Address post-merge feedback on TimeZoneInfo display names PR

src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Win32.cs

@@ -5,11 +5,10 @@
 using System.Diagnostics;
 using System.Globalization;
 using System.IO;
+using System.Runtime.InteropServices;
 using System.Security;
 using System.Threading;
 
-using Microsoft.Win32.SafeHandles;
-
 using Internal.Win32;
 
 using REG_TZI_FORMAT = Interop.Kernel32.REG_TZI_FORMAT;
@@ -36,8 +35,8 @@ public sealed partial class TimeZoneInfo
  private const int MaxKeyLength = 255;
  private const string InvariantUtcStandardDisplayName = "Coordinated Universal Time";
 
- private static readonly Dictionary<string, string> s_FileMuiPathCache = new();
- private static readonly TimeZoneInfo s_utcTimeZone = CreateUtcTimeZone();
+ private static readonly Dictionary<string, string> s_fileMuiPathCache = new();
+ private static readonly TimeZoneInfo s_utcTimeZone = CreateUtcTimeZone(); // must be initialized after s_fileMuiPathCache
 
  private sealed partial class CachedData
  {
@@ -749,19 +748,19 @@ private static string GetCachedFileMuiPath(string filePath, CultureInfo cultureI
  string? result;
  string cacheKey = $"{cultureInfo.Name};{filePath}";
 
- lock (s_FileMuiPathCache)
+ lock (s_fileMuiPathCache)
  {
- if (s_FileMuiPathCache.TryGetValue(cacheKey, out result))
+ if (s_fileMuiPathCache.TryGetValue(cacheKey, out result))
  {
  return result;
  }
  }
 
  result = GetFileMuiPath(filePath, cultureInfo);
 
- lock (s_FileMuiPathCache)
+ lock (s_fileMuiPathCache)
  {
- s_FileMuiPathCache.TryAdd(cacheKey, result);
+ s_fileMuiPathCache.TryAdd(cacheKey, result);
  }
 
  return result;
@@ -787,6 +786,7 @@ private static unsafe string GetFileMuiPath(string filePath, CultureInfo culture
  Interop.Kernel32.MUI_USE_INSTALLED_LANGUAGES,
  filePath, language, ref languageLength,
  fileMuiPath, ref fileMuiPathLength, ref enumerator);
+ fileMuiPath[Interop.Kernel32.MAX_PATH] = '\0';
 
  if (!succeeded)
  {
@@ -802,33 +802,31 @@ private static unsafe string GetFileMuiPath(string filePath, CultureInfo culture
  Interop.Kernel32.MUI_USER_PREFERRED_UI_LANGUAGES,
  filePath, language, ref languageLength,
  fileMuiPath, ref fileMuiPathLength, ref enumerator);
+ fileMuiPath[Interop.Kernel32.MAX_PATH] = '\0';
 
  if (succeeded)
  {
- fileMuiPath[Interop.Kernel32.MAX_PATH] = '\0';
  return new string(fileMuiPath);
  }
 
- // Shouldn't get here, as there's always at least one language installed.
+ Debug.Fail("Shouldn't get here, as there's always at least one language installed.");
  return string.Empty;
  }
 
  // Lookup succeeded. Check for exact match to the desired culture.
  language[Interop.Kernel32.LOCALE_NAME_MAX_LENGTH] = '\0';
- var lang = new string(language);
- if (string.Equals(lang, cultureInfo.Name, StringComparison.OrdinalIgnoreCase))
+ ReadOnlySpan<char> lang = MemoryMarshal.CreateReadOnlySpanFromNullTerminated(language);
+ if (lang.Equals(cultureInfo.Name, StringComparison.OrdinalIgnoreCase))
  {
- fileMuiPath[Interop.Kernel32.MAX_PATH] = '\0';
  return new string(fileMuiPath);
  }
 
  // Check for match of any parent of the language returned to the desired culture.
- var ci = CultureInfo.GetCultureInfo(lang);
+ var ci = CultureInfo.GetCultureInfo(lang.ToString());
  while (ci.Parent.Name != string.Empty)
  {
  if (ci.Parent.Name.Equals(cultureInfo.Name, StringComparison.OrdinalIgnoreCase))
  {
- fileMuiPath[Interop.Kernel32.MAX_PATH] = '\0';
  return new string(fileMuiPath);
  }
 
@@ -876,11 +874,11 @@ private static string GetLocalizedNameByMuiNativeResource(string resource, Cultu
  string system32 = Environment.SystemDirectory;
 
  // trim the string "@tzres.dll" => "tzres.dll"
- string tzresDll = resources[0].TrimStart('@');
+ ReadOnlySpan<char> tzresDll = resources[0].AsSpan().TrimStart('@');
 
  try
  {
- filePath = Path.Combine(system32, tzresDll);
+ filePath = Path.Join(system32, tzresDll);
  }
  catch (ArgumentException)
  {

src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.cs

@@ -6,7 +6,6 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.Globalization;
-using System.Runtime.InteropServices;
 using System.Runtime.Serialization;
 using System.Threading;