Update logging source generator to match runtime PR #124589 (ref readonly/params/scoped)

[Copilot]

Aligns Microsoft.Gen.Logging source generator with dotnet/runtime#124589, which changed how params, ref readonly, and scoped parameter modifiers are handled in [LoggerMessage] methods.

Key changes

• Parser — Added params and scoped checks that emit new LOGGEN039 diagnostic; added RefKind.RefReadOnlyParameter handling. Scoped check is ordered after the ref/out check because out parameters are implicitly scoped in C# 11+.
• Model — Removed IsScoped from LoggingMethodParameter (no longer needed since scoped is forbidden rather than supported).
• Emitter — Removed scoped prefix generation from GenParameters.
• Diagnostics — New LOGGEN039 covers both params and scoped modifiers.

Example

// ref readonly — now supported, qualifier preserved in generated method
[LoggerMessage(0, LogLevel.Info, "Value: {x}")]
static partial void LogValue(ILogger logger, ref readonly int x); // ✅

// params — new LOGGEN039 error
[LoggerMessage(1, LogLevel.Info, "Values")]
static partial void LogValues(ILogger logger, params int[] values); // ❌ LOGGEN039

// scoped — new LOGGEN039 error  
[LoggerMessage(2, LogLevel.Info, "Value: {x}")]
static partial void LogScoped(ILogger logger, scoped ref readonly int x); // ❌ LOGGEN039

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[Copilot]

Pull request overview

This PR ports changes from dotnet/runtime#124589 to add support for ref readonly and scoped parameter modifiers in the logging source generator, and adds a new diagnostic (LOGGEN039) to forbid params parameters which were previously silently generating broken code.

Changes:

• Added support for ref readonly parameters by handling RefKind.RefReadOnlyParameter in the parser and preserving the ref readonly qualifier in generated signatures
• Added support for scoped modifier by tracking IsScoped in the LoggingMethodParameter model and emitting it in the generated parameter list
• Added LOGGEN039 diagnostic to produce a compile-time error for params parameters instead of silently generating incorrect code

Reviewed changes

Copilot reviewed 9 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/Shared/DiagnosticIds/DiagnosticIds.cs	Added LOGGEN039 diagnostic ID constant
src/Generators/Microsoft.Gen.Logging/Parsing/Resources.resx	Added error message resources for params parameter diagnostic
src/Generators/Microsoft.Gen.Logging/Parsing/Resources.Designer.cs	Auto-generated resource accessor code for LOGGEN039 messages
src/Generators/Microsoft.Gen.Logging/Parsing/DiagDescriptors.cs	Added LoggingMethodParameterParams diagnostic descriptor
src/Generators/Microsoft.Gen.Logging/Parsing/Parser.cs	Added params detection, ref readonly support, and scoped tracking
src/Generators/Microsoft.Gen.Logging/Model/LoggingMethodParameter.cs	Added IsScoped field to track scoped modifier
src/Generators/Microsoft.Gen.Logging/Emission/Emitter.Method.cs	Updated parameter generation to emit scoped prefix when needed
test/Generators/Microsoft.Gen.Logging/Unit/ParserTests.LogMethod.cs	Added unit tests for params, ref readonly, and scoped modifiers
test/Generators/Microsoft.Gen.Logging/TestClasses/RefReadOnlyParameterTestExtensions.cs	Added test class with ref readonly and scoped ref readonly methods
test/Generators/Microsoft.Gen.Logging/Generated/LogMethodTests.cs	Added runtime test for ref readonly parameters
docs/list-of-diagnostics.md	Documented LOGGEN039 diagnostic

Files not reviewed (1)

• src/Generators/Microsoft.Gen.Logging/Parsing/Resources.Designer.cs: Language not supported