[tcgc] Support @typespec/openapi3 in scope

[wanlwanl]

Clear and concise description of the problem

openapi3 and TCGC are used together for service team now. e.g. https://github.com/Azure/azure-rest-api-specs/blob/main/specification/ai/OpenAI.Assistants/tspconfig.yaml#L10

But the current implemetation doesn't support @typespec/openapi3 due to:

typespec-azure/packages/typespec-client-generator-core/src/internal-utils.ts

Line 74 in 0ec0106

const regex = /(?:cadl|typespec|client|server)-([^\\/-]*)/;

Please support @typespec/openapi3 in scope

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For feature request in the typespec language or core libraries file it in the TypeSpec repo
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[timotheeguerin]

there is 2 things here:

1. openapi3 shouldn't use tcgc anyway, what are you trying to do?
2. the scope here should always allow the emitter full name

[wanlwanl]

@timotheeguerin

1. I'm trying set @clentname with scope. java emitter and autorest emitter has different behaviors as you share screen before. When openAPI's version increases inthe future, I feel like we might need to customize some where. e.g. OpenAI.Assistants used tcgc and emit OAS3. https://github.com/Azure/azure-rest-api-specs/blob/main/specification/ai/OpenAI.Assistants/client.tsp .
2. No, I tried: [DO NOT REVIEW] Test scope #1751
   I got

AssertionError: Expected values to be strictly equal:
+ actual - expected

+ 'Test'
- 'TestOAS3'
       ^

Expected: "TestOAS3"
Received: "Test"

[timotheeguerin]

For 2. I mean this should be how it works, and it was supposed to work that way with tcgc so they definitely have a bug if it doesn't.

For 1. there is 2 reason why it doesn't make sense to support in openapi3:

1. this is an azure library, none of the @typespec/ packages should be using them
2. OpenAPI doesn't describe client, it describe the service contract. There is nowhere to put a client name in the spec apart from using x- extensions and we explicitly don't want the openapi3 emitter to have any of those. Autorest swagger emits it because it target the augmented version of swagger 2.0 meant for autorest.

[wanlwanl]

Thanks for the explain. I thought we need to keep the same behavior to autorest swagger.