TRLS004 — Result is double-wrapped

• Severity: Warning
• Category: Trellis

What it detects

Flags declared or inferred Result<Result<T>>, and also flags Result.Ok(existingResult) or Result.Fail(existingResult) when the value is already a Result<T>.

Why it matters

Double-wrapped results are awkward to handle and usually mean the pipeline used Map where Bind was intended.

Warning

A nested Result is almost never the domain model you actually want. It usually signals a flattened pipeline that never got flattened.

Bad example

using Trellis;

static class Example
{
    public static Result<Result<int>> Bad() =>
        Result.Ok(Result.Ok(42));
}

Good example

using Trellis;

static class Example
{
    public static Result<int> Good() =>
        Result.Ok(42);
}

Code fix available

No.

Configuration

Use standard Roslyn configuration if you need to suppress this rule in a specific scope.

dotnet_diagnostic.TRLS004.severity = none

#pragma warning disable TRLS004
// Intentional: documented exception or test-only pattern.
#pragma warning restore TRLS004

Tip

If the inner expression already returns Result<T>, switch to Bind or return the inner result directly.