The mask of shiftAmount in IShiftOperators<byte, int, byte> should be 7 instead of 31

[skyoxZ]

Description

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

Lines 1117 to 1124 in 0f0981f

	/// <inheritdoc cref="IShiftOperators{TSelf, TOther, TResult}.op_LeftShift(TSelf, TOther)" />
	static byte IShiftOperators<byte, int, byte>.operator <<(byte value, int shiftAmount) => (byte)(value << shiftAmount);
	/// <inheritdoc cref="IShiftOperators{TSelf, TOther, TResult}.op_RightShift(TSelf, TOther)" />
	static byte IShiftOperators<byte, int, byte>.operator >>(byte value, int shiftAmount) => (byte)(value >> shiftAmount);
	/// <inheritdoc cref="IShiftOperators{TSelf, TOther, TResult}.op_UnsignedRightShift(TSelf, TOther)" />
	static byte IShiftOperators<byte, int, byte>.operator >>>(byte value, int shiftAmount) => (byte)(value >>> shiftAmount);

Reproduction Steps

using System;
using System.Numerics;

BinaryIntegerWrapper<byte> a = new(2);
Console.WriteLine((a << 11).Value);

public struct BinaryIntegerWrapper<T> : IShiftOperators<BinaryIntegerWrapper<T>, int, BinaryIntegerWrapper<T>>
            where T : IBinaryInteger<T>
{
    public T Value;

    public BinaryIntegerWrapper(T value) => Value = value;

    public static implicit operator BinaryIntegerWrapper<T>(T value) => new BinaryIntegerWrapper<T>(value);

    public static BinaryIntegerWrapper<T> operator <<(BinaryIntegerWrapper<T> value, int shiftAmount) => value.Value << shiftAmount;
    public static BinaryIntegerWrapper<T> operator >>(BinaryIntegerWrapper<T> value, int shiftAmount) => value.Value >> shiftAmount;
    public static BinaryIntegerWrapper<T> operator >>>(BinaryIntegerWrapper<T> value, int shiftAmount) => value.Value >>> shiftAmount;
}

Expected behavior

16

Actual behavior

0

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

Per this comment from @tannergooding:

This is also notably an issue with sbyte, short, and ushort. It is also, unfortunately, a breaking change and will need a bar check.

The intent had indeed been to correctly mask, which is being done in other operations but was missed for these ones.

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Tagging subscribers to this area: @dotnet/area-system-numerics
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[dotnet-policy-service]

Added needs-breaking-change-doc-created label because this issue has the breaking-change label.

1. Create and link to this issue a matching issue in the dotnet/docs repo using the breaking change documentation template, then remove this needs-breaking-change-doc-created label.

Tagging @dotnet/compat for awareness of the breaking change.

[jeffhandley]

I've added this to the 10.0.0 milestone as it would be beneficial to apply the breaking change fix early in an LTS release.