[leak-fix] Fix GeometryGroup.Children memory leak (Fixes #36365)

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Note

This pull request was generated automatically by the Memory Leak Fixer agentic workflow. It contains regression tests, including one proven to fail on unpatched main, and the managed product fix that makes them pass.

Fixes #36365
Refs: #36365
Target branch: main
Attempt: 1/3

The leak

GeometryGroup subscribed to its Children (GeometryCollection) via plain CollectionChanged += OnChildrenCollectionChanged and to each child Geometry via PropertyChanged += OnChildrenPropertyChanged. When the GeometryCollection is shared/long-lived, those strong delegate references from the collection (and children) back to the GeometryGroup keep the group — and everything it roots — alive after it should have been collected.

Retention path: shared GeometryCollection → CollectionChanged delegate → GeometryGroup (never released while the collection lives).

The fix

Replace the strong subscriptions in src/Controls/src/Core/Shapes/GeometryGroup.cs with the weak-subscription helpers already used across the codebase (WeakNotifyCollectionChangedProxy / WeakNotifyPropertyChangedProxy from Internals/WeakEventProxy.cs), managed by a private ChildrenSubscriptions holder with a finalizer that unsubscribes. Collection add/remove/reset events keep child PropertyChanged subscriptions in sync. Rendering and flattening treat a null Children collection and null entries within it as empty, and Android, iOS/macOS, Tizen, and Windows geometry conversion paths apply the same behavior. Finalizer cleanup unsubscribes child proxies in place to avoid allocating while releasing the group. No public API change (private nested class + fields).

Regression tests

Added src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:

• GeometryGroupDoesNotLeakWhenSharingChildren — verifies a shared collection does not retain the group.
• GeometryGroupDoesNotLeakWhenSharingChild — verifies a shared child does not retain the group.
• ChildGeometryChangesStillInvalidateAfterGc — preserves live child invalidation after GC.
• AssigningChildrenWithNullEntrySubscribesValidChildren — covers direct assignment with a null entry while preserving valid-child invalidation.
• AppendPathSkipsNullChildren — verifies rendering skips null entries while still appending valid geometry.
• AppendPathAllowsNullChildrenCollection — verifies rendering treats a null Children collection as empty.
• FlattenGeometrySkipsNullChildren / FlattenGeometryAllowsNullChildrenCollection — verify flattening follows the same null-as-empty contract.
• SharedChildrenInvalidateEachLiveGroupAfterGc — preserves invalidation for multiple groups sharing one collection.
• RemovingAndReplacingChildrenMovesSubscriptions — moves subscriptions for item removal and replacement.
• ReplacingChildrenCollectionMovesSubscriptions — detaches the old collection and children and attaches the replacement collection and children.
• ReplacingChildrenThroughNullMovesSubscriptions — verifies old → null → new transitions detach stale sources and resume invalidation on the replacement.
• MovingChildrenPreservesSubscriptions — reordering children preserves exactly one invalidation subscription per child.
• DuplicateChildrenPreserveOccurrenceSubscriptions — tracks duplicate occurrences independently.
• ResetChildrenResubscribesLaterAdditions — detaches cleared children and subscribes later additions.

State	Result
Without fix (origin/main)	Leak and subscription-lifecycle tests fail
With fix	All 15 GeometryGroupMemoryTests pass

Scope

Changes are limited to GeometryGroup subscription cleanup, null-safe geometry conversion and flattening paths on Android, iOS/macOS, Tizen, and Windows, plus focused unit tests. No public API changes.

Generated by Memory Leak Fixer · 392.8 AIC · ⌖ 30.3 AIC · ⊞ 19.6K · ◷

[kubaflo]

🔍 AI-generated review follow-up (GitHub Copilot CLI, on behalf of @kubaflo)

@MauiBot The current-head review contains zero errors, warnings, suggestions, or inline findings. There is no actionable code feedback and no no-op commit is needed. Ready for another review.

[kubaflo]

🔍 AI-generated review follow-up (GitHub Copilot CLI, on behalf of @kubaflo)

@MauiBot The current-head review reports zero errors, warnings, suggestions, inline findings, or code correctness issues. Its low-confidence verdict is only unavailable authenticated required-CI metadata, so no no-op code change is warranted. Ready for another review.

