From 950377faab65c997a1ac49af6f2f4968dd35fc73 Mon Sep 17 00:00:00 2001
From: "Mathias R. Jessen" <IISResetMe@users.noreply.github.com>
Date: Fri, 30 Nov 2018 12:48:27 +0100
Subject: [PATCH] Conditionally mark getter/setter implementations virtual in
 generated classes (#8303)

When implementing interfaces, PowerShell incorrectly produces non-virtual get/set methods for interface-defined properties.
This commit adds a lookup method for interface-defined properties and marks get/set methods for properties with matching signatures virtual.
---
 .../engine/parser/PSType.cs                    | 18 ++++++++++++++++++
 .../scripting.Classes.inheritance.tests.ps1    |  8 ++++++++
 2 files changed, 26 insertions(+)

diff --git a/src/System.Management.Automation/engine/parser/PSType.cs b/src/System.Management.Automation/engine/parser/PSType.cs
index 475f0cebb..a495ea5f5 100644
--- a/src/System.Management.Automation/engine/parser/PSType.cs
+++ b/src/System.Management.Automation/engine/parser/PSType.cs
@@ -434,6 +434,19 @@ namespace System.Management.Automation.Language
                 return baseClass ?? typeof(object);
             }
 
+            private bool ShouldImplementProperty(string name, Type type)
+            {
+                foreach (var interfaceType in _typeBuilder.GetInterfaces())
+                {
+                    if (interfaceType.GetProperty(name, type) != null)
+                    {
+                        return true;
+                    }
+                }
+
+                return false;
+            }
+
             public void DefineMembers()
             {
                 // If user didn't provide any instance ctors or static ctor we will generate default ctor or static ctor respectively.
@@ -576,6 +589,11 @@ namespace System.Management.Automation.Language
                 // The property set and property get methods require a special set of attributes.
                 var getSetAttributes = Reflection.MethodAttributes.SpecialName | Reflection.MethodAttributes.HideBySig;
                 getSetAttributes |= propertyMemberAst.IsPublic ? Reflection.MethodAttributes.Public : Reflection.MethodAttributes.Private;
+                if (ShouldImplementProperty(propertyMemberAst.Name, type))
+                {
+                    getSetAttributes |= Reflection.MethodAttributes.Virtual;
+                }
+
                 if (propertyMemberAst.IsStatic)
                 {
                     backingFieldAttributes |= FieldAttributes.Static;
diff --git a/test/powershell/Language/Classes/scripting.Classes.inheritance.tests.ps1 b/test/powershell/Language/Classes/scripting.Classes.inheritance.tests.ps1
index 57179022c..caebc7181 100644
--- a/test/powershell/Language/Classes/scripting.Classes.inheritance.tests.ps1
+++ b/test/powershell/Language/Classes/scripting.Classes.inheritance.tests.ps1
@@ -63,6 +63,14 @@ Describe 'Classes inheritance syntax' -Tags "CI" {
         [MyComparable].GetInterface("System.IComparable") | Should -Not -BeNullOrEmpty
     }
 
+    It 'can implement .NET interface properties' {
+        Add-Type -TypeDefinition 'public interface InterfaceWithProperty { int Integer { get; set; } }'
+        $C1 = Invoke-Expression 'class ClassWithInterfaceProperty : InterfaceWithProperty { [int]$Integer } [ClassWithInterfaceProperty]::new()'
+        $getter = $C1.GetType().GetMember('get_Integer')
+        $getter.ReturnType.FullName | Should -Be System.Int32
+        $getter.Attributes -band [System.Reflection.MethodAttributes]::Virtual |Should -Be ([System.Reflection.MethodAttributes]::Virtual)
+    }
+
     It 'allows use of defined later type as a property type' {
         class A { static [B]$b }
         class B : A {}