From 4cf39bde45ffdeddec87aad9edce7f2c0f78b9ee Mon Sep 17 00:00:00 2001
From: Min Huang <huangmin@microsoft.com>
Date: Wed, 9 Mar 2022 18:22:42 +0800
Subject: Support .NET language features: init only setter (#619)

---
 mdoc/Consts.cs                                       |  1 +
 .../Updater/Formatters/CSharpFullMemberFormatter.cs  |  9 ++++++++-
 mdoc/mdoc.Test/FormatterTests.cs                     | 11 +++++++++++
 mdoc/mdoc.Test/SampleClasses/InitOnlySetter.cs       | 20 ++++++++++++++++++++
 mdoc/mdoc.Test/SampleClasses/IsExternalInit.cs       |  7 +++++++
 5 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 mdoc/mdoc.Test/SampleClasses/InitOnlySetter.cs
 create mode 100644 mdoc/mdoc.Test/SampleClasses/IsExternalInit.cs

diff --git a/mdoc/Consts.cs b/mdoc/Consts.cs
index 4d2ef7c3..e047f2af 100644
--- a/mdoc/Consts.cs
+++ b/mdoc/Consts.cs
@@ -50,5 +50,6 @@ namespace Mono.Documentation
         public const string IsReadOnlyAttribute = "System.Runtime.CompilerServices.IsReadOnlyAttribute";
         public const string InAttribute = "System.Runtime.InteropServices.InAttribute";
         public const string TupleElementNamesAttribute = "System.Runtime.CompilerServices.TupleElementNamesAttribute";
+        public const string IsExternalInit = "System.Runtime.CompilerServices.IsExternalInit";
     }
 }
diff --git a/mdoc/Mono.Documentation/Updater/Formatters/CSharpFullMemberFormatter.cs b/mdoc/Mono.Documentation/Updater/Formatters/CSharpFullMemberFormatter.cs
index e885df57..3a36a5e7 100644
--- a/mdoc/Mono.Documentation/Updater/Formatters/CSharpFullMemberFormatter.cs
+++ b/mdoc/Mono.Documentation/Updater/Formatters/CSharpFullMemberFormatter.cs
@@ -725,7 +725,14 @@ namespace Mono.Documentation.Updater.Formatters
             {
                 if (set_visible != visibility)
                     buf.Append (' ').Append (set_visible);
-                buf.Append (" set;");
+                if (property.SetMethod.ReturnType is RequiredModifierType returnType && returnType.ModifierType.FullName == Consts.IsExternalInit)
+                {
+                    buf.Append(" init;");
+                }
+                else
+                {
+                    buf.Append(" set;");
+                }
             }
             buf.Append (" }");
 
diff --git a/mdoc/mdoc.Test/FormatterTests.cs b/mdoc/mdoc.Test/FormatterTests.cs
index 868def32..fd987dec 100644
--- a/mdoc/mdoc.Test/FormatterTests.cs
+++ b/mdoc/mdoc.Test/FormatterTests.cs
@@ -453,6 +453,17 @@ namespace mdoc.Test
             Assert.AreEqual(expectedSignature, methodSignature);
         }
 
+        [TestCase("Property1", "public int Property1 { get; set; }")]
+        [TestCase("Property2", "public int Property2 { get; init; }")]
+        [TestCase("Property3", "public int Property3 { get; protected init; }")]
+        [TestCase("Item", "public int this[int index] { get; init; }")]
+        public void CSharpInitOnlySetterTest(string propertyName, string expectedSignature)
+        {
+            var property = GetProperty(typeof(SampleClasses.InitOnlySetter), p => p.Name == propertyName);
+            var propertySignature = formatter.GetDeclaration(property);
+            Assert.AreEqual(expectedSignature, propertySignature);
+        }
+
         #region Helper Methods
         string RealTypeName(string name){
             switch (name) {
diff --git a/mdoc/mdoc.Test/SampleClasses/InitOnlySetter.cs b/mdoc/mdoc.Test/SampleClasses/InitOnlySetter.cs
new file mode 100644
index 00000000..4ffc55c4
--- /dev/null
+++ b/mdoc/mdoc.Test/SampleClasses/InitOnlySetter.cs
@@ -0,0 +1,20 @@
+namespace mdoc.Test.SampleClasses
+{
+    public class InitOnlySetter
+    {
+        public int Property1 { get; set; }
+        public int Property2 { get; init; }
+        public int Property3 { get; protected init; }
+        public int this[int index]
+        {
+            get
+            {
+                throw null;
+            }
+            init
+            {
+                throw null;
+            }
+        }
+    }
+}
diff --git a/mdoc/mdoc.Test/SampleClasses/IsExternalInit.cs b/mdoc/mdoc.Test/SampleClasses/IsExternalInit.cs
new file mode 100644
index 00000000..48584312
--- /dev/null
+++ b/mdoc/mdoc.Test/SampleClasses/IsExternalInit.cs
@@ -0,0 +1,7 @@
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices
+{
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    internal class IsExternalInit { }
+}
\ No newline at end of file
-- 
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