Turn on clippy for Rust and fix lints for non-generated code (#7575)

Co-authored-by: Casper Neo <cneo@google.com>

rust/flexbuffers/src/buffer.rs

@@ -70,7 +70,7 @@ impl<'de> Buffer for &'de [u8] {
     /// Based off of the `empty` function, allows override for optimization purposes.
     #[inline]
     fn empty_str() -> Self::BufferString {
-        &""
+        ""
     }
 
     #[inline]

rust/flexbuffers/src/builder/map.rs

@@ -49,7 +49,7 @@ impl<'a> MapBuilder<'a> {
         // Nested vector.
         let start = Some(self.builder.values.len());
         VectorBuilder {
-            builder: &mut self.builder,
+            builder: self.builder,
             start,
         }
     }
@@ -64,7 +64,7 @@ impl<'a> MapBuilder<'a> {
         // Nested map.
         let start = Some(self.builder.values.len());
         MapBuilder {
-            builder: &mut self.builder,
+            builder: self.builder,
             start,
         }
     }

rust/flexbuffers/src/builder/ser.rs

@@ -98,7 +98,7 @@ impl ser::Error for Error {
         Self::Serde(format!("{}", msg))
     }
 }
-impl<'a> ser::SerializeSeq for &mut FlexbufferSerializer {
+impl ser::SerializeSeq for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_element<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
@@ -113,14 +113,14 @@ impl<'a> ser::SerializeSeq for &mut FlexbufferSerializer {
 }
 // This is unlike a flexbuffers map which requires CString like keys.
 // Its implemented as alternating keys and values (hopefully).
-impl<'a> ser::SerializeMap for &'a mut FlexbufferSerializer {
+impl ser::SerializeMap for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_key<T: ?Sized>(&mut self, key: &T) -> Result<(), Self::Error>
     where
         T: Serialize,
     {
-        key.serialize(MapKeySerializer(&mut **self))
+        key.serialize(MapKeySerializer(self))
     }
     fn serialize_value<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
     where
@@ -132,7 +132,7 @@ impl<'a> ser::SerializeMap for &'a mut FlexbufferSerializer {
         self.end_map()
     }
 }
-impl<'a> ser::SerializeTuple for &mut FlexbufferSerializer {
+impl ser::SerializeTuple for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_element<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
@@ -145,7 +145,7 @@ impl<'a> ser::SerializeTuple for &mut FlexbufferSerializer {
         self.end_vector()
     }
 }
-impl<'a> ser::SerializeTupleStruct for &mut FlexbufferSerializer {
+impl ser::SerializeTupleStruct for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
@@ -158,7 +158,7 @@ impl<'a> ser::SerializeTupleStruct for &mut FlexbufferSerializer {
         self.end_vector()
     }
 }
-impl<'a> ser::SerializeStruct for &mut FlexbufferSerializer {
+impl ser::SerializeStruct for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_field<T: ?Sized>(
@@ -176,7 +176,7 @@ impl<'a> ser::SerializeStruct for &mut FlexbufferSerializer {
         self.end_map()
     }
 }
-impl<'a> ser::SerializeTupleVariant for &mut FlexbufferSerializer {
+impl ser::SerializeTupleVariant for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_field<T: ?Sized>(&mut self, value: &T) -> Result<(), Self::Error>
@@ -190,7 +190,7 @@ impl<'a> ser::SerializeTupleVariant for &mut FlexbufferSerializer {
         self.end_map()
     }
 }
-impl<'a> ser::SerializeStructVariant for &mut FlexbufferSerializer {
+impl ser::SerializeStructVariant for &mut FlexbufferSerializer {
     type Ok = ();
     type Error = Error;
     fn serialize_field<T: ?Sized>(

rust/flexbuffers/src/builder/vector.rs

@@ -39,7 +39,7 @@ impl<'a> VectorBuilder<'a> {
     pub fn start_vector(&mut self) -> VectorBuilder {
         let start = Some(self.builder.values.len());
         VectorBuilder {
-            builder: &mut self.builder,
+            builder: self.builder,
             start,
         }
     }
@@ -48,7 +48,7 @@ impl<'a> VectorBuilder<'a> {
     pub fn start_map(&mut self) -> MapBuilder {
         let start = Some(self.builder.values.len());
         MapBuilder {
-            builder: &mut self.builder,
+            builder: self.builder,
             start,
         }
     }

rust/flexbuffers/src/lib.rs

@@ -29,7 +29,7 @@
 //             Serde with maps - field names and type names.
 
 // Until flat/flexbuffers is on Rust v1.42, we cannot use the previously unstable matches! macro.
-#![allow(clippy::unknown_clippy_lints)]
+#![allow(unknown_lints)]
 #![allow(clippy::match_like_matches_macro)]
 
 #[macro_use]

rust/flexbuffers/src/reader/mod.rs

@@ -380,7 +380,7 @@ impl<B: Buffer> Reader<B> {
     }
 
     pub fn as_blob(&self) -> Blob<B> {
-        self.get_blob().unwrap_or(Blob(B::empty()))
+        self.get_blob().unwrap_or_else(|_| Blob(B::empty()))
     }
 
     /// Retrieves str pointer, errors if invalid UTF-8, or the provided index
@@ -580,8 +580,8 @@ impl<B: Buffer> Reader<B> {
     /// Returns empty string if you're not trying to read a string.
     pub fn as_str(&self) -> B::BufferString {
         match self.fxb_type {
-            FlexBufferType::String => self.get_str().unwrap_or(B::empty_str()),
-            FlexBufferType::Key => self.get_key().unwrap_or(B::empty_str()),
+            FlexBufferType::String => self.get_str().unwrap_or_else(|_| B::empty_str()),
+            FlexBufferType::Key => self.get_key().unwrap_or_else(|_| B::empty_str()),
             _ => B::empty_str(),
         }
     }