[clangd] Track document versions, include them with diags, enhance logs

[sammccall]

Summary

This ties to an LSP feature (diagnostic versioning) but really a lot
of the value is in being able to log what's happening with file versions
and queues more descriptively and clearly.

As such it's fairly invasive, for a logging patch :-\

Key decisions:

• at the LSP layer, we don't reqire the client to provide versions (LSP makes it mandatory but we never enforced it). If not provided, versions start at 0 and increment. DraftStore handles this.
• don't propagate magically using contexts, but rather manually: addDocument -> ParseInputs -> (ParsedAST, Preamble, various callbacks) Context-propagation would hide the versions from ClangdServer, which would make producing good log messages hard
• within ClangdServer, treat versions as opaque and unordered. json::Value is a convenient type for this, and allows richer versions for embedders. They're "mandatory" but nullptr is a sensible default.

[sammccall]

Fix accidental default.

[sammccall]

Fix incomplete message.

[hokein]

looks good, just a reminder -- the API change of the clangdServer::Callback would break out our internal integration.

[kadircet]

clang-tools-extra/clangd/ClangdServer.h

73

can we rather have Optional<int>s here(both for callbacks and addDocument)?

as clangdserver layer doesn't touch json objects at all currently.

clang-tools-extra/clangd/Compiler.h

49

again this (and other clangdserver structs) can hold a optional<int> right?

[sammccall]

Use string instead of json Value

[sammccall]

clang-tools-extra/clangd/ClangdServer.h

73

I really do want to make these opaque at the lower layer.
json is a bit fiddly though, reworked to use strings instead.

[kadircet]

clang-tools-extra/clangd/ClangdServer.h

73

looks better thanks !

clang-tools-extra/clangd/ClangdLSPServer.h

 #include "FindSymbols.h"
 #include "GlobalCompilationDatabase.h"
 #include "Path.h"
 #include "Protocol.h"
 #include "Transport.h"
 #include "clang/Tooling/Core/Replacement.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringSet.h"
+#include "llvm/Support/JSON.h"
 #include <memory>
 
 namespace clang {
 namespace clangd {
 
 class SymbolIndex;
 
 /// This class exposes ClangdServer's capabilities via Language Server Protocol.
public:
   /// Run LSP server loop, communicating with the Transport provided in the
   /// constructor. This method must not be executed more than once.
   ///
   /// \return Whether we shut down cleanly with a 'shutdown' -> 'exit' sequence.
   bool run();
 
 private:
   // Implement ClangdServer::Callbacks.
-  void onDiagnosticsReady(PathRef File, std::vector<Diag> Diagnostics) override;
+  void onDiagnosticsReady(PathRef File, const llvm::json::Value &Version,
+                          std::vector<Diag> Diagnostics) override;
   void onFileUpdated(PathRef File, const TUStatus &Status) override;
   void
-  onHighlightingsReady(PathRef File,
+  onHighlightingsReady(PathRef File, const llvm::json::Value &Version,
                        std::vector<HighlightingToken> Highlightings) override;
   void onBackgroundIndexProgress(const BackgroundQueue::Stats &Stats) override;
 
   // LSP methods. Notifications have signature void(const Params&).
   // Calls have signature void(const Params&, Callback<Response>).
   void onInitialize(const InitializeParams &, Callback<llvm::json::Value>);
   void onInitialized(const InitializedParams &);
   void onShutdown(const ShutdownParams &, Callback<std::nullptr_t>);

clang-tools-extra/clangd/ClangdLSPServer.cpp

 }
 
 void ClangdLSPServer::onDocumentDidOpen(
     const DidOpenTextDocumentParams &Params) {
   PathRef File = Params.textDocument.uri.file();
 
   const std::string &Contents = Params.textDocument.text;
 
-  DraftMgr.addDraft(File, Params.textDocument.version, Contents);
-  Server->addDocument(File, Contents, WantDiagnostics::Yes);
+  auto Version = DraftMgr.addDraft(File, Params.textDocument.version, Contents);
+  Server->addDocument(File, Contents, Version, WantDiagnostics::Yes);
 }
 
 void ClangdLSPServer::onDocumentDidChange(
     const DidChangeTextDocumentParams &Params) {
   auto WantDiags = WantDiagnostics::Auto;
   if (Params.wantDiagnostics.hasValue())
     WantDiags = Params.wantDiagnostics.getValue() ? WantDiagnostics::Yes
                                                   : WantDiagnostics::No;
 
   PathRef File = Params.textDocument.uri.file();
   llvm::Expected<DraftStore::Draft> Draft = DraftMgr.updateDraft(
       File, Params.textDocument.version, Params.contentChanges);
   if (!Draft) {
     // If this fails, we are most likely going to be not in sync anymore with
     // the client.  It is better to remove the draft and let further operations
     // fail rather than giving wrong results.
     DraftMgr.removeDraft(File);
     Server->removeDocument(File);
     elog("Failed to update {0}: {1}", File, Draft.takeError());
     return;
   }
 
-  Server->addDocument(File, Draft->Contents, WantDiags, Params.forceRebuild);
+  Server->addDocument(File, Draft->Contents, Draft->Version, WantDiags,
+                      Params.forceRebuild);
 }
 
 void ClangdLSPServer::onFileEvent(const DidChangeWatchedFilesParams &Params) {
   Server->onFileEvent(Params);
 }
 
 void ClangdLSPServer::onCommand(const ExecuteCommandParams &Params,
                                 Callback<llvm::json::Value> Reply) {
if (Trigger == ">")
     return Code->Contents[*Offset - 2] == '-'; // trigger only on '->'.
   if (Trigger == ":")
     return Code->Contents[*Offset - 2] == ':'; // trigger only on '::'.
   assert(false && "unhandled trigger character");
   return true;
 }
 
 void ClangdLSPServer::onHighlightingsReady(
-    PathRef File, std::vector<HighlightingToken> Highlightings) {
+    PathRef File, const llvm::json::Value &Version,
+    std::vector<HighlightingToken> Highlightings) {
   std::vector<HighlightingToken> Old;
   std::vector<HighlightingToken> HighlightingsCopy = Highlightings;
   {
     std::lock_guard<std::mutex> Lock(HighlightingsMutex);
     Old = std::move(FileToHighlightings[File]);
     FileToHighlightings[File] = std::move(HighlightingsCopy);
   }
   // LSP allows us to send incremental edits of highlightings. Also need to diff
   // to remove highlightings from tokens that should no longer have them.
   std::vector<LineHighlightings> Diffed = diffHighlightings(Highlightings, Old);
-  publishSemanticHighlighting(
-      {{URIForFile::canonicalize(File, /*TUPath=*/File)},
-       toSemanticHighlightingInformation(Diffed)});
+  SemanticHighlightingParams Notification;
+  Notification.TextDocument.uri =
+      URIForFile::canonicalize(File, /*TUPath=*/File);
+  Notification.TextDocument.version = Version.getAsInteger();
+  Notification.Lines = toSemanticHighlightingInformation(Diffed);
+  publishSemanticHighlighting(Notification);
 }
 
 void ClangdLSPServer::onDiagnosticsReady(PathRef File,
+                                         const llvm::json::Value &Version,
                                          std::vector<Diag> Diagnostics) {
   PublishDiagnosticsParams Notification;
+  Notification.version = Version.getAsInteger();
   Notification.uri = URIForFile::canonicalize(File, /*TUPath=*/File);
   DiagnosticToReplacementMap LocalFixIts; // Temporary storage
   for (auto &Diag : Diagnostics) {
     toLSPDiags(Diag, Notification.uri, DiagOpts,
                [&](clangd::Diagnostic Diag, llvm::ArrayRef<Fix> Fixes) {
                  auto &FixItsForDiagnostic = LocalFixIts[Diag];
                  llvm::copy(Fixes, std::back_inserter(FixItsForDiagnostic));
                  Notification.diagnostics.push_back(std::move(Diag));

 
 void ClangdLSPServer::reparseOpenedFiles(
     const llvm::StringSet<> &ModifiedFiles) {
   if (ModifiedFiles.empty())
     return;
   // Reparse only opened files that were modified.
   for (const Path &FilePath : DraftMgr.getActiveFiles())
     if (ModifiedFiles.find(FilePath) != ModifiedFiles.end())
-      Server->addDocument(FilePath, DraftMgr.getDraft(FilePath)->Contents,
-                          WantDiagnostics::Auto);
+      if (auto Draft = DraftMgr.getDraft(FilePath)) // else disappeared in race?
+        Server->addDocument(FilePath, std::move(Draft->Contents),
+                            Draft->Version, WantDiagnostics::Auto);
 }
 
 } // namespace clangd
 } // namespace clang

clang-tools-extra/clangd/ClangdServer.h

public:
   /// Interface with hooks for users of ClangdServer to be notified of events.
   class Callbacks {
   public:
     virtual ~Callbacks() = default;
 
     /// Called by ClangdServer when \p Diagnostics for \p File are ready.
     /// May be called concurrently for separate files, not for a single file.
     virtual void onDiagnosticsReady(PathRef File,
+                                    const llvm::json::Value &Version,
                                     std::vector<Diag> Diagnostics) {}
     /// Called whenever the file status is updated.
     /// May be called concurrently for separate files, not for a single file.
     virtual void onFileUpdated(PathRef File, const TUStatus &Status) {}
 
     /// Called by ClangdServer when some \p Highlightings for \p File are ready.
     /// May be called concurrently for separate files, not for a single file.
     virtual void
-    onHighlightingsReady(PathRef File,
+    onHighlightingsReady(PathRef File, const llvm::json::Value &Version,
                          std::vector<HighlightingToken> Highlightings) {}
 
