Isolate C# back-compat parameter renaming from serialization

[Copilot]

With a back-compat contract loaded, restoring historical public constructor names mutated variable expressions shared with serialization parameters. Azure management’s name-based constructor repair then discarded parsed Boolean/enum arguments, removed their declarations, and substituted defaults.

• Parameter ownership: Give public input variants independent variable expressions while retaining property/field associations and wire metadata.
• Compatibility: Preserve historical public parameter names and custom constructor associations; keep internal serialization identifiers aligned with native properties.
• Regression coverage: Add loaded-contract and no-back-compat cases covering renamed Boolean/enum properties, optional enums, retained aliases, generated compilation, and true/false deserialization. Update only affected internal-constructor baselines.

The serialization path consistently retains the parsed value:

bool isEnabled = default;

// Inside the JSON-property loop:
isEnabled = prop.Value.GetBoolean();

return new VirtualNetworkEncryption(
    isEnabled, enforcement, additionalBinaryDataProperties);

• Fixes [http-client-csharp] Renamed property deserialization emits undeclared variable and default constructor argument with a back-compat version #12148

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[pkg-pr-new]

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npm i https://pkg.pr.new/@typespec/http-client-csharp@12164

commit: 95cde59

[Copilot]

🟢 Approval recommended

The focused ownership change preserves public compatibility while comprehensive regression coverage verifies serialization correctness.

0 open findings

What changed in this PR

Isolates public constructor parameter renaming from internal serialization variables, preventing renamed Boolean and enum values from being discarded during deserialization.

Changes:

• Gives public input parameters independent variable expressions.
• Updates internal-constructor baselines.
• Adds back-compatibility, compilation, alias, and runtime deserialization coverage.

File	Description
ParameterProvider.cs	Stops public input variants from sharing serialization variables.
ParameterProviderTests.cs	Verifies independent variable ownership.
BackCompat_ConstructorSameTypedNonExactParameterIsRestoredWithExactRename.cs	Updates internal-constructor baseline.
BackCompat_ConstructorParameterRenameRestoredBySignatureMatch.cs	Updates renamed-parameter baseline.
BackCompat_ConstructorParameterPreservesDateTimeSuffix.cs	Updates DateTime parameter baseline.
BackCompat_ConstructorParameterChainedRenameRestoredBySignatureMatch.cs	Updates chained-rename baseline.
BackCompat_ConstructorParameterCasingAndRotationRestoredBySignatureMatch(Casing).cs	Updates casing baseline.
BackCompat_ConstructorNonExactParameterIsRestoredWithExactRename.cs	Updates non-exact rename baseline.
BackCompat_RenamedPropertiesKeepSerializationParameters(Previous)/​MockInputModel.cs	Defines the previous public contract.
BackCompat_RenamedPropertiesKeepSerializationParameters(Custom)/​MockInputModel.cs	Defines retained compatibility aliases.
BackCompat_RenamedPropertiesKeepSerializationParameters(Context).cs	Supplies compilation test context.
BackCompat_RenamedPropertiesKeepSerializationParameters.cs	Captures expected deserializer output.
SerializationCustomizationTests.cs	Adds loaded-contract, control, compilation, and runtime regression tests.

🧠 Review effort: Balanced

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[Copilot]

🟡 Changes recommended

The regression lacks the promised full generated compilation and runtime Boolean deserialization validation.

1 open finding

• Add integration test for generated compilation and Boolean preservation · New

🧠 Review effort: Balanced

[Jorge Rangel (jorgerangel-msft)]

Copilot there's test failures we need to address. Ensure we rerun Generate.ps1 and all spector tests are passing:

ersioning.TypeChangedFrom.V1 -> /mnt/vss/_work/1/s/packages/http-client-csharp/generator/artifacts/bin/Versioning.TypeChangedFrom.V1/Debug/net8.0/Versioning.TypeChangedFrom.V1.dll
  Failed PublicInputVariantPreservesVariableAndMetadata [17 ms]
  Error Message:
     Expected: same as <VariableExpression { Type = global::System.Collections.Generic.IList<string>, Declaration = Microsoft.TypeSpec.Generator.Primitives.CodeWriterDeclaration }>
  But was:  <VariableExpression { Type = global::System.Collections.Generic.IEnumerable<string>, Declaration = Microsoft.TypeSpec.Generator.Primitives.CodeWriterDeclaration }>

  Stack Trace:
     at Microsoft.TypeSpec.Generator.Tests.Providers.ParameterProviderTests.PublicInputVariantPreservesVariableAndMetadata() in /mnt/vss/_work/1/s/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator/test/Providers/ParameterProviderTests.cs:line 229

1)  

[Copilot]

🔵 Needs a closer look

The regression test does not yet compile generated output or verify true/false deserialization as promised.

0 open findings

1 resolved since last review

• Add integration test for generated compilation and Boolean preservation

🧠 Review effort: Balanced