Ignore drive casing when comparing on windows platforms

src/Compilers/Core/Portable/CommandLine/AnalyzerConfig.cs

@@ -260,8 +260,10 @@ public static AnalyzerConfig Parse(SourceText text, string? pathToFile)
 
             void addNewSection()
             {
+                var sectionName = PathUtilities.NormalizeDriveLetter(activeSectionName);
+
                 // Close out the previous section
-                var previousSection = new Section(activeSectionName, activeSectionProperties.ToImmutable());
+                var previousSection = new Section(sectionName, activeSectionProperties.ToImmutable());
                 if (activeSectionName == "")
                 {
                     // This is the global section

src/Compilers/Core/Portable/CommandLine/AnalyzerConfigSet.cs

@@ -185,23 +185,12 @@ public AnalyzerConfigOptionsResult GetOptionsForSourcePath(string sourcePath)
 
             var normalizedPath = PathUtilities.CollapseWithForwardSlash(sourcePath.AsSpan());
             normalizedPath = PathUtilities.ExpandAbsolutePathWithRelativeParts(normalizedPath);
+            normalizedPath = PathUtilities.NormalizeDriveLetter(normalizedPath);
 
             // If we have a global config, add any sections that match the full path. We can have at most one section since
             // we would have merged them earlier.
             foreach (var section in _globalConfig.NamedSections)
             {
-                if (!PathUtilities.IsUnixLikePlatform
-                    && section.Name.Length > 2
-                    && normalizedPath.Length > 2
-                    && normalizedPath[1] == PathUtilities.VolumeSeparatorChar
-                    && section.Name[1] == PathUtilities.VolumeSeparatorChar
-                    && char.ToUpperInvariant(normalizedPath[0]) == char.ToUpperInvariant(section.Name[0])
-                    && normalizedPath[2..].Equals(section.Name[2..], Section.NameComparer))
-                {
-                    sectionKey.Add(section);
-                    break;
-                }
-
                 if (normalizedPath.Equals(section.Name, Section.NameComparer))
                 {
                     sectionKey.Add(section);

src/Compilers/Core/Portable/FileSystem/PathUtilities.cs

@@ -735,6 +735,16 @@ public static string NormalizePathPrefix(string filePath, ImmutableArray<KeyValu
             return filePath;
         }
 
+        public static string NormalizeDriveLetter(string filePath)
+        {
+            if (!IsUnixLikePlatform && IsDriveRootedAbsolutePath(filePath))
+            {
+                filePath = char.ToUpper(filePath[0]) + filePath.Substring(1);
+            }
+
+            return filePath;
+        }
+
         /// <summary>
         /// Unfortunately, we cannot depend on Path.GetInvalidPathChars() or Path.GetInvalidFileNameChars()
         /// From MSDN: The array returned from this method is not guaranteed to contain the complete set of characters