[mdoc] Fixes an issue with member and type deletion.

Specifically, when updating classic and unified assemblies, members
that were completely removed from one or both assemblies were not
being removed from the XML. This patch updates mdoc's `DeleteMember`
method to properly handle deletion in all scenarios (normal, classic, unified).

Of course, deletion will still not happen if one of two things is true:

- `--delete` is *not* passed into the `mdoc update` call and the member node
  contains existing documentation.
- `--preserve` *is* passed into the `mdoc update` invocation.

In both of those cases, the member will not be deleted, and a message stating
as such will be written as a warning to the output.

7 files changed, 344 insertions, 0 deletions

diff --git a/mdoc/Test/DocTest-DropNS-classic.cs b/mdoc/Test/DocTest-DropNS-classic.cs
index a279b0e8..8346834b 100644
--- a/mdoc/Test/DocTest-DropNS-classic.cs
+++ b/mdoc/Test/DocTest-DropNS-classic.cs
@@ -4,5 +4,25 @@ namespace MyFramework.MyNamespace {
 		public float Hello(int value) {
 			return 0.0f;
 		}
+		#if DELETETEST
+		public string InBoth {get;set;}
+		public string InBothClassic {get;set;}
+		public int InBothMagicType {get;set;}
+		#endif
+
+		#if DELETETEST && V2
+		public string AddedInV2 {get;set;}
+		public string AddedInV2Classic {get;set;}
+		#endif
+		#if DELETETEST && !V2
+		public string WillDeleteInV2 {get;set;}
+		public string WillDeleteInV2Classic {get;set;}
+		#endif
 	}
+
+	#if DELETETEST && !V2
+	public class WillDelete {
+		public string Name {get;set;}
+	}
+	#endif
 }
diff --git a/mdoc/Test/DocTest-DropNS-unified.cs b/mdoc/Test/DocTest-DropNS-unified.cs
index 8ee5e8a6..9b0c364a 100644
--- a/mdoc/Test/DocTest-DropNS-unified.cs
+++ b/mdoc/Test/DocTest-DropNS-unified.cs
@@ -4,5 +4,30 @@ namespace MyNamespace {
 		public float Hello(int value) {
 			return 0.0f;
 		}
+		#if DELETETEST
+		public string InBoth {get;set;}
+		public string InBothUnified {get;set;}
+		public nint InBothMagicType {get;set;}
+		#endif
+
+		#if DELETETEST && V2
+		public string AddedInV2 {get;set;}
+		public string AddedInV2Unified {get;set;}
+		#endif
+		#if DELETETEST && !V2
+		public string WillDeleteInV2 {get;set;}
+		public string WillDeleteInV2Unified {get;set;}
+		#endif
 	}
+
+	#if DELETETEST
+	public struct nint {
+
+	}
+	#endif
+	#if DELETETEST && !V2
+	public class WillDelete {
+		public string Name {get;set;}
+	}
+	#endif
 }
diff --git a/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/MyClass.xml b/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/MyClass.xml
new file mode 100644
index 00000000..cb620b81
--- /dev/null
+++ b/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/MyClass.xml
@@ -0,0 +1,204 @@
+<Type Name="MyClass" FullName="MyFramework.MyNamespace.MyClass">
+  <TypeSignature Language="C#" Value="public class MyClass" />
+  <TypeSignature Language="ILAsm" Value=".class public auto ansi beforefieldinit MyClass extends System.Object" />
+  <AssemblyInfo apistyle="classic">
+    <AssemblyName>DocTest-DropNS-classic-deletetest</AssemblyName>
+    <AssemblyVersion>0.0.0.0</AssemblyVersion>
+  </AssemblyInfo>
+  <AssemblyInfo apistyle="unified">
+    <AssemblyName>DocTest-DropNS-unified-deletetest</AssemblyName>
+    <AssemblyVersion>0.0.0.0</AssemblyVersion>
+  </AssemblyInfo>
+  <Base>
+    <BaseTypeName>System.Object</BaseTypeName>
+  </Base>
+  <Interfaces />
+  <Docs>
+    <summary>To be added.</summary>
+    <remarks>To be added.</remarks>
+  </Docs>
+  <Members>
+    <Member MemberName=".ctor">
+      <MemberSignature Language="C#" Value="public MyClass ();" />
+      <MemberSignature Language="ILAsm" Value=".method public hidebysig specialname rtspecialname instance void .ctor() cil managed" />
