Add LINQ `FirstOrDefault` support parity across generic NS collections - #25509

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rolfbjarne with Copilot wants to merge 7 commits into

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copilot/fix-linq-methods-inconsistent-ns-collections

Copilot AI commented May 22, 2026 •

edited by rolfbjarne

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Understand the issue: NS generic collections (NSSet<T>, NSMutableSet<T>, NSArray<T>, NSMutableArray<T>, NSOrderedSet<T>, NSMutableOrderedSet<T>) inherit from non-generic base classes that implement IEnumerable<NSObject>, causing LINQ type-inference ambiguity
Review existing FirstOrDefault extension overloads in NSCollectionLinqExtensions.cs
Expand NSCollectionLinqExtensions.cs with all common LINQ method overloads for all 6 collection types (First, FirstOrDefault, Last, LastOrDefault, Single, SingleOrDefault, ElementAt, ElementAtOrDefault, Any, All, Count, LongCount, Where, Select, OrderBy, OrderByDescending, Skip, SkipWhile, Take, TakeWhile, Distinct, Reverse, Concat, ToList, ToArray, Aggregate), each with XML docs
Add comprehensive LINQ tests in tests/monotouch-test/Foundation/NSCollectionLinqTest.cs covering all 6 generic NS collections
Validate the build compiles

Fixes #4597.


          Initial plan

080ebc0

Copilot AI assigned Copilot and rolfbjarne

Copilot started work on behalf of rolfbjarne

May 22, 2026 14:54

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Copilot AI linked an issue

that may be closed by this pull request

System.Linq methods on NS collections is inconsistent #4597

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Copilot AI and others added 2 commits

May 22, 2026 15:07


          Add LINQ FirstOrDefault support wrappers for NS collection generics

64da99f

Agent-Logs-Url: https://github.com/dotnet/macios/sessions/04597ed5-86b1-4feb-b522-8990c6006023

Co-authored-by: rolfbjarne <249268+rolfbjarne@users.noreply.github.com>


          Align generic type naming in NS collection LINQ extensions

c40d839

Agent-Logs-Url: https://github.com/dotnet/macios/sessions/04597ed5-86b1-4feb-b522-8990c6006023

Co-authored-by: rolfbjarne <249268+rolfbjarne@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Fix inconsistent LINQ methods on NS collections~~ Add LINQ FirstOrDefault support parity across generic NS collections

Copilot finished work on behalf of rolfbjarne

May 22, 2026 15:09

Copilot AI requested a review from rolfbjarne

May 22, 2026 15:09

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Copilot started work on behalf of rolfbjarne

May 25, 2026 07:48

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          Add all LINQ method overloads with XML docs and tests for all 6 NS ge…

21dd1ba

…neric collections

Agent-Logs-Url: https://github.com/dotnet/macios/sessions/64b2c1cf-9d19-4995-a591-9392aad2cfc5

Co-authored-by: rolfbjarne <249268+rolfbjarne@users.noreply.github.com>

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rolfbjarne and others added 2 commits

May 27, 2026 17:30


          Fix build: use ObjCRuntime.INativeObject in LINQ extension constraints

14c2c6d

INativeObject is defined in the ObjCRuntime namespace, not Foundation.
The generic type constraints on all 228 extension methods were referencing
Foundation.INativeObject which doesn't exist, causing CS0234/CS0311 errors.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>


          Auto-format source code

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          Merge branch 'main' into copilot/fix-linq-methods-inconsistent-ns-col…

acba1c5

…lections

vs-mobiletools-engineering-service2 commented Sep 8, 2026

Collaborator

✅ API diff for current PR / commit

NET (empty diffs)

iOS: vsdrops gist ( No breaking changes )
tvOS: vsdrops gist ( No breaking changes )
MacCatalyst: vsdrops gist ( No breaking changes )
macOS: vsdrops gist ( No breaking changes )