[kubaflo]

🔍 AI-generated review follow-up (GitHub Copilot CLI, on behalf of @kubaflo)

@MauiBot Reviewed the current-head result for cbe51d0f747. It reports zero errors, warnings, suggestions, or inline findings, and the expert lifecycle review selects the submitted GeometryGroup weak-proxy ownership model as the narrowest and most robust option over both broader alternatives.

No code change is needed. Ready for re-review.

[kubaflo]

🔍 AI-generated review follow-up (GitHub Copilot CLI, on behalf of @kubaflo)

@MauiBot Reviewed the latest current-head result for cbe51d0f747. It reports no correctness findings and selects the submitted GeometryGroup weak-proxy implementation as the only passing approach that preserves dynamic add/remove/reset behavior while avoiding stale local tokens and invalid public finalizers.

No code change is needed. Ready for re-review.

[MauiBot]

AI Review Summary

@github-actions[bot] — new AI review results are available based on this last commit: 4d59222. To request a fresh review after new comments or commits, comment /review rerun.

---

🗂️ Review Sessions — click to expand

🚦 Gate — Test Before & After Fix

Gate Result: ✅ PASSED

Platform: ANDROID · Base: main · Merge base: 0395a53b

Test	Without Fix (expect FAIL)	With Fix (expect PASS)
🧪 GeometryGroupMemoryTests GeometryGroupMemoryTests	✅ FAIL — 114s	✅ PASS — 84s

🔴 Without fix — 🧪 GeometryGroupMemoryTests: FAIL ✅ · 114s

(truncated to last 15,000 chars)

