// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#nullable enable

// Copied from:
// https://github.com/dotnet/runtime/blob/fdd104ec5e1d0d2aa24a6723995a98d0124f724b/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/CompilerFeatureRequiredAttribute.cs

#if NET8_0_OR_GREATER

using System.Runtime.CompilerServices;

#pragma warning disable RS0016 // Add public types and members to the declared API (this is a supporting forwarder for an internal polyfill API)
[assembly: TypeForwardedTo(typeof(CompilerFeatureRequiredAttribute))]
#pragma warning restore RS0016 // Add public types and members to the declared API

#else

namespace System.Runtime.CompilerServices
{
    /// <summary>
    /// Indicates that compiler support for a particular feature is required for the location where this attribute is applied.
    /// </summary>
    [AttributeUsage(AttributeTargets.All, AllowMultiple = true, Inherited = false)]
    internal sealed class CompilerFeatureRequiredAttribute : Attribute
    {
        public CompilerFeatureRequiredAttribute(string featureName)
        {
            FeatureName = featureName;
        }

        /// <summary>
        /// The name of the compiler feature.
        /// </summary>
        public string FeatureName { get; }

        /// <summary>
        /// If true, the compiler can choose to allow access to the location where this attribute is applied if it does not understand <see cref="FeatureName"/>.
        /// </summary>
        public bool IsOptional { get; init; }

        /// <summary>
        /// The <see cref="FeatureName"/> used for the ref structs C# feature.
        /// </summary>
        public const string RefStructs = nameof(RefStructs);

        /// <summary>
        /// The <see cref="FeatureName"/> used for the required members C# feature.
        /// </summary>
        public const string RequiredMembers = nameof(RequiredMembers);
    }
}

#endif
