Find functions that are syntactically declared in an anonymous namespace

// FuncDeclarator [ ancestor::NamespaceDecl [ @Id =] ]

1   namespace {
2       // finds this 
3       void f(); 
4   } 
5   namespace my {
6       // no match - namespace has name
7       void f(); 
8   }
9   // no match - on the global level
10  void f();