Constraints on parameter types allow ref struct (#727)

* update

* add unit test

* update

* update

* update

* update

* update

* update

* update

* update ut case

* update

* update

* update

* upgrade version

Author: v-fuquanli

external/Test/AllowsRefStructDemo.dll

@@ -3,7 +3,7 @@ namespace Mono.Documentation
 {
     public static class Consts
     {
-        public static string MonoVersion = "5.9.3.8";
+        public static string MonoVersion = "5.9.4";
         public const string DocId = "DocId";
         public const string CppCli = "C++ CLI";
         public const string CppCx = "C++ CX";

mdoc/Consts.cs

@@ -44,6 +44,9 @@ internal static void MakeTypeParameterConstraints(XmlElement root, XmlElement e,
                 AppendElementText(ce, "ParameterAttribute", "NotNullableValueTypeConstraint");
             if ((attrs & GenericParameterAttributes.ReferenceTypeConstraint) != 0)
                 AppendElementText(ce, "ParameterAttribute", "ReferenceTypeConstraint");
+            // Check for 'allows ref struct' constraint
+            if ((attrs & (GenericParameterAttributes)0x0020) != 0) // Assuming 0x0020 is the flag for 'allows ref struct'
+                AppendElementText(ce, "ParameterAttribute", "AllowByRefLike");
 
 #if NEW_CECIL
             foreach (GenericParameterConstraint c in constraints)

mdoc/Mono.Documentation/MDocUpdater.Member.cs

@@ -314,9 +314,10 @@ private StringBuilder AppendConstraints (StringBuilder buf, IList<GenericParamet
                 bool isref = (attrs & GenericParameterAttributes.ReferenceTypeConstraint) != 0;
                 bool isvt = (attrs & GenericParameterAttributes.NotNullableValueTypeConstraint) != 0;
                 bool isnew = (attrs & GenericParameterAttributes.DefaultConstructorConstraint) != 0;
+                bool isAllowsRefStruct = (attrs & (GenericParameterAttributes)0x0020) != 0; // Assuming 0x0020 is the flag for 'allows ref struct'
                 bool comma = false;
 
-                if (!isref && !isvt && !isnew && constraints.Count == 0)
+                if (!isref && !isvt && !isAllowsRefStruct && !isnew && constraints.Count == 0)
                     continue;
                 buf.Append (" where ").Append (genArg.Name).Append (" : ");
                 if (isref)
@@ -350,6 +351,14 @@ private StringBuilder AppendConstraints (StringBuilder buf, IList<GenericParamet
                         buf.Append (", ");
                     buf.Append ("new()");
                 }
+
+                // Handle 'allows ref struct' constraint
+                if (isAllowsRefStruct)
+                {
+                    if (comma || constraints.Count > 0 || isnew)
+                        buf.Append(", ");
+                    buf.Append("allows ref struct");
+                }
             }
             return buf;
         }

mdoc/Mono.Documentation/Updater/Formatters/CSharpFullMemberFormatter.cs

@@ -601,6 +601,24 @@ public void CSharpStaticEventImplementation(string typeFullName, string eventNam
             TestEventSignature(staticVirtualMemberDllPath, typeFullName, eventName, expectedSignature);
         }
 
+        [TestCase("AllowsRefStructDemo.IRefStructProcessor`1",
+            "public interface IRefStructProcessor<T> where T : allows ref struct")]
+        public void CSharpAllowsRefStructForTypeTest(string typeFullName, string expectedSignature)
+        {
+            var allowsRefStructDllPath = "../../../../external/Test/AllowsRefStructDemo.dll";
+            TestTypeSignature(allowsRefStructDllPath, typeFullName, expectedSignature);
+        }
+
+        [TestCase("AllowsRefStructDemo.Immutable", "Update",
+            "public bool Update<TArg> (TArg transformerArgument) where TArg : new(), allows ref struct;")]
+        [TestCase("AllowsRefStructDemo.RefStructHandler", "Handle",
+            "public void Handle<T> (ref T item) where T : new(), allows ref struct;")]
+        public void CSharpAllowsRefStructForMemberTest(string typeFullName, string methodName, string expectedSignature)
+        {
+            var allowsRefStructDllPath = "../../../../external/Test/AllowsRefStructDemo.dll";
+            TestMethodSignature(allowsRefStructDllPath, typeFullName, methodName, expectedSignature);
+        }
+
         #region Helper Methods
         string RealTypeName(string name){
             switch (name) {

mdoc/mdoc.Test/FormatterTests.cs

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>mdoc</id>
-    <version>5.9.3.8</version>
+    <version>5.9.4</version>
     <title>mdoc</title>
     <authors>Microsoft</authors>
     <owners>Microsoft</owners>