cts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.100-ci+azdo.14650840
  Controls.Xaml -> /home/vsts/work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0/Microsoft.Maui.Controls.Xaml.dll
  ##vso[build.updatebuildnumber]10.0.100-ci+azdo.14650840
  Controls.Maps -> /home/vsts/work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0/Microsoft.Maui.Controls.Maps.dll
  TestUtils -> /home/vsts/work/1/s/artifacts/bin/TestUtils/Debug/netstandard2.0/Microsoft.Maui.TestUtils.dll
  Controls.Core.UnitTests -> /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll
Test run for /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.16]   Discovering: Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.39]   Discovered:  Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.41]   Starting:    Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.50]     AssigningChildrenWithNullEntrySubscribesValidChildren [FAIL]
[xUnit.net 00:00:01.50]       System.NullReferenceException : Object reference not set to an instance of an object.
[xUnit.net 00:00:01.50]       Stack Trace:
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(75,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.UpdateChildren(GeometryCollection oldCollection, GeometryCollection newCollection)
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(21,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.OnChildrenChanged(BindableObject bindable, Object oldValue, Object newValue)
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/BindableObject.cs(701,0): at Microsoft.Maui.Controls.BindableObject.OnBindablePropertySet(BindableProperty property, Object original, Object value, Boolean didChange, Boolean willFirePropertyChanged)
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/BindableObject.cs(688,0): at Microsoft.Maui.Controls.BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, Object value, Boolean currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, Boolean silent)
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/BindableObject.cs(616,0): at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/BindableObject.cs(521,0): at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value)
[xUnit.net 00:00:01.50]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(41,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.set_Children(GeometryCollection value)
[xUnit.net 00:00:01.50]         /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs(77,0): at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.AssigningChildrenWithNullEntrySubscribesValidChildren()
[xUnit.net 00:00:01.50]            at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
[xUnit.net 00:00:01.50]            at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
[xUnit.net 00:00:01.52]     AppendPathSkipsNullChildren [FAIL]
[xUnit.net 00:00:01.52]       System.NullReferenceException : Object reference not set to an instance of an object.
[xUnit.net 00:00:01.52]       Stack Trace:
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(75,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.UpdateChildren(GeometryCollection oldCollection, GeometryCollection newCollection)
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(21,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.OnChildrenChanged(BindableObject bindable, Object oldValue, Object newValue)
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/BindableObject.cs(701,0): at Microsoft.Maui.Controls.BindableObject.OnBindablePropertySet(BindableProperty property, Object original, Object value, Boolean didChange, Boolean willFirePropertyChanged)
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/BindableObject.cs(688,0): at Microsoft.Maui.Controls.BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, Object value, Boolean currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, Boolean silent)
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/BindableObject.cs(616,0): at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity)
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/BindableObject.cs(521,0): at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value)
[xUnit.net 00:00:01.52]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(41,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.set_Children(GeometryCollection value)
[xUnit.net 00:00:01.52]         /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs(92,0): at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.AppendPathSkipsNullChildren()
[xUnit.net 00:00:01.52]            at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
[xUnit.net 00:00:01.52]            at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
[xUnit.net 00:00:01.53]     AppendPathAllowsNullChildrenCollection [FAIL]
[xUnit.net 00:00:01.53]       System.NullReferenceException : Object reference not set to an instance of an object.
[xUnit.net 00:00:01.53]       Stack Trace:
[xUnit.net 00:00:01.53]         /_/src/Controls/src/Core/Shapes/GeometryGroup.cs(118,0): at Microsoft.Maui.Controls.Shapes.GeometryGroup.AppendPath(PathF path)
[xUnit.net 00:00:01.53]         /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs(113,0): at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.AppendPathAllowsNullChildrenCollection()
[xUnit.net 00:00:01.53]            at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
[xUnit.net 00:00:01.53]            at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
[xUnit.net 00:00:02.61]     GeometryGroupDoesNotLeakWhenSharingChild [FAIL]
[xUnit.net 00:00:02.61]       GeometryGroup should not be alive!
[xUnit.net 00:00:02.61]       Stack Trace:
[xUnit.net 00:00:02.61]         /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs(50,0): at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.GeometryGroupDoesNotLeakWhenSharingChild()
[xUnit.net 00:00:02.61]         --- End of stack trace from previous location ---
  Passed MovingChildrenPreservesSubscriptions [15 ms]
  Failed AssigningChildrenWithNullEntrySubscribesValidChildren [2 ms]
  Error Message:
   System.NullReferenceException : Object reference not set to an instance of an object.
  Stack Trace:
     at Microsoft.Maui.Controls.Shapes.GeometryGroup.UpdateChildren(GeometryCollection oldCollection, GeometryCollection newCollection) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 75
   at Microsoft.Maui.Controls.Shapes.GeometryGroup.OnChildrenChanged(BindableObject bindable, Object oldValue, Object newValue) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 21
   at Microsoft.Maui.Controls.BindableObject.OnBindablePropertySet(BindableProperty property, Object original, Object value, Boolean didChange, Boolean willFirePropertyChanged) in /_/src/Controls/src/Core/BindableObject.cs:line 701
   at Microsoft.Maui.Controls.BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, Object value, Boolean currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, Boolean silent) in /_/src/Controls/src/Core/BindableObject.cs:line 688
   at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity) in /_/src/Controls/src/Core/BindableObject.cs:line 616
   at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value) in /_/src/Controls/src/Core/BindableObject.cs:line 521
   at Microsoft.Maui.Controls.Shapes.GeometryGroup.set_Children(GeometryCollection value) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 41
   at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.AssigningChildrenWithNullEntrySubscribesValidChildren() in /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:line 77
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
  Passed ReplacingChildrenCollectionMovesSubscriptions [< 1 ms]
  Failed AppendPathSkipsNullChildren [< 1 ms]
  Error Message:
   System.NullReferenceException : Object reference not set to an instance of an object.
  Stack Trace:
     at Microsoft.Maui.Controls.Shapes.GeometryGroup.UpdateChildren(GeometryCollection oldCollection, GeometryCollection newCollection) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 75
   at Microsoft.Maui.Controls.Shapes.GeometryGroup.OnChildrenChanged(BindableObject bindable, Object oldValue, Object newValue) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 21
   at Microsoft.Maui.Controls.BindableObject.OnBindablePropertySet(BindableProperty property, Object original, Object value, Boolean didChange, Boolean willFirePropertyChanged) in /_/src/Controls/src/Core/BindableObject.cs:line 701
   at Microsoft.Maui.Controls.BindableObject.SetValueActual(BindableProperty property, BindablePropertyContext context, Object value, Boolean currentlyApplying, SetValueFlags attributes, SetterSpecificity specificity, Boolean silent) in /_/src/Controls/src/Core/BindableObject.cs:line 688
   at Microsoft.Maui.Controls.BindableObject.SetValueCore(BindableProperty property, Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes, SetterSpecificity specificity) in /_/src/Controls/src/Core/BindableObject.cs:line 616
   at Microsoft.Maui.Controls.BindableObject.SetValue(BindableProperty property, Object value) in /_/src/Controls/src/Core/BindableObject.cs:line 521
   at Microsoft.Maui.Controls.Shapes.GeometryGroup.set_Children(GeometryCollection value) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 41
   at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.AppendPathSkipsNullChildren() in /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:line 92
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
  Failed AppendPathAllowsNullChildrenCollection [1 ms]
  Error Message:
   System.NullReferenceException : Object reference not set to an instance of an object.
  Stack Trace:
     at Microsoft.Maui.Controls.Shapes.GeometryGroup.AppendPath(PathF path) in /_/src/Controls/src/Core/Shapes/GeometryGroup.cs:line 118
   at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.AppendPathAllowsNullChildrenCollection() in /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:line 113
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
  Passed RemovingAndReplacingChildrenMovesSubscriptions [1 ms]
  Failed GeometryGroupDoesNotLeakWhenSharingChild [1 s]
  Error Message:
   GeometryGroup should not be alive!
  Stack Trace:
     at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.GeometryGroupDoesNotLeakWhenSharingChild() in /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:line 50
--- End of stack trace from previous location ---
  Passed DuplicateChildrenPreserveOccurrenceSubscriptions [< 1 ms]
  Passed SharedChildrenInvalidateEachLiveGroupAfterGc [24 ms]
  Passed ChildGeometryChangesStillInvalidateAfterGc [25 ms]
[xUnit.net 00:00:03.70]     GeometryGroupDoesNotLeakWhenSharingChildren [FAIL]
[xUnit.net 00:00:03.70]       GeometryGroup should not be alive!
[xUnit.net 00:00:03.70]       Stack Trace:
[xUnit.net 00:00:03.70]         /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs(40,0): at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.GeometryGroupDoesNotLeakWhenSharingChildren()
[xUnit.net 00:00:03.70]         --- End of stack trace from previous location ---
[xUnit.net 00:00:03.70]     ResetChildrenResubscribesLaterAdditions [FAIL]
[xUnit.net 00:00:03.70]       Assert.False() Failure
[xUnit.net 00:00:03.70]       Expected: False
[xUnit.net 00:00:03.70]       Actual:   True
[xUnit.net 00:00:03.70]       Stack Trace:
[xUnit.net 00:00:03.70]         /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs(264,0): at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.ResetChildrenResubscribesLaterAdditions()
[xUnit.net 00:00:03.70]            at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
[xUnit.net 00:00:03.70]            at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)
[xUnit.net 00:00:03.71]   Finished:    Microsoft.Maui.Controls.Core.UnitTests
  Failed GeometryGroupDoesNotLeakWhenSharingChildren [1 s]
  Error Message:
   GeometryGroup should not be alive!
  Stack Trace:
     at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.GeometryGroupDoesNotLeakWhenSharingChildren() in /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:line 40
--- End of stack trace from previous location ---
  Failed ResetChildrenResubscribesLaterAdditions [1 ms]
  Error Message:
   Assert.False() Failure
Expected: False
Actual:   True
  Stack Trace:
     at Microsoft.Maui.Controls.Core.UnitTests.GeometryGroupMemoryTests.ResetChildrenResubscribesLaterAdditions() in /_/src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs:line 264
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

