From ff083dfec1ee1b9b4b9a54426a425ee4065b0601 Mon Sep 17 00:00:00 2001
From: Philippe-Cholet <44676486+Philippe-Cholet@users.noreply.github.com>
Date: Thu, 1 Feb 2024 23:29:06 +0100
Subject: [PATCH 1/4] `iproduct`: allow commas at the end

---
 src/lib.rs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 1f39379e2..f3e295301 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -249,13 +249,13 @@ macro_rules! iproduct {
     (@flatten $I:expr, $J:expr, $($K:expr,)*) => (
         $crate::iproduct!(@flatten $crate::cons_tuples($crate::iproduct!($I, $J)), $($K,)*)
     );
-    ($I:expr) => (
+    ($I:expr $(,)?) => (
         $crate::__std_iter::IntoIterator::into_iter($I)
     );
-    ($I:expr, $J:expr) => (
+    ($I:expr, $J:expr $(,)?) => (
         $crate::Itertools::cartesian_product($crate::iproduct!($I), $crate::iproduct!($J))
     );
-    ($I:expr, $J:expr, $($K:expr),+) => (
+    ($I:expr, $J:expr, $($K:expr),+ $(,)?) => (
         $crate::iproduct!(@flatten $crate::iproduct!($I, $J), $($K,)+)
     );
 }

From 518efd395e7879f97453486c185956c4b7605209 Mon Sep 17 00:00:00 2001
From: Philippe-Cholet <44676486+Philippe-Cholet@users.noreply.github.com>
Date: Thu, 1 Feb 2024 23:36:05 +0100
Subject: [PATCH 2/4] `iproduct(it)`: yield 1-tuples instead

---
 src/lib.rs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index f3e295301..a3998fdac 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -250,10 +250,13 @@ macro_rules! iproduct {
         $crate::iproduct!(@flatten $crate::cons_tuples($crate::iproduct!($I, $J)), $($K,)*)
     );
     ($I:expr $(,)?) => (
-        $crate::__std_iter::IntoIterator::into_iter($I)
+        $crate::__std_iter::IntoIterator::into_iter($I).map(|elt| (elt,))
     );
     ($I:expr, $J:expr $(,)?) => (
-        $crate::Itertools::cartesian_product($crate::iproduct!($I), $crate::iproduct!($J))
+        $crate::Itertools::cartesian_product(
+            $crate::__std_iter::IntoIterator::into_iter($I),
+            $crate::__std_iter::IntoIterator::into_iter($J),
+        )
     );
     ($I:expr, $J:expr, $($K:expr),+ $(,)?) => (
         $crate::iproduct!(@flatten $crate::iproduct!($I, $J), $($K,)+)

From 8297524cc8d7c285ae3dc779e16e9b39d7703f8d Mon Sep 17 00:00:00 2001
From: Philippe-Cholet <44676486+Philippe-Cholet@users.noreply.github.com>
Date: Thu, 1 Feb 2024 23:32:06 +0100
Subject: [PATCH 3/4] `iproduct`: yield one unit for the empty product

---
 src/lib.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index a3998fdac..5d49b7fc6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -249,6 +249,9 @@ macro_rules! iproduct {
     (@flatten $I:expr, $J:expr, $($K:expr,)*) => (
         $crate::iproduct!(@flatten $crate::cons_tuples($crate::iproduct!($I, $J)), $($K,)*)
     );
+    () => (
+        $crate::__std_iter::once(())
+    );
     ($I:expr $(,)?) => (
         $crate::__std_iter::IntoIterator::into_iter($I).map(|elt| (elt,))
     );

From 5ab11d66c2d59eb7882e4a2a9dc9d67bbd2d74bc Mon Sep 17 00:00:00 2001
From: Philippe-Cholet <44676486+Philippe-Cholet@users.noreply.github.com>
Date: Fri, 2 Feb 2024 12:15:59 +0100
Subject: [PATCH 4/4] Update `iproduct` tests

Test name `iproduct1` starts with `i` because `product1` is for another kind of test.
---
 tests/macros_hygiene.rs |  1 +
 tests/test_core.rs      | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/tests/macros_hygiene.rs b/tests/macros_hygiene.rs
index d1111245d..20b59fba8 100644
--- a/tests/macros_hygiene.rs
+++ b/tests/macros_hygiene.rs
@@ -1,5 +1,6 @@
 #[test]
 fn iproduct_hygiene() {
+    let _ = itertools::iproduct!();
     let _ = itertools::iproduct!(0..6);
     let _ = itertools::iproduct!(0..6, 0..9);
     let _ = itertools::iproduct!(0..6, 0..9, 0..12);
diff --git a/tests/test_core.rs b/tests/test_core.rs
index 45a8df438..db77a1e3e 100644
--- a/tests/test_core.rs
+++ b/tests/test_core.rs
@@ -18,6 +18,23 @@ use crate::it::Itertools;
 use core::iter;
 use itertools as it;
 
+#[test]
+fn product0() {
+    let mut prod = iproduct!();
+    assert_eq!(prod.next(), Some(()));
+    assert!(prod.next().is_none());
+}
+
+#[test]
+fn iproduct1() {
+    let s = "αβ";
+
+    let mut prod = iproduct!(s.chars());
+    assert_eq!(prod.next(), Some(('α',)));
+    assert_eq!(prod.next(), Some(('β',)));
+    assert!(prod.next().is_none());
+}
+
 #[test]
 fn product2() {
     let s = "αβ";