     /// Called when background indexing tasks are enqueued/started/completed.
     /// Not called concurrently.
     virtual void
     onBackgroundIndexProgress(const BackgroundQueue::Stats &Stats) {}
   };
 
public:
   ClangdServer(const GlobalCompilationDatabase &CDB,
                const FileSystemProvider &FSProvider, const Options &Opts,
                Callbacks *Callbacks = nullptr);
 
   /// Add a \p File to the list of tracked C++ files or update the contents if
   /// \p File is already tracked. Also schedules parsing of the AST for it on a
   /// separate thread. When the parsing is complete, DiagConsumer passed in
   /// constructor will receive onDiagnosticsReady callback.
+  /// Version identifies this snapshot and is propagated to ASTs, preambles,
+  /// diagnostics etc built from it.
   void addDocument(PathRef File, StringRef Contents,
+                   llvm::json::Value Version = nullptr,
                    WantDiagnostics WD = WantDiagnostics::Auto,
                    bool ForceRebuild = false);
 
   /// Remove \p File from list of tracked files, schedule a request to free
   /// resources associated with it. Pending diagnostics for closed files may not
   /// be delivered, even if requested with WantDiags::Auto or WantDiags::Yes.
+  /// An empty set of diagnostics will be delivered, with Version = nullptr.
   void removeDocument(PathRef File);
 
   /// Run code completion for \p File at \p Pos.
   /// Request is processed asynchronously.
   ///
   /// This method should only be called for currently tracked files. However, it
   /// is safe to call removeDocument for \p File after this method returns, even
   /// while returned future is not yet ready.

clang-tools-extra/clangd/ClangdServer.cpp

 // Update the FileIndex with new ASTs and plumb the diagnostics responses.
 struct UpdateIndexCallbacks : public ParsingCallbacks {
   UpdateIndexCallbacks(FileIndex *FIndex,
                        ClangdServer::Callbacks *ServerCallbacks,
                        bool SemanticHighlighting)
       : FIndex(FIndex), ServerCallbacks(ServerCallbacks),
         SemanticHighlighting(SemanticHighlighting) {}
 
-  void onPreambleAST(PathRef Path, ASTContext &Ctx,
-                     std::shared_ptr<clang::Preprocessor> PP,
+  void onPreambleAST(PathRef Path, const llvm::json::Value &Version,
+                     ASTContext &Ctx, std::shared_ptr<clang::Preprocessor> PP,
                      const CanonicalIncludes &CanonIncludes) override {
     if (FIndex)
-      FIndex->updatePreamble(Path, Ctx, std::move(PP), CanonIncludes);
+      FIndex->updatePreamble(Path, Version, Ctx, std::move(PP), CanonIncludes);
   }
 
   void onMainAST(PathRef Path, ParsedAST &AST, PublishFn Publish) override {
     if (FIndex)
       FIndex->updateMain(Path, AST);
 
     std::vector<Diag> Diagnostics = AST.getDiagnostics();
     std::vector<HighlightingToken> Highlightings;
     if (SemanticHighlighting)
       Highlightings = getSemanticHighlightings(AST);
 
     if (ServerCallbacks)
       Publish([&]() {
-        ServerCallbacks->onDiagnosticsReady(Path, std::move(Diagnostics));
+        ServerCallbacks->onDiagnosticsReady(Path, AST.version(),
+                                            std::move(Diagnostics));
         if (SemanticHighlighting)
-          ServerCallbacks->onHighlightingsReady(Path, std::move(Highlightings));
+          ServerCallbacks->onHighlightingsReady(Path, AST.version(),
+                                                std::move(Highlightings));
       });
   }
 
-  void onFailedAST(PathRef Path, std::vector<Diag> Diags,
-                   PublishFn Publish) override {
+  void onFailedAST(PathRef Path, const llvm::json::Value &Version,
+                   std::vector<Diag> Diags, PublishFn Publish) override {
     if (ServerCallbacks)
-      Publish([&]() { ServerCallbacks->onDiagnosticsReady(Path, Diags); });
+      Publish(
+          [&]() { ServerCallbacks->onDiagnosticsReady(Path, Version, Diags); });
   }
 
   void onFileUpdated(PathRef File, const TUStatus &Status) override {
     if (ServerCallbacks)
       ServerCallbacks->onFileUpdated(File, Status);
   }
 
 private:
BackgroundIdx = std::make_unique<BackgroundIndex>(
         });
     AddIndex(BackgroundIdx.get());
   }
   if (DynamicIdx)
     AddIndex(DynamicIdx.get());
 }
 
 void ClangdServer::addDocument(PathRef File, llvm::StringRef Contents,
+                               llvm::json::Value Version,
                                WantDiagnostics WantDiags, bool ForceRebuild) {
   auto FS = FSProvider.getFileSystem();
 
   ParseOptions Opts;
   Opts.ClangTidyOpts = tidy::ClangTidyOptions::getDefaults();
   // FIXME: call tidy options builder on the worker thread, it can do IO.
   if (GetClangTidyOptions)
     Opts.ClangTidyOpts = GetClangTidyOptions(*FS, File);
   Opts.SuggestMissingIncludes = SuggestMissingIncludes;
 
   // Compile command is set asynchronously during update, as it can be slow.
   ParseInputs Inputs;
   Inputs.FS = FS;
   Inputs.Contents = std::string(Contents);
+  Inputs.Version = std::move(Version);
   Inputs.ForceRebuild = ForceRebuild;
   Inputs.Opts = std::move(Opts);
   Inputs.Index = Index;
   bool NewFile = WorkScheduler.update(File, Inputs, WantDiags);
   // If we loaded Foo.h, we want to make sure Foo.cpp is indexed.
   if (NewFile && BackgroundIdx)
     BackgroundIdx->boostRelated(File);
 }

clang-tools-extra/clangd/Compiler.h

struct ParseOptions {
   bool SuggestMissingIncludes = false;
 };
 
 /// Information required to run clang, e.g. to parse AST or do code completion.
 struct ParseInputs {
   tooling::CompileCommand CompileCommand;
   IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS;
   std::string Contents;
+  // Version identifier for Contents, provided by the client and opaque to us.
+  llvm::json::Value Version = nullptr;
   // Prevent reuse of the cached preamble/AST. Slow! Useful to workaround
   // clangd's assumption that missing header files will stay missing.
   bool ForceRebuild = false;
   // Used to recover from diagnostics (e.g. find missing includes for symbol).
   const SymbolIndex *Index = nullptr;
   ParseOptions Opts;
 };
 

clang-tools-extra/clangd/ParsedAST.h

 class SymbolIndex;
 
 /// Stores and provides access to parsed AST.
 class ParsedAST {
 public:
   /// Attempts to run Clang and store parsed AST. If \p Preamble is non-null
   /// it is reused during parsing.
   static llvm::Optional<ParsedAST>
-  build(std::unique_ptr<clang::CompilerInvocation> CI,
+  build(llvm::json::Value Version,
+        std::unique_ptr<clang::CompilerInvocation> CI,
         llvm::ArrayRef<Diag> CompilerInvocationDiags,
         std::shared_ptr<const PreambleData> Preamble,
         std::unique_ptr<llvm::MemoryBuffer> Buffer,
         llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
         const SymbolIndex *Index, const ParseOptions &Opts);
 
   ParsedAST(ParsedAST &&Other);
   ParsedAST &operator=(ParsedAST &&Other);
public:
 
   /// Gets all macro references (definition, expansions) present in the main
   /// file, including those in the preamble region.
   const MainFileMacros &getMacros() const;
   /// Tokens recorded while parsing the main file.
   /// (!) does not have tokens from the preamble.
   const syntax::TokenBuffer &getTokens() const { return Tokens; }
 
+  /// Returns the version of the ParseInputs this AST was built from.
+  const llvm::json::Value &version() const { return Version; }
+
 private:
-  ParsedAST(std::shared_ptr<const PreambleData> Preamble,
+  ParsedAST(llvm::json::Value Version,
+            std::shared_ptr<const PreambleData> Preamble,
             std::unique_ptr<CompilerInstance> Clang,
             std::unique_ptr<FrontendAction> Action, syntax::TokenBuffer Tokens,
             MainFileMacros Macros, std::vector<Decl *> LocalTopLevelDecls,
             std::vector<Diag> Diags, IncludeStructure Includes,
             CanonicalIncludes CanonIncludes);
 
+  llvm::json::Value Version;
   // In-memory preambles must outlive the AST, it is important that this member
   // goes before Clang and Action.
   std::shared_ptr<const PreambleData> Preamble;
   // We store an "incomplete" FrontendAction (i.e. no EndSourceFile was called
   // on it) and CompilerInstance used to run it. That way we don't have to do
   // complex memory management of all Clang structures on our own. (They are
   // stored in CompilerInstance and cleaned up by
   // FrontendAction.EndSourceFile).

clang-tools-extra/clangd/ParsedAST.cpp

 
 } // namespace
 
 void dumpAST(ParsedAST &AST, llvm::raw_ostream &OS) {
   AST.getASTContext().getTranslationUnitDecl()->dump(OS, true);
 }
 
 llvm::Optional<ParsedAST>
-ParsedAST::build(std::unique_ptr<clang::CompilerInvocation> CI,
+ParsedAST::build(llvm::json::Value Version,
+                 std::unique_ptr<clang::CompilerInvocation> CI,
                  llvm::ArrayRef<Diag> CompilerInvocationDiags,
                  std::shared_ptr<const PreambleData> Preamble,
                  std::unique_ptr<llvm::MemoryBuffer> Buffer,
                  llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
                  const SymbolIndex *Index, const ParseOptions &Opts) {
   assert(CI);
   // Command-line parsing sets DisableFree to true by default, but we don't want
   // to leak memory in clangd.
ParsedAST::build(llvm::json::Value Version,
   // Add diagnostics from the preamble, if any.
   if (Preamble)
     Diags.insert(Diags.end(), Preamble->Diags.begin(), Preamble->Diags.end());
   // Finally, add diagnostics coming from the AST.
   {
     std::vector<Diag> D = ASTDiags.take(CTContext.getPointer());
     Diags.insert(Diags.end(), D.begin(), D.end());
   }
-  return ParsedAST(std::move(Preamble), std::move(Clang), std::move(Action),
-                   std::move(Tokens), std::move(Macros), std::move(ParsedDecls),
-                   std::move(Diags), std::move(Includes),
-                   std::move(CanonIncludes));
+  return ParsedAST(std::move(Version), std::move(Preamble), std::move(Clang),
+                   std::move(Action), std::move(Tokens), std::move(Macros),
+                   std::move(ParsedDecls), std::move(Diags),
+                   std::move(Includes), std::move(CanonIncludes));
 }
 