Test Run Failed.
Total tests: 12
     Passed: 6
     Failed: 6
 Total time: 4.2071 Seconds

🟢 With fix — 🧪 GeometryGroupMemoryTests: PASS ✅ · 84s

  Determining projects to restore...
  All projects are up-to-date for restore.
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  ##vso[build.updatebuildnumber]10.0.100-ci+azdo.14650840
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  Controls.BindingSourceGen -> /home/vsts/work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
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Test run for /home/vsts/work/1/s/artifacts/bin/Controls.Core.UnitTests/Debug/net10.0/Microsoft.Maui.Controls.Core.UnitTests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (x64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.15]   Discovering: Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.37]   Discovered:  Microsoft.Maui.Controls.Core.UnitTests
[xUnit.net 00:00:01.40]   Starting:    Microsoft.Maui.Controls.Core.UnitTests
  Passed MovingChildrenPreservesSubscriptions [17 ms]
  Passed AssigningChildrenWithNullEntrySubscribesValidChildren [< 1 ms]
  Passed ReplacingChildrenCollectionMovesSubscriptions [< 1 ms]
  Passed AppendPathSkipsNullChildren [4 ms]
  Passed AppendPathAllowsNullChildrenCollection [< 1 ms]
  Passed RemovingAndReplacingChildrenMovesSubscriptions [< 1 ms]
  Passed GeometryGroupDoesNotLeakWhenSharingChild [33 ms]
  Passed DuplicateChildrenPreserveOccurrenceSubscriptions [< 1 ms]
  Passed SharedChildrenInvalidateEachLiveGroupAfterGc [21 ms]
[xUnit.net 00:00:01.59]   Finished:    Microsoft.Maui.Controls.Core.UnitTests
  Passed ChildGeometryChangesStillInvalidateAfterGc [20 ms]
  Passed GeometryGroupDoesNotLeakWhenSharingChildren [21 ms]
  Passed ResetChildrenResubscribesLaterAdditions [1 ms]

