Fix casts to type parameters.

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -1307,9 +1307,20 @@ namespace ICSharpCode.Decompiler.CSharp
 				// ensure we treat the input as a reference type
 				arg = arg.ConvertTo(compilation.FindType(KnownTypeCode.Object), this);
 			}
-			return new CastExpression(ConvertType(inst.Type), arg.Expression)
+
+			IType targetType = inst.Type;
+			if (targetType.Kind == TypeKind.TypeParameter) {
+				var rr = resolver.ResolveCast(targetType, arg.ResolveResult);
+				if (rr.IsError) {
+					// C# 6.2.7 Explicit conversions involving type parameters:
+					// if we can't directly convert to a type parameter,
+					// try via its effective base class.
+					arg = arg.ConvertTo(((ITypeParameter)targetType).EffectiveBaseClass, this);
+				}
+			}
+			return new CastExpression(ConvertType(targetType), arg.Expression)
 				.WithILInstruction(inst)
-				.WithRR(new ConversionResolveResult(inst.Type, arg.ResolveResult, Conversion.UnboxingConversion));
+				.WithRR(new ConversionResolveResult(targetType, arg.ResolveResult, Conversion.UnboxingConversion));
 		}
 		
 		protected internal override TranslatedExpression VisitUnbox(Unbox inst, TranslationContext context)

ICSharpCode.Decompiler/IL/Transforms/DelegateConstruction.cs

@@ -248,7 +248,7 @@ namespace ICSharpCode.Decompiler.IL.Transforms
 				} else {
 					ILInstruction value;
 					ILVariable v;
-					if (inst.Value.MatchLdLoc(out v)) {
+					if (inst.Value.MatchLdLoc(out v) && v.Kind != VariableKind.PinnedLocal) {
 						orphanedVariableInits.Add(inst);
 						value = inst.Value;
 					} else {

ICSharpCode.Decompiler/Tests/TestCases/Correctness/Generics.cs

@@ -47,6 +47,11 @@ namespace Generics
 		{
 			Console.WriteLine(typeof(T1) + " " + typeof(T2));
 		}
+
+		public T CastToTypeParameter<T>(DerivedClass d) where T: BaseClass
+		{
+			return (T)(BaseClass)d;
+		}
 	}
 	
 	class GenericClass<T>
@@ -56,4 +61,12 @@ namespace Generics
 			self = this;
 		}
 	}
+
+	public class BaseClass
+	{
+	}
+
+	public class DerivedClass : BaseClass
+	{
+	}
 }