fix clippy

Author: xudong963

datafusion/common/src/stats.rs

@@ -451,6 +451,9 @@ impl Statistics {
 
     /// Summarize zero or more statistics into a single `Statistics` instance.
     ///
+    /// The method assumes that all statistics are for the same schema.
+    /// If not, maybe you can call `SchemaMapper::map_column_statistics` to make them consistent.
+    ///
     /// Returns an error if the statistics do not match the specified schemas.
     pub fn try_merge_iter<'a, I>(items: I, schema: &Schema) -> Result<Statistics>
     where

datafusion/core/src/datasource/mod.rs

@@ -269,7 +269,7 @@ mod tests {
             &self,
             _file_col_statistics: &[datafusion_common::ColumnStatistics],
         ) -> datafusion_common::Result<Vec<datafusion_common::ColumnStatistics>> {
-            todo!()
+            unimplemented!()
         }
     }
 }

datafusion/datasource/src/file_groups.rs

@@ -427,7 +427,7 @@ impl FileGroup {
 
     /// Get the mutable reference to the statistics for this group
     pub fn statistics_mut(&mut self) -> Option<&mut Statistics> {
-        self.statistics.as_mut().map(|arc| Arc::make_mut(arc))
+        self.statistics.as_mut().map(Arc::make_mut)
     }
 
     /// Partition the list of files into `n` groups

datafusion/datasource/src/schema_adapter.rs

@@ -409,12 +409,16 @@ mod tests {
         let mut file_stats = Statistics::default();
 
         // Statistics for column b (index 0 in file)
-        let mut b_stats = ColumnStatistics::default();
-        b_stats.null_count = Precision::Exact(5);
+        let b_stats = ColumnStatistics {
+            null_count: Precision::Exact(5),
+            ..Default::default()
+        };
 
         // Statistics for column a (index 1 in file)
-        let mut a_stats = ColumnStatistics::default();
-        a_stats.null_count = Precision::Exact(10);
+        let a_stats = ColumnStatistics {
+            null_count: Precision::Exact(10),
+            ..Default::default()
+        };
 
         file_stats.column_statistics = vec![b_stats, a_stats];