Attribute type list does not contain decimal

[martingbrown]

Section 21.2.4 defines Attribute parameter types as follows:

21.2.4 Attribute parameter types
The types of positional and named parameters for an attribute class are limited to the attribute parameter types, which are:

One of the following types: bool, byte, char, double, float, int, long, sbyte, short, string, uint, ulong, ushort.

This list of types seems to be quite limited. I was very surprised that I can't use a decimal literal. I expect there is some complex reason why this list is so limited that I'm not aware of, but it would be nice to get decimal on the list.

[KalleOlaviNiemitalo]

Yes it is limited. If you need it changed, then https://github.com/dotnet/csharplang/discussions is the place for feature requests.

[KalleOlaviNiemitalo]

For background: the CLI specification ECMA-335 does not even support System.Decimal literals as in const decimal d = 1.0m;, even though C# does; .NET instead expresses those via DecimalConstantAttribute. A similar encoding is not feasible for decimal values in arguments of attributes. However, C# has recently added support for generic attribute types, with a metadata encoding that does not comply with ECMA-335. So now it would in principle be possible to design and implement an encoding for decimal values in attributes too, if the benefits outweigh the costs.