MA0011: suppress diagnostic when all AppendFormat template arguments are culture-insensitive

[Copilot]

MA0011 was incorrectly flagged on StringBuilder.AppendFormat calls where every template argument is culture-insensitive (strings, chars, booleans, positive integers, etc.), because CultureSensitiveFormattingContext.IsCultureSensitiveOperation had no special handling for AppendFormat and defaulted to true.

Changes

• CultureSensitiveFormattingContext.cs: Added AppendFormat handling on StringBuilder mirroring the existing string.Format logic — skips the format-string argument, then checks each template argument; returns false if none are culture-sensitive. Handles the params object[], collection-expression (Roslyn 4.14+), and individual-argument overload shapes.

• UseIFormatProviderAnalyzerTests.cs: Updated the existing AppendFormat("{0}", 10) test (positive int → not culture-sensitive, no longer warrants a diagnostic; changed to -1); added no-diagnostic cases for "{0} / {1}", "X", "Y" and "{0}", 10.

Example

var sb = new StringBuilder();
sb.AppendFormat("{0} / {1}", "X", "Y");   // no longer reported
sb.AppendFormat("{0}", 10);               // no longer reported (positive int)
sb.AppendFormat("{0}", -1);              // still reported (negative int is culture-sensitive)

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• st8vsblobprodcus339.vsblob.vsassets.io
  • Triggering command: /usr/share/dotnet/dotnet dotnet restore --no-dependencies /home/REDACTED/work/Meziantou.Analyzer/Meziantou.Analyzer/Meziantou.Analyzer.slnx --packages /tmp/codeql-scratch-8ad8dc5536a632e8/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/tmp/codeql-scratch-8ad8dc5536a632e8/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/tmp/codeql-scratch-8ad8dc5536a632e8/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)
  • Triggering command: /usr/share/dotnet/dotnet dotnet restore --no-dependencies /home/REDACTED/work/Meziantou.Analyzer/Meziantou.Analyzer/tests/Meziantou.Analyzer.Test/Meziantou.Analyzer.Test.csproj --packages /tmp/codeql-scratch-8ad8dc5536a632e8/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/tmp/codeql-scratch-8ad8dc5536a632e8/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/tmp/codeql-scratch-8ad8dc5536a632e8/dbs/csharp/working/emptyFakeDotnetRoot /p:AllowMissingPrunePackageData=true (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)