private static void EmitNullableToReferenceConversion(ILGenerator il, Type typeFrom)
{
Debug.Assert(TypeUtil.IsNullableType(typeFrom));
// We've got a conversion from nullable to Object, ValueType, Enum, etc. Just box it so that
// we get the nullable semantics.
il.Emit(OpCodes.Box, typeFrom);
}
private static void EmitNullableToNonNullableConversion(ILGenerator il, Type typeFrom, Type typeTo, bool isChecked)
{
Debug.Assert(TypeUtil.IsNullableType(typeFrom));
Debug.Assert(!TypeUtil.IsNullableType(typeTo));
if (typeTo.IsValueType)
{
EmitNullableToNonNullableStructConversion(il, typeFrom, typeTo, isChecked);
}
else
{
EmitNullableToReferenceConversion(il, typeFrom);
}
}
private static void EmitNullableToNonNullableStructConversion(ILGenerator il, Type typeFrom, Type typeTo, bool isChecked)
{
Debug.Assert(TypeUtil.IsNullableType(typeFrom));
Debug.Assert(!TypeUtil.IsNullableType(typeTo));
Debug.Assert(typeTo.IsValueType);
LocalBuilder locFrom = il.DeclareLocal(typeFrom);
il.Emit(OpCodes.Stloc, locFrom);
il.Emit(OpCodes.Ldloca, locFrom);
EmitGetValue(il, typeFrom);
Type nnTypeFrom = TypeUtil.GetNonNullableType(typeFrom);
EmitConvertToType(il, nnTypeFrom, typeTo, isChecked);
}
private static void EmitNonNullableToNullableConversion(ILGenerator il, Type typeFrom, Type typeTo, bool isChecked)
{
Debug.Assert(!TypeUtil.IsNullableType(typeFrom));
Debug.Assert(TypeUtil.IsNullableType(typeTo));
LocalBuilder locTo = il.DeclareLocal(typeTo);
Type nnTypeTo = TypeUtil.GetNonNullableType(typeTo);
EmitConvertToType(il, typeFrom, nnTypeTo, isChecked);
ConstructorInfo ci = typeTo.GetConstructor(new[] { nnTypeTo });
il.Emit(OpCodes.Newobj, ci);
il.Emit(OpCodes.Stloc, locTo);
il.Emit(OpCodes.Ldloc, locTo);
}
public static void EmitConvertToType(ILGenerator il, Type typeFrom, Type typeTo, bool isChecked)
{
if (TypeUtil.AreEquivalent(typeFrom, typeTo))
{
return;
}
if (typeFrom == typeof(void) || typeTo == typeof(void))
{
throw new InvalidOperationException();
}
bool isTypeFromNullable = TypeUtil.IsNullableType(typeFrom);
bool isTypeToNullable = TypeUtil.IsNullableType(typeTo);
Type nnExprType = TypeUtil.GetNonNullableType(typeFrom);
Type nnType = TypeUtil.GetNonNullableType(typeTo);
if (typeFrom.IsInterface || // interface cast
typeTo.IsInterface ||
typeFrom == typeof(object) || // boxing cast
typeTo == typeof(object) ||
typeFrom == typeof(System.Enum) ||
typeFrom == typeof(System.ValueType) ||
TypeUtil.IsLegalExplicitVariantDelegateConversion(typeFrom, typeTo))
{
EmitCastToType(il, typeFrom, typeTo);
}
else if (isTypeFromNullable || isTypeToNullable)
{
EmitNullableConversion(il, typeFrom, typeTo, isChecked);
}
else if (!(TypeUtil.IsConvertible(typeFrom) && TypeUtil.IsConvertible(typeTo)) // primitive runtime conversion
&&
(nnExprType.IsAssignableFrom(nnType) || // down cast
nnType.IsAssignableFrom(nnExprType))) // up cast
{
EmitCastToType(il, typeFrom, typeTo);
}
else if (typeFrom.IsArray && typeTo.IsArray)
{
// See DevDiv Bugs #94657.
EmitCastToType(il, typeFrom, typeTo);
}
else
{
EmitNumericConversion(il, typeFrom, typeTo, isChecked);
}
}
private static void EmitNullableConversion(ILGenerator il, Type typeFrom, Type typeTo, bool isChecked)
{
bool isTypeFromNullable = TypeUtil.IsNullableType(typeFrom);
bool isTypeToNullable = TypeUtil.IsNullableType(typeTo);
Debug.Assert(isTypeFromNullable || isTypeToNullable);
if (isTypeFromNullable && isTypeToNullable)
{
EmitNullableToNullableConversion(il, typeFrom, typeTo, isChecked);
}
else if (isTypeFromNullable)
{
EmitNullableToNonNullableConversion(il, typeFrom, typeTo, isChecked);
}
else
{
EmitNonNullableToNullableConversion(il, typeFrom, typeTo, isChecked);
}
}
private static void EmitNullableToNullableConversion(ILGenerator il, Type typeFrom, Type typeTo, bool isChecked)
{
Debug.Assert(TypeUtil.IsNullableType(typeFrom));
Debug.Assert(TypeUtil.IsNullableType(typeTo));
LocalBuilder locFrom = il.DeclareLocal(typeFrom);
il.Emit(OpCodes.Stloc, locFrom);
LocalBuilder locTo = il.DeclareLocal(typeTo);
// test for null
il.Emit(OpCodes.Ldloca, locFrom);
EmitHasValue(il, typeFrom);
Label labIfNull = il.DefineLabel();
il.Emit(OpCodes.Brfalse_S, labIfNull);
il.Emit(OpCodes.Ldloca, locFrom);
EmitGetValueOrDefault(il, typeFrom);
Type nnTypeFrom = TypeUtil.GetNonNullableType(typeFrom);
Type nnTypeTo = TypeUtil.GetNonNullableType(typeTo);
EmitConvertToType(il, nnTypeFrom, nnTypeTo, isChecked);
// construct result type
ConstructorInfo ci = typeTo.GetConstructor(new[] { nnTypeTo });
il.Emit(OpCodes.Newobj, ci);
il.Emit(OpCodes.Stloc, locTo);
Label labEnd = il.DefineLabel();
il.Emit(OpCodes.Br_S, labEnd);
// if null then create a default one
il.MarkLabel(labIfNull);
il.Emit(OpCodes.Ldloca, locTo);
il.Emit(OpCodes.Initobj, typeTo);
il.MarkLabel(labEnd);
il.Emit(OpCodes.Ldloc, locTo);
}
