perf(serde): Use Formatter.write_str when writing string literals

src/datetime.rs

@@ -1280,7 +1280,7 @@ pub mod serde {
         type Value = DateTime<FixedOffset>;
 
         fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-            write!(formatter, "a formatted date and time string or a unix timestamp")
+            formatter.write_str("a formatted date and time string or a unix timestamp")
         }
 
         fn visit_str<E>(self, value: &str) -> Result<DateTime<FixedOffset>, E>
@@ -1462,7 +1462,7 @@ pub mod serde {
             type Value = DateTime<Utc>;
 
             fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                write!(formatter, "a unix timestamp in nanoseconds")
+                formatter.write_str("a unix timestamp in nanoseconds")
             }
 
             /// Deserialize a timestamp in nanoseconds since the epoch
@@ -1772,7 +1772,7 @@ pub mod serde {
             type Value = DateTime<Utc>;
 
             fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                write!(formatter, "a unix timestamp in microseconds")
+                formatter.write_str("a unix timestamp in microseconds")
             }
 
             /// Deserialize a timestamp in milliseconds since the epoch
@@ -1929,7 +1929,7 @@ pub mod serde {
             type Value = Option<DateTime<Utc>>;
 
             fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                write!(formatter, "a unix timestamp in microseconds or none")
+                formatter.write_str("a unix timestamp in microseconds or none")
             }
 
             /// Deserialize a timestamp in seconds since the epoch

src/lib.rs

@@ -867,7 +867,7 @@ mod weekday_serde {
         type Value = Weekday;
 
         fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
-            write!(f, "Weekday")
+            f.write_str("Weekday")
         }
 
         fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
@@ -1169,7 +1169,7 @@ mod month_serde {
         type Value = Month;
 
         fn expecting(&self, f: &mut fmt::Formatter) -> fmt::Result {
-            write!(f, "Month")
+            f.write_str("Month")
         }
 
         fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>

src/naive/date.rs

@@ -1844,7 +1844,7 @@ mod serde {
         type Value = NaiveDate;
 
         fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-            write!(formatter, "a formatted date string")
+            formatter.write_str("a formatted date string")
         }
 
         #[cfg(any(feature = "std", test))]

src/naive/datetime.rs

@@ -1751,7 +1751,7 @@ pub mod serde {
         type Value = NaiveDateTime;
 
         fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-            write!(formatter, "a formatted date and time string")
+            formatter.write_str("a formatted date and time string")
         }
 
         fn visit_str<E>(self, value: &str) -> Result<NaiveDateTime, E>

src/naive/time.rs

@@ -1490,7 +1490,7 @@ mod serde {
         type Value = NaiveTime;
 
         fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-            write!(formatter, "a formatted time string")
+            formatter.write_str("a formatted time string")
         }
 
         fn visit_str<E>(self, value: &str) -> Result<NaiveTime, E>