[GitHub] [arrow-datafusion] mslapek commented on a diff in pull request #5421: Implement/fix Eq and Hash for Expr and LogicalPlan

["mslapek (via GitHub)" <gi...@apache.org>]

mslapek commented on code in PR #5421:
URL: https://github.com/apache/arrow-datafusion/pull/5421#discussion_r1122161900


##########
datafusion/expr/src/logical_plan/plan.rs:
##########
@@ -1515,8 +1515,30 @@ pub struct TableScan {
     pub fetch: Option<usize>,
 }
 
+impl PartialEq for TableScan {
+    fn eq(&self, other: &Self) -> bool {
+        self.table_name == other.table_name

Review Comment:
   This `Arc::ptr_eq` might be **risky**... [Arc::ptr_eq](https://doc.rust-lang.org/std/sync/struct.Arc.html#method.ptr_eq) and [std::ptr::eq](https://doc.rust-lang.org/std/ptr/fn.eq.html) say that `dyn` trait comparisons are **unreliable**. 😕
   
   Even clippy gives an error [vtable_address_comparisons](https://rust-lang.github.io/rust-clippy/master/index.html#vtable_address_comparisons) from **correctness** 🔞 category.
   
   I suggest to reconsider the request about `source` comparison.



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