Implement traits for !

serde/src/de/impls.rs

@@ -49,6 +49,16 @@ impl<'de> Deserialize<'de> for () {
     }
 }
 
+#[cfg(feature = "unstable")]
+impl<'de> Deserialize<'de> for ! {
+    fn deserialize<D>(_deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        Err(Error::custom("cannot deserialize `!`"))
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 struct BoolVisitor;

serde/src/de/mod.rs

@@ -98,6 +98,7 @@
 //!    - PathBuf
 //!    - Range\<T\>
 //!    - num::NonZero*
+//!    - `!` *(unstable)*
 //!  - **Net types**:
 //!    - IpAddr
 //!    - Ipv4Addr

serde/src/lib.rs

@@ -89,7 +89,7 @@
 // discussion of these features please refer to this issue:
 //
 //    https://github.com/serde-rs/serde/issues/812
-#![cfg_attr(feature = "unstable", feature(specialization))]
+#![cfg_attr(feature = "unstable", feature(specialization, never_type))]
 #![cfg_attr(feature = "alloc", feature(alloc))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Whitelisted clippy lints

serde/src/ser/impls.rs

@@ -247,6 +247,16 @@ impl Serialize for () {
     }
 }
 
+#[cfg(feature = "unstable")]
+impl Serialize for ! {
+    fn serialize<S>(&self, _serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        *self
+    }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 macro_rules! tuple_impls {

serde/src/ser/mod.rs

@@ -93,6 +93,7 @@
 //!    - PathBuf
 //!    - Range\<T\>
 //!    - num::NonZero*
+//!    - `!` *(unstable)*
 //!  - **Net types**:
 //!    - IpAddr
 //!    - Ipv4Addr