Fix: .UseMauiCommunityToolkit() Analyzer when wrapped in preprocessor directives

[IeuanWalker]

Description of Change

Linked Issues

• Fixes [BUG] Toolkit warning when targeting net9.0 - Analyzers issue #2621

PR Checklist

• Has a linked Issue, and the Issue has been approved(bug) or Championed (feature/proposal)
• Has tests (if omitted, state reason in description)
• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard
• Documentation created or updated: https://github.com/MicrosoftDocs/CommunityToolkit/pulls

Additional information

[IeuanWalker]

Wasn't able to test it via the toolkit .sln directly as it wouldn't build (build was running for 20m+ and not ending). The unit tests also weren't showing up in the test explorer, so I have no idea if the test will pass or fail.

Was able to test it by building the nuget via powershell -

$version = "99.0.0-preview2"
$outputDir = "$PSScriptRoot\nuget"

# Ensure the output directory exists
if (-not (Test-Path $outputDir)) {
    New-Item -ItemType Directory -Path $outputDir | Out-Null
}

# Build solution
dotnet build "D:/WS/Github-Fork/MauiToolkit/src/CommunityToolkit.Maui.sln" -c Release

# Pack nuget
dotnet pack D:/WS/Github-Fork/MauiToolkit/src/CommunityToolkit.Maui/CommunityToolkit.Maui.csproj -c Release --no-restore -p:PackageVersion=$version -o $outputDir
dotnet pack D:/WS/Github-Fork/MauiToolkit/src/CommunityToolkit.Maui.Core/CommunityToolkit.Maui.Core.csproj -c Release --no-restore -p:PackageVersion=$version -o $outputDir

# Show the generated NuGet package(s)
Write-Host "Generated NuGet package(s) in ${outputDir}:"
Get-ChildItem -Path $outputDir -Filter "*.nupkg"

# Keep the PowerShell window open
Read-Host -Prompt "Press Enter to exit"

Have tested that generated nuget against my current solution, and does fix the linked issue

[TheCodeTraveler]

Thanks for getting this started @IeuanWalker!

I need your help optimizing this a bit. Using var methodText = methodDeclaration.ToString(); is very memory intensive in an Analyzer.

We've gotten in trouble with the Roslyn team for our analyzer performance in Visual Studio before and we need to ensure we don't make the performance of our analyzers worse.

I understand creating analyzers are tricky and using the built-in Roslyn types like InvocationExpressionSyntax and MemberAccessExpressionSyntax are not super intuitive. You can try running this through an agent like CoPilot or Claude to optimize the code using built-in Roslyn types to avoid using .ToString() and thus avoiding its additional memory allocation.

[IeuanWalker]

@TheCodeTraveler thanks, let me know how u get on the copilot.

Atm, the solution isn't building correctly in VS for me to debug so I can see the types, etc.

So if Copilot doesn't work, I'll see if I can spin up a VM in Azure to see if that works.

[TheCodeTraveler]

let me know how u get on the copilot.

You can use any LLM. Claude.ai is my preference. Just copy paste the analyzer code into Claude and tell it to optimize the code using Roslyn syntax.

You can lean on the existing Unit Tests and the new Unit Test you've added to this PR to test the updated analyzer code without needing a debugger.

For now, I cannot merge this PR until you update it.

[IeuanWalker]

@TheCodeTraveler Claude is awesome! been playing with Copilot in VS and been impressed, Claude seems to be on another level.

Took a few iterations to get something to work, but all seems ok now 🤞

From Claude itself -

This version is ultra-optimized:

Zero string allocations - No ToString() calls at all
Direct character access - Uses sourceText[i] indexer
Manual search loop - Avoids any internal string operations
Early termination - Stops as soon as we find a match

Performance improvements:

⚡ No memory allocations for strings
⚡ Direct character comparison
⚡ Cache-friendly sequential access pattern
⚡ Minimal overhead - Just simple loops

This should be the fastest possible version while still being robust enough to handle preprocessor directives!

