Bump clippy dependency to compile on 1.8.

README.md

@@ -579,6 +579,69 @@ impl serde::de::Visitor for PointVisitor {
 }
 ```
 
+Design Considerations and tradeoffs for Serializers and Deserializers
+=====================================================================
+
+Serde serialization and deserialization implementations are written in such a
+way that they err on being able to represent more values, and also provide
+better error messages when they are passed an incorrect type to deserialize
+from. For example, by default, it is a syntax error to deserialize a `String`
+into an `Option<String>`. This is implemented such that it is possible to
+distinguish between the values `None` and `Some(())`, if the serialization
+format supports option types.
+
+However, many formats do not have option types, and represents optional values
+as either a `null`, or some other value. Serde `Serializer`s and
+`Deserializer`s can opt-in support for this. For serialization, this is pretty
+easy. Simply implement these methods:
+
+```rust
+...
+
+    fn visit_none(&mut self) -> Result<(), Self::Error> {
+        self.visit_unit()
+    }
+
+    fn visit_some<T>(&mut self, value: T) -> Result<(), Self::Error> {
+        value.serialize(self)
+    }
+...
+```
+
+For deserialization, this can be implemented by way of the
+`Deserializer::visit_option` hook, which presumes that there is some ability to peek at what is the
+next value in the serialized token stream. This following example is from
+[serde_tests::TokenDeserializer](https://github.com/serde-rs/serde/blob/master/serde_tests/tests/token.rs#L435-L454),
+where it checks to see if the next value is an `Option`, a `()`, or some other
+value:
+
+```rust
+...
+
+    fn visit_option<V>(&mut self, mut visitor: V) -> Result<V::Value, Error>
+        where V: de::Visitor,
+    {
+        match self.tokens.peek() {
+            Some(&Token::Option(false)) => {
+                self.tokens.next();
+                visitor.visit_none()
+            }
+            Some(&Token::Option(true)) => {
+                self.tokens.next();
+                visitor.visit_some(self)
+            }
+            Some(&Token::Unit) => {
+                self.tokens.next();
+                visitor.visit_none()
+            }
+            Some(_) => visitor.visit_some(self),
+            None => Err(Error::EndOfStreamError),
+        }
+    }
+
+...
+```
+
 Annotations
 ===========
 

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "0.6.10"
+version = "0.6.11"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -17,5 +17,5 @@ num-impls = ["num-bigint", "num-complex", "num-rational"]
 num-rational = ["num/rational"]
 
 [dependencies]
-clippy = { version = "^0.0.36", optional = true }
+clippy = { version = "^0.0.37", optional = true }
 num = { version = "^0.1.27", default-features = false }

serde/src/de/impls.rs

@@ -283,6 +283,13 @@ impl<
 > Visitor for OptionVisitor<T> {
     type Value = Option<T>;
 
+    #[inline]
+    fn visit_unit<E>(&mut self) -> Result<Option<T>, E>
+        where E: Error,
+    {
+        Ok(None)
+    }
+
     #[inline]
     fn visit_none<E>(&mut self) -> Result<Option<T>, E>
         where E: Error,

serde_codegen/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_codegen"
-version = "0.6.10"
+version = "0.6.11"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros to auto-generate implementations for the serde framework"
@@ -20,7 +20,7 @@ syntex = { version = "^0.26.0", optional = true }
 
 [dependencies]
 aster = { version = "^0.10.0", default-features = false }
-clippy = { version = "^0.0.36", optional = true }
+clippy = { version = "^0.0.37", optional = true }
 quasi = { version = "^0.4.0", default-features = false }
 quasi_macros = { version = "^0.4.0", optional = true }
 syntex = { version = "^0.26.0", optional = true }

serde_macros/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_macros"
-version = "0.6.10"
+version = "0.6.11"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "Macros to auto-generate implementations for the serde framework"
@@ -13,7 +13,7 @@ name = "serde_macros"
 plugin = true
 
 [dependencies]
-clippy = "^0.0.36"
+clippy = "^0.0.37"
 serde_codegen = { version = "^0.6.10", path = "../serde_codegen", default-features = false, features = ["nightly"] }
 
 [dev-dependencies]

serde_tests/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_tests"
-version = "0.6.2"
+version = "0.6.3"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>"]
 license = "MIT/Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -25,7 +25,7 @@ serde = { version = "*", path = "../serde", features = ["num-impls"] }
 syntex = "^0.26.0"
 
 [dependencies]
-clippy = { version = "^0.0.36", optional = true }
+clippy = { version = "^0.0.37", optional = true }
 
 [[test]]
 name = "test"