Test Run Successful.
Total tests: 12
     Passed: 12
 Total time: 2.1024 Seconds

📁 Fix files reverted (1 files)

• src/Controls/src/Core/Shapes/GeometryGroup.cs

---

📱 UI Tests — Shape

Detected UI test categories: Shape

✅ Deep UI tests — 35 passed, 0 failed across 1 category on platform-pool agent (replaces in-process counts above).

🧪 UI Test Execution Results (deep, platform pool)

Category	Tests	Snapshot diffs
Shape	35/35 ✓	—
📎 Download drop-deep-uitests artifact (TRX + snapshot diffs)

---

📋 Pre-Flight — Context & Validation

Issue: #36365 - [leak-scan] GeometryGroup.Children shared GeometryCollection strongly roots GeometryGroup via CollectionChanged
PR: #36526 - [leak-fix] Fix GeometryGroup.Children memory leak (Fixes #36365)
Platforms Affected: Shared managed Controls code; Android requested for testing, but no Android-specific code path changed.
Files Changed: 1 implementation, 1 test

Key Findings

• GeometryGroup directly subscribed to shared GeometryCollection.CollectionChanged and child Geometry.PropertyChanged, creating strong source-to-group retention paths.
• PR replaces those strong subscriptions with existing weak event proxy helpers and adds focused memory/subscription regression tests.
• Gate was already passed before this run: tests fail without the fix and pass with the PR fix.
• Local targeted validation of the PR fix passed: 12/12 GeometryGroupMemoryTests.

Code Review Summary

Verdict: NEEDS_DISCUSSION
Confidence: low
Errors: 0 | Warnings: 1 | Suggestions: 2

Key code review findings:

• ⚠ Null-child support is only partial: PR makes GeometryGroup.AppendPath and subscription bookkeeping null-tolerant, while other GeometryGroup consumers may still dereference null children.
• ℹ Avoid allocation in finalizer-reachable unsubscribe: _childProxies.ToArray() could be replaced by an index loop.
• ℹ Add null reassignment lifecycle test for old collection -> null -> new collection.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #36526	Per-GeometryGroup ChildrenSubscriptions holder using existing WeakNotifyCollectionChangedProxy / WeakNotifyPropertyChangedProxy; null-safe AppendPath; focused memory tests.	✅ PASSED (Gate and local targeted test)	GeometryGroup.cs, GeometryGroupMemoryTests.cs	Original PR

---

🔬 Code Review — Deep Analysis

Code Review — PR #36526

Independent Assessment

What this changes: Replaces GeometryGroup.Children direct collection/child PropertyChanged subscriptions with weak event proxies to avoid retaining GeometryGroup through shared/long-lived geometry collections. Adds null-tolerant AppendPath behavior and memory/subscription tests.
Inferred motivation: Fix a memory leak when GeometryGroup shares GeometryCollection or child Geometry instances.

Reconciliation with PR Narrative

Author claims: PR/commit narrative claims a GeometryGroup.Children memory leak fix for #36365.
Agreement/disagreement: Agrees with the implementation: weak proxies break the strong event-reference chain while preserving invalidation behavior.

Prior Review Reconciliation

No prior ❌ Error findings could be evaluated: gh is unauthenticated, and unauthenticated GitHub REST/HTML review/comment surfaces returned rate-limit/action errors. Confidence is capped low.

Blast Radius Assessment

• Runs for all instances: Yes, all GeometryGroup children subscription paths.
• Startup impact: No direct startup path.
• Static/shared state: No new static state.

