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NDLRGEN052: Custom constructor guard method is ambiguous

Cause

More than one accessible static method with the guard's method name is compatible with the guarded field or property type on the referenced guard type.

Rule Description

Overload resolution for a custom guard method is intentionally simple and direct rather than full C# overload resolution: the generator requires exactly one accessible static method compatible with (value, string parameterName) for the guarded member's type. When two or more overloads are all compatible -- for example, two overloads that both accept the member's type through different generic constraints, or an exact match plus a compatible base-type overload -- the generator has no principled way to prefer one over the other, so it reports the ambiguity instead of guessing.

How to Fix

Remove or rename the extra overload(s) so exactly one method matches the guarded member's type, or select the intended overload with an explicit method name:

using NexusLabs.Needlr.Generators;

public static class OrderGuards
{
    // WRONG - NDLRGEN052: both overloads are compatible with IReadOnlyCollection<string>
    public static void Validate(IReadOnlyCollection<string> value, string parameterName) { }
    public static void Validate<T>(IReadOnlyCollection<T> value, string parameterName) { }
}

[GenerateConstructor]
public partial class OrderService
{
    [ConstructorGuard(typeof(OrderGuards))]
    private readonly IReadOnlyCollection<string> _orders;
}

// CORRECT - only one overload remains, or select one explicitly by name
public static class OrderGuards
{
    public static void ValidateNotEmpty(IReadOnlyCollection<string> value, string parameterName) { }
}

[GenerateConstructor]
public partial class OrderService
{
    [ConstructorGuard(typeof(OrderGuards), nameof(OrderGuards.ValidateNotEmpty))]
    private readonly IReadOnlyCollection<string> _orders;
}

See Also