fix: clippy warnings in mysql types and migrate modules

- Fix let_and_return in mysql/types/float.rs
- Fix needless_borrows_for_generic_args in chrono and time modules
- Fix len_zero by using is_empty()
- Fix unnecessary_cast by removing redundant type casts
- Fix unwrap_or_default usage
- Fix needless_borrow in json module
- Fix needless_option_as_deref in value module
- Fix get_first by using first() instead of get(0)
- Fix needless_return in migrate module

Author: cursoragent

sqlx-core/src/mysql/migrate.rs

@@ -192,11 +192,11 @@ CREATE TABLE IF NOT EXISTS _sqlx_migrations (
                     .map_err(MigrateError::AccessMigrationMetadata)?;
 
             if let Some(checksum) = checksum {
-                return if checksum == &*migration.checksum {
+                if checksum == &*migration.checksum {
                     Ok(())
                 } else {
                     Err(MigrateError::VersionMismatch(migration.version))
-                };
+                }
             } else {
                 Err(MigrateError::VersionMissing(migration.version))
             }

sqlx-core/src/mysql/types/chrono.rs

@@ -25,7 +25,7 @@ impl<T: TimeZone> Type<MySql> for DateTime<T> {
 /// Note: assumes the connection's `time_zone` is set to `+00:00` (UTC).
 impl Encode<'_, MySql> for DateTime<Utc> {
     fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
-        Encode::<MySql>::encode(&self.naive_utc(), buf)
+        Encode::<MySql>::encode(self.naive_utc(), buf)
     }
 }
 
@@ -40,7 +40,7 @@ impl<'r> Decode<'r, MySql> for DateTime<Utc> {
 /// Note: assumes the connection's `time_zone` is set to `+00:00` (UTC).
 impl Encode<'_, MySql> for DateTime<Local> {
     fn encode_by_ref(&self, buf: &mut Vec<u8>) -> IsNull {
-        Encode::<MySql>::encode(&self.naive_utc(), buf)
+        Encode::<MySql>::encode(self.naive_utc(), buf)
     }
 }
 
@@ -242,7 +242,7 @@ fn encode_date(date: &NaiveDate, buf: &mut Vec<u8>) {
 }
 
 fn decode_date(mut buf: &[u8]) -> Option<NaiveDate> {
-    if buf.len() == 0 {
+    if buf.is_empty() {
         // MySQL specifies that if there are no bytes, this is all zeros
         None
     } else {
@@ -257,7 +257,7 @@ fn encode_time(time: &NaiveTime, include_micros: bool, buf: &mut Vec<u8>) {
     buf.push(time.second() as u8);
 
     if include_micros {
-        buf.extend(&((time.nanosecond() / 1000) as u32).to_le_bytes());
+        buf.extend(&(time.nanosecond() / 1000).to_le_bytes());
     }
 }
 
@@ -274,5 +274,5 @@ fn decode_time(len: u8, mut buf: &[u8]) -> NaiveTime {
     };
 
     NaiveTime::from_hms_micro_opt(hour as u32, minute as u32, seconds as u32, micros as u32)
-        .unwrap_or_else(NaiveTime::default)
+        .unwrap_or_default()
 }

sqlx-core/src/mysql/types/float.rs

@@ -73,8 +73,7 @@ impl Decode<'_, MySql> for f64 {
             }
             _ => {
                 let str_val = value.as_str()?;
-                let parsed = str_val.parse()?;
-                parsed
+                str_val.parse()?
             }
         })
     }

sqlx-core/src/mysql/types/json.rs

@@ -41,7 +41,7 @@ where
     fn decode(value: MySqlValueRef<'r>) -> Result<Self, BoxDynError> {
         let string_value = <&str as Decode<MySql>>::decode(value)?;
 
-        serde_json::from_str(&string_value)
+        serde_json::from_str(string_value)
             .map(Json)
             .map_err(Into::into)
     }

sqlx-core/src/mysql/types/time.rs

@@ -26,7 +26,7 @@ impl Encode<'_, MySql> for OffsetDateTime {
         let utc_dt = self.to_offset(UtcOffset::UTC);
         let primitive_dt = PrimitiveDateTime::new(utc_dt.date(), utc_dt.time());
 
-        Encode::<MySql>::encode(&primitive_dt, buf)
+        Encode::<MySql>::encode(primitive_dt, buf)
     }
 }
 
@@ -238,8 +238,8 @@ fn decode_date(buf: &[u8]) -> Result<Option<Date>, BoxDynError> {
 
     Date::from_calendar_date(
         LittleEndian::read_u16(buf) as i32,
-        time::Month::try_from(buf[2] as u8)?,
-        buf[3] as u8,
+        time::Month::try_from(buf[2])?,
+        buf[3],
     )
     .map_err(Into::into)
     .map(Some)
@@ -251,7 +251,7 @@ fn encode_time(time: &Time, include_micros: bool, buf: &mut Vec<u8>) {
     buf.push(time.second());
 
     if include_micros {
-        buf.extend(&((time.nanosecond() / 1000) as u32).to_le_bytes());
+        buf.extend(&(time.nanosecond() / 1000).to_le_bytes());
     }
 }
 

sqlx-core/src/mysql/value.rs

@@ -93,7 +93,7 @@ impl<'r> ValueRef<'r> for MySqlValueRef<'r> {
 
     #[inline]
     fn is_null(&self) -> bool {
-        is_null(self.value.as_deref(), &self.type_info)
+        is_null(self.value, &self.type_info)
     }
 }
 
@@ -125,7 +125,7 @@ fn is_null(value: Option<&[u8]>, ty: &MySqlTypeInfo) -> bool {
         if matches!(
             ty.r#type,
             ColumnType::Date | ColumnType::Timestamp | ColumnType::Datetime
-        ) && (value.get(0) == Some(&0)
+        ) && (value.first() == Some(&0)
             || value == b"0000-00-00"
             || value == b"0000-00-00 00:00:00")
         {