From e12b377ac3cc25f880626d512b9cfac5d43079b1 Mon Sep 17 00:00:00 2001
From: sabiwara <sabiwara@gmail.com>
Date: Sun, 2 Mar 2025 09:26:23 +0900
Subject: [PATCH 1/2] Fix zipping on cycle stream

Close https://github.com/elixir-lang/elixir/issues/14306
---
 lib/elixir/lib/stream.ex             |  2 +-
 lib/elixir/test/elixir/enum_test.exs | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/elixir/lib/stream.ex b/lib/elixir/lib/stream.ex
index 07fd4a701eb..73f5508df36 100644
--- a/lib/elixir/lib/stream.ex
+++ b/lib/elixir/lib/stream.ex
@@ -1447,7 +1447,7 @@ defmodule Stream do
   defp check_cycle_first_element(reduce) do
     fn acc ->
       case reduce.(acc) do
-        {state, []} when state in [:done, :halted] ->
+        {:done, []} ->
           raise ArgumentError, "cannot cycle over an empty enumerable"
 
         other ->
diff --git a/lib/elixir/test/elixir/enum_test.exs b/lib/elixir/test/elixir/enum_test.exs
index d39c415514d..c9529dec51e 100644
--- a/lib/elixir/test/elixir/enum_test.exs
+++ b/lib/elixir/test/elixir/enum_test.exs
@@ -1521,6 +1521,18 @@ defmodule EnumTest do
     assert Enum.zip([], []) == []
   end
 
+  test "zip/2 with infinite streams" do
+    assert Enum.zip([], Stream.cycle([1, 2])) == []
+    assert Enum.zip([], Stream.cycle(1..2)) == []
+    assert Enum.zip(.., Stream.cycle([1, 2])) == []
+    assert Enum.zip(.., Stream.cycle(1..2)) == []
+
+    assert Enum.zip(Stream.cycle([1, 2]), ..) == []
+    assert Enum.zip(Stream.cycle(1..2), ..) == []
+    assert Enum.zip(Stream.cycle([1, 2]), ..) == []
+    assert Enum.zip(Stream.cycle(1..2), ..) == []
+  end
+
   test "zip/1" do
     assert Enum.zip([[:a, :b], [1, 2], ["foo", "bar"]]) == [{:a, 1, "foo"}, {:b, 2, "bar"}]
 

From f040f1c76d07d1d5894b709c3827af955db477dd Mon Sep 17 00:00:00 2001
From: sabiwara <sabiwara@gmail.com>
Date: Sun, 2 Mar 2025 09:38:52 +0900
Subject: [PATCH 2/2] Add test for cycling over empty enumerable

---
 lib/elixir/test/elixir/stream_test.exs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/elixir/test/elixir/stream_test.exs b/lib/elixir/test/elixir/stream_test.exs
index 47de51beb2a..e78ff7cd83f 100644
--- a/lib/elixir/test/elixir/stream_test.exs
+++ b/lib/elixir/test/elixir/stream_test.exs
@@ -245,6 +245,10 @@ defmodule StreamTest do
       Stream.cycle(%{}) |> Enum.to_list()
     end
 
+    assert_raise ArgumentError, "cannot cycle over an empty enumerable", fn ->
+      Stream.cycle(..) |> Enum.to_list()
+    end
+
     assert Stream.cycle([1, 2, 3]) |> Stream.take(5) |> Enum.to_list() == [1, 2, 3, 1, 2]
     assert Enum.take(stream, 5) == [1, 2, 3, 1, 2]
   end