From 2ebe6688fd71b3ced75fbb2f5390b15f75fd471c Mon Sep 17 00:00:00 2001
From: Holger Just <git@holgerjust.de>
Date: Fri, 9 Jan 2026 19:28:44 +0100
Subject: [PATCH 1/2] 4.0: Fix typo in class name for Set example

---
 4.0.md      | 6 +++---
 _src/4.0.md | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/4.0.md b/4.0.md
index f5f11a2..97690a3 100644
--- a/4.0.md
+++ b/4.0.md
@@ -8,9 +8,9 @@ description: Ruby 4.0 full and annotated changelog
 # Ruby 4.0
 
 * **Released at:** Dec 25, 2025 (<a class="github" href="https://github.com/ruby/ruby/blob/v4.0.0/NEWS.md">NEWS.md</a> file)
-* **Status (as of Dec 26, 2025):** 4.0 is just released
+* **Status (as of Jan 09, 2026):** 4.0 is just released
 * **This document first published:** Dec 26, 2025
-* **Last change to this document:** Dec 26, 2025
+* **Last change to this document:** Jan 09, 2026
 
 <!--
 * **Reason:**
@@ -352,7 +352,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
   # Note that if your code relied on `@hash` instance variable directly
   # (which it shouldn't have), it will be broken despite the compatibility
   # layer:
-  class SmallStringsSet
+  class SmallStringSet
     # Somebody decided using internal variable would be more efficient
     def numeric? = @hash.keys.all?(Numeric)
   end
diff --git a/_src/4.0.md b/_src/4.0.md
index 5641eef..5d8b29c 100644
--- a/_src/4.0.md
+++ b/_src/4.0.md
@@ -352,7 +352,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
   # Note that if your code relied on `@hash` instance variable directly
   # (which it shouldn't have), it will be broken despite the compatibility
   # layer:
-  class SmallStringsSet
+  class SmallStringSet
     # Somebody decided using internal variable would be more efficient
     def numeric? = @hash.keys.all?(Numeric)
   end

From 82d52ecf1d6df9f3f6bdaf7f0c2c7de2277dfe25 Mon Sep 17 00:00:00 2001
From: Holger Just <git@holgerjust.de>
Date: Fri, 9 Jan 2026 19:30:04 +0100
Subject: [PATCH 2/2] 4.0: Inherit from correct Set classes in Set examples

The first change is necessary for the example to work at all. The lower
two changes are not strictly necessary though, but they may help when
trying or copying parts of the example.
---
 4.0.md      | 6 +++---
 _src/4.0.md | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/4.0.md b/4.0.md
index 97690a3..5a8c43e 100644
--- a/4.0.md
+++ b/4.0.md
@@ -339,7 +339,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
 
   # Now, as methods of SubclassCompatible are implemented mostly as they were before,
   # old assumptions work:
-  class SmallStringSet
+  class SmallStringSet < Set
     def initialize(items) = super(items.to_a[...5])
     def add(item) = super(item.to_s)
   end
@@ -352,7 +352,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
   # Note that if your code relied on `@hash` instance variable directly
   # (which it shouldn't have), it will be broken despite the compatibility
   # layer:
-  class SmallStringSet
+  class SmallStringSet < Set
     # Somebody decided using internal variable would be more efficient
     def numeric? = @hash.keys.all?(Numeric)
   end
@@ -371,7 +371,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
 
   # It would be faster, but the assumptions which methods calls which
   # internally aren't necessary correct anymore
-  class SmallStringSet2
+  class SmallStringSet2 < Set::CoreSet
     def initialize(items) = super(items.to_a[...5])
     def add(item) = super(item.to_s)
   end
diff --git a/_src/4.0.md b/_src/4.0.md
index 5d8b29c..202e207 100644
--- a/_src/4.0.md
+++ b/_src/4.0.md
@@ -339,7 +339,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
 
   # Now, as methods of SubclassCompatible are implemented mostly as they were before,
   # old assumptions work:
-  class SmallStringSet
+  class SmallStringSet < Set
     def initialize(items) = super(items.to_a[...5])
     def add(item) = super(item.to_s)
   end
@@ -352,7 +352,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
   # Note that if your code relied on `@hash` instance variable directly
   # (which it shouldn't have), it will be broken despite the compatibility
   # layer:
-  class SmallStringSet
+  class SmallStringSet < Set
     # Somebody decided using internal variable would be more efficient
     def numeric? = @hash.keys.all?(Numeric)
   end
@@ -371,7 +371,7 @@ By redefinining `#instance_variables_to_inspect`, the default output of `#inspec
 
   # It would be faster, but the assumptions which methods calls which
   # internally aren't necessary correct anymore
-  class SmallStringSet2
+  class SmallStringSet2 < Set::CoreSet
     def initialize(items) = super(items.to_a[...5])
     def add(item) = super(item.to_s)
   end