From 362c12db7bb85db6574d397437704854776005c9 Mon Sep 17 00:00:00 2001
From: Jeremy Koritzinsky <jekoritz@microsoft.com>
Date: Thu, 2 Jan 2025 13:49:51 -0800
Subject: [PATCH] Don't require there to be a supported runtime pack runtime
 identifier for crossgen2 (#45487)

---
 .../ProcessFrameworkReferences.cs             |  2 +
 .../ResolveReadyToRunCompilers.cs             | 52 +++++++++++++------
 2 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/ProcessFrameworkReferences.cs b/src/Tasks/Microsoft.NET.Build.Tasks/ProcessFrameworkReferences.cs
index 245aa9bdf5aa..b9704a7e11c8 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/ProcessFrameworkReferences.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/ProcessFrameworkReferences.cs
@@ -814,6 +814,8 @@ private ToolPackSupport AddToolPack(
                     runtimePackToDownload.SetMetadata(MetadataKeys.Version, packVersion);
                 }
 
+                runtimePackItem.SetMetadata(MetadataKeys.RuntimeIdentifier, hostRuntimeIdentifier);
+
                 switch (toolPackType)
                 {
                     case ToolPackType.Crossgen2:
diff --git a/src/Tasks/Microsoft.NET.Build.Tasks/ResolveReadyToRunCompilers.cs b/src/Tasks/Microsoft.NET.Build.Tasks/ResolveReadyToRunCompilers.cs
index af35bd3bcd0b..4f2c34b8e54d 100644
--- a/src/Tasks/Microsoft.NET.Build.Tasks/ResolveReadyToRunCompilers.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/ResolveReadyToRunCompilers.cs
@@ -52,21 +52,7 @@ protected override void ExecuteCore()
             _runtimePack = GetNETCoreAppRuntimePack();
             _targetRuntimeIdentifier = _runtimePack?.GetMetadata(MetadataKeys.RuntimeIdentifier);
 
-            // Get the list of runtime identifiers that we support and can target
-            ITaskItem targetingPack = GetNETCoreAppTargetingPack();
-            string supportedRuntimeIdentifiers = targetingPack?.GetMetadata(MetadataKeys.RuntimePackRuntimeIdentifiers);
-
-            var runtimeGraph = new RuntimeGraphCache(this).GetRuntimeGraph(RuntimeGraphPath);
-            var supportedRIDsList = supportedRuntimeIdentifiers == null ? Array.Empty<string>() : supportedRuntimeIdentifiers.Split(';');
-
-            // Get the best RID for the host machine, which will be used to validate that we can run crossgen for the target platform and architecture
-            _hostRuntimeIdentifier = NuGetUtils.GetBestMatchingRid(
-                runtimeGraph,
-                NETCoreSdkRuntimeIdentifier,
-                supportedRIDsList,
-                out _);
-
-            if (_hostRuntimeIdentifier == null || _targetRuntimeIdentifier == null)
+            if (_targetRuntimeIdentifier == null)
             {
                 Log.LogError(Strings.ReadyToRunNoValidRuntimePackageError);
                 return;
@@ -96,6 +82,13 @@ protected override void ExecuteCore()
 
         private bool ValidateCrossgenSupport()
         {
+            _hostRuntimeIdentifier = GetHostRuntimeIdentifierForCrossgen();
+            if (_hostRuntimeIdentifier == null)
+            {
+                Log.LogError(Strings.ReadyToRunNoValidRuntimePackageError);
+                return false;
+            }
+
             _crossgenTool.PackagePath = _runtimePack?.GetMetadata(MetadataKeys.PackageDirectory);
             if (_crossgenTool.PackagePath == null)
             {
@@ -121,12 +114,39 @@ private bool ValidateCrossgenSupport()
             }
 
             return true;
+
+            string GetHostRuntimeIdentifierForCrossgen()
+            {
+                // Crossgen's host RID comes from the runtime pack that Crossgen will be loaded from.
+
+                // Get the list of runtime identifiers that we support and can target
+                ITaskItem targetingPack = GetNETCoreAppTargetingPack();
+                string supportedRuntimeIdentifiers = targetingPack?.GetMetadata(MetadataKeys.RuntimePackRuntimeIdentifiers);
+
+                var runtimeGraph = new RuntimeGraphCache(this).GetRuntimeGraph(RuntimeGraphPath);
+                var supportedRIDsList = supportedRuntimeIdentifiers == null ? Array.Empty<string>() : supportedRuntimeIdentifiers.Split(';');
+
+                // Get the best RID for the host machine, which will be used to validate that we can run crossgen for the target platform and architecture
+                return NuGetUtils.GetBestMatchingRid(
+                    runtimeGraph,
+                    NETCoreSdkRuntimeIdentifier,
+                    supportedRIDsList,
+                    out _);
+            }
         }
 
         private bool ValidateCrossgen2Support()
         {
             ITaskItem crossgen2Pack = Crossgen2Packs?.FirstOrDefault();
-            _crossgen2Tool.PackagePath = crossgen2Pack?.GetMetadata(MetadataKeys.PackageDirectory);
+
+            _hostRuntimeIdentifier = crossgen2Pack?.GetMetadata(MetadataKeys.RuntimeIdentifier);
+            if (_hostRuntimeIdentifier == null)
+            {
+                Log.LogError(Strings.ReadyToRunNoValidRuntimePackageError);
+                return false;
+            }
+
+            _crossgen2Tool.PackagePath = crossgen2Pack.GetMetadata(MetadataKeys.PackageDirectory);
 
             if (string.IsNullOrEmpty(_crossgen2Tool.PackagePath) ||
                 !NuGetVersion.TryParse(crossgen2Pack.GetMetadata(MetadataKeys.NuGetPackageVersion), out NuGetVersion crossgen2PackVersion))