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LDC-E2112 — A refinement inside a variant case field

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# LDC-E2112 — A refinement inside a variant case field

## What it means

Variant case fields carry a plain type and nothing more: a `where`
refinement on a field has no executable meaning yet, and accepting it
would pretend a check exists that never runs. The compiler rejects the
refinement at the field rather than lowering a promise it cannot keep.

Dropping the refinement and keeping the bare type is the fix. Any
condition the refinement expressed belongs in a rule, where it is
actually evaluated.

## Example

```law
language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

type Identifier = Checked { value: Text where self == self; } | Anonymous;
```

## Fix

```law
language "law.core" version "0.2";
package demo.diagnostics version "0.1.0";
namespace "urn:law:demo:diagnostics";

type Identifier = Checked { value: Text; } | Anonymous;
```

## Engine message

The engine reports this in its own wording:

```text
example.law:5:29: error LDC-E2112: variant type "Identifier", case "Checked", field "value": refinement `where` is not yet supported in M1 — there is no executable typed binding (§39/§41)
```

## Related

- [Vocabulary](/constructs/vocabulary/) — how variant types declare their cases.