From 5c4352c37e0adffbb4943d36c21f357b8a60e881 Mon Sep 17 00:00:00 2001
From: Sampo Kuokkanen <sampo.kuokkanen@gmail.com>
Date: Wed, 27 May 2026 22:21:05 +0900
Subject: [PATCH 1/2] Add specs for Enumerable value packing rule (0->nil,
 1->value, N->Array)

The rb_enum_values_pack rule in enum.c packs yielded source values when they flow through any Enumerable collection method or Lazy stage: 0 args -> nil, 1 arg -> the value, N args -> Array.

Pin this explicitly via a shared describe used by both Enumerable#take and Enumerator::Lazy#take.
---
 core/enumerable/shared/value_packing.rb | 25 +++++++++++++++++++++++++
 core/enumerable/take_spec.rb            |  8 ++++++++
 core/enumerator/lazy/take_spec.rb       |  8 ++++++++
 3 files changed, 41 insertions(+)
 create mode 100644 core/enumerable/shared/value_packing.rb

diff --git a/core/enumerable/shared/value_packing.rb b/core/enumerable/shared/value_packing.rb
new file mode 100644
index 000000000..9c4b4edb1
--- /dev/null
+++ b/core/enumerable/shared/value_packing.rb
@@ -0,0 +1,25 @@
+describe :enumerable_value_packing, shared: true do
+  # @take must be set to a Proc that returns the take-result whose #each
+  # yields packed values (e.g. -> e { e.take(1) } or -> e { e.lazy.take(1) }).
+
+  it "yields a single nil for a zero-argument source yield" do
+    e = Enumerator.new { |y| y.yield }
+    args = nil
+    @take.call(e).each { |*a| args = a }
+    args.should == [nil]
+  end
+
+  it "yields the value for a single-argument source yield" do
+    e = Enumerator.new { |y| y.yield :v }
+    args = nil
+    @take.call(e).each { |*a| args = a }
+    args.should == [:v]
+  end
+
+  it "yields a packed Array for a multi-argument source yield" do
+    e = Enumerator.new { |y| y.yield 1, 2 }
+    args = nil
+    @take.call(e).each { |*a| args = a }
+    args.should == [[1, 2]]
+  end
+end
diff --git a/core/enumerable/take_spec.rb b/core/enumerable/take_spec.rb
index 8cc746f88..ca439b750 100644
--- a/core/enumerable/take_spec.rb
+++ b/core/enumerable/take_spec.rb
@@ -1,6 +1,7 @@
 require_relative '../../spec_helper'
 require_relative 'fixtures/classes'
 require_relative 'shared/take'
+require_relative 'shared/value_packing'
 
 describe "Enumerable#take" do
   it "requires an argument" do
@@ -10,4 +11,11 @@
   describe "when passed an argument" do
     it_behaves_like :enumerable_take, :take
   end
+
+  describe "value packing of source yields" do
+    before :each do
+      @take = -> e { e.take(1) }
+    end
+    it_behaves_like :enumerable_value_packing, nil
+  end
 end
diff --git a/core/enumerator/lazy/take_spec.rb b/core/enumerator/lazy/take_spec.rb
index f92360f54..2dd5b939e 100644
--- a/core/enumerator/lazy/take_spec.rb
+++ b/core/enumerator/lazy/take_spec.rb
@@ -2,8 +2,16 @@
 
 require_relative '../../../spec_helper'
 require_relative 'fixtures/classes'
+require_relative '../../enumerable/shared/value_packing'
 
 describe "Enumerator::Lazy#take" do
+  describe "value packing of source yields (matches Enumerable#take)" do
+    before :each do
+      @take = -> e { e.lazy.take(1) }
+    end
+    it_behaves_like :enumerable_value_packing, nil
+  end
+
   before :each do
     @yieldsmixed = EnumeratorLazySpecs::YieldsMixed.new.to_enum.lazy
     @eventsmixed = EnumeratorLazySpecs::EventsMixed.new.to_enum.lazy

From 8bb8782e6d855afe12e986a463ff77a056b63a35 Mon Sep 17 00:00:00 2001
From: Benoit Daloze <eregontp@gmail.com>
Date: Wed, 27 May 2026 22:53:35 +0200
Subject: [PATCH 2/2] Add comment for where the behavior comes from

---
 core/enumerable/shared/value_packing.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/core/enumerable/shared/value_packing.rb b/core/enumerable/shared/value_packing.rb
index 9c4b4edb1..ff77f45cd 100644
--- a/core/enumerable/shared/value_packing.rb
+++ b/core/enumerable/shared/value_packing.rb
@@ -1,3 +1,4 @@
+# This is the behavior of rb_enum_values_pack() in CRuby
 describe :enumerable_value_packing, shared: true do
   # @take must be set to a Proc that returns the take-result whose #each
   # yields packed values (e.g. -> e { e.take(1) } or -> e { e.lazy.take(1) }).