From 8b0c7fbe85a53779dd437a1e40f0cf2fc1ff6d7d Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Tue, 4 Apr 2023 20:19:14 +0200
Subject: [PATCH] Fix #2921: struct type definition contains duplicate default
 constructor.

---
 .../TypeSystem/TypeSystemLoaderTests.cs              | 10 ++++++++++
 .../TypeSystem/TypeSystemTestCase.cs                 |  5 +++++
 .../Implementation/MetadataTypeDefinition.cs         | 12 +++++++++---
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemLoaderTests.cs b/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemLoaderTests.cs
index 38435f1d0a..b6346f0fde 100644
--- a/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemLoaderTests.cs
+++ b/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemLoaderTests.cs
@@ -616,6 +616,16 @@ public void DefaultConstructorAddedToStruct()
 			Assert.IsTrue(ctors.All(c => c.Accessibility == Accessibility.Public));
 		}
 
+		[Test]
+		public void NoDefaultConstructorAddedToStruct()
+		{
+			var ctors = compilation.FindType(typeof(MyStructWithDefaultCtor)).GetConstructors();
+			Assert.AreEqual(1, ctors.Count());
+			Assert.IsFalse(ctors.Any(c => c.IsStatic));
+			Assert.IsTrue(ctors.All(c => c.ReturnType.Kind == TypeKind.Void));
+			Assert.IsTrue(ctors.All(c => c.Accessibility == Accessibility.Public));
+		}
+
 		[Test]
 		public void NoDefaultConstructorAddedToClass()
 		{
diff --git a/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemTestCase.cs b/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemTestCase.cs
index 1a55b5cce5..a526c793ff 100644
--- a/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemTestCase.cs
+++ b/ICSharpCode.Decompiler.Tests/TypeSystem/TypeSystemTestCase.cs
@@ -140,6 +140,11 @@ public struct MyStructWithCtor
 		public MyStructWithCtor(int a) { }
 	}
 
+	public struct MyStructWithDefaultCtor
+	{
+		public MyStructWithDefaultCtor() { }
+	}
+
 	public class MyClassWithCtor
 	{
 		private MyClassWithCtor(int a) { }
diff --git a/ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataTypeDefinition.cs b/ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataTypeDefinition.cs
index 4fe5a35867..1cb4c5954b 100644
--- a/ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataTypeDefinition.cs
+++ b/ICSharpCode.Decompiler/TypeSystem/Implementation/MetadataTypeDefinition.cs
@@ -259,17 +259,23 @@ public IEnumerable<IMethod> Methods {
 				var methodsCollection = metadata.GetTypeDefinition(handle).GetMethods();
 				var methodsList = new List<IMethod>(methodsCollection.Count);
 				var methodSemantics = module.PEFile.MethodSemanticsLookup;
+				bool hasDefaultCtor = false;
 				foreach (MethodDefinitionHandle h in methodsCollection)
 				{
 					var md = metadata.GetMethodDefinition(h);
 					if (methodSemantics.GetSemantics(h).Item2 == 0 && module.IsVisible(md.Attributes))
 					{
-						methodsList.Add(module.GetDefinition(h));
+						IMethod method = module.GetDefinition(h);
+						if (method.SymbolKind == SymbolKind.Constructor && !method.IsStatic && method.Parameters.Count == 0)
+						{
+							hasDefaultCtor = true;
+						}
+						methodsList.Add(method);
 					}
 				}
-				if (this.Kind == TypeKind.Struct || this.Kind == TypeKind.Enum)
+				if (!hasDefaultCtor && (this.Kind == TypeKind.Struct || this.Kind == TypeKind.Enum))
 				{
-					methodsList.Add(FakeMethod.CreateDummyConstructor(Compilation, this, IsAbstract ? Accessibility.Protected : Accessibility.Public));
+					methodsList.Add(FakeMethod.CreateDummyConstructor(Compilation, this, Accessibility.Public));
 				}
 				if ((module.TypeSystemOptions & TypeSystemOptions.Uncached) != 0)
 					return methodsList;