✅ API diff vs stable

NET (empty diffs)

iOS: vsdrops gist ( No breaking changes )
tvOS: vsdrops gist ( No breaking changes )
MacCatalyst: vsdrops gist ( No breaking changes )
macOS: vsdrops gist ( No breaking changes )

ℹ️ Generator diff

Generator Diff: vsdrops (html) vsdrops (raw diff) gist (raw diff) - Please review changes)

Pipeline on Agent
Hash: acba1c5ed0ee173047adaa9f573acac3528360aa [PR build]

vs-mobiletools-engineering-service2 commented Sep 8, 2026

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🔥 [PR Build #acba1c5] Build failed (Build macOS tests) 🔥

Build failed for the job 'Build macOS tests' (with job status 'Failed')

Pipeline on Agent
Hash: acba1c5ed0ee173047adaa9f573acac3528360aa [PR build]

vs-mobiletools-engineering-service2 commented Sep 8, 2026

Collaborator

🔥 [CI Build #acba1c5] Test results 🔥

Test results

❌ Tests failed on VSTS: test results

3 tests crashed, 108 tests failed, 141 tests passed.

Failures

❌ cecil tests

1 tests failed, 0 tests passed.

Failed tests

Cecil-based tests: Failed (Execution failed with exit code 1)
- Cecil.Tests.Documentation.VerifyEveryVisibleMemberIsDocumented: Found 1 undocumented APIs (not known failures) and 0 APIs that were marked as known failures but are now documented. If this is ...

Html Report (VSDrops) Download

❌ dotnettests tests (iOS)

1 tests failed, 0 tests passed.

Failed tests

DotNet tests: Failed (Execution failed with exit code 1)
- Xamarin.Tests.DotNetProjectTest.BuildFatMonoTouchTest(iOS,"iossi...: 'dotnet build' failed with exit code 1
  Full command: /Users/cloudtest/vss/_work/1/s/macios/builds/downloads/dotnet-sdk-11.0.100-...
- Xamarin.Tests.DotNetProjectTest.PublishAotMonoTouchTest_NoIL2009...: 'dotnet build' failed with exit code 1
  Full command: /Users/cloudtest/vss/_work/1/s/macios/builds/downloads/dotnet-sdk-11.0.100-...

Html Report (VSDrops) Download

❌ dotnettests tests (MacCatalyst)

1 tests failed, 0 tests passed.

Failed tests

DotNet tests: Failed (Execution failed with exit code 1)
- Xamarin.Tests.DotNetProjectTest.BuildFatMonoTouchTest(MacCatalys...: 'dotnet build' failed with exit code 1
  Full command: /Users/cloudtest/vss/_work/1/s/macios/builds/downloads/dotnet-sdk-11.0.100-...
- Xamarin.Tests.DotNetProjectTest.PublishAotMonoTouchTest_NoIL2009...: 'dotnet build' failed with exit code 1
  Full command: /Users/cloudtest/vss/_work/1/s/macios/builds/downloads/dotnet-sdk-11.0.100-...

Html Report (VSDrops) Download

❌ dotnettests tests (macOS)

1 tests failed, 0 tests passed.

Failed tests

DotNet tests: Failed (Execution failed with exit code 1)
- Xamarin.Tests.AppSizeTest.CoreCLR_Interpreter_TrimmableStatic(Ma...: App size changed significantly (+20,308 bytes (19.8 KB = 0.0 MB) different > tolerance of +-10,240 bytes (10.0 KB = 0.0 MB)). Ex...
- Xamarin.Tests.AppSizeTest.CoreCLR_Interpreter(MacOSX,"osx-arm64;...: App size changed significantly (+20,308 bytes (19.8 KB = 0.0 MB) different > tolerance of +-10,240 bytes (10.0 KB = 0.0 MB)). Ex...
- Xamarin.Tests.AppSizeTest.CoreCLR_R2R(MacOSX,"osx-arm64;osx-x64"...: App size changed significantly (+122,196 bytes (119.3 KB = 0.1 MB) different > tolerance of +-10,240 bytes (10.0 KB = 0.0 MB)). ...
- ... and 2 more

Html Report (VSDrops) Download

❌ dotnettests tests (tvOS)

1 tests failed, 0 tests passed.