CI Status

• Required-check result: undetermined — gh pr checks --required failed due missing authentication.
• Classification: undetermined.
• Action taken: capped confidence; local targeted test passed: GeometryGroupMemoryTests 12/12.

Findings

⚠️ Warning — Null-child support is only partial

GeometryGroup.cs:79 and GeometryGroup.cs:190 now tolerate null children/null Children for subscription and AppendPath, and tests assert this behavior. Other GeometryGroup.Children consumers still dereference children/collection directly, e.g. GeometryHelper.cs:46-48, Windows GeometryExtensions.cs:50-52, Android compatibility GeometryExtensions.cs:61-63. If null children are now supported, those paths may still throw; if not, tests should avoid implying broader support.

💡 Suggestion — Avoid allocation in finalizer-reachable unsubscribe

GeometryGroup.cs:162 copies _childProxies with ToArray() before unsubscribing. Since proxy.Unsubscribe() does not mutate _childProxies, an index loop plus Clear() would avoid finalizer-thread allocation.

💡 Suggestion — Add null reassignment lifecycle test

Current tests cover Children = null for AppendPath, but not old collection -> null -> new collection subscription behavior. A test would lock down that old children stop invalidating and new children resume invalidating.

Failure-Mode Probing

• Shared collection outlives group: weak proxies allow collection; covered by tests.
• Child changes after GC while group alive: handler delegate is kept by group field; covered by tests.
• Reset/remove/replace/move/duplicates: current tests cover expected subscription counts.
• Null children/collection across all consumers: only partially covered; see warning.

Verdict: NEEDS_DISCUSSION

Confidence: low
Summary: Core leak fix appears sound and targeted tests pass locally. I cannot LGTM because required CI and prior-review surfaces were unavailable, and null tolerance may be inconsistent across existing GeometryGroup consumers.

---

🛠️ Fix — Analysis & Comparison

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix	Static ConditionalWeakTable per-source weak subscription registry with weak fan-out to groups.	❌ FAIL	1 file	Failed required null-safe AppendPath tests; also more complex than PR.
2	try-fix	Per-instance weak delegate closures capturing only WeakReference<GeometryGroup> plus generation; full child-subscription rebuild.	✅ PASS	1 file	Avoids proxy helpers but leaves dead weak delegates on inactive long-lived sources until later source activity. Not demonstrably better.
3	try-fix	Move child PropertyChanged aggregation into GeometryCollection; GeometryGroup observes collection-level weak aggregate events.	✅ PASS	2 files	Potential O(children) sharing benefit, but broader blast radius: changes GeometryCollection from passive collection to active observer. Not preferable for this bug fix.
PR	PR #36526	Per-group holder using existing weak proxy helpers; finalizer cleanup; focused null-safe render handling and tests.	✅ PASSED (Gate)	2 files	Original PR; selected as best balance of scope and reliability.

Cross-Pollination

Model	Round	New Ideas?	Details
maui-expert-reviewer	1	Yes	Suggested static per-source weak fan-out registry.
maui-expert-reviewer	2	Yes	After candidate 1 null failures, suggested per-instance weak delegate closures preserving null-safe AppendPath.
maui-expert-reviewer	3	Yes	Suggested GeometryCollection-owned child aggregation; tested as final distinct approach.
maui-expert-reviewer	4	No	Remaining alternatives are either trivial variations of candidate 2/3 or converge back to the PR's existing weak proxy holder pattern.

Exhausted: Yes
Selected Fix: PR's fix — Candidate 2 and Candidate 3 pass the targeted tests, but neither is demonstrably better. Candidate 2 has stale-delegate cleanup tradeoffs; Candidate 3 has broader blast radius by changing GeometryCollection internals. The PR uses existing MAUI weak event proxy infrastructure in a localized one-file product change and remains the best candidate.

Candidate Detail Files

• try-fix-1/content.md
• try-fix-2/content.md
• try-fix-3/content.md

---

🧭 Next Steps — review latest findings

No alternative fix was selected for this run. Review the session findings and CI results before merging.

[kubaflo]

🔍 AI-generated review response (GitHub Copilot CLI, on behalf of @kubaflo)

@MauiBot Review 4694695329 repeats findings that are already addressed by the reviewed head 4d592222844:

• UnsubscribeChildren() already uses indexed iteration followed by Clear(), with no ToArray() allocation.
• Null Children and null entries are already handled by GeometryHelper, Android, iOS/macOS, Tizen, and Windows conversion paths.
• ReplacingChildrenThroughNullMovesSubscriptions, FlattenGeometrySkipsNullChildren, and FlattenGeometryAllowsNullChildrenCollection are already present.

