Resolve needless_borrow clippy lints

    error: the borrowed expression implements the required traits
       --> src/value/ser.rs:198:60
        |
    198 |         values.insert(String::from(variant), tri!(to_value(&value)));
        |                                                            ^^^^^^ help: change this to: `value`
        |
        = note: `-D clippy::needless-borrow` implied by `-D clippy::all`
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

    error: the borrowed expression implements the required traits
       --> src/value/ser.rs:317:37
        |
    317 |         self.vec.push(tri!(to_value(&value)));
        |                                     ^^^^^^ help: change this to: `value`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

    error: the borrowed expression implements the required traits
       --> src/value/ser.rs:366:37
        |
    366 |         self.vec.push(tri!(to_value(&value)));
        |                                     ^^^^^^ help: change this to: `value`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

    error: the borrowed expression implements the required traits
       --> src/value/ser.rs:409:47
        |
    409 |                 map.insert(key, tri!(to_value(&value)));
        |                                               ^^^^^^ help: change this to: `value`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

    error: the borrowed expression implements the required traits
       --> src/value/ser.rs:666:58
        |
    666 |         self.map.insert(String::from(key), tri!(to_value(&value)));
        |                                                          ^^^^^^ help: change this to: `value`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

    error: the borrowed expression implements the required traits
      --> tests/test.rs:98:26
       |
    98 |         let v = to_value(&value).unwrap();
       |                          ^^^^^^ help: change this to: `value`
       |
       = note: `-D clippy::needless-borrow` implied by `-D clippy::all`
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

    error: the borrowed expression implements the required traits
       --> tests/test.rs:114:26
        |
    114 |         let v = to_value(&value).unwrap();
        |                          ^^^^^^ help: change this to: `value`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow

src/value/ser.rs

@@ -195,7 +195,7 @@ impl serde::Serializer for Serializer {
         T: ?Sized + Serialize,
     {
         let mut values = Map::new();
-        values.insert(String::from(variant), tri!(to_value(&value)));
+        values.insert(String::from(variant), tri!(to_value(value)));
         Ok(Value::Object(values))
     }
 
@@ -314,7 +314,7 @@ impl serde::ser::SerializeSeq for SerializeVec {
     where
         T: ?Sized + Serialize,
     {
-        self.vec.push(tri!(to_value(&value)));
+        self.vec.push(tri!(to_value(value)));
         Ok(())
     }
 
@@ -363,7 +363,7 @@ impl serde::ser::SerializeTupleVariant for SerializeTupleVariant {
     where
         T: ?Sized + Serialize,
     {
-        self.vec.push(tri!(to_value(&value)));
+        self.vec.push(tri!(to_value(value)));
         Ok(())
     }
 
@@ -406,7 +406,7 @@ impl serde::ser::SerializeMap for SerializeMap {
                 // Panic because this indicates a bug in the program rather than an
                 // expected failure.
                 let key = key.expect("serialize_value called before serialize_key");
-                map.insert(key, tri!(to_value(&value)));
+                map.insert(key, tri!(to_value(value)));
                 Ok(())
             }
             #[cfg(feature = "arbitrary_precision")]
@@ -663,7 +663,7 @@ impl serde::ser::SerializeStructVariant for SerializeStructVariant {
     where
         T: ?Sized + Serialize,
     {
-        self.map.insert(String::from(key), tri!(to_value(&value)));
+        self.map.insert(String::from(key), tri!(to_value(value)));
         Ok(())
     }
 

tests/test.rs

@@ -95,7 +95,7 @@ where
         let s = to_string(value).unwrap();
         assert_eq!(s, out);
 
-        let v = to_value(&value).unwrap();
+        let v = to_value(value).unwrap();
         let s = to_string(&v).unwrap();
         assert_eq!(s, out);
     }
@@ -111,7 +111,7 @@ where
         let s = to_string_pretty(value).unwrap();
         assert_eq!(s, out);
 
-        let v = to_value(&value).unwrap();
+        let v = to_value(value).unwrap();
         let s = to_string_pretty(&v).unwrap();
         assert_eq!(s, out);
     }