Hide implementation details for NonZero auto traits.

Author: reitermarkus

library/core/src/num/nonzero.rs

@@ -6,6 +6,7 @@ use crate::hash::{Hash, Hasher};
 use crate::intrinsics;
 use crate::marker::StructuralPartialEq;
 use crate::ops::{BitOr, BitOrAssign, Div, Neg, Rem};
+use crate::panic::{RefUnwindSafe, UnwindSafe};
 use crate::ptr;
 use crate::str::FromStr;
 
@@ -129,6 +130,25 @@ impl_nonzero_fmt!(Octal);
 impl_nonzero_fmt!(LowerHex);
 impl_nonzero_fmt!(UpperHex);
 
+macro_rules! impl_nonzero_auto_trait {
+    (unsafe $Trait:ident) => {
+        #[stable(feature = "nonzero", since = "1.28.0")]
+        unsafe impl<T> $Trait for NonZero<T> where T: ZeroablePrimitive + $Trait {}
+    };
+    ($Trait:ident) => {
+        #[stable(feature = "nonzero", since = "1.28.0")]
+        impl<T> $Trait for NonZero<T> where T: ZeroablePrimitive + $Trait {}
+    };
+}
+
+// Implement auto-traits manually based on `T` to avoid docs exposing
+// the `ZeroablePrimitive::NonZeroInner` implementation detail.
+impl_nonzero_auto_trait!(RefUnwindSafe);
+impl_nonzero_auto_trait!(unsafe Send);
+impl_nonzero_auto_trait!(unsafe Sync);
+impl_nonzero_auto_trait!(Unpin);
+impl_nonzero_auto_trait!(UnwindSafe);
+
 #[stable(feature = "nonzero", since = "1.28.0")]
 impl<T> Clone for NonZero<T>
 where