Fix MA0183 false positive when formatting argument is wrapped in parentheses

[Copilot]

MA0183 incorrectly fires when a formatting argument is wrapped in extra parentheses, even when the format string contains a valid placeholder.

// False positive — format string has {0} but diagnostic is reported
_ = string.Format(CultureInfo.InvariantCulture, SR.PlaceHolder, (obj is null ? string.Empty : "X"));

// Correct — no diagnostic
_ = string.Format(CultureInfo.InvariantCulture, SR.PlaceHolder, obj is null ? string.Empty : "X");

Root cause

HasFormattingArguments skipped arguments where IArgumentOperation.IsImplicit == true. Roslyn sets IsImplicit = true on parenthesized expressions even when ArgumentKind = Explicit, causing the argument to be treated as if it wasn't provided — resulting in a spurious "no formatting arguments" conclusion and a false positive diagnostic.

Fix

• Replace if (arg.IsImplicit) continue; with if (arg.ArgumentKind is ArgumentKind.DefaultValue) continue; in HasFormattingArguments
• DefaultValue correctly identifies arguments that were genuinely omitted (optional parameters using their defaults), without incorrectly skipping parenthesized expressions

Original prompt

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This section details on the original issue you should resolve

<issue_title>MA0183: False positive when using extra parentheses</issue_title>
<issue_description>### Version of the Meziantou.Analyzer NuGet package

3.0.15

Rule Identifier

MA0183

Target Framework

.NET 10.0

C# Language version

C# 14

Description

When the "placeholder" argument to a formatting method is enclosed in extra parentheses, then MA0183 is wrongfully reported.

Reproduction Steps

Minimal code:

using System.Globalization;

_ = string.Format(CultureInfo.InvariantCulture, SR.PlaceHolder, (obj is null ? string.Empty : "X")); // NOK, MA0183 is reported
_ = string.Format(CultureInfo.InvariantCulture, SR.PlaceHolder, obj is null ? string.Empty : "X"); // // OK, MA0183 is not reported

_ = string.Format(CultureInfo.InvariantCulture, SR.NoPlaceHolder, (obj is null ? string.Empty : "X")); // OK, MA0183 is not reported
_ = string.Format(CultureInfo.InvariantCulture, SR.NoPlaceHolder, obj is null ? string.Empty : "X"); // OK, MA0183 is not reported

internal static class SR
{
    public const string PlaceHolder = "Format string with placeholder: '{0}'.";
    public const string NoPlaceHolder = "Format string without placeholder.";
}

Other information

No response</issue_description>

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

• Fixes MA0183: False positive when using extra parentheses #1043

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