Constraints on parameter types allow ref struct

mdoc/Mono.Documentation/MDocUpdater.Member.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/Updater/Formatters/CSharpFullMemberFormatter.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 || isref || isvt || isnew)
+                        buf.Append(", ");
+                    buf.Append("allows ref struct");
+                }
             }
             return buf;
         }

mdoc/mdoc.Test/MDocUpdaterTests.cs

@@ -253,5 +253,41 @@ public void Run_WithOptionsOAndFx_ShouldProcessFrameworks()
             Assert.IsTrue(File.Exists(Path.Combine(outputDir, "index.xml")));
             Assert.IsTrue(File.Exists(Path.Combine(outputDir, "ns-TestLibrary.xml")));
         }
+
+        [Test]
+        public void Test_RunWithRefStructValidation()
+        {
+            // Arrange
+            var baseDir = Path.Combine(Path.GetDirectoryName(this.GetType().Module.Assembly.Location), "SampleClasses/TestUpdate");
+            var outputDir = Path.Combine(baseDir, "outputDir");
+            Directory.CreateDirectory(outputDir);
+
+            var args = new List<string> { "update", "-o", outputDir, "-fx", Path.Combine(baseDir) };
+            var updater = new MDocUpdater();
+
+            // Act
+            updater.Run(args);
+
+            // Assert
+            var iRefStructProcessorPath = Path.Combine(outputDir, "RefStructDemo", "IRefStructProcessor`1.xml");
+            var refStructHandlerPath = Path.Combine(outputDir, "RefStructDemo", "RefStructHandler.xml");
+
+            Assert.IsTrue(File.Exists(iRefStructProcessorPath));
+            Assert.IsTrue(File.Exists(refStructHandlerPath));
+
+            var iRefStructProcessorDoc = new XmlDocument();
+            iRefStructProcessorDoc.Load(iRefStructProcessorPath);
+            var iRefStructProcessorNode = iRefStructProcessorDoc.SelectSingleNode("//TypeParameters/TypeParameter/Constraints/ParameterAttribute[text()='AllowByRefLike']");
+            Assert.IsNotNull(iRefStructProcessorNode, "Missing <ParameterAttribute>AllowByRefLike</ParameterAttribute> in IRefStructProcessor`1.xml");
+            var iRefStructProcessorTypeSignatureNode = iRefStructProcessorDoc.SelectSingleNode("//TypeSignature[@Language='C#' and contains(@Value, 'where T : allows ref struct')]");
+            Assert.IsNotNull(iRefStructProcessorTypeSignatureNode, "Missing TypeSignature with 'where T : allows ref struct' in IRefStructProcessor`1.xml");
+
+            var refStructHandlerDoc = new XmlDocument();
+            refStructHandlerDoc.Load(refStructHandlerPath);
+            var refStructHandlerNode = refStructHandlerDoc.SelectSingleNode("//Members/Member/TypeParameters/TypeParameter/Constraints/ParameterAttribute[text()='AllowByRefLike']");
+            Assert.IsNotNull(refStructHandlerNode, "Missing <ParameterAttribute>AllowByRefLike</ParameterAttribute> in RefStructHandler.xml");
+            var refStructHandlerMemberSignatureNode = refStructHandlerDoc.SelectSingleNode("//Members/Member/MemberSignature[@Language='C#' and contains(@Value, 'where T : allows ref struct')]");
+            Assert.IsNotNull(refStructHandlerMemberSignatureNode, "Missing MemberSignature with 'where T : allows ref struct' in RefStructHandler.xml");
+        }
     }
 }

mdoc/mdoc.Test/SampleClasses/TestUpdate/frameworks.xml

@@ -3,4 +3,7 @@
 	<Framework Name="net-8.0" Source="net-8.0">
 		<assemblySearchPath>dependencies\net-8.0</assemblySearchPath>
 	</Framework>
+	<Framework Name="net-9.0" Source="net-9.0">
+		<assemblySearchPath>dependencies\net-9.0</assemblySearchPath>
+	</Framework>
 </Frameworks>

mdoc/mdoc.Test/mdoc.Test.csproj

@@ -72,6 +72,10 @@
 		  <Link>SampleClasses\TestUpdate\net-8.0\TestLibrary.dll</Link>
 		  <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
 	  </Content>
+	  <Content Include="SampleClasses\TestUpdate\net-9.0\RefStructDemo.dll">
+		  <Link>SampleClasses\TestUpdate\net-9.0\RefStructDemo.dll</Link>
+		  <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+	  </Content>
 	  <Content Include="SampleClasses\TestUpdate\frameworks.xml">
 		  <Link>SampleClasses\TestUpdate\frameworks.xml</Link>
 		  <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>