 ParsedAST::ParsedAST(ParsedAST &&Other) = default;
 
 ParsedAST &ParsedAST::operator=(ParsedAST &&Other) = default;
 
 ParsedAST::~ParsedAST() {
   if (Action) {

 const IncludeStructure &ParsedAST::getIncludeStructure() const {
   return Includes;
 }
 
 const CanonicalIncludes &ParsedAST::getCanonicalIncludes() const {
   return CanonIncludes;
 }
 
-ParsedAST::ParsedAST(std::shared_ptr<const PreambleData> Preamble,
+ParsedAST::ParsedAST(llvm::json::Value Version,
+                     std::shared_ptr<const PreambleData> Preamble,
                      std::unique_ptr<CompilerInstance> Clang,
                      std::unique_ptr<FrontendAction> Action,
                      syntax::TokenBuffer Tokens, MainFileMacros Macros,
                      std::vector<Decl *> LocalTopLevelDecls,
                      std::vector<Diag> Diags, IncludeStructure Includes,
                      CanonicalIncludes CanonIncludes)
-    : Preamble(std::move(Preamble)), Clang(std::move(Clang)),
-      Action(std::move(Action)), Tokens(std::move(Tokens)),
-      Macros(std::move(Macros)), Diags(std::move(Diags)),
+    : Version(std::move(Version)), Preamble(std::move(Preamble)),
+      Clang(std::move(Clang)), Action(std::move(Action)),
+      Tokens(std::move(Tokens)), Macros(std::move(Macros)),
+      Diags(std::move(Diags)),
       LocalTopLevelDecls(std::move(LocalTopLevelDecls)),
       Includes(std::move(Includes)), CanonIncludes(std::move(CanonIncludes)) {
   assert(this->Clang);
   assert(this->Action);
 }
 
 llvm::Optional<ParsedAST>
 buildAST(PathRef FileName, std::unique_ptr<CompilerInvocation> Invocation,
          llvm::ArrayRef<Diag> CompilerInvocationDiags,
          const ParseInputs &Inputs,
          std::shared_ptr<const PreambleData> Preamble) {
   trace::Span Tracer("BuildAST");
   SPAN_ATTACH(Tracer, "File", FileName);
 
   auto VFS = Inputs.FS;
   if (Preamble && Preamble->StatCache)
     VFS = Preamble->StatCache->getConsumingFS(std::move(VFS));
   if (VFS->setCurrentWorkingDirectory(Inputs.CompileCommand.Directory)) {
     log("Couldn't set working directory when building the preamble.");
     // We proceed anyway, our lit-tests rely on results for non-existing working
     // dirs.
   }
 
   return ParsedAST::build(
-      std::make_unique<CompilerInvocation>(*Invocation),
+      Inputs.Version, std::make_unique<CompilerInvocation>(*Invocation),
       CompilerInvocationDiags, Preamble,
       llvm::MemoryBuffer::getMemBufferCopy(Inputs.Contents, FileName),
       std::move(VFS), Inputs.Index, Inputs.Opts);
 }
 
 } // namespace clangd
 } // namespace clang

clang-tools-extra/clangd/Preamble.h

 namespace clang {
 namespace clangd {
 
 /// The parsed preamble and associated data.
 ///
 /// As we must avoid re-parsing the preamble, any information that can only
 /// be obtained during parsing must be eagerly captured and stored here.
 struct PreambleData {
-  PreambleData(PrecompiledPreamble Preamble, std::vector<Diag> Diags,
-               IncludeStructure Includes, MainFileMacros Macros,
+  PreambleData(llvm::json::Value Version, PrecompiledPreamble Preamble,
+               std::vector<Diag> Diags, IncludeStructure Includes,
+               MainFileMacros Macros,
                std::unique_ptr<PreambleFileStatusCache> StatCache,
                CanonicalIncludes CanonIncludes);
 
+  // Version of the ParseInputs this preamble was built from.
+  llvm::json::Value Version;
   tooling::CompileCommand CompileCommand;
   PrecompiledPreamble Preamble;
   std::vector<Diag> Diags;
   // Processes like code completions and go-to-definitions will need #include
   // information, and their compile action skips preamble range.
   IncludeStructure Includes;
   // Macros defined in the preamble section of the main file.
   // Users care about headers vs main-file, not preamble vs non-preamble.

clang-tools-extra/clangd/Preamble.cpp

private:
   MainFileMacros Macros;
   std::unique_ptr<CommentHandler> IWYUHandler = nullptr;
   const clang::LangOptions *LangOpts = nullptr;
   const SourceManager *SourceMgr = nullptr;
 };
 
 } // namespace
 
-PreambleData::PreambleData(PrecompiledPreamble Preamble,
+PreambleData::PreambleData(llvm::json::Value Version,
+                           PrecompiledPreamble Preamble,
                            std::vector<Diag> Diags, IncludeStructure Includes,
                            MainFileMacros Macros,
                            std::unique_ptr<PreambleFileStatusCache> StatCache,
                            CanonicalIncludes CanonIncludes)
-    : Preamble(std::move(Preamble)), Diags(std::move(Diags)),
-      Includes(std::move(Includes)), Macros(std::move(Macros)),
-      StatCache(std::move(StatCache)), CanonIncludes(std::move(CanonIncludes)) {
-}
+    : Version(std::move(Version)), Preamble(std::move(Preamble)),
+      Diags(std::move(Diags)), Includes(std::move(Includes)),
+      Macros(std::move(Macros)), StatCache(std::move(StatCache)),
+      CanonIncludes(std::move(CanonIncludes)) {}
 
 std::shared_ptr<const PreambleData>
 buildPreamble(PathRef FileName, CompilerInvocation &CI,
               std::shared_ptr<const PreambleData> OldPreamble,
               const tooling::CompileCommand &OldCompileCommand,
               const ParseInputs &Inputs, bool StoreInMemory,
               PreambleParsedCallback PreambleCallback) {
   // Note that we don't need to copy the input contents, preamble can live
   // without those.
   auto ContentsBuffer =
       llvm::MemoryBuffer::getMemBuffer(Inputs.Contents, FileName);
   auto Bounds =
       ComputePreambleBounds(*CI.getLangOpts(), ContentsBuffer.get(), 0);
 
   if (OldPreamble &&
       compileCommandsAreEqual(Inputs.CompileCommand, OldCompileCommand) &&
       OldPreamble->Preamble.CanReuse(CI, ContentsBuffer.get(), Bounds,
                                      Inputs.FS.get())) {
-    vlog("Reusing preamble for {0}", FileName);
+    vlog("Reusing preamble version {0} for version {1} of {2}",
+         OldPreamble->Version, Inputs.Version, FileName);
     return OldPreamble;
   }
-  vlog(OldPreamble ? "Rebuilding invalidated preamble for {0}"
-                   : "Building first preamble for {0}",
-       FileName);
+  if (OldPreamble)
+    vlog("Rebuilding invalidated preamble for {0} version {1} "
+         "(previous was version {2})",
+         FileName, Inputs.Version, OldPreamble->Version);
+  else
+    vlog("Building first preamble for {0} verson {1}", FileName,
+         Inputs.Version);
 
   trace::Span Tracer("BuildPreamble");
   SPAN_ATTACH(Tracer, "File", FileName);
   StoreDiags PreambleDiagnostics;
   llvm::IntrusiveRefCntPtr<DiagnosticsEngine> PreambleDiagsEngine =
       CompilerInstance::createDiagnostics(&CI.getDiagnosticOpts(),
                                           &PreambleDiagnostics, false);
 
auto BuiltPreamble = PrecompiledPreamble::Build(
       std::make_shared<PCHContainerOperations>(), StoreInMemory,
       SerializedDeclsCollector);
 
   // When building the AST for the main file, we do want the function
   // bodies.
   CI.getFrontendOpts().SkipFunctionBodies = false;
 
   if (BuiltPreamble) {
-    vlog("Built preamble of size {0} for file {1}", BuiltPreamble->getSize(),
-         FileName);
+    vlog("Built preamble of size {0} for file {1} version {2}",
+         BuiltPreamble->getSize(), FileName, Inputs.Version);
     std::vector<Diag> Diags = PreambleDiagnostics.take();
     return std::make_shared<PreambleData>(
-        std::move(*BuiltPreamble), std::move(Diags),
+        Inputs.Version, std::move(*BuiltPreamble), std::move(Diags),
         SerializedDeclsCollector.takeIncludes(),
         SerializedDeclsCollector.takeMacros(), std::move(StatCache),
         SerializedDeclsCollector.takeCanonicalIncludes());
   } else {
-    elog("Could not build a preamble for file {0}", FileName);
+    elog("Could not build a preamble for file {0} version {2}", FileName,
+         Inputs.Version);
     return nullptr;
   }
 }
 
