Fix LSP File watching so it correctly reports the baseUri if there's a trailing slash

src/Features/LanguageServer/Microsoft.CodeAnalysis.LanguageServer.UnitTests/LspFileChangeWatcherTests.cs

@@ -67,7 +67,7 @@ public async Task CreatingDirectoryWatchRequestsDirectoryWatch()
 
         var watcher = GetSingleFileWatcher(dynamicCapabilitiesRpcTarget);
 
-        Assert.Equal(tempDirectory.Path + Path.DirectorySeparatorChar, watcher.GlobPattern.BaseUri.LocalPath);
+        Assert.Equal(tempDirectory.Path, watcher.GlobPattern.BaseUri.LocalPath);
         Assert.Equal("**/*", watcher.GlobPattern.Pattern);
 
         // Get rid of the registration and it should be gone again

src/Features/LanguageServer/Microsoft.CodeAnalysis.LanguageServer/HostWorkspace/FileWatching/LspFileChangeWatcher.cs

@@ -65,8 +65,9 @@ private class FileChangeContext : IFileChangeContext
         /// The list of file paths we're watching manually that were outside the directories being watched. The count in this case counts
         /// the number of 
         /// </summary>
-        private readonly Dictionary<string, int> _watchedFiles = new Dictionary<string, int>(_stringComparer);
-        private static readonly StringComparer _stringComparer = RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase;
+        private readonly Dictionary<string, int> _watchedFiles = new Dictionary<string, int>(s_stringComparer);
+        private static readonly StringComparer s_stringComparer = RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ? StringComparer.Ordinal : StringComparer.OrdinalIgnoreCase;
+        private static readonly StringComparison s_stringComparison = RuntimeInformation.IsOSPlatform(OSPlatform.Linux) ? StringComparison.Ordinal : StringComparison.OrdinalIgnoreCase;
 
         public FileChangeContext(ImmutableArray<WatchedDirectory> watchedDirectories, LspFileChangeWatcher lspFileChangeWatcher)
         {
@@ -80,7 +81,7 @@ public FileChangeContext(ImmutableArray<WatchedDirectory> watchedDirectories, Ls
                 {
                     GlobPattern = new RelativePattern
                     {
-                        BaseUri = ProtocolConversions.CreateAbsoluteUri(d.Path),
+                        BaseUri = ProtocolConversions.CreateRelativePatternBaseUri(d.Path),
                         Pattern = d.ExtensionFilter is not null ? "**/*" + d.ExtensionFilter : "**/*"
                     }
                 }).ToArray();
@@ -99,7 +100,7 @@ private void WatchedFilesHandler_OnNotificationRaised(object? sender, DidChangeW
 
                 // Unfortunately the LSP protocol doesn't give us any hint of which of the file watches we might have sent to the client
                 // was the one that registered for this change, so we have to check paths to see if this one we should respond to.
-                if (WatchedDirectory.FilePathCoveredByWatchedDirectories(_watchedDirectories, filePath, StringComparison.Ordinal))
+                if (WatchedDirectory.FilePathCoveredByWatchedDirectories(_watchedDirectories, filePath, s_stringComparison))
                 {
                     FileChanged?.Invoke(this, filePath);
                 }
@@ -128,7 +129,7 @@ public void Dispose()
         public IWatchedFile EnqueueWatchingFile(string filePath)
         {
             // If we already have this file under our path, we may not have to do additional watching
-            if (WatchedDirectory.FilePathCoveredByWatchedDirectories(_watchedDirectories, filePath, StringComparison.OrdinalIgnoreCase))
+            if (WatchedDirectory.FilePathCoveredByWatchedDirectories(_watchedDirectories, filePath, s_stringComparison))
                 return NoOpWatchedFile.Instance;
 
             // Record that we're now watching this file

src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs

@@ -199,6 +199,22 @@ public static Uri CreateAbsoluteUri(string absolutePath)
             }
         }
 
+        internal static Uri CreateRelativePatternBaseUri(string path)
+        {
+            // According to VSCode LSP RelativePattern spec, 
+            // found at https://github.com/microsoft/vscode/blob/9e1974682eb84eebb073d4ae775bad1738c281f6/src/vscode-dts/vscode.d.ts#L2226
+            // the baseUri should not end in a trailing separator, nor should it 
+            // have any relative segmeents (., ..)
+            if (path[^1] == System.IO.Path.DirectorySeparatorChar)
+            {
+                path = path[..^1];
+            }
+
+            Debug.Assert(!path.Split(System.IO.Path.DirectorySeparatorChar).Any(p => p == "." || p == ".."));
+
+            return CreateAbsoluteUri(path);
+        }
+
         // Implements workaround for https://github.com/dotnet/runtime/issues/89538:
         internal static string GetAbsoluteUriString(string absolutePath)
         {

src/Features/LanguageServer/ProtocolUnitTests/ProtocolConversionsTests.cs

@@ -103,6 +103,47 @@ public void CreateAbsoluteUri_LocalPaths_Unix(string filePath, string expectedAb
             Assert.Equal(filePath, uri.LocalPath);
         }
 
