From c758c5a3e23274ee74df6c101ca9349f07ee7bcb Mon Sep 17 00:00:00 2001
From: Jubilee Young <workingjubilee@gmail.com>
Date: Wed, 19 Apr 2023 14:59:24 -0700
Subject: [PATCH 1/3] Fix Iterator overrides for ArrayIntoIterator

count, nth, and size_hint did not account for element exhaustion.
---
 pgrx/src/datum/array.rs | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/pgrx/src/datum/array.rs b/pgrx/src/datum/array.rs
index 645c5c201..d7b95e309 100644
--- a/pgrx/src/datum/array.rs
+++ b/pgrx/src/datum/array.rs
@@ -424,18 +424,27 @@ impl<'a, T: FromDatum> Iterator for ArrayIntoIterator<'a, T> {
     }
 
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (0, Some(self.array.nelems))
+        // If asking for size, it's not clear if they want "actual size"
+        // or "size minus nulls"? Let's lower bound on 0 if nulls exist.
+        let left = self.array.nelems - self.curr;
+        if let NullKind::Strict(_) = self.array.null_slice {
+            (left, Some(left))
+        } else {
+            (0, Some(left))
+        }
     }
 
     fn count(self) -> usize
     where
         Self: Sized,
     {
-        self.array.nelems
+        // TODO: This code is dangerously under-exercised in the test suite.
+        self.array.nelems - self.curr
     }
 
     fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        self.array.get(n)
+        // TODO: This code is dangerously under-exercised in the test suite.
+        self.array.get(self.curr + n)
     }
 }
 

From 6ffed4fb1b77133c4d017af1c021d0d4e5da17c9 Mon Sep 17 00:00:00 2001
From: Jubilee Young <workingjubilee@gmail.com>
Date: Wed, 19 Apr 2023 15:04:03 -0700
Subject: [PATCH 2/3] relax ArrayIntoIterator::count bounds

---
 pgrx/src/datum/array.rs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/pgrx/src/datum/array.rs b/pgrx/src/datum/array.rs
index d7b95e309..0dbda97ad 100644
--- a/pgrx/src/datum/array.rs
+++ b/pgrx/src/datum/array.rs
@@ -434,10 +434,7 @@ impl<'a, T: FromDatum> Iterator for ArrayIntoIterator<'a, T> {
         }
     }
 
-    fn count(self) -> usize
-    where
-        Self: Sized,
-    {
+    fn count(self) -> usize {
         // TODO: This code is dangerously under-exercised in the test suite.
         self.array.nelems - self.curr
     }

From caae6aa6813a2f2671738e9601dddf4d952d9480 Mon Sep 17 00:00:00 2001
From: Jubilee Young <workingjubilee@gmail.com>
Date: Wed, 19 Apr 2023 17:24:53 -0700
Subject: [PATCH 3/3] Just drop the nth optimization

It will be made incorrect by zero-copy arrays.
---
 pgrx/src/datum/array.rs | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/pgrx/src/datum/array.rs b/pgrx/src/datum/array.rs
index 0dbda97ad..9a27dc7cb 100644
--- a/pgrx/src/datum/array.rs
+++ b/pgrx/src/datum/array.rs
@@ -438,11 +438,6 @@ impl<'a, T: FromDatum> Iterator for ArrayIntoIterator<'a, T> {
         // TODO: This code is dangerously under-exercised in the test suite.
         self.array.nelems - self.curr
     }
-
-    fn nth(&mut self, n: usize) -> Option<Self::Item> {
-        // TODO: This code is dangerously under-exercised in the test suite.
-        self.array.get(self.curr + n)
-    }
 }
 
 impl<'a, T: FromDatum> FromDatum for VariadicArray<'a, T> {