chore: Format examples in doc strings - common (#18336)

## Which issue does this PR close?
Part of #16915

## Rationale for this change
Format code examples in documentation comments to improve readability
and maintain consistent code style across the codebase. This is part of
a multi-PR effort to format all doc comment examples and eventually
enable CI checks to enforce this formatting.

## What changes are included in this PR?
Run `cargo fmt -p datafusion-common -- --config
format_code_in_doc_comments=true`

## Are these changes tested?
No testing needed - this is purely a formatting change with no
functional modifications.

## Are there any user-facing changes?
No - this only affects documentation formatting.

Author: CuteChuanChuan

datafusion/common/src/config.rs

@@ -57,7 +57,7 @@ use std::sync::Arc;
 ///        /// Field 3 doc
 ///        field3: Option<usize>, default = None
 ///    }
-///}
+/// }
 /// ```
 ///
 /// Will generate
@@ -1326,36 +1326,35 @@ impl ConfigOptions {
 /// # Example
 /// ```
 /// use datafusion_common::{
-///     config::ConfigExtension, extensions_options,
-///     config::ConfigOptions,
+///     config::ConfigExtension, config::ConfigOptions, extensions_options,
 /// };
-///  // Define a new configuration struct using the `extensions_options` macro
-///  extensions_options! {
-///     /// My own config options.
-///     pub struct MyConfig {
-///         /// Should "foo" be replaced by "bar"?
-///         pub foo_to_bar: bool, default = true
+/// // Define a new configuration struct using the `extensions_options` macro
+/// extensions_options! {
+///    /// My own config options.
+///    pub struct MyConfig {
+///        /// Should "foo" be replaced by "bar"?
+///        pub foo_to_bar: bool, default = true
 ///
-///         /// How many "baz" should be created?
-///         pub baz_count: usize, default = 1337
-///     }
-///  }
+///        /// How many "baz" should be created?
+///        pub baz_count: usize, default = 1337
+///    }
+/// }
 ///
-///  impl ConfigExtension for MyConfig {
+/// impl ConfigExtension for MyConfig {
 ///     const PREFIX: &'static str = "my_config";
-///  }
+/// }
 ///
-///  // set up config struct and register extension
-///  let mut config = ConfigOptions::default();
-///  config.extensions.insert(MyConfig::default());
+/// // set up config struct and register extension
+/// let mut config = ConfigOptions::default();
+/// config.extensions.insert(MyConfig::default());
 ///
-///  // overwrite config default
-///  config.set("my_config.baz_count", "42").unwrap();
+/// // overwrite config default
+/// config.set("my_config.baz_count", "42").unwrap();
 ///
-///  // check config state
-///  let my_config = config.extensions.get::<MyConfig>().unwrap();
-///  assert!(my_config.foo_to_bar,);
-///  assert_eq!(my_config.baz_count, 42,);
+/// // check config state
+/// let my_config = config.extensions.get::<MyConfig>().unwrap();
+/// assert!(my_config.foo_to_bar,);
+/// assert_eq!(my_config.baz_count, 42,);
 /// ```
 ///
 /// # Note:

datafusion/common/src/datatype.rs

@@ -81,7 +81,6 @@ pub trait FieldExt {
     /// assert_eq!(list_field.data_type(), &DataType::List(Arc::new(
     ///     Field::new("item", DataType::Int32, true)
     /// )));
-    ///
     fn into_list(self) -> Self;
 
     /// Return a new Field representing this Field as the item type of a
@@ -107,7 +106,6 @@ pub trait FieldExt {
     ///    Field::new("item", DataType::Int32, true)),
     ///    3
     /// ));
-    ///
     fn into_fixed_size_list(self, list_size: i32) -> Self;
 
