Collapse slashes in directory name

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

@@ -183,8 +183,14 @@ public AnalyzerConfigOptionsResult GetOptionsForSourcePath(string sourcePath)
 
             var sectionKey = _sectionKeyPool.Allocate();
 
-            var normalizedPath = PathUtilities.NormalizeWithForwardSlash(sourcePath);
-            normalizedPath = PathUtilities.ExpandAbsolutePathWithRelativeParts(normalizedPath);
+            // Note: GetDirectoryName collapses multiple slashes into a single slash and hence
+            // makes the path consistent and comparable with AnalyzerConfig.NormalizedDirectory
+            // which normalizes the directory path similarly.
+            var normalizedDirectory = sourcePath.Length == 0 ? sourcePath : Path.GetDirectoryName(sourcePath) ?? sourcePath;
+            normalizedDirectory = PathUtilities.NormalizeWithForwardSlash(normalizedDirectory);
+            normalizedDirectory = PathUtilities.ExpandAbsolutePathWithRelativeParts(normalizedDirectory);
+
+            var normalizedPath = PathUtilities.EnsureTrailingSeparator(normalizedDirectory) + Path.GetFileName(sourcePath);
 
             // 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.