Preserve generated model operator parameter names

[Copilot]

Generated model conversion operators could rename parameters from a previous contract, causing CP0017 API compatibility failures.

• Back compatibility
  • Match explicit conversion operators against the last contract by signature.
  • Restore the published parameter name for JSON and XML model operators.
  • Keep the current name when no matching contract exists.

public static explicit operator AcknowledgeResult(Response result)

• Fixes Handle Back Compat In Generated Model Operators Param Names #11669

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npm i https://pkg.pr.new/@typespec/http-client-csharp@11670

commit: ec58d8a

[Copilot]

Pull request overview

This PR updates the C# client generator’s back-compat processing so generated serialization type providers also participate, ensuring public conversion operator parameter names are preserved from the last published contract (preventing CP0017 APICompat breaks like result → response).

Changes:

• Recursively runs back-compat processing for a type’s SerializationProviders so operator/member signature preservation applies to generated serialization partials.
• Updates MrwSerializationTypeDefinition back-compat method handling to run the base back-compat logic specifically for generated operator methods.
• Adds tests + baseline assets verifying operator parameter names are preserved when a last-contract exists, and left as-is when it doesn’t.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/src/Providers/TypeProvider.cs	Ensures back-compat processing is applied to serialization providers, not only top-level providers.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.cs	Applies base back-compat method logic to operator methods to preserve prior parameter names without introducing overloads.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/MrwSerializationTypeDefinitionTests.cs	Adds coverage for parameter name preservation with/without a last-contract baseline.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/ExplicitClientResultOperatorPreservesLastContractParameterName/MockInputModel.cs	Provides last-contract input defining the published operator parameter name (result).
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/ExplicitClientResultOperatorPreservesLastContractParameterName.cs	Expected generated output verifying the preserved operator parameter name when last-contract is present.
packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/MrwSerializationTypeDefinitions/TestData/MrwSerializationTypeDefinitionTests/ExplicitClientResultOperatorKeepsCurrentParameterNameWithoutLastContract.cs	Expected generated output verifying current parameter name is kept when no last-contract exists.

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[Jorge Rangel (jorgerangel-msft)]

Copilot I'd like to see a unit test where TestTypePRovider is setup with serialiation provider that has back compat operators. Then we process both types for back compat and validate the generated code looks as expected

[Copilot]

Copilot I'd like to see a unit test where TestTypePRovider is setup with serialiation provider that has back compat operators. Then we process both types for back compat and validate the generated co...

Added in 1c7536a: a new TypeProviderTests unit test sets up a TestTypeProvider with a serialization provider that has an explicit operator, processes both providers for back-compat, and validates generated code via TestData baselines.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

Suppressed comments (1)

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/ScmOutputLibrary.cs:97

• Adding serialization providers as top-level providers duplicates them: each remains in its model's SerializationProviders, while CSharpGen.cs:98-122 writes both every top-level provider and each provider's serializers, and LibraryVisitor.cs:21-85 visits both paths. This causes every model serialization file to be added and processed twice and can make non-idempotent visitors run twice. Keep TypeProviders unique and instead recurse into SerializationProviders when running back-compatibility processing.

                ..serializationTypes,