     /// Update the field to have the default list field name ("item")

datafusion/common/src/dfschema.rs

@@ -56,12 +56,10 @@ pub type DFSchemaRef = Arc<DFSchema>;
 /// an Arrow schema.
 ///
 /// ```rust
-/// use datafusion_common::{DFSchema, Column};
 /// use arrow::datatypes::{DataType, Field, Schema};
+/// use datafusion_common::{Column, DFSchema};
 ///
-/// let arrow_schema = Schema::new(vec![
-///    Field::new("c1", DataType::Int32, false),
-/// ]);
+/// let arrow_schema = Schema::new(vec![Field::new("c1", DataType::Int32, false)]);
 ///
 /// let df_schema = DFSchema::try_from_qualified_schema("t1", &arrow_schema).unwrap();
 /// let column = Column::from_qualified_name("t1.c1");
@@ -77,12 +75,10 @@ pub type DFSchemaRef = Arc<DFSchema>;
 /// Create an unqualified schema using TryFrom:
 ///
 /// ```rust
-/// use datafusion_common::{DFSchema, Column};
 /// use arrow::datatypes::{DataType, Field, Schema};
+/// use datafusion_common::{Column, DFSchema};
 ///
-/// let arrow_schema = Schema::new(vec![
-///    Field::new("c1", DataType::Int32, false),
-/// ]);
+/// let arrow_schema = Schema::new(vec![Field::new("c1", DataType::Int32, false)]);
 ///
 /// let df_schema = DFSchema::try_from(arrow_schema).unwrap();
 /// let column = Column::new_unqualified("c1");
@@ -94,13 +90,15 @@ pub type DFSchemaRef = Arc<DFSchema>;
 /// Use the `Into` trait to convert `DFSchema` into an Arrow schema:
 ///
 /// ```rust
+/// use arrow::datatypes::{Field, Schema};
 /// use datafusion_common::DFSchema;
-/// use arrow::datatypes::{Schema, Field};
 /// use std::collections::HashMap;
 ///
-/// let df_schema = DFSchema::from_unqualified_fields(vec![
-///    Field::new("c1", arrow::datatypes::DataType::Int32, false),
-/// ].into(),HashMap::new()).unwrap();
+/// let df_schema = DFSchema::from_unqualified_fields(
+///     vec![Field::new("c1", arrow::datatypes::DataType::Int32, false)].into(),
+///     HashMap::new(),
+/// )
+/// .unwrap();
 /// let schema: &Schema = df_schema.as_arrow();
 /// assert_eq!(schema.fields().len(), 1);
 /// ```
@@ -884,22 +882,26 @@ impl DFSchema {
     /// # Example
     ///
     /// ```
-    /// use datafusion_common::DFSchema;
     /// use arrow::datatypes::{DataType, Field, Schema};
+    /// use datafusion_common::DFSchema;
     /// use std::collections::HashMap;
     ///
     /// let schema = DFSchema::from_unqualified_fields(
     ///     vec![
     ///         Field::new("id", DataType::Int32, false),
     ///         Field::new("name", DataType::Utf8, true),
-    ///     ].into(),
-    ///     HashMap::new()
-    /// ).unwrap();
+    ///     ]
+    ///     .into(),
+    ///     HashMap::new(),
+    /// )
+    /// .unwrap();
     ///
-    /// assert_eq!(schema.tree_string().to_string(),
-    /// r#"root
+    /// assert_eq!(
+    ///     schema.tree_string().to_string(),
+    ///     r#"root
     ///  |-- id: int32 (nullable = false)
-    ///  |-- name: utf8 (nullable = true)"#);
+    ///  |-- name: utf8 (nullable = true)"#
+    /// );
     /// ```
     pub fn tree_string(&self) -> impl Display + '_ {
         let mut result = String::from("root\n");

