Fix HybridWebView NativeAOT warning path by simonrozsival · Pull Request #34958 · dotnet/maui

simonrozsival · 2026-04-14T12:23:16Z

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Fixes #34867

Summary

Prevent NativeAOT/full-trim analysis from surfacing HybridWebViewHandler warnings when HybridWebView is feature-switched off.

Root cause

HybridWebView was already being disabled for PublishAot=true / TrimMode=full via MauiHybridWebViewSupported=false. The warning still leaked because the default controls handler registration path directly referenced HybridWebViewHandler, which carries RequiresDynamicCode / RequiresUnreferencedCode annotations.

What changed

keep the existing RuntimeFeature.IsHybridWebViewSupported gate
move the HybridWebView registration into a guarded local helper
attach the AOT/trimming annotations to that guarded path instead of the default registration flow

Why this approach

This fixes the actual reachability/analysis shape instead of suppressing the warning or expanding the expected-warning baseline.

Validation

dotnet build src/Controls/src/Core/Controls.Core.csproj -f net11.0
local NativeAOT integration flow no longer emitted the previous unexpected HybridWebViewHandler warning; remaining local failures were unrelated environment/feed restore issues

github-actions · 2026-04-14T12:23:27Z

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://github.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 34958

Or

Run remotely in PowerShell:

iex "& { $(irm https://github.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 34958"

Copilot

Pull request overview

This PR aims to prevent NativeAOT/full-trim analysis from reporting HybridWebViewHandler dynamic-code warnings when HybridWebView is feature-switched off by isolating the handler registration behind the feature gate. In addition, it introduces new AOT-safe EventTrigger factory APIs and updates the XAML source generator to emit those factories when EventTrigger.Event is set, along with new unit tests.

Changes:

Isolate HybridWebViewHandler registration into an annotated, feature-gated local path to avoid warning reachability under NativeAOT/full-trim.
Add EventTrigger.Create(...) factory methods and refactor EventTrigger internals to use pluggable subscription strategies (reflection vs static).
Extend SourceGen to generate AOT-safe EventTrigger.Create(...) instantiation and add coverage across Core/XAML/SourceGen unit tests.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
src/Controls/src/Core/Hosting/AppHostBuilderExtensions.cs	Moves HybridWebView handler registration behind a local helper annotated for trimming/AOT analysis.
src/Controls/src/Core/Interactivity/EventTrigger.cs	Adds AOT-safe `EventTrigger.Create` APIs and refactors subscription logic into strategies with trimming/AOT annotations.
src/Controls/src/SourceGen/Visitors/CreateValuesVisitor.cs	Special-cases `EventTrigger` so it’s declared before child `TriggerAction` processing and can be created via SourceGen provider.
src/Controls/src/SourceGen/NodeSGExtensions.cs	Registers `EventTriggerValueProvider` as a known value provider for SourceGen.
src/Controls/src/SourceGen/EventTriggerValueProvider.cs	Implements AOT-safe SourceGen emission for `EventTrigger` by using `EventTrigger.Create` when possible.
src/Controls/src/Core/PublicAPI/*/PublicAPI.Unshipped.txt	Adds new public API entries for the `EventTrigger.Create` overloads across TFMs.
src/Controls/tests/Xaml.UnitTests/Issues/Maui33591.xaml	Adds a XAML repro page using `EventTrigger` for multi-inflator validation.
src/Controls/tests/Xaml.UnitTests/Issues/Maui33591.xaml.cs	Adds XAML unit tests validating `EventTrigger.Event` population and element creation across inflators.
src/Controls/tests/SourceGen.UnitTests/Maui33591SourceGenTests.cs	Adds a snapshot-style test asserting SourceGen emits `EventTrigger.Create(...)` with static lambdas.
src/Controls/tests/Core.UnitTests/Triggers/EventTriggerBaseTests.cs	Adds Core unit tests validating `EventTrigger.Create(...)` behavior (attach/detach/invocation).

