From e3791f12005bf628ea2f893794df98fdb9ef8022 Mon Sep 17 00:00:00 2001
From: Simon Rozsival <simon@rozsival.com>
Date: Sat, 27 Jun 2026 22:41:33 +0200
Subject: [PATCH 1/2] [TrimmableTypeMap] Fix DesignTimeBuildSignAndroidPackage
 on NativeAOT

The NativeAOT trimmable typemap is consumed only in the inner per-RID ILC build
(via _AddTrimmableTypeMapAssembliesToIlc -> _ReadGeneratedTrimmableTypeMapAssemblies),
which cannot generate it: _GenerateTrimmableTypeMap is gated to the outer build
(_OuterIntermediateOutputPath == ''). Its only trigger is AfterTargets="CoreCompile",
which does not fire when compilation is up-to-date - e.g. the IDE's separate
"Compile" then "SignAndroidPackage" invocations (BuildingInsideVisualStudio=true).
The outer build therefore never generated obj/.../typemap/typemap-assemblies.txt and
the inner build failed with "Trimmable typemap assembly list ... was not found".

Force _GenerateTrimmableTypeMap to run in the outer build before _ResolveAssemblies
spawns the inner per-RID build. _ResolveAssemblies runs after compilation (it consumes
@(IntermediateAssembly)), so the generator still observes the compiled app assembly.
Mirrors the CoreCLR _AddTrimmableTypeMapToLinker target, which forces generation before
the (outer) ILLink.

Verified locally: DesignTimeBuildSignAndroidPackage(NativeAOT) now passes (was failing);
DesignTimeBuildSignAndroidPackage(CoreCLR) continues to pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 ...oid.Sdk.TypeMap.Trimmable.NativeAOT.targets | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets b/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets
index 6ef82b37f11..e5c15a68853 100644
--- a/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets
+++ b/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets
@@ -41,6 +41,24 @@
     </ItemGroup>
   </Target>
 
+  <!--
+    Force the typemap to be generated in the OUTER build (RuntimeIdentifier == '') before
+    _ResolveAssemblies spawns the inner per-RID ILC build. The inner build consumes the typemap
+    assembly list (via _AddTrimmableTypeMapAssembliesToIlc -> _ReadGeneratedTrimmableTypeMapAssemblies)
+    but cannot generate it: _GenerateTrimmableTypeMap is gated to the outer build (it requires
+    '$(_OuterIntermediateOutputPath)' == ''). _GenerateTrimmableTypeMap's own AfterTargets="CoreCompile"
+    trigger does not fire when compilation is up-to-date - e.g. the IDE's separate "Compile" then
+    "SignAndroidPackage" invocations (BuildingInsideVisualStudio=true) - leaving the file ungenerated
+    and the inner build failing with "Trimmable typemap assembly list ... was not found".
+    This mirrors the CoreCLR _AddTrimmableTypeMapToLinker target, which forces generation before the
+    (outer) ILLink. _ResolveAssemblies runs after compilation (it consumes @(IntermediateAssembly)), so
+    the generator still observes the compiled app assembly.
+  -->
+  <Target Name="_EnsureTrimmableTypeMapGeneratedForNativeAotInnerBuild"
+      Condition=" '$(RuntimeIdentifier)' == '' "
+      BeforeTargets="_ResolveAssemblies"
+      DependsOnTargets="_GenerateTrimmableTypeMap" />
+
   <Target Name="_CollectTrimmableNativeAotDgmlFiles"
       Condition=" '$(PublishTrimmed)' == 'true' and '$(_ProguardProjectConfiguration)' != '' ">
     <ItemGroup>

From e68ee2c1c74c6a25189b1001a02cb822baaa4e09 Mon Sep 17 00:00:00 2001
From: Simon Rozsival <simon@rozsival.com>
Date: Sun, 28 Jun 2026 16:56:33 +0200
Subject: [PATCH 2/2] Address review: gate on _OuterIntermediateOutputPath, not
 RuntimeIdentifier
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The "outer build" is the build that is not an inner per-RID build, which is
determined by '$(_OuterIntermediateOutputPath)' == '' — the same discriminator
_GenerateTrimmableTypeMap itself uses. The previous 'RuntimeIdentifier == ''
condition missed the single-RID outer build (e.g. -p:RuntimeIdentifier=android-arm64),
where RuntimeIdentifier is non-empty but the build is still the outer one, leaving
the typemap ungenerated and reproducing the same failure this change fixes.

The inner build receives _OuterIntermediateOutputPath via _ResolveAssemblies
AdditionalProperties, so the target is still correctly skipped there.

Verified locally: DesignTimeBuildSignAndroidPackage(NativeAOT) and (CoreCLR) both pass.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 ...ndroid.Sdk.TypeMap.Trimmable.NativeAOT.targets | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets b/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets
index e5c15a68853..fb655661a24 100644
--- a/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets
+++ b/src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.TypeMap.Trimmable.NativeAOT.targets
@@ -42,9 +42,10 @@
   </Target>
 
   <!--
-    Force the typemap to be generated in the OUTER build (RuntimeIdentifier == '') before
-    _ResolveAssemblies spawns the inner per-RID ILC build. The inner build consumes the typemap
-    assembly list (via _AddTrimmableTypeMapAssembliesToIlc -> _ReadGeneratedTrimmableTypeMapAssemblies)
+    Force the typemap to be generated in the OUTER build (the build that is not an inner
+    per-RID build, i.e. '$(_OuterIntermediateOutputPath)' == '') before _ResolveAssemblies
+    spawns the inner per-RID ILC build. The inner build consumes the typemap assembly list
+    (via _AddTrimmableTypeMapAssembliesToIlc -> _ReadGeneratedTrimmableTypeMapAssemblies)
     but cannot generate it: _GenerateTrimmableTypeMap is gated to the outer build (it requires
     '$(_OuterIntermediateOutputPath)' == ''). _GenerateTrimmableTypeMap's own AfterTargets="CoreCompile"
     trigger does not fire when compilation is up-to-date - e.g. the IDE's separate "Compile" then
@@ -53,9 +54,15 @@
     This mirrors the CoreCLR _AddTrimmableTypeMapToLinker target, which forces generation before the
     (outer) ILLink. _ResolveAssemblies runs after compilation (it consumes @(IntermediateAssembly)), so
     the generator still observes the compiled app assembly.
+
+    The condition matches on '$(_OuterIntermediateOutputPath)' == '' (the same discriminator
+    _GenerateTrimmableTypeMap uses) rather than 'RuntimeIdentifier == ''' so that single-RID outer
+    builds (e.g. -p:RuntimeIdentifier=android-arm64) are covered too; the inner build sets
+    _OuterIntermediateOutputPath via _ResolveAssemblies AdditionalProperties, so this target is
+    correctly skipped there.
   -->
   <Target Name="_EnsureTrimmableTypeMapGeneratedForNativeAotInnerBuild"
-      Condition=" '$(RuntimeIdentifier)' == '' "
+      Condition=" '$(_OuterIntermediateOutputPath)' == '' "
       BeforeTargets="_ResolveAssemblies"
       DependsOnTargets="_GenerateTrimmableTypeMap" />