Prevent SFX restores from overwriting assets for another RID

eng/targets/Sfx.Common.targets

@@ -27,6 +27,28 @@
     <GetSharedFrameworkFilesForReadyToRunDependsOn>$(GetSharedFrameworkFilesForReadyToRunDependsOn);_AddOptimizationDataForReadyToRun</GetSharedFrameworkFilesForReadyToRunDependsOn>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <_RestoreRuntimeTargetCommand Condition="$([MSBuild]::IsOSPlatform('Windows'))">.\restore.cmd -Architecture $(TargetArchitecture) -p:RestoreForce=true</_RestoreRuntimeTargetCommand>
+    <_RestoreRuntimeTargetCommand Condition="!$([MSBuild]::IsOSPlatform('Windows'))">./restore.sh --os-name $(TargetOsName) --arch $(TargetArchitecture) -p:RestoreForce=true</_RestoreRuntimeTargetCommand>
+  </PropertyGroup>
+
+  <Target Name="_ValidateProjectAssetsRuntimeTarget"
+          BeforeTargets="ResolvePackageAssets"
+          Condition="'$(TargetFramework)' != '' AND
+                     '$(RuntimeIdentifier)' != '' AND
+                     Exists('$(ProjectAssetsFile)')">
+    <CheckProjectAssetsRuntimeTarget
+        ProjectAssetsFile="$(ProjectAssetsFile)"
+        TargetFramework="$(TargetFramework)"
+        RuntimeIdentifier="$(RuntimeIdentifier)">
+      <Output TaskParameter="RuntimeTargetExists" PropertyName="_ProjectAssetsRuntimeTargetExists" />
+    </CheckProjectAssetsRuntimeTarget>
+
+    <Error
+        Condition="'$(_ProjectAssetsRuntimeTargetExists)' != 'true'"
+        Text="The restore assets for $(MSBuildProjectName) do not contain the requested target '$(TargetFramework)/$(RuntimeIdentifier)'. From the repository root, run '$(_RestoreRuntimeTargetCommand)'." />
+  </Target>
+
   <!-- IBC data packages don't follow NuGet conventions.  -->
   <Target Name="_AddOptimizationDataForReadyToRun">
     <ItemGroup>

eng/tools/RepoTasks/CheckProjectAssetsRuntimeTarget.cs

@@ -0,0 +1,62 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.IO;
+using System.Text.Json;
+using Microsoft.Build.Framework;
+
+namespace RepoTasks;
+
+/// <summary>
+/// Checks whether a NuGet assets file contains a target for a target framework
+/// and runtime identifier.
+/// </summary>
+public sealed class CheckProjectAssetsRuntimeTarget : Microsoft.Build.Utilities.Task
+{
+    /// <summary>
+    /// Gets or sets the NuGet project assets file to inspect.
+    /// </summary>
+    [Required]
+    public string ProjectAssetsFile { get; set; }
+
+    /// <summary>
+    /// Gets or sets the target framework to find.
+    /// </summary>
+    [Required]
+    public string TargetFramework { get; set; }
+
+    /// <summary>
+    /// Gets or sets the runtime identifier to find.
+    /// </summary>
+    [Required]
+    public string RuntimeIdentifier { get; set; }
+
+    /// <summary>
+    /// Gets whether the requested runtime target exists.
+    /// </summary>
+    [Output]
+    public bool RuntimeTargetExists { get; private set; }
+
+    /// <inheritdoc />
+    public override bool Execute()
+    {
+        try
+        {
+            using var stream = File.OpenRead(ProjectAssetsFile);
+            using var document = JsonDocument.Parse(stream);
+            var targetName = $"{TargetFramework}/{RuntimeIdentifier}";
+
+            RuntimeTargetExists =
+                document.RootElement.TryGetProperty("targets", out var targets) &&
+                targets.TryGetProperty(targetName, out _);
+
+            return true;
+        }
+        catch (Exception exception) when (exception is IOException or UnauthorizedAccessException or JsonException or InvalidOperationException)
+        {
+            Log.LogError($"Unable to inspect NuGet assets file '{ProjectAssetsFile}': {exception.Message}");
+            return false;
+        }
+    }
+}

eng/tools/RepoTasks/RepoTasks.tasks

@@ -7,4 +7,5 @@
   <UsingTask TaskName="RepoTasks.GenerateGuid" AssemblyFile="$(_RepoTaskAssembly)" TaskFactory="TaskHostFactory" Runtime="NET" />
   <UsingTask TaskName="RepoTasks.GenerateTestDevCert" AssemblyFile="$(_RepoTaskAssembly)" TaskFactory="TaskHostFactory" Runtime="NET" />
   <UsingTask TaskName="RepoTasks.BatchHelixWorkItems" AssemblyFile="$(_RepoTaskAssembly)" TaskFactory="TaskHostFactory" Runtime="NET" />
+  <UsingTask TaskName="RepoTasks.CheckProjectAssetsRuntimeTarget" AssemblyFile="$(_RepoTaskAssembly)" TaskFactory="TaskHostFactory" Runtime="NET" />
 </Project>