The review body appears to use the earlier 12-test/two-file snapshot; the current focused suite contains 15 tests. No additional product change is needed. Ready for re-review.

[kubaflo]

/azp run

[azure-pipelines]

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[azure-pipelines]

Azure Pipelines:
Successfully started running 3 pipeline(s).

[Copilot]

Pull request overview

This PR addresses a confirmed managed memory leak in GeometryGroup caused by strong event subscriptions to a shared/long-lived GeometryCollection (and its child Geometry items). It updates GeometryGroup to use the existing weak-event proxy infrastructure to avoid retaining the group, and adds focused unit tests to prevent regressions.

Changes:

• Replace strong CollectionChanged/PropertyChanged subscriptions in GeometryGroup with WeakNotifyCollectionChangedProxy / WeakNotifyPropertyChangedProxy, including subscription lifecycle management for add/remove/reset.
• Make geometry flattening/rendering/conversion paths treat Children == null and null child entries as empty (skip safely) across supported platforms.
• Add a comprehensive unit test suite validating both “no leak” behavior and correct invalidation/subscription behavior (including duplicates, move, reset, replace).

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Controls/tests/Core.UnitTests/GeometryGroupMemoryTests.cs	Adds regression tests covering the leak scenario and subscription lifecycle correctness.
src/Controls/src/Core/Shapes/GeometryHelper.cs	Updates flattening to skip null Children and null child entries.
src/Controls/src/Core/Shapes/GeometryGroup.cs	Implements weak subscription management and null-safe AppendPath behavior.
src/Controls/src/Core/Platform/Windows/Extensions/GeometryExtensions.cs	Makes Windows geometry conversion skip null Children / null children.
src/Controls/src/Core/Compatibility/Android/Extensions/GeometryExtensions.cs	Makes Android geometry conversion skip null Children / null children.
src/Compatibility/Core/src/Tizen/Extensions/GeometryExtensions.cs	Makes Tizen geometry conversion skip null Children / null children.
src/Compatibility/Core/src/iOS/Extensions/GeometryExtensions.cs	Makes iOS/macOS geometry conversion skip null Children / null children.

[kubaflo]

🔍 AI-generated merge-readiness analysis (GitHub Copilot CLI, on behalf of @kubaflo): good to merge.

All three current-head pipelines completed for 4d592222:

• maui-pr 1510858 succeeded.
• maui-pr-devicetests 1510860 succeeded; all seven published device-test runs contain zero failed results.
• maui-pr-uitests 1510859 is red only for unrelated test/environment failures:
  • Mac ListView: Issue1939Test timed out (tracked by [ci-scan-net11] Controls ListView: Issue1939Test fails on macOS — recurring UI test failure on net11.0 #36048/[ci-scan] Recurring: MemoryLeakB42329 and Issue1939Test fail with Appium timeout in Controls ListView on macOS MacCatalyst (maui-pr-uitest [Content truncated due to length] #35957) and BindingToValuesTypesAndScrollingNoCrash hit an Appium app-unresponsive teardown. Their seven-day histories are 423/429 and 426/429 passes, and each had four passing platform/shard results in this same build.
  • Mac Navigation: Issue59172RecoveryTest timed out; its seven-day history is 844/858 passes, including nine passes in this build.
  • Android API 30 SoftInput/Stepper/Switch/SwipeView failed before tests because ADB hit a broken pipe and could not install the APK.
  • Mac Picker: PickerDialogDoesNotCrashWhenPagePoppedWhileDialogOpen timed out, matching [ci-scan] Recurring: PickerDialogDoesNotCrashWhenPagePoppedWhileDialogOpen (Issue31731) flaky on macOS in maui-pr-uitests #36536/[ci-scan-net11] Controls Page/Picker UITests — PickerDialogDoesNotCrashWhenPagePoppedWhileDialogOpen times out / stale element on MacCatalyst (n [Content truncated due to length] #36453; its seven-day history is 420/434 passes, including four passes in this build.

The exact base commit’s UI build (1503618 at 0395a53b) passed every listed test, and the failing classes all passed again in concurrent later builds. None intersects the GeometryGroup implementation or regression tests changed here, so no PR fix or rerun is warranted for merge readiness.

