Diagnostics

The TeaLeaf source generator reports diagnostics (warnings and errors) through the standard C# compiler diagnostic system.

Diagnostic Codes

TL001: Type Must Be Partial

The source generator needs to add methods to your class. This requires the partial modifier.

// ERROR: TL001
[TeaLeaf]
public class User { }  // Missing 'partial'

// FIXED
[TeaLeaf]
public partial class User { }

TL002: Unsupported Property Type

A property type isn’t directly mappable to a TeaLeaf type.

[TeaLeaf]
public partial class Config
{
    public IntPtr NativeHandle { get; set; }  // WARNING: TL002
}

The property will be skipped. Supported types include all primitives, string, DateTime, DateTimeOffset, byte[], List<T>, Dictionary<string, T>, enums, and other [TeaLeaf]-annotated classes.

TL003: Invalid TLType Value

The [TLType] attribute was given an unrecognized type name.

[TeaLeaf]
public partial class Event
{
    [TLType("datetime")]   // ERROR: TL003 -- "datetime" is not a valid type
    public long Created { get; set; }

    [TLType("timestamp")]  // CORRECT
    public long Updated { get; set; }
}

Valid values: bool, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, float, float32, float64, string, bytes, timestamp.

TL004: Nested Type Not Annotated

A property references a class type that doesn’t have the [TeaLeaf] attribute.

public class Address  // Missing [TeaLeaf]
{
    public string City { get; set; } = "";
}

[TeaLeaf]
public partial class User
{
    public Address Home { get; set; } = new();  // WARNING: TL004
}

Fix by adding [TeaLeaf] to the nested type:

[TeaLeaf]
public partial class Address
{
    public string City { get; set; } = "";
}

TL005: Circular Type Reference

A type references itself (directly or transitively), which may cause a stack overflow at runtime during serialization.

[TeaLeaf]
public partial class TreeNode
{
    public string Name { get; set; } = "";
    public TreeNode? Child { get; set; }  // WARNING: TL005 -- circular reference
}

The code will still compile, but recursive structures must be bounded (e.g., use [TLOptional] with null termination) to avoid infinite recursion.

TL006: Open Generic Types

Generic type parameters are not supported:

// ERROR: TL006
[TeaLeaf]
public partial class Container<T>
{
    public T Value { get; set; }
}

Use concrete types instead. For generic scenarios, use the Reflection Serializer.

Viewing Diagnostics

Diagnostics appear in:

• Visual Studio – Error List window
• VS Code – Problems panel (with C# extension)
• dotnet build – terminal output
• MSBuild – build log

Example compiler output:

User.cs(3,22): error TL001: TeaLeaf type 'User' must be declared as partial
Config.cs(8,16): warning TL004: Property 'Address' type is not annotated with [TeaLeaf]