Merge branch '5.0.x' of https://github.com/icsharpcode/ILSpy

ICSharpCode.Decompiler.Tests/TestCases/Pretty/DelegateConstruction.cs

@@ -376,5 +376,14 @@ namespace ICSharpCode.Decompiler.Tests.TestCases.Pretty
 				return captured;
 			};
 		}
+
+		public static Func<TCaptured> CapturedTypeParameter2<TNonCaptured, TCaptured>(TNonCaptured a, Func<TNonCaptured, List<TCaptured>> f)
+		{
+			List<TCaptured> captured = f(a);
+			return delegate {
+				Console.WriteLine(captured.GetType().FullName);
+				return captured.FirstOrDefault();
+			};
+		}
 	}
 }

ICSharpCode.Decompiler/IL/Transforms/TransformDisplayClassUsage.cs

@@ -278,11 +278,11 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			inst.Value.AcceptVisitor(this);
 			if (IsParameterAssignment(inst, out var displayClass, out var field, out var parameter)) {
 				context.Step($"Detected parameter assignment {parameter.Name}", inst);
-				displayClass.Variables.Add(field, parameter);
+				displayClass.Variables.Add((IField)field.MemberDefinition, parameter);
 				instructionsToRemove.Add(inst);
 			} else if (IsDisplayClassAssignment(inst, out displayClass, out field, out var variable)) {
 				context.Step($"Detected display-class assignment {variable.Name}", inst);
-				displayClass.Variables.Add(field, variable);
+				displayClass.Variables.Add((IField)field.MemberDefinition, variable);
 				instructionsToRemove.Add(inst);
 			} else {
 				inst.Target.AcceptVisitor(this);
@@ -324,7 +324,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				return false;
 			if (!(inst.Value.MatchLdLoc(out var v) && v.Kind == VariableKind.Parameter && v.Function == currentFunction))
 				return false;
-			if (displayClass.Variables.ContainsKey(field))
+			if (displayClass.Variables.ContainsKey((IField)field.MemberDefinition))
 				return false;
 			if (displayClassVar.Function != currentFunction)
 				return false;
@@ -339,7 +339,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			field = null;
 			if (!(inst is LdFlda ldflda))
 				return false;
-			field = (IField)ldflda.Field.MemberDefinition;
+			field = ldflda.Field;
 			return IsDisplayClassLoad(ldflda.Target, out displayClassVar)
 				&& displayClasses.TryGetValue(displayClassVar, out displayClass);
 		}
@@ -350,11 +350,16 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 			// Get display class info
 			if (!IsDisplayClassFieldAccess(inst, out _, out DisplayClass displayClass, out IField field))
 				return;
+			// We want the specialized version, so that display-class type parameters are
+			// substituted with the type parameters from the use-site.
+			var fieldType = field.Type;
+			// However, use the unspecialized member definition to make reference comparisons in dictionary possible.
+			field = (IField)field.MemberDefinition;
 			if (!displayClass.Variables.TryGetValue(field, out var v)) {
 				context.Step($"Introduce captured variable for {field.FullName}", inst);
 				// Introduce a fresh variable for the display class field.
 				Debug.Assert(displayClass.Definition == field.DeclaringTypeDefinition);
-				v = displayClass.DeclaringFunction.RegisterVariable(VariableKind.Local, GetVariableTypeFromClosureField(field), field.Name);
+				v = displayClass.DeclaringFunction.RegisterVariable(VariableKind.Local, fieldType, field.Name);
 				v.HasInitialValue = true;
 				v.CaptureScope = displayClass.CaptureScope;
 				inst.ReplaceWith(new LdLoca(v).WithILRange(inst));
@@ -364,20 +369,5 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				inst.ReplaceWith(new LdLoca(v).WithILRange(inst));
 			}
 		}
-
-		private IType GetVariableTypeFromClosureField(IField field)
-		{
-			if (!(field.Type is ITypeParameter typeParameter))
-				return field.Type;
-			var rootMethod = context.Function.Method;
-			if (typeParameter.Owner != field.DeclaringTypeDefinition)
-				return field.Type;
-			if (typeParameter.Index >= rootMethod.TypeParameters.Count) {
-				Debug.Assert(false, "Cannot map display-class type parameter to method type parameter");
-				return field.Type;
-			}
-
-			return rootMethod.TypeParameters[typeParameter.Index];
-		}
 	}
 }