[IeuanWalker]

Ran the unit tests via cmd line and all pass -

[TheCodeTraveler]

Hey @IeuanWalker! It looks like Claude is hallucinating a bit. The code needs some more work to avoid degrading our benchmarks.

Analyzer Benchmark (main)

Method	Mean	Error	StdDev	Median	Gen0	Gen1	Allocated
VerifyNoErrorsWhenUseMauiCommunityToolkit	7.093 ms	0.2889 ms	0.7908 ms	6.717 ms	93.7500	31.2500	1.65 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitHasAdditionalWhitespace	7.288 ms	0.5125 ms	1.4116 ms	6.503 ms	93.7500	31.2500	1.65 MB
VerifyErrorsWhenMissingUseMauiCommunityToolkit	11.119 ms	1.0230 ms	2.7830 ms	9.683 ms	125.0000	62.5000	2.35 MB

Analyzer Benchmar (this PR)

Method	Mean	Error	StdDev	Median	Gen0	Gen1	Gen2	Allocated
VerifyNoErrorsWhenUseMauiCommunityToolkit	23.946 ms	0.4756 ms	0.8203 ms	23.945 ms	-	-	-	3.54 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitHasAdditionalWhitespace	7.209 ms	0.4074 ms	1.1015 ms	6.767 ms	93.7500	31.2500	-	1.65 MB
VerifyErrorsWhenMissingUseMauiCommunityToolkit	10.242 ms	0.1855 ms	0.5015 ms	10.175 ms	156.2500	93.7500	31.2500	2.29 MB

---

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[IeuanWalker]

@TheCodeTraveler hopefully this is better, im guessing there is still going to be an increase in memory but id think it be marginal.
The updated code still calls .ToString(), but only as a last resort and only on a subset of the syntax tree

[TheCodeTraveler]

Excellent work! I'll copy this implementation across our other analyzers and merge the PR shortly.

Analyzer Benchmark (this PR)

Method	Mean	Error	StdDev	Median	Gen0	Gen1	Allocated
VerifyNoErrorsWhenUseMauiCommunityToolkit	7.610 ms	0.3397 ms	0.9357 ms	7.300 ms	93.7500	31.2500	1.65 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitHasAdditionalWhitespace	7.538 ms	0.2848 ms	0.7699 ms	7.346 ms	93.7500	31.2500	1.65 MB
VerifyErrorsWhenMissingUseMauiCommunityToolkit	12.294 ms	0.7193 ms	2.0169 ms	11.378 ms	133.3333	66.6667	2.36 MB

[Copilot]

Pull Request Overview

This pull request fixes the .UseMauiCommunityToolkit() analyzer to correctly handle cases when the corresponding calls are wrapped in preprocessor directives or commented out.

• Refactored analyzers to extract detection logic into helper methods that check both active syntax nodes and disabled code in trivia.
• Added unit tests to verify the analyzer behavior when the toolkit initialization calls are conditionally compiled or commented out.
• Adjusted type references in tests to align with recent changes.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/CommunityToolkit.Maui.MediaElement.Analyzers/UseCommunityToolkitMediaElementInitializationAnalyzer.cs	Refactored analyzer to use a helper method for call detection in both active code and disabled trivia.
src/CommunityToolkit.Maui.Camera.Analyzers/UseCommunityToolkitCameraInitializationAnalyzer.cs	Similar refactoring for camera analyzer with improved detection of conditional code.
src/CommunityToolkit.Maui.Analyzers/UseCommunityToolkitInitializationAnalyzer.cs	Updated analyzer logic to use a helper method for call detection in active and disabled code.
src/CommunityToolkit.Maui.Analyzers.UnitTests/UseCommunityToolkitMediaElementInitializationAnalyzerTests.cs	Added unit test to validate that preprocessor-wrapped calls do not trigger diagnostics and updated type reference.
src/CommunityToolkit.Maui.Analyzers.UnitTests/UseCommunityToolkitInitializationAnalyzerTests.cs	Added unit tests to verify analyzer behavior when the call is wrapped in preprocessor directives or commented out.
src/CommunityToolkit.Maui.Analyzers.UnitTests/UseCommunityToolkitCameraInitializationAnalyzerTests.cs	Added unit test for verifying analyzer behavior for camera initialization with preprocessor directives.

