[CIR] Implement lowering for LinkageSpecDecl (#137634)

Like the NamespaceDecl, this is just emitted as a decl-context, where
all its internal declarations get emitted for it. The incubator doesn't
seem to have any good tests for this, so I wrote what I could think of
as a half-decent test for this one, though the lowering doesn't manage
whether these should be mangled, so the test is mostly just for
spot-checking purposes.

I'm implementing this as it will make writing further tests for future
features a little easier.

1 files changed, 2 insertions, 1 deletions

diff --git a/clang/lib/CIR/CodeGen/CIRGenModule.cpp b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
index b9cc2da..a6a4330 100644
--- a/clang/lib/CIR/CodeGen/CIRGenModule.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenModule.cpp
@@ -677,8 +677,9 @@ void CIRGenModule::emitTopLevelDecl(Decl *decl) {
     break;
 
   // C++ Decls
+  case Decl::LinkageSpec:
   case Decl::Namespace:
-    emitDeclContext(cast<NamespaceDecl>(decl));
+    emitDeclContext(Decl::castToDeclContext(decl));
     break;
   }
 }