[github-actions]

Tests Failure Analysis

@kubaflo — test-failure review results are available based on commit 4d59222.
To request a fresh review after new comments, commits, or CI runs, comment /review tests.

Test Failure Review: Not ready - click to expand

Overall verdict: Not ready. One build leg is a deterministic regression versus main (red on the PR, green on all 5 recently sampled base builds), and 12 further failures could not be attributed — flaky-on-base UITest timeouts, unexplained/aborted build legs, and Android SDK provisioning breaks. Only 2 of 13 distinct failures also appear on main, and both are attributed only inconclusively.

• ✗ PR-related — Android UITests build break (~1 leg): the Controls (API 30) SoftInput,Stepper,Switch,SwipeView leg exits with ##[error]PowerShell exited with code '1' and is red on the PR but green across all 5 sampled base builds → deterministic regression-vs-base.
• i Uncertain — flaky UITest timeouts (~7 tests): repeated System.TimeoutException : Timed out waiting for element, e.g. Issue59172RecoveryTest, all flaky-on-base and attributed indeterminate — neither provably PR-caused nor dismissible.
• i Uncertain — unexplained / aborted build legs (~15 legs): failed build legs produced no extractable failure, plus maui-pr-uitests (macOS UITests Controls Layout) did not finish cleanly (cancelled) and Publish the mac_ui_tests_controls test results reported build errors.
• i Uncertain — Android SDK provisioning (~2 legs): Failed to find package 'platform-tools;35.0.2' also fails on base but attribution is indeterminate (succeeded-on-base-unconfirmed), so it is not dismissible.

Coverage: 162 checks · 155 passing · 7 failing · 0 pending · 0 inaccessible · 1 unmapped · 15 unexplained build legs · 0 unaccounted failing checks · 1 aborted failing check · 0 canceled-build checks · 0 device-test unverified · 12 unattributed · 1 regressed-vs-base. Deterministic ceiling: Not ready — 1 leg is a deterministic regression vs base and 12 failures are unattributed, plus an aborted check and 1 check (Build Analysis) with no inspectable AzDO evidence.

Builds (this PR): maui-pr-uitests 1510859, maui-pr-devicetests 1510860. Base sampling (main, 5 recent builds for maui-pr-uitests): 1503618, 1503332, 1503036, 1499834, 1499259.

Recommended action

A human should inspect the regressed Controls (API 30) SoftInput,Stepper,Switch,SwipeView build leg (PowerShell exit 1) — it is a deterministic regression vs main — and confirm the flaky-on-base UITest timeouts and Android SDK provisioning failures are infrastructure noise before merging.

[kubaflo]

🔍 AI-generated follow-up analysis (GitHub Copilot CLI, on behalf of @kubaflo)

The /review tests Android "deterministic regression" is a wrapper-level false positive, not a GeometryGroup failure.

In UI build 1510859, the failing Mono API-30 job never installed the app or ran tests: ADB reported broken pipe and cmd: Can't find service: package, then XHarness exited 78 (PACKAGE_INSTALLATION_FAILURE). This matches Android emulator infrastructure issue dotnet/android#12119. The same-build CoreCLR counterpart ran the identical filter and passed 143/143, and exact-base build 1503618 passed both variants 143/143. Main 1510858 and device 1510860 also succeeded on the same merge commit.

The PR changes only GeometryGroup subscription cleanup and tests, with no emulator/XHarness/provisioning overlap. No code change is required.

[kubaflo]

🔍 AI-generated (GitHub Copilot CLI, on behalf of @kubaflo)

Rebased onto inflight/current and resolved the conflict with the already-merged #36232 (GeometryGroup shared-children fix). #36232 kept strong CollectionChanged / PropertyChanged subscriptions — which is exactly the leak this PR (#36365) reports. This revision converts them to WeakNotifyCollectionChangedProxy / WeakNotifyPropertyChangedProxy so a shared or long-lived GeometryCollection no longer roots the GeometryGroup, while preserving the Clear()/Reset teardown from #36232 (still guarded by GeometryGroupTests.ClearUnsubscribesPreviousChildrenFromPropertyChanged).

Verified locally on the net TFM: all 16 GeometryGroup tests pass (base guard test + the new GeometryGroupMemoryTests). Force-pushed as a single clean commit.