Fix MA0011 not reported for types with ToString(IFormatProvider) but no IFormattable

[Copilot]

MA0011 was not reported when a type declares both ToString() and ToString(IFormatProvider) but does not implement IFormattable. The analyzer's culture-sensitivity check would exit early for non-IFormattable types before checking for the overload.

public sealed class Location
{
    public override string ToString() => ToString(CultureInfo.CurrentCulture);
    public string ToString(IFormatProvider formatProvider) => "...";
}

// Previously: no diagnostic
// Now: MA0011 reported
location.ToString();

Changes

• UseIFormatProviderAnalyzer: Added early check for ToString() calls with IFormatProvider overload before culture-sensitive type validation
• Test coverage: Added ToString_WithIFormatProviderOverload_WithoutIFormattable test case

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>MA0011 not reported when type does not implement IFormattable</issue_title>
<issue_description>### Version of the Meziantou.Analyzer NuGet package

2.0.243

Rule Identifier

MA0011

Target Framework

.NET 9.0

C# Language version

4.14.0-3.25412.6 (c167adef)

Description

When a given type does not implement IFormattable and has both a ToString() and a ToString(IFormatProvider), then MA0011 is not reported when ToString() is invoked.

Reproduction Steps

Minimal code:

using System;
using System.Globalization;

internal sealed class Program
{
    private static void Main()
    {
        Location location = new()
            {
                Start = 1,
                End = 5
            };
        Console.WriteLine(location.ToString());
    }
}

public sealed class Location
{
    public required int Start { get; init; }

    public required int End { get; init; }

    public override string ToString()
    {
        return ToString(CultureInfo.CurrentCulture);
    }

    public string ToString(IFormatProvider formatProvider)
    {
        return string.Empty;
    }
}

Other information

No response</issue_description>

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

• Fixes MA0011 not reported when type does not implement IFormattable #909

---

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[Copilot]

Pull Request Overview

This PR refactors the OverloadFinder API to use new structured types (OverloadOptions and OverloadParameterType) for better encapsulation and extensibility. It also enhances the culture-sensitive type detection to recognize types with ToString(IFormatProvider) methods even when they don't implement IFormattable.

• Introduced OverloadOptions record struct to consolidate multiple boolean and nullable parameters into a single options object
• Introduced OverloadParameterType record struct to support inheritance-based type matching for overload parameters
• Enhanced IsCultureSensitiveType logic to detect types with ToString(IFormatProvider) overloads that don't implement IFormattable

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Meziantou.Analyzer/Internals/OverloadParameterType.cs	New record struct for parameter type specification with optional inheritance support
src/Meziantou.Analyzer/Internals/OverloadOptions.cs	New record struct to consolidate overload finder options
src/Meziantou.Analyzer/Internals/OverloadFinder.cs	Refactored to use new option types, added overloads for IOperation types, and improved type matching logic
src/Meziantou.Analyzer/Internals/CultureSensitiveFormattingContext.cs	Enhanced to detect formattable types without IFormattable interface; moved format provider check earlier
src/Meziantou.Analyzer/Rules/UseIFormatProviderAnalyzer.cs	Updated to use new OverloadFinder API with OverloadOptions
src/Meziantou.Analyzer/Rules/UseStringComparisonAnalyzer.cs	Updated to use new OverloadFinder API with OverloadOptions
src/Meziantou.Analyzer/Rules/UseStringComparerAnalyzer.cs	Updated to use new OverloadFinder API with OverloadOptions
src/Meziantou.Analyzer/Rules/UseAnOverloadThatHasTimeProviderAnalyzer.cs	Updated to use new OverloadFinder API with OverloadOptions
src/Meziantou.Analyzer/Rules/UseAnOverloadThatHasCancellationTokenAnalyzer.cs	Updated to use new OverloadFinder API with OverloadOptions
src/Meziantou.Analyzer/Rules/EmbedCaughtExceptionAsInnerExceptionAnalyzer.cs	Updated to use new OverloadFinder API with OverloadOptions
src/Meziantou.Analyzer/Rules/DoNotUseBlockingCallInAsyncContextAnalyzer.cs	Updated to use new static HasSimilarParameters API
tests/Meziantou.Analyzer.Test/Rules/UseIFormatProviderAnalyzerTests.cs	Added test for types with ToString(IFormatProvider) overload without IFormattable