[API proposal] Attribute for passing caller identity implicitly (original) (raw)

Rationale

Number of libraries, including the new minimal ASP.NET host, use Assembly.GetCallingAssembly() for convenience. Assembly.GetCallingAssembly() is slow and unreliable API, and also not compatible with AOT technologies (e.g. dotnet/runtime#53825). We need a fast, reliable and AOT-friendly replacement of Assembly.GetCallingAssembly().

Proposal

namespace System.Runtime.CompilerServices { [AttributeUsage(AttributeTargets.Parameter, AllowMultiple = false, Inherited = false)] public sealed class CallerIdentityAttribute : Attribute { public CallerIdentityAttribute(); } }

This attribute can be applied to parameters of type System.Reflection.Assembly, System.Reflection.Type, System.Reflection.MethodBase. When the C# compiler sees parameter tagged with this attribute, it will provide default value for it, according to the caller context:

• System.Reflection.Assembly: typeof(containing_type).Assembly
• System.Reflection.Type: typeof(containing_type)
• System.Reflection.MethodBase: MethodBase.GetMethodFromHandle(ldtoken containing_method)

Design meetings

• https://github.com/dotnet/csharplang/blob/main/meetings/2021/LDM-2021-09-22.md#calleridentityattribute
• https://github.com/dotnet/csharplang/blob/main/meetings/2022/LDM-2022-01-24.md#attribute-for-passing-caller-identity-implicitly