 } // namespace clangd
 } // namespace clang

clang-tools-extra/clangd/Protocol.h

 struct TextDocumentIdentifier {
   /// The text document's URI.
   URIForFile uri;
 };
 llvm::json::Value toJSON(const TextDocumentIdentifier &);
 bool fromJSON(const llvm::json::Value &, TextDocumentIdentifier &);
 
 struct VersionedTextDocumentIdentifier : public TextDocumentIdentifier {
-  // The version number of this document. If a versioned text document
-  // identifier is sent from the server to the client and the file is not open
-  // in the editor (the server has not received an open notification before) the
-  // server can send `null` to indicate that the version is known and the
-  // content on disk is the master (as speced with document content ownership).
-  //
-  // The version number of a document will increase after each change, including
-  // undo/redo. The number doesn't need to be consecutive.
+  /// The version number of this document. If a versioned text document
+  /// identifier is sent from the server to the client and the file is not open
+  /// in the editor (the server has not received an open notification before)
+  /// the server can send `null` to indicate that the version is known and the
+  /// content on disk is the master (as speced with document content ownership).
+  ///
+  /// The version number of a document will increase after each change,
+  /// including undo/redo. The number doesn't need to be consecutive.
+  ///
+  /// clangd extension: versions are optional, and synthesized if missing.
   llvm::Optional<std::int64_t> version;
 };
 llvm::json::Value toJSON(const VersionedTextDocumentIdentifier &);
 bool fromJSON(const llvm::json::Value &, VersionedTextDocumentIdentifier &);
 
 struct Position {
   /// Line position in a document (zero-based).
   int line = 0;

 struct TextDocumentItem {
   /// The text document's URI.
   URIForFile uri;
 
   /// The text document's language identifier.
   std::string languageId;
 
   /// The version number of this document (it will strictly increase after each
-  std::int64_t version = 0;
+  /// change, including undo/redo.
+  /// clangd extension: versions are optional, and synthesized if missing.
+  llvm::Optional<int64_t> version = 0;
 
   /// The content of the opened text document.
   std::string text;
 };
 bool fromJSON(const llvm::json::Value &, TextDocumentItem &);
 
 enum class TraceLevel {
   Off = 0,

 bool fromJSON(const llvm::json::Value &, Diagnostic &);
 llvm::raw_ostream &operator<<(llvm::raw_ostream &, const Diagnostic &);
 
 struct PublishDiagnosticsParams {
   /// The URI for which diagnostic information is reported.
   URIForFile uri;
   /// An array of diagnostic information items.
   std::vector<Diagnostic> diagnostics;
+  /// The version number of the document the diagnostics are published for.
+  llvm::Optional<int64_t> version;
 };
 llvm::json::Value toJSON(const PublishDiagnosticsParams &);
 
 struct CodeActionContext {
   /// An array of diagnostics.
   std::vector<Diagnostic> diagnostics;
 };
 bool fromJSON(const llvm::json::Value &, CodeActionContext &);

 };
 bool operator==(const SemanticHighlightingInformation &Lhs,
                 const SemanticHighlightingInformation &Rhs);
 llvm::json::Value toJSON(const SemanticHighlightingInformation &Highlighting);
 
 /// Parameters for the semantic highlighting (server-side) push notification.
 struct SemanticHighlightingParams {
   /// The textdocument these highlightings belong to.
-  TextDocumentIdentifier TextDocument;
+  VersionedTextDocumentIdentifier TextDocument;
   /// The lines of highlightings that should be sent.
   std::vector<SemanticHighlightingInformation> Lines;
 };
 llvm::json::Value toJSON(const SemanticHighlightingParams &Highlighting);
 
 struct SelectionRangeParams {
   /// The text document.
   TextDocumentIdentifier textDocument;

clang-tools-extra/clangd/Protocol.cpp

 
 bool fromJSON(const llvm::json::Value &Params, TextDocumentIdentifier &R) {
   llvm::json::ObjectMapper O(Params);
   return O && O.map("uri", R.uri);
 }
 
 llvm::json::Value toJSON(const VersionedTextDocumentIdentifier &R) {
   auto Result = toJSON(static_cast<const TextDocumentIdentifier &>(R));
-  if (R.version)
-    Result.getAsObject()->try_emplace("version", R.version);
   return Result;
 }
 
 bool fromJSON(const llvm::json::Value &Params,
               VersionedTextDocumentIdentifier &R) {
   llvm::json::ObjectMapper O(Params);
   return fromJSON(Params, static_cast<TextDocumentIdentifier &>(R)) && O &&
          O.map("version", R.version);
bool fromJSON(const llvm::json::Value &Params, Diagnostic &R) {
   O.map("category", R.category);
   O.map("code", R.code);
   O.map("source", R.source);
   return true;
 }
 
 llvm::json::Value toJSON(const PublishDiagnosticsParams &PDP) {
   return llvm::json::Object{
       {"uri", PDP.uri},
       {"diagnostics", PDP.diagnostics},
+      {"version", PDP.version},
   };
 }
 
 bool fromJSON(const llvm::json::Value &Params, CodeActionContext &R) {
   llvm::json::ObjectMapper O(Params);
   return O && O.map("diagnostics", R.diagnostics);
 }
 

clang-tools-extra/clangd/TUScheduler.h

 
 class ParsingCallbacks {
 public:
   virtual ~ParsingCallbacks() = default;
 
   /// Called on the AST that was built for emitting the preamble. The built AST
   /// contains only AST nodes from the #include directives at the start of the
   /// file. AST node in the current file should be observed on onMainAST call.
-  virtual void onPreambleAST(PathRef Path, ASTContext &Ctx,
+  virtual void onPreambleAST(PathRef Path, const llvm::json::Value &Version,
+                             ASTContext &Ctx,
                              std::shared_ptr<clang::Preprocessor> PP,
                              const CanonicalIncludes &) {}
 
   /// The argument function is run under the critical section guarding against
   /// races when closing the files.
   using PublishFn = llvm::function_ref<void(llvm::function_ref<void()>)>;
   /// Called on the AST built for the file itself. Note that preamble AST nodes
   /// are not deserialized and should be processed in the onPreambleAST call
public:
   ///   }
   /// This guarantees that clients will see results in the correct sequence if
   /// the file is concurrently closed and/or reopened. (The lambda passed to
   /// Publish() may never run in this case).
   virtual void onMainAST(PathRef Path, ParsedAST &AST, PublishFn Publish) {}
 
   /// Called whenever the AST fails to build. \p Diags will have the diagnostics
   /// that led to failure.
-  virtual void onFailedAST(PathRef Path, std::vector<Diag> Diags,
-                           PublishFn Publish) {}
+  virtual void onFailedAST(PathRef Path, const llvm::json::Value &Version,
+                           std::vector<Diag> Diags, PublishFn Publish) {}
 
   /// Called whenever the TU status is updated.
   virtual void onFileUpdated(PathRef File, const TUStatus &Status) {}
 };
 
 /// Handles running tasks for ClangdServer and managing the resources (e.g.,
 /// preambles and ASTs) for opened files.
 /// TUScheduler is not thread-safe, only one thread should be providing updates

clang-tools-extra/clangd/TUScheduler.cpp

 #ifndef NDEBUG
   std::lock_guard<std::mutex> Lock(Mutex);
   assert(Done && "handle was not destroyed");
   assert(Requests.empty() && "unprocessed requests when destroying ASTWorker");
 #endif
 }
 
 void ASTWorker::update(ParseInputs Inputs, WantDiagnostics WantDiags) {
-  llvm::StringRef TaskName = "Update";
+  std::string TaskName = llvm::formatv("Update ({0})", Inputs.Version);
   auto Task = [=]() mutable {
     auto RunPublish = [&](llvm::function_ref<void()> Publish) {
       // Ensure we only publish results from the worker if the file was not
       // removed, making sure there are not race conditions.
       std::lock_guard<std::mutex> Lock(PublishMu);
       if (CanPublishResults)
         Publish();
     };
auto Task = [=]() mutable {
     tooling::CompileCommand OldCommand = PrevInputs->CompileCommand;
     bool RanCallbackForPrevInputs = RanASTCallback;
     {
       std::lock_guard<std::mutex> Lock(Mutex);
       FileInputs = std::make_shared<ParseInputs>(Inputs);
     }
     RanASTCallback = false;
     emitTUStatus({TUAction::BuildingPreamble, TaskName});
-    log("Updating file {0} with command {1}\n[{2}]\n{3}", FileName,
-        Inputs.CompileCommand.Heuristic,
+    log("ASTWorker building file {0} version {1} with command {2}\n[{3}]\n{4}",
+        FileName, Inputs.Version, Inputs.CompileCommand.Heuristic,
         Inputs.CompileCommand.Directory,
         llvm::join(Inputs.CompileCommand.CommandLine, " "));
     // Rebuild the preamble and the AST.
     StoreDiags CompilerInvocationDiagConsumer;
     std::vector<std::string> CC1Args;
     std::unique_ptr<CompilerInvocation> Invocation = buildCompilerInvocation(
         Inputs, CompilerInvocationDiagConsumer, &CC1Args);
     // Log cc1 args even (especially!) if creating invocation failed.
     if (!CC1Args.empty())
       vlog("Driver produced command: cc1 {0}", llvm::join(CC1Args, " "));
     std::vector<Diag> CompilerInvocationDiags =
         CompilerInvocationDiagConsumer.take();
     if (!Invocation) {
       elog("Could not build CompilerInvocation for file {0}", FileName);
       // Remove the old AST if it's still in cache.
       IdleASTs.take(this);
       TUStatus::BuildDetails Details;
       Details.BuildFailed = true;
       emitTUStatus({TUAction::BuildingPreamble, TaskName}, &Details);
       // Report the diagnostics we collected when parsing the command line.
-      Callbacks.onFailedAST(FileName, std::move(CompilerInvocationDiags),
-                            RunPublish);
+      Callbacks.onFailedAST(FileName, Inputs.Version,
+                            std::move(CompilerInvocationDiags), RunPublish);
       // Make sure anyone waiting for the preamble gets notified it could not
       // be built.
       PreambleWasBuilt.notify();
       return;
     }
 