[TheCodeTraveler]

Thanks again @IeuanWalker! Great job on fixing the bug and improving the Analyzer performance across the board 🙌

Analyzer Benchmarks (this PR)

Method	Mean	Error	StdDev	Median	Gen0	Gen1	Allocated
VerifyNoErrorsWhenUseMauiCommunityToolkit	6.802 ms	0.2621 ms	0.7040 ms	6.454 ms	93.7500	31.2500	1.65 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitHasAdditionalWhitespace	7.131 ms	0.4847 ms	1.3105 ms	6.472 ms	93.7500	31.2500	1.65 MB
VerifyErrorsWhenMissingUseMauiCommunityToolkit	11.226 ms	1.0566 ms	2.8384 ms	9.996 ms	125.0000	62.5000	2.35 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitCamera	6.693 ms	0.5236 ms	1.4067 ms	5.878 ms	93.7500	31.2500	-
VerifyNoErrorsWhenUseMauiCommunityToolkitCameraHasAdditionalWhitespace	6.560 ms	0.3950 ms	1.0544 ms	5.965 ms	93.7500	31.2500	-
VerifyErrorsWhenMissingUseMauiCommunityToolkitCamera	9.735 ms	0.3216 ms	0.8748 ms	9.417 ms	156.2500	93.7500	31.2500
VerifyNoErrorsWhenUseMauiCommunityToolkitMediaElement	6.777 ms	0.4193 ms	1.1337 ms	6.168 ms	93.7500	31.2500	-
VerifyNoErrorsWhenUseMauiCommunityToolkitMediaElementHasAdditionalWhitespace	6.723 ms	0.3987 ms	1.0846 ms	6.121 ms	93.7500	31.2500	-
VerifyErrorsWhenMissingUseMauiCommunityToolkitMediaElement	9.753 ms	0.2622 ms	0.7089 ms	9.479 ms	156.2500	93.7500	31.2500

Analyzer Benchmarks (main)

Method	Mean	Error	StdDev	Median	Gen0	Gen1	Allocated
VerifyNoErrorsWhenUseMauiCommunityToolkit	7.093 ms	0.2889 ms	0.7908 ms	6.717 ms	93.7500	31.2500	1.65 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitHasAdditionalWhitespace	7.288 ms	0.5125 ms	1.4116 ms	6.503 ms	93.7500	31.2500	1.65 MB
VerifyErrorsWhenMissingUseMauiCommunityToolkit	11.119 ms	1.0230 ms	2.7830 ms	9.683 ms	125.0000	62.5000	2.35 MB
VerifyNoErrorsWhenUseMauiCommunityToolkitCamera	6.605 ms	0.3626 ms	0.9678 ms	6.209 ms	93.7500	31.2500	-
VerifyNoErrorsWhenUseMauiCommunityToolkitCameraHasAdditionalWhitespace	6.578 ms	0.3306 ms	0.8939 ms	6.280 ms	93.7500	31.2500	-
VerifyErrorsWhenMissingUseMauiCommunityToolkitCamera	9.803 ms	0.3622 ms	0.9915 ms	9.389 ms	156.2500	93.7500	31.2500
VerifyNoErrorsWhenUseMauiCommunityToolkitMediaElement	6.600 ms	0.3916 ms	1.0653 ms	5.982 ms	93.7500	31.2500	-
VerifyNoErrorsWhenUseMauiCommunityToolkitMediaElementHasAdditionalWhitespace	6.936 ms	0.4109 ms	1.1108 ms	6.460 ms	93.7500	31.2500	-
VerifyErrorsWhenMissingUseMauiCommunityToolkitMediaElement	10.101 ms	0.3188 ms	0.8563 ms	9.834 ms	156.2500	93.7500	31.2500