> ## Documentation Index
> Fetch the complete documentation index at: https://ancplua.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# AL0043 - TrimSafe violation

> [TrimSafe] code must not call methods with [RequiresUnreferencedCode]

Source: [AL0043TrimSafeViolationAnalyzer.cs](https://github.com/ANcpLua/ANcpLua.Analyzers/blob/main/src/ANcpLua.Analyzers/Analyzers/AL0043TrimSafeViolationAnalyzer.cs)

## Description

Code marked with `[TrimSafe]` guarantees it will work correctly in trimmed applications. Calling methods with `[RequiresUnreferencedCode]` violates this guarantee because those methods may fail at runtime when types are trimmed.

## Bad Code

```csharp theme={null}
[TrimSafe]
public void ProcessData(object data) {
    // Warning: violates trim safety
    var json = JsonSerializer.Serialize(data);  // Uses reflection
}

[TrimSafe]
public T CreateInstance<T>() where T : new() {
    // Warning: Activator.CreateInstance uses reflection
    return Activator.CreateInstance<T>();
}
```

## Good Code

```csharp theme={null}
[TrimSafe]
public void ProcessData<T>(T data) {
    // Use source-generated serializer
    var json = JsonSerializer.Serialize(data, MyJsonContext.Default.GetTypeInfo<T>());
}

[TrimSafe]
public T CreateInstance<T>() where T : new() {
    // Direct constructor call - trim safe
    return new T();
}
```

## Properties

* **Category**: Reliability
* **Severity**: Warning
* **Enabled by default**: True
* **Code fix available**: False

## Configuration

```editorconfig theme={null}
dotnet_diagnostic.AL0043.severity = warning
```

## Notes

* Trimming removes unused code to reduce binary size
* Reflection-based code may fail when referenced types are trimmed
* Use source generators instead of reflection for trim-safe code