     std::shared_ptr<const PreambleData> OldPreamble =
         Inputs.ForceRebuild ? std::shared_ptr<const PreambleData>()
                             : getPossiblyStalePreamble();
     std::shared_ptr<const PreambleData> NewPreamble = buildPreamble(
         FileName, *Invocation, OldPreamble, OldCommand, Inputs,
         StorePreambleInMemory,
-        [this](ASTContext &Ctx, std::shared_ptr<clang::Preprocessor> PP,
-               const CanonicalIncludes &CanonIncludes) {
-          Callbacks.onPreambleAST(FileName, Ctx, std::move(PP), CanonIncludes);
+        [this, Version(Inputs.Version)](
+            ASTContext &Ctx, std::shared_ptr<clang::Preprocessor> PP,
+          Callbacks.onPreambleAST(FileName, Version, Ctx, std::move(PP),
+                                  CanonIncludes);
         });
 
     bool CanReuseAST = InputsAreTheSame && (OldPreamble == NewPreamble);
     {
       std::lock_guard<std::mutex> Lock(Mutex);
       LastBuiltPreamble = NewPreamble;
     }
     // Before doing the expensive AST reparse, we want to release our reference
if (*AST) {
 
       Callbacks.onMainAST(FileName, **AST, RunPublish);
       RanASTCallback = true;
     } else {
       // Failed to build the AST, at least report diagnostics from the command
       // line if there were any.
       // FIXME: we might have got more errors while trying to build the AST,
       //        surface them too.
-      Callbacks.onFailedAST(FileName, CompilerInvocationDiags, RunPublish);
+      Callbacks.onFailedAST(FileName, Inputs.Version, CompilerInvocationDiags,
+                            RunPublish);
     }
     // Stash the AST in the cache for further use.
     IdleASTs.put(this, std::move(*AST));
   };
   startTask(TaskName, std::move(Task), WantDiags);
 }
 
 void ASTWorker::runWithAST(
     llvm::StringRef Name,
     llvm::unique_function<void(llvm::Expected<InputsAndAST>)> Action) {
   auto Task = [=, Action = std::move(Action)]() mutable {
     if (isCancelled())
       return Action(llvm::make_error<CancelledError>());
     llvm::Optional<std::unique_ptr<ParsedAST>> AST = IdleASTs.take(this);
     auto CurrentInputs = getCurrentFileInputs();
     if (!AST) {
       StoreDiags CompilerInvocationDiagConsumer;
       std::unique_ptr<CompilerInvocation> Invocation = buildCompilerInvocation(
           *CurrentInputs, CompilerInvocationDiagConsumer);
       // Try rebuilding the AST.
+      vlog("ASTWorker rebuilding evicted AST to run {0}: {1} version {2}", Name,
+           FileName, CurrentInputs->Version);
       llvm::Optional<ParsedAST> NewAST =
           Invocation
               ? buildAST(FileName,
                          std::make_unique<CompilerInvocation>(*Invocation),
                          CompilerInvocationDiagConsumer.take(), *CurrentInputs,
                          getPossiblyStalePreamble())
               : None;
       AST = NewAST ? std::make_unique<ParsedAST>(std::move(*NewAST)) : nullptr;
     }
     // Make sure we put the AST back into the LRU cache.
     auto _ = llvm::make_scope_exit(
         [&AST, this]() { IdleASTs.put(this, std::move(*AST)); });
     // Run the user-provided action.
     if (!*AST)
       return Action(llvm::make_error<llvm::StringError>(
           "invalid AST", llvm::errc::invalid_argument));
+    vlog("ASTWorker running {0} on version {2} of {1}", Name, FileName,
+         CurrentInputs->Version);
     Action(InputsAndAST{*CurrentInputs, **AST});
   };
   startTask(Name, std::move(Task), /*UpdateType=*/None);
 }
 
 std::shared_ptr<const PreambleData>
 ASTWorker::getPossiblyStalePreamble() const {
   std::lock_guard<std::mutex> Lock(Mutex);
if (I->UpdateType == None) {
       Requests.push_front(std::move(R));
       return Deadline::zero();
     }
     // Cancelled updates are downgraded to auto-diagnostics, and may be elided.
     if (I->UpdateType == WantDiagnostics::Yes)
       I->UpdateType = WantDiagnostics::Auto;
   }
 
-  while (shouldSkipHeadLocked())
+  while (shouldSkipHeadLocked()) {
+    vlog("ASTWorker skipping {0}", Requests.front().Name);
     Requests.pop_front();
+  }
   assert(!Requests.empty() && "skipped the whole queue");
   // Some updates aren't dead yet, but never end up being used.
   // e.g. the first keystroke is live until obsoleted by the second.
   // We debounce "maybe-unused" writes, sleeping in case they become dead.
   // But don't delay reads (including updates where diagnostics are needed).
   for (const auto &R : Requests)
     if (R.UpdateType == None || R.UpdateType == WantDiagnostics::Yes)
       return Deadline::zero();

clang-tools-extra/clangd/index/FileIndex.h

 /// This manages symbols from files and an in-memory index on all symbols.
 /// FIXME: Expose an interface to remove files that are closed.
 class FileIndex : public MergedIndex {
 public:
   FileIndex(bool UseDex = true);
 
   /// Update preamble symbols of file \p Path with all declarations in \p AST
   /// and macros in \p PP.
-  void updatePreamble(PathRef Path, ASTContext &AST,
-                      std::shared_ptr<Preprocessor> PP,
+  void updatePreamble(PathRef Path, const llvm::json::Value &Version,
+                      ASTContext &AST, std::shared_ptr<Preprocessor> PP,
                       const CanonicalIncludes &Includes);
 
   /// Update symbols and references from main file \p Path with
   /// `indexMainDecls`.
   void updateMain(PathRef Path, ParsedAST &AST);
 
 private:
   bool UseDex; // FIXME: this should be always on.

 
 /// Retrieves symbols and refs of local top level decls in \p AST (i.e.
 /// `AST.getLocalTopLevelDecls()`).
 /// Exposed to assist in unit tests.
 SlabTuple indexMainDecls(ParsedAST &AST);
 
 /// Index declarations from \p AST and macros from \p PP that are declared in
 /// included headers.
-SlabTuple indexHeaderSymbols(ASTContext &AST, std::shared_ptr<Preprocessor> PP,
+SlabTuple indexHeaderSymbols(const llvm::json::Value &Version, ASTContext &AST,
+                             std::shared_ptr<Preprocessor> PP,
                              const CanonicalIncludes &Includes);
 
 } // namespace clangd
 } // namespace clang
 
 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_INDEX_FILEINDEX_H

clang-tools-extra/clangd/index/FileIndex.cpp

 
 namespace clang {
 namespace clangd {
 
 static SlabTuple indexSymbols(ASTContext &AST, std::shared_ptr<Preprocessor> PP,
                               llvm::ArrayRef<Decl *> DeclsToIndex,
                               const MainFileMacros *MacroRefsToIndex,
                               const CanonicalIncludes &Includes,
-                              bool IsIndexMainAST) {
+                              bool IsIndexMainAST,
+                              const llvm::json::Value &Version) {
   SymbolCollector::Options CollectorOpts;
   CollectorOpts.CollectIncludePath = true;
   CollectorOpts.Includes = &Includes;
   CollectorOpts.CountReferences = false;
   CollectorOpts.Origin = SymbolOrigin::Dynamic;
 
   index::IndexingOptions IndexOpts;
   // We only need declarations, because we don't count references.
static SlabTuple indexSymbols(ASTContext &AST, std::shared_ptr<Preprocessor> PP,
   const auto *MainFileEntry = SM.getFileEntryForID(SM.getMainFileID());
   std::string FileName =
       std::string(MainFileEntry ? MainFileEntry->getName() : "");
 
   auto Syms = Collector.takeSymbols();
   auto Refs = Collector.takeRefs();
   auto Relations = Collector.takeRelations();
 
-  vlog("index AST for {0} (main={1}): \n"
-       "  symbol slab: {2} symbols, {3} bytes\n"
-       "  ref slab: {4} symbols, {5} refs, {6} bytes\n"
-       "  relations slab: {7} relations, {8} bytes",
-       FileName, IsIndexMainAST, Syms.size(), Syms.bytes(), Refs.size(),
-       Refs.numRefs(), Refs.bytes(), Relations.size(), Relations.bytes());
+  vlog("indexed {0} AST for {1} version {2}:\n"
+       "  symbol slab: {3} symbols, {4} bytes\n"
+       "  ref slab: {5} symbols, {6} refs, {7} bytes\n"
+       "  relations slab: {8} relations, {9} bytes",
+       IsIndexMainAST ? "file" : "preamble", FileName, Version, Syms.size(),
+       Syms.bytes(), Refs.size(), Refs.numRefs(), Refs.bytes(),
+       Relations.size(), Relations.bytes());
   return std::make_tuple(std::move(Syms), std::move(Refs),
                          std::move(Relations));
 }
 
 SlabTuple indexMainDecls(ParsedAST &AST) {
   return indexSymbols(AST.getASTContext(), AST.getPreprocessorPtr(),
                       AST.getLocalTopLevelDecls(), &AST.getMacros(),
                       AST.getCanonicalIncludes(),
-                      /*IsIndexMainAST=*/true);
+                      /*IsIndexMainAST=*/true, AST.version());
 }
 
