Trivial cast error when using `#[quickcheck]` inside macro

This is a minimal example:
```
crate::my_macro!(u32);

#[macro_export]
macro_rules! my_macro {
($my_type:ty) => {
#[quickcheck]
fn fuzz_my_type(my: $my_type) {
// ...
}
}
}
```

Results in

```
error: trivial cast: `fn(u32) {fuzz_my_type::fuzz_my_type}` as `fn(u32)`
--> ~/fuzz_tests.rs:13:9
|
2 | crate::my_macro!(u32);
| ---------------------- in this macro invocation
...
13 | / #[quickcheck]
14 | | fn fuzz_my_type(my: $my_type) {
| |_______________________^
```

It works if I add `#[allow(trivial_casts)]`, but it should work without flags to the compiler.