote:
> martong wrote:
> > martong wrote:
> > > Is there any guarantee that the before any subsequent
> > > clang::ASTImporter::Import call this newly created node is registered as
> > > imported (via ASTImporter::MapImported)?
> > >
> > > The reason why I am asking this is because we have to enforce in
> > > clang::ASTImporter that after every Decl is created then immediately it
> > > is registered as an imported Decl, see
> > > `ASTImporter::GetImportedOrCreateDecl`. This we we make sure that no
> > > subsequent import calls will create the same node again.
> > > The cycles in the AST are handled properly only this way.
> > >
> > > This is one reason which makes me worried about exposing the import
> > > mechanism via `ImportInternal`. Would it be working if
> > > `GetImportedOrCreateDecl` was virtual and overridden here?
> > > Would it be working if GetImportedOrCreateDecl was virtual and overridden
> > > here?
> >
> > Sorry, that would certainly not work, but perhaps a virtual hook inside
> > that function could work...
> Sorry for the late reply.
>
> So I was looking into changing the code to your suggestion, but I don't think
> we can get this working reliably. The problem is that if we intercept the
> importing in GetImportedOrCreateDecl then we need to intercept not just
> `std::vector` but also all related imports that the ASTImporter may make
> before importing `std::vector` itself, e.g. DeclContext, parent classes,
> return type, template args, etc. Also we constantly would need to update this
> list in case the standard library or the ASTImporter change internally to
> make sure we intercept everything.
>
> Maybe we could instead implement an mechanism in the LLDB code that ensures
> we do call MapImported and add the decl to the lookup directly after creating
> a decl? E.g. by implementing something similar to ASTImporter's
> `GetImportedOrCreateDecl`?
Yes, I think that could work.
So, we could have a new function:
```
void CreateDeclPostamble(Decl *FromD, Decl* ToD) { // better naming?
// Keep track of imported Decls.
Importer.MapImported(FromD, ToD);
Importer.AddToLookupTable(ToD);
InitializeImportedDecl(FromD, ToD);
}
```
And we'd call this from `GetImportedOrCreateDecl` and here after `::Create`.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D59537/new/
https://reviews.llvm.org/D59537
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