Allow opting-in to NativeAOT publishing using runtime packs (#32100)

Author: akoeplinger

src/Tasks/Microsoft.NET.Build.Tasks/ProcessFrameworkReferences.cs

@@ -48,6 +48,8 @@ public class ProcessFrameworkReferences : TaskBase
 
         public bool AotEnabled { get; set; }
 
+        public bool AotUseKnownRuntimePackForTarget { get; set; }
+
         public string RuntimeIdentifier { get; set; }
 
         public string[] RuntimeIdentifiers { get; set; }
@@ -678,9 +680,10 @@ private bool AddToolPack(
                     case ToolPackType.ILCompiler:
                         HostILCompilerPacks = new[] { runtimePackItem };
 
-                        // ILCompiler supports cross target compilation. If there is a cross-target request, we need to download that package as well
+                        // ILCompiler supports cross target compilation. If there is a cross-target request,
+                        // we need to download that package as well unless we use KnownRuntimePack entries for the target.
                         // We expect RuntimeIdentifier to be defined during publish but can allow during build
-                        if (RuntimeIdentifier != null)
+                        if (RuntimeIdentifier != null && !AotUseKnownRuntimePackForTarget)
                         {
                             var targetRuntimeIdentifier = NuGetUtils.GetBestMatchingRid(runtimeGraph, RuntimeIdentifier, packSupportedRuntimeIdentifiers, out bool wasInGraph2);
                             if (targetRuntimeIdentifier == null)

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.DefaultItems.props

@@ -89,6 +89,11 @@ Copyright (c) .NET Foundation. All rights reserved.
                         RuntimePackLabels="Mono"
                         Condition="'$(UseMonoRuntime)' == 'true' And ('$(_TargetFrameworkVersionWithoutV)' != '') And ('$(_TargetFrameworkVersionWithoutV)' >= '6.0')" />
 
+    <!-- Allow opt-in to NativeAOT runtime pack for .NET 8.0 or higher -->
+    <FrameworkReference Update="Microsoft.NETCore.App"
+                        RuntimePackLabels="NativeAOT"
+                        Condition="'$(PublishAotUsingRuntimePack)' == 'true' And ('$(_TargetFrameworkVersionWithoutV)' != '') And ('$(_TargetFrameworkVersionWithoutV)' >= '8.0')" />
+
   </ItemGroup>
 
 </Project>

src/Tasks/Microsoft.NET.Build.Tasks/targets/Microsoft.NET.Sdk.FrameworkReferenceResolution.targets

@@ -101,6 +101,7 @@ Copyright (c) .NET Foundation. All rights reserved.
                                 ReadyToRunUseCrossgen2="$(PublishReadyToRunUseCrossgen2)"
                                 TrimmingEnabled="$(_IsTrimmingEnabled)"
                                 AotEnabled="$(PublishAot)"
+                                AotUseKnownRuntimePackForTarget="$(PublishAotUsingRuntimePack)"
                                 RuntimeIdentifier="$(RuntimeIdentifier)"
                                 RuntimeIdentifiers="$(RuntimeIdentifiers)"
                                 RuntimeFrameworkVersion="$(RuntimeFrameworkVersion)"