Don't offer "Introduce parameter" on member initializer names

[Copilot]

Summary: Fix "Introduce parameter for" on member initializer left-hand side

This PR fixes the issue where the "Introduce parameter for" refactoring was incorrectly being offered on the left-hand side (member name) of member initializers.

Problem

When the user placed the cursor on the identifier in the name position of a member initializer (e.g., a in new { a = ... } or X in new Foo { X = ... }), the "Introduce parameter" refactoring was offered. This doesn't make sense because the identifier represents the member name, not a value that could be parameterized.

Solution

Added validation in IsValidExpression to detect and exclude these cases:

1. For regular object initializers (new Foo { X = ... }): The existing IsMemberInitializerNamedAssignmentIdentifier method already handles this case.

2. For anonymous object initializers (new { a = ... }): Added a new abstract method IsAnonymousObjectMemberDeclaratorNameIdentifier with language-specific implementations:

   • C#: Checks if expression is an IdentifierNameSyntax → NameEqualsSyntax → AnonymousObjectMemberDeclaratorSyntax
   • VB: Checks if expression is an IdentifierNameSyntax → NamedFieldInitializerSyntax → AnonymousObjectCreationExpressionSyntax

Changes Made

• AbstractIntroduceParameterCodeRefactoringProvider.cs: Added abstract method and updated IsValidExpression to check both cases
• CSharpIntroduceParameterCodeRefactoringProvider.cs: Implemented C#-specific check for anonymous object member names
• VisualBasicIntroduceParameterCodeRefactoringProvider.vb: Implemented VB-specific check for anonymous object member names
• IntroduceParameterTests.cs: Added 4 new tests with WorkItem attributes to verify the refactoring is not offered on member initializer names

Testing

• ✅ All new tests pass with proper WorkItem attribution
• ✅ Tests use 'Goo' naming convention per code review feedback
• ✅ Code builds successfully for both C# and VB
• ✅ Security check completed (no issues found)

Checklist:

• Understand the issue and investigate the codebase
• Add abstract method IsAnonymousObjectMemberDeclaratorNameIdentifier
• Implement the method in C# provider
• Implement the method in VB provider
• Update IsValidExpression to use both checks
• Add tests for anonymous object member initializers
• Add tests for regular object initializers
• Build and verify the changes compile successfully
• Run new tests to verify refactoring is not offered
• Address code review feedback (use 'Goo', add WorkItem attributes)
• Run security checks

Original prompt

---

This section details on the original issue you should resolve

<issue_title>"Introduce parameter for" produces invalid code for nested anonymous type</issue_title>
<issue_description>Version Used: VS 18.0.0 Insiders [11201.2]

Steps to Reproduce:
At the marked location, open the lightbulb menu and select "Introduce parameter for 'a'" > "into extracted method to invoke at callsites".

class C
{
    object M() => new
    {
        $$a = new { },
    };
}

Expected Behavior:
Valid, compilable code is produced.

Actual Behavior:
Uncompilable code is generated:

class C
{
    private global::System.Object GetA() // <- Name is not simplified
    {
        return a; // CS0103: The name 'a' does not exist in the current context
    }

    object M(var a) => new
//           ~~~ CS0825: The contextual keyword 'var' may only appear within a local variable declaration or in script code
    {
        a = new { },
    };
}

<agent_instructions>@copilot 'introduce parameter for' should not be offered on the left-hand-side of a member-initializer. That includes a member initializer in an anonymous type (like new { X = ... }) or a normal type (like new Foo { X = ... })</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes "Introduce parameter for" produces invalid code for nested anonymous type #81013

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[CyrusNajmabadi]

@copilot use 'Goo' instead of 'Foo' in all tests.
use [Fact, WorkItem("...")] for all the tests you added.

[Copilot]

Done in 0cc1448. Renamed 'Foo' to 'Goo' in all tests and added WorkItem attributes with the issue URL.