Keep the HybridWebView handler registration on its own guarded local path so NativeAOT/full-trim analysis does not pick up the dynamic-code handler from the default controls registration list.\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Use a local const string for the AOT/trimming annotation message instead of referencing HybridWebViewHandler.DynamicFeatures from Controls. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Add Section 23 to review-rules.md covering IL2026/IL3050 annotation chain analysis, the extract-method pattern for feature-guarded types, and why [UnconditionalSuppressMessage] is almost always wrong for these warnings. Sourced from the HybridWebViewHandler incident (Issue #34867, PR #34958) where AI agents consistently recommended suppression instead of the correct structural fix when they didn't read the source code first. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

PureWeen · 2026-04-14T18:52:16Z

/azp run maui-pr-uitests, maui-pr-devicetests

azure-pipelines · 2026-04-14T18:52:38Z

Azure Pipelines successfully started running 2 pipeline(s).

…ethod The local function pattern from PR #34958 compiles to a compiler- generated method (<AddControlsHandlers>g__AddHybridWebViewHandler|2_0) which newer ILC versions (SDK 26203.107+) trace back to the caller, defeating the [FeatureGuard] suppression. The IL3050 warning leaks because ILC doesn't treat local functions as independent annotation boundaries. Moving to a proper private static method on the class creates a real method boundary in IL metadata that the [FeatureGuard] on RuntimeFeature.IsHybridWebViewSupported can properly suppress. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

@simonrozsival

…ethod (#34986) ## Problem PR #34958's fix for the HybridWebView IL3050 warning used a **local function** inside `AddControlsHandlers`. This worked with SDK `26166.111` but **fails with the newer SDK** `26203.107` (from #34852): ``` Unexpected warning: AppHostBuilderExtensions.<AddControlsHandlers>g__AddHybridWebViewHandler|2_0 has 'RequiresDynamicCodeAttribute' can break functionality when AOT compiling. ``` The C# compiler emits local functions as `<EnclosingMethod>g__Name|N_M` — a compiler-generated method that newer ILC versions trace back to the caller, defeating the `[FeatureGuard]` suppression on `RuntimeFeature.IsHybridWebViewSupported`. ## Fix Move the local function to a **private static method** on the class. This creates a real method boundary in IL metadata that the `[FeatureGuard]` can properly suppress — the standard pattern documented in our [trim/AOT review rules](https://github.com/dotnet/maui/blob/main/.github/skills/code-review/references/review-rules.md#23-trim--nativeaot-safety). cc @simonrozsival — this builds on your #34958 fix, just moving from local function to class method for the newer ILC. ## Validation `dotnet build Controls.Core.csproj -f net11.0 -p:TreatWarningsAsErrors=true` — 0 errors --------- Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings April 14, 2026 12:23

Copilot started reviewing on behalf of simonrozsival April 14, 2026 12:24 View session

Copilot AI reviewed Apr 14, 2026

View reviewed changes

simonrozsival force-pushed the dev/simonrozsival/investigate-34867-hybridwebview-aot branch from 8744ffd to 42efef8 Compare April 14, 2026 12:45

Address Copilot review on HybridWebView fix

85b80da

Use a local const string for the AOT/trimming annotation message instead of referencing HybridWebViewHandler.DynamicFeatures from Controls. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

PureWeen mentioned this pull request Apr 14, 2026

Add Trim/NativeAOT safety rules to code review skill #34962

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PureWeen approved these changes Apr 14, 2026

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PureWeen merged commit c223f8b into net11.0 Apr 15, 2026
45 of 220 checks passed

PureWeen deleted the dev/simonrozsival/investigate-34867-hybridwebview-aot branch April 15, 2026 00:30

build-analysis Bot mentioned this pull request Apr 15, 2026

slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883

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3 tasks

This was referenced Apr 15, 2026

Move HybridWebView AOT helper from local function to private static method #34986

Merged

[ILC/Android NativeAOT] FeatureGuard does not suppress IL3050 after PR #124801 decoupled ILC from ManagedAssemblyToLink dotnet/runtime#127017

Closed

This was referenced Apr 30, 2026

[iOS] IL2026 trim errors from Managed Registrar referencing HybridWebViewHandler nested classes dotnet/macios#25285

Open

[iOS] Suppress IL2026 trim warnings on HybridWebViewHandler nested classes #35262

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Fix HybridWebView NativeAOT warning path#34958

Fix HybridWebView NativeAOT warning path#34958
PureWeen merged 2 commits intonet11.0from
dev/simonrozsival/investigate-34867-hybridwebview-aot

simonrozsival commented Apr 14, 2026 •

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Summary

Root cause

What changed

Why this approach

Validation

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Pull request overview

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simonrozsival commented Apr 14, 2026 •

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