From c538423da4632a218f507e2d416b5d0181f90999 Mon Sep 17 00:00:00 2001
From: Jon Skeet <skeet@pobox.com>
Date: Wed, 20 Mar 2024 11:16:45 +0000
Subject: [PATCH 1/3] Initial setup and release of 1.0.0

Class1 contains a void parameterless method, and an Int32-returning
property.

The project targets netstandard2.1.
---
 CompatIssue/Class1.cs          | 10 ++++++++++
 CompatIssue/CompatIssue.csproj | 12 ++++++++++++
 CompatIssue/README.md          |  2 ++
 CompatIssue/global.json        |  6 ++++++
 4 files changed, 30 insertions(+)
 create mode 100644 CompatIssue/Class1.cs
 create mode 100644 CompatIssue/CompatIssue.csproj
 create mode 100644 CompatIssue/README.md
 create mode 100644 CompatIssue/global.json

diff --git a/CompatIssue/Class1.cs b/CompatIssue/Class1.cs
new file mode 100644
index 00000000..7f7a3901
--- /dev/null
+++ b/CompatIssue/Class1.cs
@@ -0,0 +1,10 @@
+namespace CompatIssue;
+
+public class Class1
+{
+    public void Method()
+    {
+    }
+    
+    public int Property => 10;
+}
diff --git a/CompatIssue/CompatIssue.csproj b/CompatIssue/CompatIssue.csproj
new file mode 100644
index 00000000..8460ee4b
--- /dev/null
+++ b/CompatIssue/CompatIssue.csproj
@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <Version>1.0.0</Version>
+    <TargetFramework>netstandard2.1</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>    
+    <Nullable>enable</Nullable>
+    <LangVersion>latest</LangVersion>
+    <EnablePackageValidation>true</EnablePackageValidation>
+  </PropertyGroup>
+
+</Project>
diff --git a/CompatIssue/README.md b/CompatIssue/README.md
new file mode 100644
index 00000000..ad137f50
--- /dev/null
+++ b/CompatIssue/README.md
@@ -0,0 +1,2 @@
+This directory exists to demonstrate an issue with the MS compat tool.
+See https://github.com/dotnet/sdk/issues/39629 for details
\ No newline at end of file
diff --git a/CompatIssue/global.json b/CompatIssue/global.json
new file mode 100644
index 00000000..282c5a85
--- /dev/null
+++ b/CompatIssue/global.json
@@ -0,0 +1,6 @@
+{
+  "sdk": {
+    "version": "8.0.203",
+    "rollForward": "latestFeature"
+  }
+}
\ No newline at end of file

From e0065b0f117815136e388d15e9519b7c79e73e94 Mon Sep 17 00:00:00 2001
From: Jon Skeet <skeet@pobox.com>
Date: Wed, 20 Mar 2024 11:21:38 +0000
Subject: [PATCH 2/3] Add a nullable-returning property and an enum, and
 release 1.1.0

Note: changing the target framework to netstandard2.0 at *this*
point does not cause any compatibility errors.
---
 CompatIssue/Class1.cs          | 2 ++
 CompatIssue/CompatIssue.csproj | 3 ++-
 CompatIssue/SampleEnum.cs      | 7 +++++++
 3 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 CompatIssue/SampleEnum.cs

diff --git a/CompatIssue/Class1.cs b/CompatIssue/Class1.cs
index 7f7a3901..7e6e5e37 100644
--- a/CompatIssue/Class1.cs
+++ b/CompatIssue/Class1.cs
@@ -7,4 +7,6 @@ public void Method()
     }
     
     public int Property => 10;
+    
+    public int? NullableProperty => 10;
 }
diff --git a/CompatIssue/CompatIssue.csproj b/CompatIssue/CompatIssue.csproj
index 8460ee4b..ffbea760 100644
--- a/CompatIssue/CompatIssue.csproj
+++ b/CompatIssue/CompatIssue.csproj
@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <Version>1.0.0</Version>
+    <Version>1.1.0</Version>
+    <PackageValidationBaselineVersion>1.0.0</PackageValidationBaselineVersion>
     <TargetFramework>netstandard2.1</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>    
     <Nullable>enable</Nullable>
diff --git a/CompatIssue/SampleEnum.cs b/CompatIssue/SampleEnum.cs
new file mode 100644
index 00000000..1d5de75e
--- /dev/null
+++ b/CompatIssue/SampleEnum.cs
@@ -0,0 +1,7 @@
+namespace CompatIssue;
+
+public enum SampleEnum
+{
+    Value0,
+    Value1
+}

From 91aa6db9d5f356ba29bbadb117a9cae257f39fb0 Mon Sep 17 00:00:00 2001
From: Jon Skeet <skeet@pobox.com>
Date: Wed, 20 Mar 2024 11:22:53 +0000
Subject: [PATCH 3/3] Change the target to netstandard2.0 and try to release
 1.2.0

This fails to pack with compatibility errors:

```text
error : API compatibility errors between 'lib/netstandard2.1/CompatIssue.dll' (...\packages\compatissue\1.1.0\compatissue.1.1.0.nupkg) and 'lib/netstandard2.0/CompatIssue.dll' (...\CompatIssue.csproj)
error CP0002: Member 'System.Nullable<int> CompatIssue.Class1.NullableProperty.get' exists on [Baseline] lib/netstandard2.1/CompatIssue.dll but not on lib/netstandard2.0/CompatIssue.dll [...\CompatIssue.csproj]
error CP0002: Member 'CompatIssue.SampleEnum CompatIssue.SampleEnum.Value0' exists on [Baseline] lib/netstandard2.1/CompatIssue.dll but not on lib/netstandard2.0/CompatIssue.dll [...\CompatIssue.csproj]
error CP0002: Member 'CompatIssue.SampleEnum CompatIssue.SampleEnum.Value1' exists on [Baseline] lib/netstandard2.1/CompatIssue.dll but not on lib/netstandard2.0/CompatIssue.dll [...\CompatIssue.csproj]
```
---
 CompatIssue/CompatIssue.csproj | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/CompatIssue/CompatIssue.csproj b/CompatIssue/CompatIssue.csproj
index ffbea760..4bbd7a07 100644
--- a/CompatIssue/CompatIssue.csproj
+++ b/CompatIssue/CompatIssue.csproj
@@ -1,9 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <Version>1.1.0</Version>
-    <PackageValidationBaselineVersion>1.0.0</PackageValidationBaselineVersion>
-    <TargetFramework>netstandard2.1</TargetFramework>
+    <Version>1.2.0</Version>
+    <PackageValidationBaselineVersion>1.1.0</PackageValidationBaselineVersion>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>    
     <Nullable>enable</Nullable>
     <LangVersion>latest</LangVersion>