Failed tests

DotNet tests: Failed (Execution failed with exit code 1)
- Xamarin.Tests.DotNetProjectTest.PublishAotMonoTouchTest_NoIL2009...: 'dotnet build' failed with exit code 1
  Full command: /Users/cloudtest/vss/_work/1/s/macios/builds/downloads/dotnet-sdk-11.0.100-...

Html Report (VSDrops) Download

❌ introspection tests

7 tests failed, 0 tests passed.

Failed tests

introspection/macOS/Debug: Failed (Test run failed.
Tests run: 34 Passed: 32 Inconclusive: 0 Failed: 2 Ignored: 0)
introspection/Mac Catalyst/Debug: Failed (Test run failed.
Tests run: 43 Passed: 39 Inconclusive: 0 Failed: 2 Ignored: 2)
introspection/Mac Catalyst/CoreCLR: Failed (Test run failed.
Tests run: 43 Passed: 39 Inconclusive: 0 Failed: 2 Ignored: 2)
introspection/iOS - simulator/Debug: Failed
introspection/iOS - simulator/CoreCLR: Failed
introspection/tvOS - simulator/Debug: Failed
introspection/tvOS - simulator/CoreCLR: Failed

Html Report (VSDrops) Download

❌ monotouch tests (iOS)

25 tests failed, 0 tests passed.

Failed tests

monotouch-test/iOS - simulator/Debug: BuildFailure
monotouch-test/iOS - simulator/Debug (CoreCLR): BuildFailure
monotouch-test/iOS - simulator/Release (CoreCLR, ARM64): BuildFailure
monotouch-test/iOS - simulator/Release (CoreCLR, Universal): BuildFailure
monotouch-test/iOS - simulator/Release (link sdk): BuildFailure
monotouch-test/iOS - simulator/Release (link all): BuildFailure
monotouch-test/iOS - simulator/Debug (PrepareAssemblies): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/iOS - simulator/Debug (PrepareAssemblies, Trimmable Static Registrar, link sdk): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/iOS - simulator/Debug (LinkSdk): BuildFailure
monotouch-test/iOS - simulator/Debug (static registrar): BuildFailure
monotouch-test/iOS - simulator/Release (all optimizations): BuildFailure
monotouch-test/iOS - simulator/Release (NativeAOT): BuildFailure
monotouch-test/iOS - simulator/Release (trimmable static registrar, NativeAOT): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/iOS - simulator/Debug (managed static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/iOS - simulator/Debug (trimmable static registrar): BuildFailure
monotouch-test/iOS - simulator/Release (managed static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/iOS - simulator/Debug (trimmable static registrar, all optimizations): BuildFailure
monotouch-test/iOS - simulator/Release (trimmable static registrar, all optimizations): BuildFailure
monotouch-test/iOS - simulator/Debug (interpreter): BuildFailure
monotouch-test/iOS - simulator/Release (interpreter): BuildFailure
monotouch-test/iOS - simulator/Release (compat inline Class.GetHandle): BuildFailure
monotouch-test/iOS - simulator/Release (strict inline Class.GetHandle): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/iOS - simulator/Release (compat inline dlfcn): BuildFailure
monotouch-test/iOS - simulator/Release (strict inline dlfcn, link sdk): BuildFailure
monotouch-test/iOS - simulator/Release (NativeAOT, .NET 11 defaults): BuildFailure

Html Report (VSDrops) Download

❌ monotouch tests (MacCatalyst)

25 tests failed, 0 tests passed.

