[Bug]: How to locate/decorate union variant in union?

[MaryGao]

Describe the bug

Say we have following spec and we want to add a better name for enum item 3, but the compile reports errors. Is this a bug?

import "@typespec/http";
import "@azure-tools/typespec-client-generator-core";

using TypeSpec.Http;
using Azure.ClientGenerator.Core;

union ExtensibleNumber {
  One: 1,
  Two: 2,
  3,
  int8,
}
model Foo {
  extensibleNumber: ExtensibleNumber;
}
op post(@body body: Foo): void;

@@clientName(ExtensibleNumber.One, "ItemOne");
@@clientName(ExtensibleNumber.Two, "ItemTwo");
@@clientName(ExtensibleNumber.`3`, "ItemThree");

Reproduction

playground

Checklist

• Follow our Code of Conduct
• Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion.
• The provided reproduction is a minimal reproducible example of the bug.

[markcowl]

@markcowl look for design issue on referencing union variants

[markcowl]

@MaryGao It is by design that union variants cannot be decorated, and so cannot be referenced in augment decorators. The workaround would be to create a scalar type with the needed decoration and use that as the union variant. You can also use enums for these scenarios, as shown here

[MaryGao]

@markcowl thanks for the info. With the union as enum feature in azure, emitters would have the requirement to emit a member name and rename it if necessary. So I was wondering if we could add this ability using type metadata(::) similar to model expression.

I notice that union variant without a name is common usage for customers e.g example spec. I was also wondering if we should add a linter in azure to warn always having a variant member name.