+        [ConditionalTheory(typeof(WindowsOnly))]
+        [InlineData("C:\\a\\b", "file:///C:/a/b")]
+        [InlineData("C:\\a\\b\\", "file:///C:/a/b")]
+        [InlineData("C:\\a\\\\b", "file:///C:/a//b")]
+        [InlineData("C:\\%25\ue25b/a\\b", "file:///C:/%2525%EE%89%9B/a/b")]
+        [InlineData("C:\\%25\ue25b/a\\\\b", "file:///C:/%2525%EE%89%9B/a//b")]
+        [InlineData("C:\\\u0089\uC7BD", "file:///C:/%C2%89%EC%9E%BD")]
+        [InlineData("/\\server\ue25b\\%25\ue25b\\b", "file://server/%2525%EE%89%9B/b")]
+        [InlineData("\\\\server\ue25b\\%25\ue25b\\b", "file://server/%2525%EE%89%9B/b")]
+        [InlineData("\\\\server\ue25b\\%25\ue25b\\b\\", "file://server/%2525%EE%89%9B/b")]
+        [InlineData("C:\\ !$&'()+,-;=@[]_~#", "file:///C:/%20!$&'()+,-;=@[]_~%23")]
+        [InlineData("C:\\ !$&'()+,-;=@[]_~#\ue25b", "file:///C:/%20!$&'()+,-;=@[]_~%23%EE%89%9B")]
+        [InlineData("C:\\\u0073\u0323\u0307", "file:///C:/s%CC%A3%CC%87")] // combining marks
+        [InlineData("A:/\\\u200e//", "file:///A://%E2%80%8E//")] // cases from https://github.com/dotnet/runtime/issues/1487
+        [InlineData("B:\\/\u200e", "file:///B://%E2%80%8E")]
+        [InlineData("C:/\\\\-Ā\r", "file:///C:///-%C4%80%0D")]
+        [InlineData("D:\\\\\\\\\\\u200e", "file:///D://///%E2%80%8E")]
+        public void CreateRelativePatternBaseUri_LocalPaths_Windows(string filePath, string expectedUri)
+        {
+            var uri = ProtocolConversions.CreateRelativePatternBaseUri(filePath);
+            Assert.Equal(expectedUri, uri.AbsoluteUri);
+        }
+
+        [ConditionalTheory(typeof(UnixLikeOnly))]
+        [InlineData("/", "file://")]
+        [InlineData("/u", "file:///u")]
+        [InlineData("/unix/", "file:///unix")]
+        [InlineData("/unix/path", "file:///unix/path")]
+        [InlineData("/%25\ue25b/\u0089\uC7BD", "file:///%2525%EE%89%9B/%C2%89%EC%9E%BD")]
+        [InlineData("/!$&'()+,-;=@[]_~#", "file:///!$&'()+,-;=@[]_~%23")]
+        [InlineData("/!$&'()+,-;=@[]_~#", "file:///!$&'()+,-;=@[]_~%23%EE%89%9B")]
+        [InlineData("/\\\u200e//", "file:////%E2%80%8E//")] // cases from https://github.com/dotnet/runtime/issues/1487
+        [InlineData("\\/\u200e", "file:////%E2%80%8E")]
+        [InlineData("/\\\\-Ā\r", "file://///-%C4%80%0D")]
+        [InlineData("\\\\\\\\\\\u200e", "file:///////%E2%80%8E")]
+        public void CreateRelativePatternBaseUri_LocalPaths_Unix(string filePath, string expectedRelativeUri)
+        {
+            var uri = ProtocolConversions.CreateRelativePatternBaseUri(filePath);
+            Assert.Equal(expectedRelativeUri, uri.AbsoluteUri);
+        }
+
         [ConditionalTheory(typeof(UnixLikeOnly))]
         [InlineData("/a/./b", "file:///a/./b", "file:///a/b")]
         [InlineData("/a/../b", "file:///a/../b", "file:///b")]