+      <MemberType>Constructor</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <Parameters />
+      <Docs>
+        <summary>To be added.</summary>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="AddedInV2">
+      <MemberSignature Language="C#" Value="public string AddedInV2 { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string AddedInV2" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="AddedInV2Classic">
+      <MemberSignature Language="C#" Value="public string AddedInV2Classic { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string AddedInV2Classic" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="AddedInV2Unified">
+      <MemberSignature Language="C#" Value="public string AddedInV2Unified { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string AddedInV2Unified" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="Hello">
+      <MemberSignature Language="C#" Value="public float Hello (int value);" />
+      <MemberSignature Language="ILAsm" Value=".method public hidebysig instance float32 Hello(int32 value) cil managed" />
+      <MemberType>Method</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.Single</ReturnType>
+      </ReturnValue>
+      <Parameters>
+        <Parameter Name="value" Type="System.Int32" />
+      </Parameters>
+      <Docs>
+        <param name="value">To be added.</param>
+        <summary>To be added.</summary>
+        <returns>To be added.</returns>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="InBoth">
+      <MemberSignature Language="C#" Value="public string InBoth { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string InBoth" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="InBothClassic">
+      <MemberSignature Language="C#" Value="public string InBothClassic { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string InBothClassic" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="InBothMagicType">
+      <MemberSignature Language="C#" Value="public int InBothMagicType { get; set; }" apistyle="classic" />
+      <MemberSignature Language="ILAsm" Value=".property instance int32 InBothMagicType" apistyle="classic" />
+      <MemberSignature Language="C#" Value="public MyFramework.MyNamespace.nint InBothMagicType { get; set; }" apistyle="unified" />
+      <MemberSignature Language="ILAsm" Value=".property instance valuetype MyFramework.MyNamespace.nint InBothMagicType" apistyle="unified" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType apistyle="classic">System.Int32</ReturnType>
+        <ReturnType apistyle="unified">MyFramework.MyNamespace.nint</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="InBothUnified">
+      <MemberSignature Language="C#" Value="public string InBothUnified { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string InBothUnified" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="MyProperty">
+      <MemberSignature Language="C#" Value="public string MyProperty { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string MyProperty" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+  </Members>
+</Type>
diff --git a/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/WillDelete.xml.remove b/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/WillDelete.xml.remove
new file mode 100644
index 00000000..775b8aff
--- /dev/null
+++ b/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/WillDelete.xml.remove
@@ -0,0 +1,49 @@
+<Type Name="WillDelete" FullName="MyFramework.MyNamespace.WillDelete">
+  <TypeSignature Language="C#" Value="public class WillDelete" />
+  <TypeSignature Language="ILAsm" Value=".class public auto ansi beforefieldinit WillDelete extends System.Object" />
+  <Base>
+    <BaseTypeName>System.Object</BaseTypeName>
+  </Base>
