Mark casts as checked/unchecked.

ICSharpCode.Decompiler/Ast/AstMethodBodyBuilder.cs

@@ -369,7 +369,14 @@ namespace ICSharpCode.Decompiler.Ast
 				case ILCode.Conv_U8:
 				case ILCode.Conv_I:
 				case ILCode.Conv_U:
-					return arg1; // conversion is handled by Convert() function using the info from type analysis
+					{
+						// conversion was handled by Convert() function using the info from type analysis
+						CastExpression cast = arg1 as CastExpression;
+						if (cast != null) {
+							cast.AddAnnotation(AddCheckedBlocks.UncheckedAnnotation);
+						}
+						return arg1;
+					}
 					case ILCode.Conv_R4:   return arg1.CastTo(typeof(float));
 					case ILCode.Conv_R8:   return arg1.CastTo(typeof(double));
 					case ILCode.Conv_R_Un: return arg1.CastTo(typeof(double)); // TODO
@@ -389,7 +396,14 @@ namespace ICSharpCode.Decompiler.Ast
 				case ILCode.Conv_Ovf_U2_Un:
 				case ILCode.Conv_Ovf_U4_Un:
 				case ILCode.Conv_Ovf_U8_Un:
-					return arg1; // conversion was handled by Convert() function using the info from type analysis
+					{
+						// conversion was handled by Convert() function using the info from type analysis
+						CastExpression cast = arg1 as CastExpression;
+						if (cast != null) {
+							cast.AddAnnotation(AddCheckedBlocks.CheckedAnnotation);
+						}
+						return arg1;
+					}
 					case ILCode.Conv_Ovf_I:     return arg1.CastTo(typeof(IntPtr)); // TODO
 					case ILCode.Conv_Ovf_U:     return arg1.CastTo(typeof(UIntPtr));
 					case ILCode.Conv_Ovf_I_Un:  return arg1.CastTo(typeof(IntPtr));

ICSharpCode.Decompiler/ILAst/TypeAnalysis.cs

@@ -689,7 +689,9 @@ namespace ICSharpCode.Decompiler.ILAst
 			} else if (targetBitSize >= NativeInt && argType is PointerType) {
 				return argType;
 			}
-			return (GetInformationAmount(expectedType) == targetBitSize && IsSigned(expectedType) == targetSigned) ? expectedType : targetType;
+			TypeReference resultType = (GetInformationAmount(expectedType) == targetBitSize && IsSigned(expectedType) == targetSigned) ? expectedType : targetType;
+			arg.ExpectedType = resultType; // store the expected type in the argument so that AstMethodBodyBuilder will insert a cast
+			return resultType;
 		}
 		
 		static TypeReference GetFieldType(FieldReference fieldReference)

ICSharpCode.Decompiler/Tests/CheckedUnchecked.cs

@@ -19,6 +19,14 @@ public class CheckedUnchecked
 		int u5 = unchecked(a % b);
 	}
 	
+	public void Cast(int a)
+	{
+		short c1 = checked((short)a);
+		short u1 = unchecked((short)a);
+		byte c2 = checked((byte)a);
+		byte u2 = unchecked((byte)a);
+	}
+	
 	public void ForWithCheckedIteratorAndUncheckedBody(int n)
 	{
 		checked {