chore: enforce clippy::allow_attributes for optimizer and macros (#19310)

## Which issue does this PR close?

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- Part of #18881 

## Rationale for this change

We want to use `#[expect]` in place of `#[allow]` on the workspace level
but to get there we wanted to do this in few crates at a time before
enabling it in workspace.

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in the issue then this section is not needed.
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your changes and offer better suggestions for fixes.
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## What changes are included in this PR?

Attributes changes for the following crates:

- datafusion-macros
- datafusion-optimizer

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## Are these changes tested?

Yes 

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## Are there any user-facing changes?

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Author: kumarUjjawal

datafusion/core/src/execution/session_state_defaults.rs

@@ -103,7 +103,7 @@ impl SessionStateDefaults {
 
     /// returns the list of default [`ScalarUDF`]s
     pub fn default_scalar_functions() -> Vec<Arc<ScalarUDF>> {
-        #[cfg_attr(not(feature = "nested_expressions"), allow(unused_mut))]
+        #[cfg_attr(not(feature = "nested_expressions"), expect(unused_mut))]
         let mut functions: Vec<Arc<ScalarUDF>> = functions::all_default_functions();
 
         #[cfg(feature = "nested_expressions")]
@@ -155,7 +155,7 @@ impl SessionStateDefaults {
     }
 
     /// registers all the builtin array functions
-    #[cfg_attr(not(feature = "nested_expressions"), allow(unused_variables))]
+    #[cfg_attr(not(feature = "nested_expressions"), expect(unused_variables))]
     pub fn register_array_functions(state: &mut SessionState) {
         // register crate of array expressions (if enabled)
         #[cfg(feature = "nested_expressions")]

datafusion/macros/src/user_doc.rs

@@ -20,6 +20,7 @@
     html_favicon_url = "https://raw.githubusercontent.com/apache/datafusion/19fe44cf2f30cbdd63d4a4f52c74055163c6cc38/docs/logos/standalone_logo/logo_original.svg"
 )]
 #![cfg_attr(docsrs, feature(doc_cfg))]
+#![deny(clippy::allow_attributes)]
 
 extern crate proc_macro;
 use datafusion_doc::scalar_doc_sections::doc_sections_const;

datafusion/optimizer/src/decorrelate_lateral_join.rs

@@ -37,7 +37,7 @@ use datafusion_expr::{LogicalPlan, LogicalPlanBuilder};
 pub struct DecorrelateLateralJoin {}
 
 impl DecorrelateLateralJoin {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self::default()
     }

datafusion/optimizer/src/decorrelate_predicate_subquery.rs

@@ -44,7 +44,7 @@ use log::debug;
 pub struct DecorrelatePredicateSubquery {}
 
 impl DecorrelatePredicateSubquery {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self::default()
     }

datafusion/optimizer/src/eliminate_cross_join.rs

@@ -33,7 +33,7 @@ use datafusion_expr::{ExprSchemable, Operator, and, build_join_schema};
 pub struct EliminateCrossJoin;
 
 impl EliminateCrossJoin {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self {}
     }

datafusion/optimizer/src/eliminate_duplicated_expr.rs

@@ -32,7 +32,7 @@ use indexmap::IndexSet;
 pub struct EliminateDuplicatedExpr;
 
 impl EliminateDuplicatedExpr {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self {}
     }

datafusion/optimizer/src/eliminate_filter.rs

@@ -34,7 +34,7 @@ use crate::{OptimizerConfig, OptimizerRule};
 pub struct EliminateFilter;
 
 impl EliminateFilter {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self {}
     }

datafusion/optimizer/src/eliminate_limit.rs

@@ -34,7 +34,7 @@ use std::sync::Arc;
 pub struct EliminateLimit;
 
 impl EliminateLimit {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self {}
     }
@@ -77,7 +77,7 @@ impl OptimizerRule for EliminateLimit {
                 } else if matches!(limit.get_skip_type()?, SkipType::Literal(0)) {
                     // If fetch is `None` and skip is 0, then Limit takes no effect and
                     // we can remove it. Its input also can be Limit, so we should apply again.
-                    #[allow(clippy::used_underscore_binding)]
+                    #[expect(clippy::used_underscore_binding)]
                     return self.rewrite(Arc::unwrap_or_clone(limit.input), _config);
                 }
                 Ok(Transformed::no(LogicalPlan::Limit(limit)))

datafusion/optimizer/src/eliminate_outer_join.rs

@@ -52,7 +52,7 @@ use std::sync::Arc;
 pub struct EliminateOuterJoin;
 
 impl EliminateOuterJoin {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self {}
     }

datafusion/optimizer/src/extract_equijoin_predicate.rs

@@ -42,7 +42,7 @@ type EquijoinPredicate = (Expr, Expr);
 pub struct ExtractEquijoinPredicate;
 
 impl ExtractEquijoinPredicate {
-    #[allow(missing_docs)]
+    #[expect(missing_docs)]
     pub fn new() -> Self {
         Self {}
     }