Fix IDE0032: Code fixer adds setter for static properties with instance constructor writes

[Copilot]

The IDE0032 code fixer incorrectly produced invalid code when a static field was assigned in an instance constructor, resulting in CS0200 (cannot assign to read-only property).

// Before: Valid code
private static Test? s_instance;
public static Test Instance => s_instance!;

public Test() { s_instance = this; }  // Instance ctor writes static field

// After applying old fix: Compiler error CS0200
public static Test Instance => field!;

public Test() { Instance = this; }  // Cannot assign to static read-only property

Changes

Code fixer logic (AbstractUseAutoPropertyCodeFixProvider.cs)

• Modified constructor filtering to match static-ness of the field
• For static fields, only static constructors are considered valid initialization contexts
• For instance fields, only instance constructors are considered valid initialization contexts
• Instance constructor writes to static fields are now treated as "outside constructor", causing a private setter to be added

Result
The code fixer now generates valid code with a private setter:

public static Test Instance { get; private set; }

public Test()
{
    Instance = this;  // Valid - property has a setter
}

Tests

• Static field + instance constructor write → property with private setter

• Static field + static constructor write → property with initializer (no setter needed)

• Static field with existing setter + instance constructor write → property preserves setter

• Fixes IDE0032 code fixer produces invalid code for static field assigned in constructor #81320

Original prompt

---

This section details on the original issue you should resolve

<issue_title>IDE0032 code fixer produces invalid code for static field assigned in constructor</issue_title>
<issue_description>Version Used:
Visual Studio 2026 v18.0.0
.NET 10

Steps to Reproduce:

1. Use the following minimal code sample:

   public sealed class Test
   {
       private static Test? s_instance;
       public static Test Instance => s_instance!;
   
       public Test()
       {
           s_instance = this;
       }
   }

2. Observe that the analyzer reports IDE0032 for s_instance.

3. Apply the code fix suggested by the IDE.

4. Observe that the produced code cannot be compiled.

Diagnostic Id:
IDE0032: Use auto-implemented property

Expected Behavior:
The code fixer should not create invalid code that will not compile.

Actual Behavior:

The code fixer rewrites the class to:

public sealed class Test
{
    public static Test Instance => field!;

    public Test()
    {
        Instance = this;
    }
}

This results in the following compiler error:

CS0200: Property or indexer 'Test.Instance' cannot be assigned to — it is read only
```</issue_description>

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

<comments>
</comments>

• Fixes IDE0032 code fixer produces invalid code for static field assigned in constructor #81320

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[CyrusNajmabadi]

@copilot the analyzer/fixer checks if there are writes to the field to determine if it should make a private setter. However it ignores writes inside of constructors (as a private setter isn't needed for an instance property in that case).

However, as this is a static property we should not ignore instance constructor writes.

[Copilot]

@copilot the analyzer/fixer checks if there are writes to the field to determine if it should make a private setter. However it ignores writes inside of constructors (as a private setter isn't needed ...

Fixed in dafbf3f. The code fixer now filters constructors by static-ness - for static fields, only static constructors are included when determining if writes are "outside constructor". Instance constructor writes to static fields now correctly trigger a private setter to be added.