Move marshal method pipeline from outer build to inner (per-RID) build

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.LlvmIr.targets

@@ -78,13 +78,6 @@
         EnableNativeRuntimeLinking="$(_AndroidEnableNativeRuntimeLinking)">
     </GenerateJavaStubs>
 
-    <RewriteMarshalMethods
-        Condition=" '$(_AndroidUseMarshalMethods)' == 'true' And '$(AndroidIncludeDebugSymbols)' == 'false' "
-        EnableManagedMarshalMethodsLookup="$(_AndroidUseManagedMarshalMethodsLookup)"
-        Environments="@(_EnvironmentFiles)"
-        IntermediateOutputDirectory="$(IntermediateOutputPath)">
-    </RewriteMarshalMethods>
-
     <GenerateTypeMappings
         AndroidRuntime="$(_AndroidRuntime)"
         Debug="$(AndroidIncludeDebugSymbols)"
@@ -250,6 +243,44 @@
         Deterministic="$(Deterministic)" />
   </Target>
 
+  <!--
+    Inner-build marshal method handling.  Always runs (for every RID) to generate
+    the marshal_methods.<abi>.ll LLVM IR file.
+
+    When marshal methods are enabled (Release + PublishTrimmed), the task also
+    classifies marshal methods, rewrites assemblies (adds [UnmanagedCallersOnly]
+    wrappers, removes connectors), and generates a full .ll with marshal method
+    native functions.
+
+    When marshal methods are disabled (Debug, or Release without marshal methods),
+    the task generates an empty/minimal .ll containing only the structural
+    scaffolding the native runtime always links against.
+
+    Runs AfterTargets="_PostTrimmingPipeline" which is itself AfterTargets="ILLink".
+    MSBuild fires AfterTargets hooks even when the referenced target is
+    condition-skipped, so this target runs in both trimmed and untrimmed builds.
+    When trimming IS active, _PostTrimmingPipeline completes first, ensuring
+    assemblies are trimmed before any rewrite.  Runs before ReadyToRun/crossgen2
+    so that R2R images are generated from the rewritten assemblies.
+
+    The .ll file is written to $(_OuterIntermediateOutputPath)android/ so the
+    outer build's _CompileNativeAssemblySources can compile it.
+  -->
+  <Target Name="_RewriteMarshalMethodsInner"
+      AfterTargets="_PostTrimmingPipeline">
+    <ItemGroup>
+      <_MarshalMethodsAssembly Include="@(ResolvedFileToPublish)" Condition=" '%(Extension)' == '.dll' " />
+    </ItemGroup>
+    <RewriteMarshalMethods
+        Assemblies="@(_MarshalMethodsAssembly)"
+        EnableManagedMarshalMethodsLookup="$(_AndroidUseManagedMarshalMethodsLookup)"
+        EnableMarshalMethods="$(_AndroidUseMarshalMethods)"
+        Environments="@(_EnvironmentFiles)"
+        MarshalMethodsOutputDirectory="$(_OuterIntermediateOutputPath)android"
+        AndroidRuntime="$(_AndroidRuntime)"
+        RuntimeIdentifier="$(RuntimeIdentifier)" />
+  </Target>
+
   <!-- Inject _TypeMapKind into the property cache -->
   <Target Name="_SetTypemapProperties"
       BeforeTargets="_CreatePropertiesCache">

src/Xamarin.Android.Build.Tasks/Tasks/GenerateJavaStubs.cs

@@ -244,12 +244,10 @@ internal static Dictionary<string, ITaskItem> MaybeGetArchAssemblies (Dictionary
 				return (false, null);
 			}
 
-			MarshalMethodsCollection? marshalMethodsCollection = null;
-
-			if (useMarshalMethods)
-				marshalMethodsCollection = MarshalMethodsCollection.FromAssemblies (arch, assemblies.Values.ToList (), resolver, Log);
-
-			return (true, new NativeCodeGenState (arch, tdCache, resolver, allJavaTypes, javaTypesForJCW, marshalMethodsCollection));
+			// Marshal method classification is now done in the inner build by
+			// RewriteMarshalMethods, so we never classify here.  The NativeCodeGenState
+			// will have a null Classifier; downstream tasks must handle that.
+			return (true, new NativeCodeGenState (arch, tdCache, resolver, allJavaTypes, javaTypesForJCW, classifier: null));
 		}
 
 		(List<TypeDefinition> allJavaTypes, List<TypeDefinition> javaTypesForJCW) ScanForJavaTypes (XAAssemblyResolver res, TypeDefinitionCache cache, Dictionary<string, ITaskItem> assemblies, Dictionary<string, ITaskItem> userAssemblies, bool useMarshalMethods)