-SlabTuple indexHeaderSymbols(ASTContext &AST, std::shared_ptr<Preprocessor> PP,
+SlabTuple indexHeaderSymbols(const llvm::json::Value &Version, ASTContext &AST,
+                             std::shared_ptr<Preprocessor> PP,
                              const CanonicalIncludes &Includes) {
   std::vector<Decl *> DeclsToIndex(
       AST.getTranslationUnitDecl()->decls().begin(),
       AST.getTranslationUnitDecl()->decls().end());
   return indexSymbols(AST, std::move(PP), DeclsToIndex,
                       /*MainFileMacros=*/nullptr, Includes,
-                      /*IsIndexMainAST=*/false);
+                      /*IsIndexMainAST=*/false, Version);
 }
 
 void FileSymbols::update(PathRef Path, std::unique_ptr<SymbolSlab> Symbols,
                          std::unique_ptr<RefSlab> Refs,
                          std::unique_ptr<RelationSlab> Relations,
                          bool CountReferences) {
   std::lock_guard<std::mutex> Lock(Mutex);
   if (!Symbols)
FileSymbols::buildIndex(IndexType Type, DuplicateHandling DuplicateHandle) {
   llvm_unreachable("Unknown clangd::IndexType");
 }
 
 FileIndex::FileIndex(bool UseDex)
     : MergedIndex(&MainFileIndex, &PreambleIndex), UseDex(UseDex),
       PreambleIndex(std::make_unique<MemIndex>()),
       MainFileIndex(std::make_unique<MemIndex>()) {}
 
-void FileIndex::updatePreamble(PathRef Path, ASTContext &AST,
+void FileIndex::updatePreamble(PathRef Path, const llvm::json::Value &Version,
+                               ASTContext &AST,
                                std::shared_ptr<Preprocessor> PP,
                                const CanonicalIncludes &Includes) {
-  auto Slabs = indexHeaderSymbols(AST, std::move(PP), Includes);
+  auto Slabs = indexHeaderSymbols(Version, AST, std::move(PP), Includes);
   PreambleSymbols.update(
       Path, std::make_unique<SymbolSlab>(std::move(std::get<0>(Slabs))),
       std::make_unique<RefSlab>(),
       std::make_unique<RelationSlab>(std::move(std::get<2>(Slabs))),
       /*CountReferences=*/false);
   PreambleIndex.reset(
       PreambleSymbols.buildIndex(UseDex ? IndexType::Heavy : IndexType::Light,
                                  DuplicateHandling::PickOne));

clang-tools-extra/clangd/test/diagnostic-category.test

 # RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{"textDocument":{"publishDiagnostics":{"categorySupport":true}}},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"struct Point {}; union Point p;"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"struct Point {}; union Point p;"}}}
 #      CHECK:    "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:    "params": {
 # CHECK-NEXT:     "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "category": "Semantic Issue",
 # CHECK-NEXT:        "code": "use_with_wrong_tag",
 # CHECK-NEXT:        "message": "Use of 'Point' with tag type that does not match previous declaration (fix available)\n\nfoo.c:1:8: note: previous use is here",
 # CHECK-NEXT:        "range": {

 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 7,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 3
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":4,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/diagnostics-no-tidy.test

 # RUN: clangd -lit-test -clang-tidy=false < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"void main() {\n(void)sizeof(42);\n}"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"void main() {\n(void)sizeof(42);\n}"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "-Wmain-return-type",
 # CHECK-NEXT:        "message": "Return type of 'main' is not 'int' (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 4,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          },
 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 0,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 2,
 # CHECK-NEXT:        "source": "clang"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":2,"method":"sync","params":null}
 ---
 {"jsonrpc":"2.0","method":"textDocument/didClose","params":{"textDocument":{"uri":"test:///foo.c"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": null
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":5,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/diagnostics-notes.test

 # RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{"textDocument":{"publishDiagnostics":{"relatedInformation":true}}},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.cc","languageId":"cpp","version":1,"text":"int x;\nint x;"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.cc","languageId":"cpp","text":"int x;\nint x;"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "redefinition",
 # CHECK-NEXT:        "message": "Redefinition of 'x'",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {

 # CHECK-NEXT:            },
 # CHECK-NEXT:            "message": "Previous definition is here"
 # CHECK-NEXT:          }
 # CHECK-NEXT:        ],
 # CHECK-NEXT:        "severity": 1,
 # CHECK-NEXT:        "source": "clang"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.cc"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.cc",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":5,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/diagnostics.test

 # RUN: clangd -lit-test -clang-tidy-checks=bugprone-sizeof-expression < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"void main() {\n(void)sizeof(42);\n}"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"void main() {\n(void)sizeof(42);\n}"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "-Wmain-return-type",
 # CHECK-NEXT:        "message": "Return type of 'main' is not 'int' (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {

 # CHECK-NEXT:            "character": 6,
 # CHECK-NEXT:            "line": 1
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 2,
 # CHECK-NEXT:        "source": "clang-tidy"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":2,"method":"sync","params":null}
 ---
 {"jsonrpc":"2.0","method":"textDocument/didClose","params":{"textDocument":{"uri":"test:///foo.c"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": null
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":5,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/did-change-configuration-params.test

 # RUN: clangd -compile_args_from=lsp -lit-test < %s 2> %t | FileCheck -strict-whitespace %s
 # RUN: cat %t | FileCheck --check-prefix=ERR %s
 # UNSUPPORTED: windows-gnu,windows-msvc
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 ---
 {"jsonrpc":"2.0","method":"workspace/didChangeConfiguration","params":{"settings":{"compilationDatabaseChanges":{"/clangd-test/foo.c": {"workingDirectory":"/clangd-test", "compilationCommand": ["clang", "-c", "foo.c"]}}}}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"int main() { int i; return i; }"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"int main() { int i; return i; }"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///bar.c","languageId":"c","version":1,"text":"int main() { int i; return i; }"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///bar.c","languageId":"c","text":"int main() { int i; return i; }"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [],
-# CHECK-NEXT:    "uri": "file://{{.*}}/bar.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/bar.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","method":"workspace/didChangeConfiguration","params":{"settings":{"compilationDatabaseChanges":{"/clangd-test/foo.c": {"workingDirectory":"/clangd-test2", "compilationCommand": ["clang", "-c", "foo.c", "-Wall", "-Werror"]}}}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "-Wuninitialized",
 # CHECK-NEXT:        "message": "Variable 'i' is uninitialized when used here (fix available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 28,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          },
 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 27,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 1,
 # CHECK-NEXT:        "source": "clang"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 #
-# ERR: Updating file {{.*}}foo.c with command
+# ERR: ASTWorker building file {{.*}}foo.c version 0 with command
 # ERR: [{{.*}}clangd-test2]
 # ERR: clang -c foo.c -Wall -Werror
 ---
 {"jsonrpc":"2.0","id":5,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}
 
 

clang-tools-extra/clangd/test/execute-command.test

 # RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"int main(int i, char **a) { if (i = 2) {}}"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"int main(int i, char **a) { if (i = 2) {}}"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "-Wparentheses",
 # CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses (fixes available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 37,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          },
 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 32,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 2,
 # CHECK-NEXT:        "source": "clang"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 # No command name
 {"jsonrpc":"2.0","id":3,"method":"workspace/executeCommand","params":{}}
 ---
 # Invalid, non-scalar command name
 {"jsonrpc":"2.0","id":4,"method":"workspace/executeCommand","params":{"command": {}}}
 ---

clang-tools-extra/clangd/test/fixits-codeaction.test

 # RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{"textDocument":{"codeAction":{"codeActionLiteralSupport":{}}}},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"int main(int i, char **a) { if (i = 2) {}}"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"int main(int i, char **a) { if (i = 2) {}}"}}}
 #      CHECK:    "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "-Wparentheses",
 # CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses (fixes available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 37,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          },
 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 32,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 2,
 # CHECK-NEXT:        "source": "clang"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":2,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":0,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses (fixes available)", "code": "-Wparentheses", "source": "clang"}]}}}
 #      CHECK:  "id": 2,
 # CHECK-NEXT:  "jsonrpc": "2.0",
 # CHECK-NEXT:  "result": [
 # CHECK-NEXT:    {
 # CHECK-NEXT:      "diagnostics": [

clang-tools-extra/clangd/test/fixits-command.test

 # RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"int main(int i, char **a) { if (i = 2) {}}"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"int main(int i, char **a) { if (i = 2) {}}"}}}
 #      CHECK:    "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "-Wparentheses",
 # CHECK-NEXT:        "message": "Using the result of an assignment as a condition without parentheses (fixes available)",
 # CHECK-NEXT:        "range": {
 # CHECK-NEXT:          "end": {
 # CHECK-NEXT:            "character": 37,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          },
 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 32,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 2,
 # CHECK-NEXT:        "source": "clang"
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":2,"method":"textDocument/codeAction","params":{"textDocument":{"uri":"test:///foo.c"},"range":{"start":{"line":0,"character":13},"end":{"line":0,"character":35}},"context":{"diagnostics":[{"range":{"start": {"line": 0, "character": 32}, "end": {"line": 0, "character": 37}},"severity":2,"message":"Using the result of an assignment as a condition without parentheses (fixes available)"}]}}}
 #      CHECK:  "id": 2,
 # CHECK-NEXT:  "jsonrpc": "2.0",
 # CHECK-NEXT:  "result": [
 # CHECK-NEXT:    {
 # CHECK-NEXT:      "arguments": [

clang-tools-extra/clangd/test/fixits-embed-in-diagnostic.test

 # RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{"textDocument":{"publishDiagnostics":{"codeActionsInline":true}}},"trace":"off"}}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"struct Point {}; union Point p;"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":"struct Point {}; union Point p;"}}}
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "code": "use_with_wrong_tag",
 # CHECK-NEXT:        "codeActions": [
 # CHECK-NEXT:          {
 # CHECK-NEXT:            "edit": {

