Clang libtooling with MatchFinder - c++

Question

I'm beginner with libtooling, I try to learn with easy c++ code. I try to parse/print typedef expression like below lines:
namespace DEBUG {
typedef void(*function_pointer_t)(int&);
typedef int myInt;
}
clang++ -Xclang -ast-dump -fsyntax-only output:
`-NamespaceDecl 0x3e4fe331a8 <test.h:3:1, line:7:1> line:3:11 TESTS
|-TypedefDecl 0x3e4fe333b8 <line:4:2, col:42> col:18 function_pointer_t 'double (*)(int &)'
| `-PointerType 0x3e4fe33350 'double (*)(int &)'
| `-ParenType 0x3e4fe332f0 'double (int &)' sugar
| `-FunctionProtoType 0x3e4fe332b0 'double (int &)' cdecl
| |-BuiltinType 0x3e4fe32b60 'double'
| `-LValueReferenceType 0x3e4fe33210 'int &'
| `-BuiltinType 0x3e4fe32a40 'int'
`-TypedefDecl 0x3e4fe33420 <line:5:2, col:14> col:14 myInt 'int'
`-BuiltinType 0x3e4fe32a40 'int'
To parse it I create a class that inherite from MatchFinder::MatchCallback and overload MatchFinder::MatchCallback::run:
class TypdefDeclFinder : public MatchFinder::MatchCallback {
public:
virtual void run(const MatchFinder::MatchResult& result)
{
auto Item = result.Nodes.getNodeAs<clang::TypedefDecl>("typedefDeclMatch");
if (!Item) return;
if (!IsDeclFromInputFiles(Item, result.SourceManager)) return;
if (!Item->getIdentifier()) return;
if (IsInsideTemplateContext(Item)) return;
print(Item);
}
};
But the Item pointer is equal to null. I can parse/print function, variable, class, struct template, method templates, enum ... with MacthFinder::MatchCallback, but this way doesn't run on typedef.
What's wrong with this code?