Mark the new tensor APIs as experimental for .NET 9 (#105268)

* Mark the new tensor APIs as experimental for .NET 9

* Apply SNTEXP0001 to other internal API

* Suppress SNTEXP0001 in System.Numerics.Tensors.Tests

* Use SYSLIB5001. Central registration of experimental API diagnostic ids.

* Add Experimentals.cs (missed in prior commit)

* Revert SLN changes. Add UrlFormat property to attributes where missing.

* Ensure the net8 tensors tests also don't warn for the experimental API usage

---------

Co-authored-by: Eric StJohn <ericstj@microsoft.com>
Co-authored-by: Jeff Handley <jeffhandley@users.noreply.github.com>

docs/project/list-of-diagnostics.md

@@ -276,3 +276,20 @@ The diagnostic id values reserved for .NET Libraries analyzer warnings are `SYSL
 | __`SYSLIBSUPPRESS0001`__ | CA1822                   | Do not offer to make methods static when the methods need to be instance methods for a custom marshaller shape. |
 | __`SYSLIBSUPPRESS0002`__ | IL2026                   | ConfigurationBindingGenerator: suppress RequiresUnreferencedCode diagnostic for binding call that has been intercepted by a generated static variant. |
 | __`SYSLIBSUPPRESS0003`__ | IL3050                   | ConfigurationBindingGenerator: suppress RequiresDynamicCode diagnostic for binding call that has been intercepted by a generated static variant. |
+
+## Experimental APIs
+
+APIs can be marked as `[Experimental]` if their shape or functionality is included in a release but not yet officially supported. Experimental APIs offer the opportunity to collect customer feedback on these APIs in a major release, usually refining the APIs and removing the `[Experimental]` attribute in the next release. The `[Experimental]` attribute differs from `[RequiresPreviewFeatures]`, wherein:
+
+* `[RequiresPreviewFeatures]` APIs require a corresponding preview feature in another product area such as the compiler or SDK
+* `[Experimental]` APIs are entirely self-contained within the libraries and do not require preview features in other parts of the product
+
+The diagnostic id values reserved for experimental APIs are `SYSLIB5001` through `SYSLIB5999`. When marking an API as `[Experimental]`, claim the next three-digit identifier in the `SYSLIB5###` sequence and add it to the list below. The URL template for all experimental APIs is `https://aka.ms/dotnet-warnings/{0}`. The `{0}` placeholder is replaced by the compiler with the `SYSLIB5###` identifier.
+
+### Experimental Diagnostics (`SYSLIB5001` - `SYSLIB5999`)
+
+Diagnostic id values for experimental APIs must not be recycled, as that could silently opt customers into new experimental APIs where they had previously suppressed the ID for a previous usage of the value.
+
+| Diagnostic ID     | Introduced | Removed | Description |
+| :---------------- | ---------: | ------: | :---------- |
+|  __`SYSLIB5001`__ |     .NET 9 |     TBD | `Tensor<T>` and related APIs in System.Numerics.Tensors are experimental in .NET 9 |

src/libraries/Common/src/System/Experimentals.cs

@@ -0,0 +1,25 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace System
+{
+    internal static class Experimentals
+    {
+        internal const string SharedUrlFormat = "https://aka.ms/dotnet-warnings/{0}";
+
+        // Please see docs\project\list-of-diagnostics.md for instructions on the steps required
+        // to introduce an experimental API, claim a diagnostic id, and ensure the
+        // "aka.ms/dotnet-warnings/{0}" URL points to documentation for the API.
+        // The diagnostic IDs reserved for experimental APIs are SYSLIB5### (SYSLIB5001 - SYSLIB5999).
+
+        // When an API is no longer marked as experimental, the diagnostic ID should be removed from this file
+        // but retained in the table in docs\project\list-of-diagnostics.md to prevent reuse. Be sure to remove
+        // suppressions from the codebase as well.
+
+        // Tensor<T> and related APIs are marked as [Experimental] in .NET 9
+        internal const string TensorTDiagId = "SYSLIB5001";
+
+        // When adding a new diagnostic ID, add it to the table in docs\project\list-of-diagnostics.md as well.
+        // Keep new const identifiers above this comment.
+    }
+}

