From 2e79fa317763289c447ee07f54373b711196c2aa Mon Sep 17 00:00:00 2001
From: Sven Boemer <sbomer@gmail.com>
Date: Tue, 21 Apr 2026 16:11:33 -0700
Subject: [PATCH 1/2] Make PrepareTrimConfiguration a public extension point
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Rename _PrepareTrimConfiguration to PrepareTrimConfiguration so that
external SDKs (e.g. MAUI) can hook BeforeTargets="PrepareTrimConfiguration"
to add RuntimeHostConfigurationOption items before they are snapshotted
into _TrimmerFeatureSettings.

PR #124801 extracted the RHCO → _TrimmerFeatureSettings conversion from
PrepareForILLink into _PrepareTrimConfiguration, which runs as a
dependency of PrepareForILLink. This caused MAUI's feature switches
(added via BeforeTargets="PrepareForILLink") to arrive after the
snapshot, so ILC never received --feature flags for switches like
IsHybridWebViewSupported. The result was spurious IL3050 warnings on
Android NativeAOT where RunILLink=true.

Making the target public gives SDKs a stable, intentional hook point
for adding feature switch configuration that flows to both ILLink and
ILC.

Fixes #127017

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Assisted-by: Claude:claude-opus-4.6-1m
---
 .../Microsoft.NETCore.Native.Publish.targets           |  6 +++---
 .../ILLink.Tasks/build/Microsoft.NET.ILLink.targets    | 10 +++++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets
index bf473414890f6c..487271bdf16608 100644
--- a/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets
+++ b/src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Publish.targets
@@ -3,7 +3,7 @@
   <Target Name="_ComputeIlcCompileInputs"
           Condition="'$(BuildingFrameworkLibrary)' != 'true'"
           BeforeTargets="ComputeIlcCompileInputs"
-          DependsOnTargets="$(IlcDynamicBuildPropertyDependencies);_ComputeAssembliesToCompileToNative;_PrepareTrimConfiguration">
+          DependsOnTargets="$(IlcDynamicBuildPropertyDependencies);_ComputeAssembliesToCompileToNative;PrepareTrimConfiguration">
 
     <ItemGroup>
       <_IlcManagedInputAssemblies Include="@(ResolvedFileToPublish)" Condition="'%(ResolvedFileToPublish.PostprocessAssembly)' == 'true'" />
@@ -24,7 +24,7 @@
     The SDK typically sequences this target in the publish pipeline as:
       ComputeResolvedFilesToPublishList -> ILLink (when RunILLink is true) -> NativeCompile -> ...
 
-    This gives us a clean, explicit position after trim configuration (_PrepareTrimConfiguration),
+    This gives us a clean, explicit position after trim configuration (PrepareTrimConfiguration),
     regardless of whether ILLink itself runs.
     ============================================================
   -->
@@ -84,7 +84,7 @@
   <UsingTask TaskName="ComputeManagedAssembliesToCompileToNative" AssemblyFile="$(IlcBuildTasksPath)" />
   <Target Name="_ComputeAssembliesToCompileToNative"
           DependsOnTargets="$(IlcDynamicBuildPropertyDependencies);_ComputeAssembliesToPostprocessOnPublish"
-          BeforeTargets="_PrepareTrimConfiguration">
+          BeforeTargets="PrepareTrimConfiguration">
 
     <Warning Condition="Exists($(UserRuntimeConfig))" Text="The published project has a runtimeconfig.template.json that is not supported by PublishAot. Move the configuration to the project file using RuntimeHostConfigurationOption." />
     <!-- Fail with descriptive error message for common mistake. -->
diff --git a/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets b/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets
index 92976f23cd65ba..8d89a954a0e330 100644
--- a/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets
+++ b/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets
@@ -195,7 +195,7 @@ Copyright (c) .NET Foundation. All rights reserved.
 
   <!--
     ============================================================
-                     _PrepareTrimConfiguration
+                     PrepareTrimConfiguration
 
     Set up shared trim configuration properties and metadata on ResolvedFileToPublish.
     This target is shared between ILLink and ILC (NativeAOT). It sets default values for
@@ -203,11 +203,15 @@ Copyright (c) .NET Foundation. All rights reserved.
     and _TrimmerFeatureSettings, and applies TrimmerSingleWarn metadata to
     ResolvedFileToPublish items for the intermediate assembly and project references.
 
+    This is a public extension point. Other targets may hook into it via
+    BeforeTargets="PrepareTrimConfiguration" to add RuntimeHostConfigurationOption items
+    that will be included in _TrimmerFeatureSettings for both ILLink and ILC.
+
     Consumers that need trim metadata on ResolvedFileToPublish should depend on this target.
     Metadata set here flows to ManagedAssemblyToLink via _ComputeManagedAssemblyToLink (which
     depends on this target), since ComputeManagedAssemblies preserves metadata from its inputs.
    -->
-   <Target Name="_PrepareTrimConfiguration"
+   <Target Name="PrepareTrimConfiguration"
            DependsOnTargets="_ComputeAssembliesToPostprocessOnPublish">
 
     <!-- Set up TrimMode. -->
@@ -335,7 +339,7 @@ Copyright (c) .NET Foundation. All rights reserved.
     ============================================================
     -->
   <UsingTask TaskName="ComputeManagedAssemblies" AssemblyFile="$(ILLinkTasksAssembly)" Condition="'$(ILLinkTasksAssembly)' != ''" TaskFactory="TaskHostFactory" />
-  <Target Name="_ComputeManagedAssemblyToLink" DependsOnTargets="_PrepareTrimConfiguration">
+  <Target Name="_ComputeManagedAssemblyToLink" DependsOnTargets="PrepareTrimConfiguration">
 
     <!-- NB: There should not be non-managed assemblies in this list, but we still give the ILLink a chance to
          further refine this list. It currently drops C++/CLI assemblies in ComputeManageAssemblies. -->

From e190b4816230e6faf170eba71d9d2eccae1471a6 Mon Sep 17 00:00:00 2001
From: Sven Boemer <sbomer@gmail.com>
Date: Wed, 22 Apr 2026 07:35:15 +0800
Subject: [PATCH 2/2] Clarify comment

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
---
 .../src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets      | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets b/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets
index 8d89a954a0e330..1c3af30514ab6f 100644
--- a/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets
+++ b/src/tools/illink/src/ILLink.Tasks/build/Microsoft.NET.ILLink.targets
@@ -204,8 +204,9 @@ Copyright (c) .NET Foundation. All rights reserved.
     ResolvedFileToPublish items for the intermediate assembly and project references.
 
     This is a public extension point. Other targets may hook into it via
-    BeforeTargets="PrepareTrimConfiguration" to add RuntimeHostConfigurationOption items
-    that will be included in _TrimmerFeatureSettings for both ILLink and ILC.
+    BeforeTargets="PrepareTrimConfiguration" to add RuntimeHostConfigurationOption items.
+    Only items with Trim="true" metadata will be included in _TrimmerFeatureSettings
+    for both ILLink and ILC.
 
     Consumers that need trim metadata on ResolvedFileToPublish should depend on this target.
     Metadata set here flows to ManagedAssemblyToLink via _ComputeManagedAssemblyToLink (which