All VoloGen diagnostics use the VoloGen category and are errors by default. Diagnostic messages are localized via .resx resource files.

VG0001

MissingTryParseMethod

Trigger: [AutoParsable] is applied to a type that does not define the required core method.

Required signature:

public static bool TryParse(ReadOnlySpan<char> s, IFormatProvider? provider, out T result)

Fix: Add the TryParse method with the exact signature shown above to the annotated type.

VG0002

MustBePartial

Trigger: Any VoloGen attribute is applied to a type that is not declared as partial.

Fix: Add the partial modifier to the type declaration.

- [AutoEquality]
- public struct UserId { ... }
+ [AutoEquality]
+ public partial struct UserId { ... }

VG0003

CannotBeStatic

Trigger: Any VoloGen attribute is applied to a static type.

Fix: Remove the static modifier. Source generators add instance members that cannot exist on static types.

- [AutoEquality]
- public static partial class Utilities { ... }
+ [AutoEquality]
+ public partial class Utilities { ... }

VG0004

CannotBeAbstract

Trigger: [AutoParsable] is applied to an abstract type.

Fix: Remove the abstract modifier or use a concrete type.

VG0005

MissingComparableField

Trigger: [AutoComparable]

Required signature:

public static int Compare(T left, T right)

Fix: Add the Compare method with the exact signature shown above to the annotated type.

VG0006

MissingEquatableField

Trigger: [AutoEquality]

Required signatures:

public static bool Equal(T left, T right)
public override int GetHashCode()

Fix: Ensure both methods are present on the annotated type.

VG0007

MissingTryFormatMethod

Trigger: [AutoFormattable]

Required signature:

public bool TryFormat(Span<char> destination, out int charsWritten,
    ReadOnlySpan<char> format, IFormatProvider? provider)

Fix: Add the TryFormat method with the exact signature shown above to the annotated type.

VG0008

MissingToStringOrMaxBufferSize

Trigger: [AutoFormattable] is applied to a type that has TryFormat but provides neither a custom ToString(string?, IFormatProvider?) method nor a const int MaxBufferSize field.

The generator needs one of these to produce the ToString overload:

  • const int MaxBufferSize – the generator creates a stackalloc / ArrayPool<char>-backed ToString
  • string ToString(string?, IFormatProvider?) – the generator uses your method directly

Fix: Add either a MaxBufferSize constant or a ToString(string?, IFormatProvider?) method.

// Option A: MaxBufferSize
public const int MaxBufferSize = 64;

// Option B: Custom ToString
public string ToString(string? format, IFormatProvider? provider)
{
    return _value.ToString(format, provider);
}

Localization

All diagnostic messages are localized via .resx resource files in the VoloGen.Common project. Currently supported locales include:

  • English (default)
  • German (de)
  • Spanish (es)
  • French (fr)
  • Japanese (ja)
  • Korean (ko)
  • Portuguese – Brazil (pt-BR)
  • Ukrainian (uk)
  • Chinese – Simplified (zh-Hans)