Failed tests

monotouch-test/Mac Catalyst/Debug: BuildFailure
monotouch-test/Mac Catalyst/Debug (CoreCLR): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (CoreCLR, ARM64): BuildFailure
monotouch-test/Mac Catalyst/Release (CoreCLR, Universal): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (link sdk): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (link all): BuildFailure
monotouch-test/Mac Catalyst/Debug (PrepareAssemblies): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Debug (PrepareAssemblies, Trimmable Static Registrar, link sdk): BuildFailure
monotouch-test/Mac Catalyst/Debug (managed static registrar): BuildFailure
monotouch-test/Mac Catalyst/Debug (trimmable static registrar): BuildFailure
monotouch-test/Mac Catalyst/Debug (static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (managed static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (trimmable static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (managed static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Debug (trimmable static registrar, all optimizations): BuildFailure
monotouch-test/Mac Catalyst/Release (trimmable static registrar, all optimizations): BuildFailure
monotouch-test/Mac Catalyst/Release (NativeAOT): BuildFailure
monotouch-test/Mac Catalyst/Release (NativeAOT, .NET 11 defaults): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (trimmable static registrar, NativeAOT): BuildFailure
monotouch-test/Mac Catalyst/Release (static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Debug (interpreter): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (interpreter): BuildFailure
monotouch-test/Mac Catalyst/Release (compat inline dlfcn): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/Mac Catalyst/Release (strict inline dlfcn, link sdk): BuildFailure

Html Report (VSDrops) Download

❌ monotouch tests (macOS)

20 tests failed, 0 tests passed.

Failed tests

monotouch-test/macOS/Debug: BuildFailure
monotouch-test/macOS/Release (link sdk): BuildFailure
monotouch-test/macOS/Release (link all): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Debug (PrepareAssemblies): BuildFailure
monotouch-test/macOS/Debug (PrepareAssemblies, Trimmable Static Registrar, link sdk): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Debug (managed static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Debug (trimmable static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Debug (static registrar): BuildFailure
monotouch-test/macOS/Release (managed static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Release (trimmable static registrar): BuildFailure
monotouch-test/macOS/Release (managed static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Debug (trimmable static registrar, all optimizations): BuildFailure
monotouch-test/macOS/Release (trimmable static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Release (NativeAOT): BuildFailure
monotouch-test/macOS/Release (NativeAOT, .NET 11 defaults): BuildFailure
monotouch-test/macOS/Release (trimmable static registrar, NativeAOT): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/macOS/Release (static registrar): BuildFailure
monotouch-test/macOS/Release (static registrar, all optimizations): BuildFailure
monotouch-test/macOS/Release (compat inline dlfcn): BuildFailure
monotouch-test/macOS/Release (strict inline dlfcn, link sdk): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))

Html Report (VSDrops) Download

❌ monotouch tests (tvOS)

25 tests failed, 0 tests passed.

