The uncached lookup is mainly used in the ASTImporter/LLDB code-path
where we're not allowed to load from external storage. When importing
a FieldDecl with a DeclContext that had no external visible storage
(but came from a Clang module or PCH) the above call to `lookup(Name)`
the regular `DeclContext::lookup` fails because:
1. `DeclContext::buildLookup` doesn't set `LookupPtr` for decls
that came from a module
2. LLDB doesn't use the `SharedImporterState`
In such a case we would never continue with the "slow" path of iterating
through the decl chain on the DeclContext. In some cases this means that
ASTNodeImporter::VisitFieldDecl ends up importing a decl into the
DeclContext a second time.
The patch removes the short-circuit in the case where we don't find
any decls via the regular lookup.
**Tests**
* Un-skip the failing LLDB API tests
Differential Revision: https://reviews.llvm.org/D133945
The problem here is that the ASTImporter adds
the template class member FieldDecl to
the DeclContext twice. This happens because
we don't construct a `LookupPtr` for decls
that originate from modules and thus the
ASTImporter never realizes that the FieldDecl
has already been imported. These duplicate
decls then break the assumption of the LayoutBuilder
which expects only a single member decl to
exist.
The test will be fixed by a follow-up revision
and is thus skipped for now.
Differential Revision: https://reviews.llvm.org/D133944
