From 32242c54a17a385afcd9472bd700394b75b9ea88 Mon Sep 17 00:00:00 2001
From: Siegfried Pammer <siegfriedpammer@gmail.com>
Date: Sat, 26 Aug 2023 11:49:06 +0200
Subject: [PATCH] Fix #3056: WriteParameterReference was using the wrong
 parameter definition in static methods.

---
 .../Disassembler/DisassemblerHelpers.cs       | 44 ++++++++++++-------
 1 file changed, 28 insertions(+), 16 deletions(-)

diff --git a/ICSharpCode.Decompiler/Disassembler/DisassemblerHelpers.cs b/ICSharpCode.Decompiler/Disassembler/DisassemblerHelpers.cs
index 6bc2e5e5e..89adb046b 100644
--- a/ICSharpCode.Decompiler/Disassembler/DisassemblerHelpers.cs
+++ b/ICSharpCode.Decompiler/Disassembler/DisassemblerHelpers.cs
@@ -141,32 +141,44 @@ namespace ICSharpCode.Decompiler.Disassembler
 			return $"'{EscapeString(identifier).Replace("'", "\\'")}'";
 		}
 
-		public static void WriteParameterReference(ITextOutput writer, MetadataReader metadata, MethodDefinitionHandle handle, int sequence)
+		public static void WriteParameterReference(ITextOutput writer, MetadataReader metadata, MethodDefinitionHandle handle, int index)
 		{
-			var methodDefinition = metadata.GetMethodDefinition(handle);
-			var signature = methodDefinition.DecodeSignature(new FullTypeNameSignatureDecoder(metadata), default);
-			var parameters = methodDefinition.GetParameters().Select(p => metadata.GetParameter(p)).ToArray();
-			var signatureHeader = signature.Header;
-			int index = sequence;
-			if (signatureHeader.IsInstance && signature.ParameterTypes.Length == parameters.Length)
+			string name = GetParameterName(index);
+			if (name == null)
 			{
-				index--;
+				writer.WriteLocalReference(index.ToString(), "param_" + index);
 			}
-			if (index < 0 || index >= parameters.Length)
+			else
 			{
-				writer.WriteLocalReference(sequence.ToString(), "param_" + index);
+				writer.WriteLocalReference(name, "param_" + index);
 			}
-			else
+
+			string GetParameterName(int parameterNumber)
 			{
-				var param = parameters[index];
-				if (param.Name.IsNil)
+				var methodDefinition = metadata.GetMethodDefinition(handle);
+				if ((methodDefinition.Attributes & System.Reflection.MethodAttributes.Static) != 0)
 				{
-					writer.WriteLocalReference(sequence.ToString(), "param_" + index);
+					parameterNumber++;
 				}
-				else
+				foreach (var p in methodDefinition.GetParameters())
 				{
-					writer.WriteLocalReference(Escape(metadata.GetString(param.Name)), "param_" + index);
+					var param = metadata.GetParameter(p);
+					if (param.SequenceNumber < parameterNumber)
+					{
+						continue;
+					}
+					else if (param.SequenceNumber == parameterNumber)
+					{
+						if (param.Name.IsNil)
+							return null;
+						return Escape(metadata.GetString(param.Name));
+					}
+					else
+					{
+						break;
+					}
 				}
+				return null;
 			}
 		}