+  <Interfaces />
+  <Docs>
+    <summary>To be added.</summary>
+    <remarks>To be added.</remarks>
+  </Docs>
+  <Members>
+    <Member MemberName=".ctor">
+      <MemberSignature Language="C#" Value="public WillDelete ();" />
+      <MemberSignature Language="ILAsm" Value=".method public hidebysig specialname rtspecialname instance void .ctor() cil managed" />
+      <MemberType>Constructor</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <Parameters />
+      <Docs>
+        <summary>To be added.</summary>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+    <Member MemberName="Name">
+      <MemberSignature Language="C#" Value="public string Name { get; set; }" />
+      <MemberSignature Language="ILAsm" Value=".property instance string Name" />
+      <MemberType>Property</MemberType>
+      <AssemblyInfo apistyle="classic">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <AssemblyInfo apistyle="unified">
+        <AssemblyVersion>0.0.0.0</AssemblyVersion>
+      </AssemblyInfo>
+      <ReturnValue>
+        <ReturnType>System.String</ReturnType>
+      </ReturnValue>
+      <Docs>
+        <summary>To be added.</summary>
+        <value>To be added.</value>
+        <remarks>To be added.</remarks>
+      </Docs>
+    </Member>
+  </Members>
+</Type>
diff --git a/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/nint.xml b/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/nint.xml
new file mode 100644
index 00000000..2a8b2e27
--- /dev/null
+++ b/mdoc/Test/en.expected-dropns-delete/MyFramework.MyNamespace/nint.xml
@@ -0,0 +1,17 @@
+<Type Name="nint" FullName="MyFramework.MyNamespace.nint">
+  <TypeSignature Language="C#" Value="public struct nint" />
+  <TypeSignature Language="ILAsm" Value=".class public sequential ansi sealed beforefieldinit nint extends System.ValueType" />
+  <AssemblyInfo apistyle="unified">
+    <AssemblyName>DocTest-DropNS-unified-deletetest</AssemblyName>
+    <AssemblyVersion>0.0.0.0</AssemblyVersion>
+  </AssemblyInfo>
+  <Base>
+    <BaseTypeName>System.ValueType</BaseTypeName>
+  </Base>
+  <Interfaces />
+  <Docs>
+    <summary>To be added.</summary>
+    <remarks>To be added.</remarks>
+  </Docs>
+  <Members />
+</Type>
diff --git a/mdoc/Test/en.expected-dropns-delete/index.xml b/mdoc/Test/en.expected-dropns-delete/index.xml
new file mode 100644
index 00000000..0988450d
--- /dev/null
+++ b/mdoc/Test/en.expected-dropns-delete/index.xml
@@ -0,0 +1,23 @@
+<Overview>
+  <Assemblies>
+    <Assembly Name="DocTest-DropNS-unified-deletetest" Version="0.0.0.0">
+      <Attributes>
+        <Attribute>
+          <AttributeName>System.Diagnostics.Debuggable(System.Diagnostics.DebuggableAttribute+DebuggingModes.IgnoreSymbolStoreSequencePoints)</AttributeName>
+        </Attribute>
+        <Attribute>
+          <AttributeName>System.Runtime.CompilerServices.RuntimeCompatibility(WrapNonExceptionThrows=true)</AttributeName>
+        </Attribute>
+      </Attributes>
+    </Assembly>
+  </Assemblies>
+  <Remarks>To be added.</Remarks>
+  <Copyright>To be added.</Copyright>
+  <Types>
+    <Namespace Name="MyFramework.MyNamespace">
+      <Type Name="MyClass" Kind="Class" />
+      <Type Name="nint" Kind="Structure" />
+    </Namespace>
+  </Types>
+  <Title>DocTest-DropNS-classic-deletetest</Title>
+</Overview>
diff --git a/mdoc/Test/en.expected-dropns-delete/ns-MyFramework.MyNamespace.xml b/mdoc/Test/en.expected-dropns-delete/ns-MyFramework.MyNamespace.xml
new file mode 100644
index 00000000..74df75af
--- /dev/null
+++ b/mdoc/Test/en.expected-dropns-delete/ns-MyFramework.MyNamespace.xml
@@ -0,0 +1,6 @@
+<Namespace Name="MyFramework.MyNamespace">
+  <Docs>
+    <summary>To be added.</summary>
+    <remarks>To be added.</remarks>
+  </Docs>
+</Namespace>