[API Proposal]: Add missing IsPlatform methods to `OperatingSystem` class

[HadrienPatte]

Background and motivation

The Proposal is the addition of an IsNetBSD, IsIllumos and IsSolaris methods to the OperatingSystem class.

The OperatingSystem class is already able to identify the following platforms through its IsOSPlatform method.

Platform	IsPlatform method available
BROWSER	✔️
WASI	✔️
WINDOWS	✔️
OSX	✔️
MACCATALYST	✔️
IOS	✔️
TVOS	✔️
ANDROID	✔️
LINUX	✔️
FREEBSD	✔️
NETBSD	❌
ILLUMOS	❌
SOLARIS	❌

API Proposal

namespace System
{
    public sealed class OperatingSystem : ISerializable, ICloneable
    {
        /// <summary>
        /// Indicates whether the current application is running on NetBSD.
        /// </summary>
        [NonVersionable]
        public static bool IsNetBSD()

        /// <summary>
        /// Indicates whether the current application is running on Illumos.
        /// </summary>
        [NonVersionable]
        public static bool IsIllumos()

        /// <summary>
        /// Indicates whether the current application is running on Solaris.
        /// </summary>
        [NonVersionable]
        public static bool IsSolaris()
    }
}

API Usage

if (OperatingSystem.IsNetBSD())
{
    Console.WriteLine("Running on NetBSD");
}
else if (OperatingSystem.IsIllumos())
{
    Console.WriteLine("Running on Illumos");
}
else if (OperatingSystem.IsSolaris())
{
    Console.WriteLine("Running on Solaris");
}

Alternative Designs

The proposed feature can already be accomplished with OperatingSystem.IsOSPlatform("NETBSD"), OperatingSystem.IsOSPlatform("ILLUMOS") and OperatingSystem.IsOSPlatform("SOLARIS"), but having an IsPlatform method available for each supported platform would make the overall API of the OperatingSystem class more consistent and predictable.

Risks

No response

[teo-tsirpanis]

We will also need Is***VersionAtLeast overloads.

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