1/// Helper function that can be used at compile time to emit a diagnostic if
2/// the type does not implement `Sync` when it should.
3///
4/// The mere act of invoking this function will cause the diagnostic to be
5/// emitted if `T` does not implement `Sync` when it should.
6///
7/// The additional `const IS_SYNC: bool` parameter is used to allow the custom
8/// diagnostic to be emitted; if `PyClassSync`
9#[allow(unused)]
10pub const fn assert_pyclass_sync<T>()
11where
12 T: PyClassSync + Sync,
13{
14}
15
16#[cfg_attr(
17 diagnostic_namespace,
18 diagnostic::on_unimplemented(
19 message = "the trait `Sync` is not implemented for `{Self}`",
20 label = "required by `#[pyclass]`",
21 note = "replace thread-unsafe fields with thread-safe alternatives",
22 note = "see <TODO INSERT PYO3 GUIDE> for more information",
23 )
24)]
25pub trait PyClassSync<T: Sync = Self> {}
26
27impl<T> PyClassSync for T where T: Sync {}
28
29mod tests {
30 #[cfg(feature = "macros")]
31 #[test]
32 fn test_assert_pyclass_sync() {
33 use super::assert_pyclass_sync;
34
35 #[crate::pyclass(crate = "crate")]
36 struct MyClass {}
37
38 assert_pyclass_sync::<MyClass>();
39 }
40}
41