 # CHECK-NEXT:          "start": {
 # CHECK-NEXT:            "character": 7,
 # CHECK-NEXT:            "line": 0
 # CHECK-NEXT:          }
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "severity": 3
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
-# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 {"jsonrpc":"2.0","id":4,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/path-mappings.test

 # Copy over the server file into test workspace
 # RUN: rm -rf %t
 # RUN: cp -r %S/Inputs/path-mappings %t
 #
 # RUN: clangd --path-mappings 'C:\client=%t/server' -lit-test < %s | FileCheck -strict-whitespace %s
 {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
 ---
 {
   "jsonrpc": "2.0",
   "method": "textDocument/didOpen",
   "params": {
     "textDocument": {
       "uri": "file:///C:/client/bar.cpp",
       "languageId": "cpp",
-      "version": 1,
       "text": "#include \"foo.h\"\nint main(){\nreturn foo();\n}"
     }
   }
 }
 # Ensure that the client gets back the same client path (clangd thinks it edited %t/server/bar.cpp)
 #      CHECK:  "method": "textDocument/publishDiagnostics",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "diagnostics": [],
-# CHECK-NEXT:    "uri": "file:///C:/client/bar.cpp"
+# CHECK-NEXT:    "uri": "file:///C:/client/bar.cpp",
+# CHECK-NEXT:    "version": 0
 # CHECK-NEXT:  }
 ---
 # We're editing bar.cpp, which includes foo.h, where foo.h "exists" at a server location 
 # With path mappings, when we go to definition on foo(), we get back a client file uri
 {
   "jsonrpc": "2.0",
   "id": 1,
   "method": "textDocument/definition",

 }
 #      CHECK:  "id": 1,
 # CHECK-NEXT:  "jsonrpc": "2.0",
 # CHECK-NEXT:  "result": [
 # CHECK-NEXT:    {
 # CHECK-NEXT:      "range": {
 # CHECK-NEXT:        "end": {
 # CHECK-NEXT:          "character": {{[0-9]+}},
-# CHECK-NEXT:          "line": {{[0-9]+}} 
+# CHECK-NEXT:          "line": {{[0-9]+}}
 # CHECK-NEXT:        },
 # CHECK-NEXT:        "start": {
 # CHECK-NEXT:          "character": {{[0-9]+}},
 # CHECK-NEXT:          "line": {{[0-9]+}}
 # CHECK-NEXT:        }
 # CHECK-NEXT:      },
 # CHECK-NEXT:      "uri": "file:///C:/client/foo.h"
 # CHECK-NEXT:    }
 # CHECK-NEXT:  ]
 #
 ---
 {"jsonrpc":"2.0","id":2,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/semantic-highlighting.test

 # CHECK-NEXT:            "entity.name.function.preprocessor.cpp"
 # CHECK-NEXT:          ],
 # CHECK-NEXT:          [
 # CHECK-NEXT:            "meta.disabled"
 # CHECK-NEXT:          ]
 # CHECK-NEXT:        ]
 # CHECK-NEXT:      },
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.cpp","languageId":"cpp","version":1,"text":"int x = 2;"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.cpp","languageId":"cpp","text":"int x = 2;"}}}
 #      CHECK:  "method": "textDocument/semanticHighlighting",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "lines": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "isInactive": false,
 # CHECK-NEXT:        "line": 0,
 # CHECK-NEXT:        "tokens": "AAAABAABAAA="
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
 # CHECK-NEXT:    "textDocument": {
-# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo.cpp"
+# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo.cpp",
+# CHECK-NEXT:      "version": 0
 # CHECK-NEXT:    }
 # CHECK-NEXT:  }
 # CHECK-NEXT:}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo2.cpp","languageId":"cpp","version":1,"text":"int x = 2;\nint y = 2;"}}}
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo2.cpp","languageId":"cpp","text":"int x = 2;\nint y = 2;"}}}
 #      CHECK:  "method": "textDocument/semanticHighlighting",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "lines": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "isInactive": false,
 # CHECK-NEXT:        "line": 0,
 # CHECK-NEXT:        "tokens": "AAAABAABAAA="
 # CHECK-NEXT:      }
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "isInactive": false,
 # CHECK-NEXT:        "line": 1,
 # CHECK-NEXT:        "tokens": "AAAABAABAAA="
 # CHECK-NEXT:      }
 # CHECK-NEXT:    ],
 # CHECK-NEXT:    "textDocument": {
-# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo2.cpp"
+# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo2.cpp",
+# CHECK-NEXT:      "version": 0
 # CHECK-NEXT:    }
 # CHECK-NEXT:  }
 # CHECK-NEXT:}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///foo.cpp","version":2},"contentChanges": [{"range":{"start": {"line": 0,"character": 10},"end": {"line": 0,"character": 10}},"rangeLength": 0,"text": "\nint y = 2;"}]}}
+{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///foo.cpp"},"contentChanges": [{"range":{"start": {"line": 0,"character": 10},"end": {"line": 0,"character": 10}},"rangeLength": 0,"text": "\nint y = 2;"}]}}
 #      CHECK:  "method": "textDocument/semanticHighlighting",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "lines": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "isInactive": false,
 # CHECK-NEXT:        "line": 1,
 # CHECK-NEXT:        "tokens": "AAAABAABAAA="
 # CHECK-NEXT:      }
 # CHECK-NEXT:   ],
 # CHECK-NEXT:    "textDocument": {
-# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo.cpp"
+# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo.cpp",
+# CHECK-NEXT:      "version": 1
 # CHECK-NEXT:    }
 # CHECK-NEXT:  }
 # CHECK-NEXT:}
 ---
-{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///foo.cpp","version":2},"contentChanges": [{"range":{"start": {"line": 0,"character": 10},"end": {"line": 1,"character": 10}},"rangeLength": 11,"text": ""}]}}
+{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///foo.cpp"},"contentChanges": [{"range":{"start": {"line": 0,"character": 10},"end": {"line": 1,"character": 10}},"rangeLength": 11,"text": ""}]}}
 #      CHECK:  "method": "textDocument/semanticHighlighting",
 # CHECK-NEXT:  "params": {
 # CHECK-NEXT:    "lines": [
 # CHECK-NEXT:      {
 # CHECK-NEXT:        "isInactive": false,
 # CHECK-NEXT:        "line": 1,
 # CHECK-NEXT:        "tokens": ""
 # CHECK-NEXT:      }
 # CHECK-NEXT:   ],
 # CHECK-NEXT:    "textDocument": {
-# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo.cpp"
+# CHECK-NEXT:      "uri": "file://{{.*}}/clangd-test/foo.cpp",
+# CHECK-NEXT:      "version": 2
 # CHECK-NEXT:    }
 # CHECK-NEXT:  }
 # CHECK-NEXT:}
 ---
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
 ---
 {"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/test/version.test

+# RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
+# Verify versions get recorded/inferred, and are reported in publishDiagnostics.
+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{}}
+---
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","text":""}}}
+# CHECK:    "version": 0
+---
+{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///foo.c","version":5},"contentChanges":[{"text":"a"}]}}
+# CHECK:    "version": 5
+---
+{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///foo.c"},"contentChanges":[{"text":"b"}]}}
+# CHECK:    "version": 6
+---
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///bar.c","version": 42, "languageId":"c","text":""}}}
+# CHECK:    "version": 42
+---
+{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///bar.c"},"contentChanges":[{"text":"c"}]}}
+# CHECK:    "version": 43
+---
+{"jsonrpc":"2.0","method":"textDocument/didChange","params":{"textDocument":{"uri":"test:///bar.c", "version": 123},"contentChanges":[{"text":"d"}]}}
+# CHECK:    "version": 123
+---
+{"jsonrpc":"2.0","id":6,"method":"shutdown"}
+---
+{"jsonrpc":"2.0","method":"exit"}

clang-tools-extra/clangd/unittests/ClangdTests.cpp

if (D.Severity == DiagnosticsEngine::Error ||
         D.Severity == DiagnosticsEngine::Fatal)
       return true;
   }
   return false;
 }
 
 class ErrorCheckingCallbacks : public ClangdServer::Callbacks {
 public:
-  void onDiagnosticsReady(PathRef File,
+  void onDiagnosticsReady(PathRef File, const llvm::json::Value &Version,
                           std::vector<Diag> Diagnostics) override {
     bool HadError = diagsContainErrors(Diagnostics);
     std::lock_guard<std::mutex> Lock(Mutex);
     HadErrorInLastDiags = HadError;
   }
 
   bool hadErrorInLastDiags() {
     std::lock_guard<std::mutex> Lock(Mutex);
     return HadErrorInLastDiags;
   }
 
 private:
   std::mutex Mutex;
   bool HadErrorInLastDiags = false;
 };
 
 /// For each file, record whether the last published diagnostics contained at
 /// least one error.
 class MultipleErrorCheckingCallbacks : public ClangdServer::Callbacks {
 public:
-  void onDiagnosticsReady(PathRef File,
+  void onDiagnosticsReady(PathRef File, const llvm::json::Value &Version,
                           std::vector<Diag> Diagnostics) override {
     bool HadError = diagsContainErrors(Diagnostics);
 
     std::lock_guard<std::mutex> Lock(Mutex);
     LastDiagsHadError[File] = HadError;
   }
 