src/libraries/System.Numerics.Tensors/ref/System.Numerics.Tensors.netcore.cs

@@ -6,6 +6,7 @@
 
 namespace System.Buffers
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public readonly partial struct NIndex : System.IEquatable<System.Buffers.NIndex>
     {
         private readonly int _dummyPrimitive;
@@ -29,6 +30,7 @@ namespace System.Buffers
         public System.Index ToIndexUnchecked() { throw null; }
         public override string ToString() { throw null; }
     }
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public readonly partial struct NRange : System.IEquatable<System.Buffers.NRange>
     {
         private readonly int _dummyPrimitive;
@@ -53,6 +55,7 @@ namespace System.Buffers
 }
 namespace System.Numerics.Tensors
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public partial interface IReadOnlyTensor<TSelf, T> : System.Collections.Generic.IEnumerable<T>, System.Collections.IEnumerable where TSelf : System.Numerics.Tensors.IReadOnlyTensor<TSelf, T>
     {
         static abstract TSelf? Empty { get; }
@@ -80,6 +83,7 @@ public partial interface IReadOnlyTensor<TSelf, T> : System.Collections.Generic.
         bool TryCopyTo(scoped System.Numerics.Tensors.TensorSpan<T> destination);
         bool TryFlattenTo(scoped System.Span<T> destination);
     }
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public partial interface ITensor<TSelf, T> : System.Collections.Generic.IEnumerable<T>, System.Collections.IEnumerable, System.Numerics.Tensors.IReadOnlyTensor<TSelf, T> where TSelf : System.Numerics.Tensors.ITensor<TSelf, T>
     {
         bool IsReadOnly { get; }
@@ -98,6 +102,7 @@ public partial interface ITensor<TSelf, T> : System.Collections.Generic.IEnumera
         void Fill(T value);
         new ref T GetPinnableReference();
     }
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public readonly ref partial struct ReadOnlyTensorSpan<T>
     {
         private readonly object _dummy;
@@ -157,6 +162,7 @@ public ref partial struct Enumerator
             public bool MoveNext() { throw null; }
         }
     }
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public static partial class Tensor
     {
         public static System.Numerics.Tensors.Tensor<T> Abs<T>(in System.Numerics.Tensors.ReadOnlyTensorSpan<T> x) where T : System.Numerics.INumberBase<T> { throw null; }
@@ -674,6 +680,7 @@ public static void Truncate<T>(System.ReadOnlySpan<T> x, System.Span<T> destinat
         public static void Xor<T>(System.ReadOnlySpan<T> x, System.ReadOnlySpan<T> y, System.Span<T> destination) where T : System.Numerics.IBitwiseOperators<T, T, T> { }
         public static void Xor<T>(System.ReadOnlySpan<T> x, T y, System.Span<T> destination) where T : System.Numerics.IBitwiseOperators<T, T, T> { }
     }
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public readonly ref partial struct TensorSpan<T>
     {
         private readonly object _dummy;
@@ -735,6 +742,7 @@ public ref partial struct Enumerator
             public bool MoveNext() { throw null; }
         }
     }
+    [System.Diagnostics.CodeAnalysis.Experimental("SYSLIB5001", UrlFormat = "https://aka.ms/dotnet-warnings/{0}")]
     public sealed partial class Tensor<T> : System.Collections.Generic.IEnumerable<T>, System.Collections.IEnumerable, System.Numerics.Tensors.IReadOnlyTensor<System.Numerics.Tensors.Tensor<T>, T>, System.Numerics.Tensors.ITensor<System.Numerics.Tensors.Tensor<T>, T>
     {
         internal Tensor() { }

src/libraries/System.Numerics.Tensors/src/System.Numerics.Tensors.csproj

@@ -7,12 +7,15 @@
     <PackageDescription>Provides support for operating over tensors.</PackageDescription>
     <GenAPIExcludeApiList>ReferenceAssemblyExclusions.txt</GenAPIExcludeApiList>
     <ApiCompatValidateAssemblies>true</ApiCompatValidateAssemblies>
+    <!-- SYSLIB5001: Tensor<T> and related APIs are Experimental in .NET 9 -->
+    <NoWarn>$(NoWarn);SYSLIB5001</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>
     <Compile Include="System\Numerics\Tensors\TensorPrimitives.Single.cs" />
     <Compile Include="System\Numerics\Tensors\TensorPrimitives.Helpers.cs" />
     <Compile Include="System\ThrowHelper.cs" />
+    <Compile Include="$(CommonPath)System\Experimentals.cs" Link="Common\System\Experimentals.cs" />
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == '.NETCoreApp'">

src/libraries/System.Numerics.Tensors/src/System/NIndex.cs

@@ -14,6 +14,7 @@ namespace System.Buffers
     /// int lastElement = someArray[^1]; // lastElement = 5
     /// </code>
     /// </remarks>
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public readonly struct NIndex : IEquatable<NIndex>
     {
         private readonly nint _value;

src/libraries/System.Numerics.Tensors/src/System/NRange.cs

@@ -15,6 +15,7 @@ namespace System.Buffers
     /// int[] subArray2 = someArray[1..^0]; // { 2, 3, 4, 5 }
     /// </code>
     /// </remarks>
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public readonly struct NRange : IEquatable<NRange>
     {
         /// <summary>Represent the inclusive start NIndex of the NRange.</summary>

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/IReadOnlyTensor.cs

@@ -7,6 +7,7 @@
 
 namespace System.Numerics.Tensors
 {
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public interface IReadOnlyTensor<TSelf, T> : IEnumerable<T>
         where TSelf : IReadOnlyTensor<TSelf, T>
     {

