support required members

Author: RexJaeschke

standard/standard-library.md

@@ -772,6 +772,13 @@ namespace System.Diagnostics.CodeAnalysis
     {
         public NotNullWhenAttribute(bool returnValue);
     }
+
+    [System.AttributeUsage(System.AttributeTargets.Constructor,
+      AllowMultiple=false, Inherited=false)]
+    public sealed class SetsRequiredMembersAttribute : Attribute
+    {
+        public SetsRequiredMembersAttribute() {}
+    }
 }
 
 namespace System.Linq.Expressions
@@ -887,6 +894,14 @@ namespace System.Runtime.CompilerServices
         public ModuleInitializerAttribute() { }
     }
 
+    [System.AttributeUsage(System.AttributeTargets.Class |
+      System.AttributeTargets.Field | System.AttributeTargets.Property |
+      System.AttributeTargets.Struct, AllowMultiple=false, Inherited=false)]
+    public sealed class RequiredMemberAttribute : Attribute
+    {
+        public RequiredMemberAttribute() {}
+    }
+
     public readonly struct TaskAwaiter : ICriticalNotifyCompletion,
         INotifyCompletion
     {
@@ -1438,6 +1453,7 @@ The following library types are referenced in this specification. The full names
 - `global::System.Diagnostics.CodeAnalysis.NotNullAttribute`
 - `global::System.Diagnostics.CodeAnalysis.NotNullIfNotNullAttribute`
 - `global::System.Diagnostics.CodeAnalysis.NotNullWhenAttribute`
+- `global::System.Diagnostics.CodeAnalysis.SetsRequiredMembersAttribute`
 - `global::System.Linq.Expressions.Expression<TDelegate>`
 - `global::System.Reflection.MemberInfo`
 - `global::System.Runtime.CompilerServices.AsyncMethodBuilderAttribute`
@@ -1453,6 +1469,7 @@ The following library types are referenced in this specification. The full names
 - `global::System.Runtime.CompilerServices.InterpolatedStringHandlerArgumentAttribute`
 - `global::System.Runtime.CompilerServices.InterpolatedStringHandlerAttribute`
 - `global::System.Runtime.CompilerServices.ModuleInitializerAttribute`
+- `global::System.Runtime.CompilerServices.RequiredMemberAttribute`
 - `global::System.Runtime.CompilerServices.TaskAwaiter`
 - `global::System.Runtime.CompilerServices.TaskAwaiter<T>`
 - `global::System.Runtime.CompilerServices.ValueTaskAwaiter`