HNI type checker

gistfile1.txt

hhvm tools/check_native_signatures.php runtime/ext/xmlwriter/ext_xmlwriter.cpp runtime/ext/xmlwriter/ext_xmlwriter.php
Mismatched argument type for function 'xmlwriter::startdocument' at index '0'. PHP: ?string C++:
                        const String&
Mismatched argument type for function 'xmlwriter::startdocument' at index '1'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::startdocument' at index '2'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::startdtd' at index '1'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::startdtd' at index '2'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::writedtd' at index '1'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::writedtd' at index '2'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::writedtd' at index '3'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::writedtdentity' at index '2'. PHP: ?bool C++: bool
Mismatched argument type for function 'xmlwriter::writedtdentity' at index '3'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::writedtdentity' at index '4'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::writedtdentity' at index '5'. PHP: ?string C++: const String&
Mismatched argument type for function 'xmlwriter::flush' at index '0'. PHP: ?bool C++:
                        bool
Mismatched argument type for function 'xmlwriter::outputmemory' at index '0'. PHP: ?bool C++:
                        bool
See https://github.com/facebook/hhvm/wiki/Extension-API for what types map to what