Possible bug in System.Numerics BigInteger bitwise AND operation `&` in dotnet 9

[Hecate2]

System.Numerics.BigInteger.Parse("-9223372036854775808") & System.Numerics.BigInteger.Parse("-9223372036854775809")

This works in dotnet 8.0.204, with a result -18446744073709551616. But in dotnet 9.0.100 it throws an exception Index was outside the bounds of the array, because System.Numerics.BigInteger.Parse("-9223372036854775808").GetBitLength() == 63, and System.Numerics.BigInteger.Parse("-9223372036854775809").GetBitLength() == 64.
(Note that -9223372036854775808 == -2^63)
I am not really sure whether this is a bug or a feature.

[Hecate2]

Yet the bitwise OR operator | works well. System.Numerics.BigInteger.Parse("-9223372036854775808") | System.Numerics.BigInteger.Parse("-9223372036854775809") is -1. Also XOR ^ is well, returning 18446744073709551615.

[Youssef1313]

This belongs to dotnet/runtime repo.

@tannergooding Is that one fixed by dotnet/runtime#105456?

[shargon]

Could someone transfer the issue to runtime?

[cschuchardt88]

@jeffhandley can you move to runtime?

[jeffhandley]

I can't transfer the issue across organizations, but I agree this is the same issue as dotnet/runtime#105456, which is fixed in main and will be included in the January 2025 servicing release.

Thank you for reporting that you encountered, @Hecate2.