/// <summary>
/// Checks if two types are compatible according to compatible-with as described in ECMA 335 I.8.7.1
/// Most of the checks are performed by the CanCastTo, but some cases are pre-filtered out.
/// </summary>
public static bool IsCompatibleWith(this TypeDesc thisType, TypeDesc otherType)
{
// Structs can be cast to the interfaces they implement, but they are not compatible according to ECMA I.8.7.1
bool isCastFromValueTypeToReferenceType = otherType.IsValueType && !thisType.IsValueType;
if (isCastFromValueTypeToReferenceType)
{
return(false);
}
// Managed pointers are compatible only if they are pointer-element-compatible-with as described in ECMA I.8.7.2
if (thisType.IsByRef && otherType.IsByRef)
{
return(AreVerificationTypesEqual(thisType.GetParameterType(), otherType.GetParameterType()));
}
// Unmanaged pointers are handled the same way as managed pointers
if (thisType.IsPointer && otherType.IsPointer)
{
return(AreVerificationTypesEqual(thisType.GetParameterType(), otherType.GetParameterType()));
}
// Function pointers are compatible only if they are method-signature-compatible-with as described in ECMA I.8.7.1
if (thisType.IsFunctionPointer && otherType.IsFunctionPointer)
{
return(IsMethodSignatureCompatibleWith(thisType, otherType));
}
// None of the types can be a managed pointer, a pointer or a function pointer here,
// all the valid cases were handled above.
if (thisType.IsByRef || otherType.IsByRef ||
thisType.IsPointer || otherType.IsPointer ||
thisType.IsFunctionPointer || otherType.IsFunctionPointer)
{
return(false);
}
// Nullable<T> can be cast to T, but this is not compatible according to ECMA I.8.7.1
bool isCastFromNullableOfTtoT = thisType.IsNullable && otherType.IsEquivalentTo(thisType.Instantiation[0]);
if (isCastFromNullableOfTtoT)
{
return(false);
}
return(otherType.CanCastTo(thisType));
}
public static bool IsCompatibleWith(this TypeDesc thisType, TypeDesc otherType)
{
// Structs can be cast to the interfaces they implement, but they are not compatible according to ECMA I.8.7.1
bool isCastFromValueTypeToReferenceType = otherType.IsValueType && !thisType.IsValueType;
if (isCastFromValueTypeToReferenceType)
{
return(false);
}
// Nullable<T> can be cast to T, but this is not compatible according to ECMA I.8.7.1
bool isCastFromNullableOfTtoT = thisType.IsNullable && otherType.IsEquivalentTo(thisType.Instantiation[0]);
if (isCastFromNullableOfTtoT)
{
return(false);
}
return(otherType.CanCastTo(thisType));
}