Failed tests

monotouch-test/tvOS - simulator/Debug: BuildFailure
monotouch-test/tvOS - simulator/Debug (CoreCLR): BuildFailure
monotouch-test/tvOS - simulator/Release (CoreCLR, ARM64): BuildFailure
monotouch-test/tvOS - simulator/Release (CoreCLR, Universal): BuildFailure
monotouch-test/tvOS - simulator/Release (link sdk): BuildFailure
monotouch-test/tvOS - simulator/Release (link all): BuildFailure
monotouch-test/tvOS - simulator/Debug (PrepareAssemblies): BuildFailure
monotouch-test/tvOS - simulator/Debug (PrepareAssemblies, Trimmable Static Registrar, link sdk): BuildFailure
monotouch-test/tvOS - simulator/Debug (LinkSdk): BuildFailure
monotouch-test/tvOS - simulator/Debug (static registrar): BuildFailure
monotouch-test/tvOS - simulator/Release (all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/tvOS - simulator/Release (NativeAOT): BuildFailure
monotouch-test/tvOS - simulator/Release (trimmable static registrar, NativeAOT): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/tvOS - simulator/Debug (managed static registrar): BuildFailure
monotouch-test/tvOS - simulator/Debug (trimmable static registrar): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/tvOS - simulator/Release (managed static registrar, all optimizations): BuildFailure
monotouch-test/tvOS - simulator/Debug (trimmable static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/tvOS - simulator/Release (trimmable static registrar, all optimizations): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/tvOS - simulator/Debug (interpreter): BuildFailure
monotouch-test/tvOS - simulator/Release (interpreter): BuildFailure
monotouch-test/tvOS - simulator/Release (compat inline Class.GetHandle): BuildFailure
monotouch-test/tvOS - simulator/Release (strict inline Class.GetHandle): BuildFailure
monotouch-test/tvOS - simulator/Release (compat inline dlfcn): BuildFailure
monotouch-test/tvOS - simulator/Release (strict inline dlfcn, link sdk): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))
monotouch-test/tvOS - simulator/Release (NativeAOT, .NET 11 defaults): BuildFailure ( (failed to parse the logs: The Writer is closed or in error state.))

Html Report (VSDrops) Download

❌ msbuild tests

1 tests failed, 1 tests passed.

Failed tests

MSBuild tasks tests: Failed (Execution failed with exit code 1)
- Xamarin.MacDev.Tasks.CompileAppManifestTaskTests.SupportedOSPlat...: Assert.That(Engine.Logger.ErrorEvents [0].Message, Is.EqualTo ("The value '\n13.0' for the property 'SupportedOSPlatformVersi...

Html Report (VSDrops) Download

❌ Tests on macOS Sonoma (14) tests

⚠️ Tests did not run because the Build macOS tests job failed.

Html Report (VSDrops) Download

❌ Tests on macOS Sequoia (15) tests

⚠️ Tests did not run because the Build macOS tests job failed.

Html Report (VSDrops) Download

❌ Tests on macOS Tahoe (26) tests

⚠️ Tests did not run because the Build macOS tests job failed.

Html Report (VSDrops) Download

Successes

✅ assembly-processing: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (Multiple platforms): All 1 tests passed. Html Report (VSDrops) Download
✅ framework: All 2 tests passed. Html Report (VSDrops) Download
✅ fsharp: All 4 tests passed. Html Report (VSDrops) Download
✅ generator: All 5 tests passed. Html Report (VSDrops) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ linker (iOS): All 31 tests passed. Html Report (VSDrops) Download
✅ linker (MacCatalyst): All 31 tests passed. Html Report (VSDrops) Download
✅ linker (macOS): All 21 tests passed. Html Report (VSDrops) Download
✅ linker (tvOS): All 31 tests passed. Html Report (VSDrops) Download
✅ sharpie: All 1 tests passed. Html Report (VSDrops) Download
✅ windows: All 3 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 4 tests passed. Html Report (VSDrops) Download
✅ xtro: All 1 tests passed. Html Report (VSDrops) Download

macOS tests

Linux Build Verification

✅ Linux build succeeded

Pipeline on Agent
Hash: acba1c5ed0ee173047adaa9f573acac3528360aa [PR build]

vs-mobiletools-engineering-service2 commented Sep 8, 2026

Collaborator

⚠️ AppSizeTest expected files changed ⚠️

The AppSizeTest detected changes in the expected app size files.

To update the expected files, add a comment with the following command:

/apply-gist https://gist.github.com/vs-mobiletools-engineering-service2/5b361c9f360c32439d64d34044827a21

Updated files

MacOSX-CoreCLR-Interpreter-size.txt
MacOSX-CoreCLR-Interpreter-TrimmableStatic-size.txt
MacOSX-CoreCLR-R2R-size.txt

Pipeline on Agent
Hash: acba1c5ed0ee173047adaa9f573acac3528360aa [PR build]

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