Why Debug.Assert is used instead of direct exception throwing in Attribute.cs?

[EmilyGraceSeville7cf]

Hello! Can somebody tell me why Debug.Assert is used instead of direct exception throwing? When this approach is better than exceptions?

[Dotnet-GitSync-Bot]

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[KalleOlaviNiemitalo]

The question refers to source code of System.Attribute:

runtime/src/libraries/System.Private.CoreLib/src/System/Attribute.cs

Lines 114 to 116 in 53976d3

	// Attributes can only contain single-dimension arrays, so we don't need to worry about
	// multidimensional arrays.
	Debug.Assert(thisValueArray.Rank == 1 && thatValueArray.Rank == 1);

That assertion actually fails in this case:

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main()
        {
            var attr = new System.Runtime.InteropServices.DefaultParameterValueAttribute(new int[1, 1]);
            attr.Equals(attr);
        }
    }
}

I guess the authors of Attribute.AreFieldValuesEqual assumed that any array value in a field of an attribute instance must have come from metadata, and the encoding defined in ECMA-335 §II.23.3 does not support multidimensional arrays, so it is not possible to have a multidimensional array in such a field. However, that assumption is not quite valid because attribute instances can be created with values that do not come from metadata, and because the derived attribute class may have methods that write to the fields.

[stephentoub]

Related to #35784

[EmilyGraceSeville7cf]

Are there any updates to this issue? 🌝