From c6a86516839d1947d5ec210a3aaa03af62fa0baa Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 30 Jul 2025 18:48:18 +0000
Subject: [PATCH 1/4] Initial plan


From 33ad624525ec7536737cedcc76e9c4e8df5c2e75 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Wed, 30 Jul 2025 19:03:01 +0000
Subject: [PATCH 2/4] Update CS0524 documentation to reflect C# 8.0 changes

Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>
---
 docs/csharp/misc/cs0524.md | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/docs/csharp/misc/cs0524.md b/docs/csharp/misc/cs0524.md
index 949d57811f3e0..10ffb7a521441 100644
--- a/docs/csharp/misc/cs0524.md
+++ b/docs/csharp/misc/cs0524.md
@@ -1,7 +1,7 @@
 ---
 description: "Compiler Error CS0524"
 title: "Compiler Error CS0524"
-ms.date: 07/20/2015
+ms.date: 01/02/2025
 f1_keywords: 
   - "CS0524"
 helpviewer_keywords: 
@@ -12,18 +12,26 @@ ms.assetid: a5cd8fb0-f5df-4580-9116-a6be4dffd1cb
 
 'type' : interfaces cannot declare types  
   
- An [interface](../language-reference/keywords/interface.md) cannot contain a user-defined type; it should contain only methods and properties.  
-  
-## Example  
+Prior to C# 8.0, an [interface](../language-reference/keywords/interface.md) could not contain user-defined types. Starting with C# 8.0, interfaces can declare [nested types](../programming-guide/classes-and-structs/nested-types.md) as part of the default interface members feature.
+
+In modern C# (C# 8.0 and later), this error is no longer generated for nested types in interfaces. The compiler now allows interfaces to contain nested classes, structs, interfaces, enums, and delegates.
+
+## Historical example
 
- The following sample generates CS0524:  
+The following sample would have generated CS0524 in C# versions prior to 8.0, but is now valid code:  
   
 ```csharp  
-// CS0524.cs  
-public interface Clx  
+// This code is valid in C# 8.0 and later
+public interface IExample  
 {  
-    public class Cly   // CS0524, delete user-defined type  
+    public class NestedClass   // Valid since C# 8.0
     {  
     }  
 }  
 ```
+
+## See also
+
+- [Interfaces](../language-reference/keywords/interface.md)  
+- [Nested types](../programming-guide/classes-and-structs/nested-types.md)  
+- [What's new in C# version history](../whats-new/csharp-version-history.md#c-version-80)

From 3e802779588201d8c8ee710971ded61f3c3a6b18 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 31 Jul 2025 15:15:39 +0000
Subject: [PATCH 3/4] Update ms.date to 07/31/2025 as requested

Co-authored-by: BillWagner <493969+BillWagner@users.noreply.github.com>
---
 docs/csharp/misc/cs0524.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/csharp/misc/cs0524.md b/docs/csharp/misc/cs0524.md
index 10ffb7a521441..fbe5fbb7a23a6 100644
--- a/docs/csharp/misc/cs0524.md
+++ b/docs/csharp/misc/cs0524.md
@@ -1,7 +1,7 @@
 ---
 description: "Compiler Error CS0524"
 title: "Compiler Error CS0524"
-ms.date: 01/02/2025
+ms.date: 07/31/2025
 f1_keywords: 
   - "CS0524"
 helpviewer_keywords: 

From f7b8a652f863eb586deeff7d72aecb4a26ccb395 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Mon, 4 Aug 2025 18:05:49 +0000
Subject: [PATCH 4/4] Improve wording as suggested by @gewarren

Co-authored-by: gewarren <24882762+gewarren@users.noreply.github.com>
---
 docs/csharp/misc/cs0524.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/csharp/misc/cs0524.md b/docs/csharp/misc/cs0524.md
index fbe5fbb7a23a6..d373390fe06d0 100644
--- a/docs/csharp/misc/cs0524.md
+++ b/docs/csharp/misc/cs0524.md
@@ -18,7 +18,7 @@ In modern C# (C# 8.0 and later), this error is no longer generated for nested ty
 
 ## Historical example
 
-The following sample would have generated CS0524 in C# versions prior to 8.0, but is now valid code:  
+The following sample generates CS0524 in C# versions prior to 8.0, but is valid in modern C# versions:  
   
 ```csharp  
 // This code is valid in C# 8.0 and later