C# Academy · Lesson

Trimming & Reflection Limitations

Handle trim warnings, use [DynamicallyAccessedMembers], and replace runtime reflection with source-generated alternatives.

What Is IL Trimming?

IL Trimming is a publish-time optimization that removes unused types, methods, and assemblies from the output. The result is a smaller executable. It is automatically enabled for Native AOT and self-contained single-file publishes.

Enabling Trimming

Enable trimming in the project file. You can control the trim mode from partial (trim unused assemblies only) to full (trim unused members within assemblies).

// .csproj
<PropertyGroup>
  <!-- Enable trimming on publish -->
  <PublishTrimmed>true</PublishTrimmed>

  <!-- full: aggressive — trims unused members within assemblies
       partial: conservative — only removes unused assemblies -->
  <TrimMode>full</TrimMode>

  <!-- Treat all trimmer warnings as errors (recommended for CI) -->
  <TrimmerRootAssemblies>MyApp</TrimmerRootAssemblies>
  <SuppressTrimAnalysisWarnings>false</SuppressTrimAnalysisWarnings>
</PropertyGroup>

// Publish:
dotnet publish -c Release -r linux-x64 --self-contained

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