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/ITensor.cs

@@ -2,9 +2,11 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Buffers;
+using System.Diagnostics.CodeAnalysis;
 
 namespace System.Numerics.Tensors
 {
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public interface ITensor<TSelf, T>
         : IReadOnlyTensor<TSelf, T>
         where TSelf : ITensor<TSelf, T>

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/ReadOnlyTensorSpan.cs

@@ -21,6 +21,7 @@ namespace System.Numerics.Tensors
     /// </summary>
     [DebuggerTypeProxy(typeof(TensorSpanDebugView<>))]
     [DebuggerDisplay("{ToString(),raw}")]
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public readonly ref struct ReadOnlyTensorSpan<T>
     {
         /// <summary>A byref or a native ptr.</summary>

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/Tensor.Factory.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.InteropServices;
 using Microsoft.VisualBasic;

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/Tensor.cs

@@ -5,6 +5,7 @@
 using System.Collections;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Reflection.Metadata.Ecma335;
 using System.Runtime.CompilerServices;
@@ -17,6 +18,7 @@
 
 namespace System.Numerics.Tensors
 {
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public sealed class Tensor<T>
         : ITensor<Tensor<T>, T>
     {

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorExtensions.cs

@@ -11,12 +11,14 @@
 using static System.Runtime.InteropServices.JavaScript.JSType;
 using System.Security.Cryptography;
 using System.Runtime.Serialization;
+using System.Diagnostics.CodeAnalysis;
 
 #pragma warning disable CS8601 // Possible null reference assignment.
 #pragma warning disable CS8618 // Non-nullable field must contain a non-null value when exiting constructor. Consider declaring as nullable.
 
 namespace System.Numerics.Tensors
 {
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public static partial class Tensor
     {
         #region AsReadOnlySpan

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorHelpers.cs

@@ -2,11 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.InteropServices;
 
 namespace System.Numerics.Tensors
 {
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     internal static class TensorHelpers
     {
 

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorShape.cs

@@ -8,6 +8,8 @@
 
 namespace System.Numerics.Tensors
 {
+
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     internal readonly struct TensorShape
     {
         // Used to determine when we need to allocate a metadata array

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorSpan.cs

@@ -21,6 +21,7 @@ namespace System.Numerics.Tensors
     /// </summary>
     [DebuggerTypeProxy(typeof(TensorSpanDebugView<>))]
     [DebuggerDisplay("{ToString(),raw}")]
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     public readonly ref struct TensorSpan<T>
     {
         /// <summary>A byref or a native ptr.</summary>

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorSpanDebugView.cs

@@ -2,9 +2,12 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 
 namespace System.Numerics.Tensors
 {
+
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     internal sealed class TensorSpanDebugView<T>
     {
         private readonly T[] _array;

src/libraries/System.Numerics.Tensors/src/System/Numerics/Tensors/netcore/TensorSpanHelpers.cs

@@ -4,12 +4,15 @@
 using System.Buffers;
 using System.Collections.Specialized;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
 
 namespace System.Numerics.Tensors
 {
+
+    [Experimental(Experimentals.TensorTDiagId, UrlFormat = Experimentals.SharedUrlFormat)]
     internal static partial class TensorSpanHelpers
     {
         internal static bool AreShapesTheSame<T>(ReadOnlyTensorSpan<T> tensor1, ReadOnlyTensorSpan<T> tensor2)

src/libraries/System.Numerics.Tensors/tests/Net8Tests/System.Numerics.Tensors.Net8.Tests.csproj

@@ -6,11 +6,12 @@
 -->
 
 <Project Sdk="Microsoft.NET.Sdk">
-  
+
   <PropertyGroup>
     <TargetFramework>$(NetCoreAppCurrent)</TargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <DefineConstants>$(DefineConstants);SNT_NET8_TESTS</DefineConstants>
+    <NoWarn>$(NoWarn);SYSLIB5001</NoWarn>
   </PropertyGroup>
 
   <ItemGroup>
@@ -21,7 +22,7 @@
     <Compile Include="..\TensorPrimitives.ConvertTo.cs" />
     <Compile Include="..\TensorPrimitives.Generic.cs" />
   </ItemGroup>
-  
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\System.Numerics.Tensors.csproj" SkipUseReferenceAssembly="true">
       <SetTargetFramework>TargetFramework=net8.0</SetTargetFramework>

src/libraries/System.Numerics.Tensors/tests/System.Numerics.Tensors.Tests.csproj

@@ -3,6 +3,8 @@
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetFrameworkMinimum)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <!-- SYSLIB5001: Tensor<T> and related APIs are Experimental in .NET 9 -->
+    <NoWarn>$(NoWarn);SYSLIB5001</NoWarn>
   </PropertyGroup>
 
   <PropertyGroup>