FFI structs sample possible dangling pointer

Please ignore my ignorance but while I'm trying to learn more about `ffi` I studied the structs sample.

I just don't understand how freeing `myHomeUtf8` does not leave a dangling pointer in the the native `Place` struct.

https://github.com/dart-lang/samples/blob/master/ffi/structs/structs_library/structs.c#L58
```c
struct Place create_place(char *name, double latitude, double longitude)
{
struct Place place;
place.name = name;
// ...
```

https://github.com/dart-lang/samples/blob/master/ffi/structs/structs.dart#L94
```dart
final myHomeUtf8 = 'My Home'.toNativeUtf8();
final createPlace =
dylib.lookupFunction('create_place');
final place = createPlace(myHomeUtf8, 42.0, 24.0);
calloc.free(myHomeUtf8);
final name = place.name.toDartString();
```

I understand that someone needs to free that memory and that in a sample memory management might not be the biggest concern. But accessing the name after freeing the memory seems especially odd to me.

Most likely I'm just missing something here.