datafusion/common/src/diagnostic.rs

@@ -30,8 +30,11 @@ use crate::Span;
 /// ```rust
 /// # use datafusion_common::{Location, Span, Diagnostic};
 /// let span = Some(Span {
-///     start: Location{ line: 2, column: 1 },
-///     end: Location{ line: 4, column: 15 }
+///     start: Location { line: 2, column: 1 },
+///     end: Location {
+///         line: 4,
+///         column: 15,
+///     },
 /// });
 /// let diagnostic = Diagnostic::new_error("Something went wrong", span)
 ///     .with_help("Have you tried turning it on and off again?", None);

datafusion/common/src/error.rs

@@ -684,7 +684,10 @@ impl DataFusionError {
 /// let mut builder = DataFusionError::builder();
 /// builder.add_error(DataFusionError::Internal("foo".to_owned()));
 /// // ok_or returns the value if no errors have been added
-/// assert_contains!(builder.error_or(42).unwrap_err().to_string(), "Internal error: foo");
+/// assert_contains!(
+///     builder.error_or(42).unwrap_err().to_string(),
+///     "Internal error: foo"
+/// );
 /// ```
 #[derive(Debug, Default)]
 pub struct DataFusionErrorBuilder(Vec<DataFusionError>);
@@ -702,7 +705,10 @@ impl DataFusionErrorBuilder {
     /// # use datafusion_common::{assert_contains, DataFusionError};
     /// let mut builder = DataFusionError::builder();
     /// builder.add_error(DataFusionError::Internal("foo".to_owned()));
-    /// assert_contains!(builder.error_or(42).unwrap_err().to_string(), "Internal error: foo");
+    /// assert_contains!(
+    ///     builder.error_or(42).unwrap_err().to_string(),
+    ///     "Internal error: foo"
+    /// );
     /// ```
     pub fn add_error(&mut self, error: DataFusionError) {
         self.0.push(error);
@@ -714,8 +720,11 @@ impl DataFusionErrorBuilder {
     /// ```
     /// # use datafusion_common::{assert_contains, DataFusionError};
     /// let builder = DataFusionError::builder()
-    ///   .with_error(DataFusionError::Internal("foo".to_owned()));
-    /// assert_contains!(builder.error_or(42).unwrap_err().to_string(), "Internal error: foo");
+    ///     .with_error(DataFusionError::Internal("foo".to_owned()));
+    /// assert_contains!(
+    ///     builder.error_or(42).unwrap_err().to_string(),
+    ///     "Internal error: foo"
+    /// );
     /// ```
     pub fn with_error(mut self, error: DataFusionError) -> Self {
         self.0.push(error);

datafusion/common/src/metadata.rs

@@ -171,7 +171,6 @@ pub fn format_type_and_metadata(
 /// // Add any metadata from `FieldMetadata` to `Field`
 /// let updated_field = metadata.add_to_field(field);
 /// ```
-///
 #[derive(Clone, PartialEq, Eq, PartialOrd, Hash, Debug)]
 pub struct FieldMetadata {
     /// The inner metadata of a literal expression, which is a map of string

datafusion/common/src/nested_struct.rs

@@ -110,16 +110,19 @@ fn cast_struct_column(
 /// temporal values are formatted when cast to strings.
 ///
 /// ```
-/// use std::sync::Arc;
-/// use arrow::array::{Int64Array, ArrayRef};
+/// use arrow::array::{ArrayRef, Int64Array};
 /// use arrow::compute::CastOptions;
 /// use arrow::datatypes::{DataType, Field};
 /// use datafusion_common::nested_struct::cast_column;
+/// use std::sync::Arc;
 ///
 /// let source: ArrayRef = Arc::new(Int64Array::from(vec![1, i64::MAX]));
 /// let target = Field::new("ints", DataType::Int32, true);
 /// // Permit lossy conversions by producing NULL on overflow instead of erroring
-/// let options = CastOptions { safe: true, ..Default::default() };
+/// let options = CastOptions {
+///     safe: true,
+///     ..Default::default()
+/// };
 /// let result = cast_column(&source, &target, &options).unwrap();
 /// assert!(result.is_null(1));
 /// ```