   /// Exposes all files consumed by onDiagnosticsReady in an unspecified order.
TEST_F(ClangdVFSTest, PropagatesContexts) {
   struct FSProvider : public FileSystemProvider {
     IntrusiveRefCntPtr<llvm::vfs::FileSystem> getFileSystem() const override {
       Got = Context::current().getExisting(Secret);
       return buildTestFS({});
     }
     mutable int Got;
   } FS;
   struct Callbacks : public ClangdServer::Callbacks {
-    void onDiagnosticsReady(PathRef File,
+    void onDiagnosticsReady(PathRef File, const llvm::json::Value &Version,
                             std::vector<Diag> Diagnostics) override {
       Got = Context::current().getExisting(Secret);
     }
     int Got;
   } Callbacks;
   MockCompilationDatabase CDB;
 
   // Verify that the context is plumbed to the FS provider and diagnostics.
   ClangdServer Server(CDB, FS, ClangdServer::optsForTest(), &Callbacks);
   {
     WithContextValue Entrypoint(Secret, 42);
     Server.addDocument(testPath("foo.cpp"), "void main(){}");
   }
   ASSERT_TRUE(Server.blockUntilIdleForTest());
   EXPECT_EQ(FS.Got, 42);
   EXPECT_EQ(Callbacks.Got, 42);
 }
 
+TEST_F(ClangdVFSTest, PropagatesVersion) {
+  MockCompilationDatabase CDB;
+  MockFSProvider FS;
+  struct Callbacks : public ClangdServer::Callbacks {
+    void onDiagnosticsReady(PathRef File, const llvm::json::Value &Version,
+                            std::vector<Diag> Diagnostics) override {
+      Got = Version;
+    }
+    llvm::json::Value Got = nullptr;
+  } Callbacks;
+
+  // Verify that the version is plumbed to diagnostics.
+  ClangdServer Server(CDB, FS, ClangdServer::optsForTest(), &Callbacks);
+  runAddDocument(Server, testPath("foo.cpp"), "void main(){}", 42);
+  EXPECT_EQ(Callbacks.Got, 42);
+}
+
 // Only enable this test on Unix
 #ifdef LLVM_ON_UNIX
 TEST_F(ClangdVFSTest, SearchLibDir) {
   // Checks that searches for GCC installation is done through vfs.
   MockFSProvider FS;
   ErrorCheckingCallbacks DiagConsumer;
   MockCompilationDatabase CDB;
   CDB.ExtraClangFlags.insert(CDB.ExtraClangFlags.end(),
)cpp";
   CDB.ExtraClangFlags = {"-xc"};
   runAddDocument(Server, FooCpp, SourceContents1);
   EXPECT_TRUE(DiagConsumer.hadErrorInLastDiags());
   runAddDocument(Server, FooCpp, SourceContents2);
   EXPECT_TRUE(DiagConsumer.hadErrorInLastDiags());
 
   // Now switch to C++ mode.
   CDB.ExtraClangFlags = {"-xc++"};
-  runAddDocument(Server, FooCpp, SourceContents2, WantDiagnostics::Auto);
+  runAddDocument(Server, FooCpp, SourceContents2);
   EXPECT_FALSE(DiagConsumer.hadErrorInLastDiags());
   // Subsequent addDocument calls should finish without errors too.
   runAddDocument(Server, FooCpp, SourceContents1);
   EXPECT_FALSE(DiagConsumer.hadErrorInLastDiags());
   runAddDocument(Server, FooCpp, SourceContents2);
   EXPECT_FALSE(DiagConsumer.hadErrorInLastDiags());
 }
 
)cpp";
 
   // Parse with define, we expect to see the errors.
   CDB.ExtraClangFlags = {"-DWITH_ERROR"};
   runAddDocument(Server, FooCpp, SourceContents);
   EXPECT_TRUE(DiagConsumer.hadErrorInLastDiags());
 
   // Parse without the define, no errors should be produced.
   CDB.ExtraClangFlags = {};
-  runAddDocument(Server, FooCpp, SourceContents, WantDiagnostics::Auto);
+  runAddDocument(Server, FooCpp, SourceContents);
   ASSERT_TRUE(Server.blockUntilIdleForTest());
   EXPECT_FALSE(DiagConsumer.hadErrorInLastDiags());
   // Subsequent addDocument call should finish without errors too.
   runAddDocument(Server, FooCpp, SourceContents);
   EXPECT_FALSE(DiagConsumer.hadErrorInLastDiags());
 }
 
 // Test ClangdServer.reparseOpenedFiles.
)cpp");
   auto Locations = runLocateSymbolAt(Server, FooCpp, FooSource.point());
   EXPECT_TRUE(bool(Locations));
   EXPECT_THAT(*Locations, ElementsAre(DeclAt(FooCpp, FooSource.range("one"))));
 
   // Undefine MACRO, close baz.cpp.
   CDB.ExtraClangFlags.clear();
   DiagConsumer.clear();
   Server.removeDocument(BazCpp);
-  Server.addDocument(FooCpp, FooSource.code(), WantDiagnostics::Auto);
-  Server.addDocument(BarCpp, BarSource.code(), WantDiagnostics::Auto);
+  Server.addDocument(FooCpp, FooSource.code());
+  Server.addDocument(BarCpp, BarSource.code());
   ASSERT_TRUE(Server.blockUntilIdleForTest());
 
   EXPECT_THAT(DiagConsumer.filesWithDiags(),
               UnorderedElementsAre(Pair(FooCpp, false), Pair(BarCpp, false)));
 
   Locations = runLocateSymbolAt(Server, FooCpp, FooSource.point());
   EXPECT_TRUE(bool(Locations));
   EXPECT_THAT(*Locations, ElementsAre(DeclAt(FooCpp, FooSource.range("two"))));
struct FileStat {
     unsigned HitsWithErrors = 0;
     bool HadErrorsInLastDiags = false;
   };
 
   class TestDiagConsumer : public ClangdServer::Callbacks {
   public:
     TestDiagConsumer() : Stats(FilesCount, FileStat()) {}
 
-    void onDiagnosticsReady(PathRef File,
+    void onDiagnosticsReady(PathRef File, const llvm::json::Value &Version,
                             std::vector<Diag> Diagnostics) override {
       StringRef FileIndexStr = llvm::sys::path::stem(File);
       ASSERT_TRUE(FileIndexStr.consume_front("Foo"));
 
       unsigned long FileIndex = std::stoul(FileIndexStr.str());
 
       bool HadError = diagsContainErrors(Diagnostics);
 
auto UpdateStatsOnRemoveDocument = [&](unsigned FileIndex) {
 
       Stats.FileIsRemoved = true;
     };
 
     auto AddDocument = [&](unsigned FileIndex, bool SkipCache) {
       bool ShouldHaveErrors = ShouldHaveErrorsDist(RandGen);
       Server.addDocument(FilePaths[FileIndex],
                          ShouldHaveErrors ? SourceContentsWithErrors
-                                          : SourceContentsWithoutErrors,
-                         WantDiagnostics::Auto);
+                                          : SourceContentsWithoutErrors);
       UpdateStatsOnAddDocument(FileIndex, ShouldHaveErrors);
     };
 
     // Various requests that we would randomly run.
     auto AddDocumentRequest = [&]() {
       unsigned FileIndex = FileIndexDist(RandGen);
       AddDocument(FileIndex, /*SkipCache=*/false);
     };

 TEST_F(ClangdThreadingTest, NoConcurrentDiagnostics) {
   class NoConcurrentAccessDiagConsumer : public ClangdServer::Callbacks {
   public:
     std::atomic<int> Count = {0};
 
     NoConcurrentAccessDiagConsumer(std::promise<void> StartSecondReparse)
         : StartSecondReparse(std::move(StartSecondReparse)) {}
 
-    void onDiagnosticsReady(PathRef, std::vector<Diag>) override {
+    void onDiagnosticsReady(PathRef, const llvm::json::Value &,
+                            std::vector<Diag>) override {
       ++Count;
       std::unique_lock<std::mutex> Lock(Mutex, std::try_to_lock_t());
       ASSERT_TRUE(Lock.owns_lock())
           << "Detected concurrent onDiagnosticsReady calls for the same file.";
 
       // If we started the second parse immediately, it might cancel the first.
       // So we don't allow it to start until the first has delivered diags...
       if (FirstRequest) {

clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp

TEST(CompletionTest, DocumentationFromChangedFileCrash) {
 
   Annotations Source(R"cpp(
     #include "foo.h"
     int func() {
       // This makes sure we have func from header in the AST.
     }
     int a = fun^
   )cpp");
-  Server.addDocument(FooCpp, Source.code(), WantDiagnostics::Yes);
+  Server.addDocument(FooCpp, Source.code(), nullptr, WantDiagnostics::Yes);
   // We need to wait for preamble to build.
   ASSERT_TRUE(Server.blockUntilIdleForTest());
 
   // Change the header file. Completion will reuse the old preamble!
   FS.Files[FooH] = R"cpp(
     int func();
   )cpp";
 
Annotations Source(R"cpp(
     template <class T>
     int Struct<T>::comments_quux() {
       int a = comments^;
     }
   )cpp");
   // FIXME: Auto-completion in a template requires disabling delayed template
   // parsing.
   CDB.ExtraClangFlags.push_back("-fno-delayed-template-parsing");
-  runAddDocument(Server, FooCpp, Source.code(), WantDiagnostics::Yes);
+  runAddDocument(Server, FooCpp, Source.code(), nullptr, WantDiagnostics::Yes);
   CodeCompleteResult Completions = cantFail(runCodeComplete(
       Server, FooCpp, Source.point(), clangd::CodeCompleteOptions()));
 
   // We should not get any of those comments in completion.
   EXPECT_THAT(
       Completions.Completions,
       UnorderedElementsAre(AllOf(Not(IsDocumented()), Named("comments_foo")),
                            AllOf(IsDocumented(), Named("comments_baz")),

clang-tools-extra/clangd/unittests/FileIndexTests.cpp

 
 // Adds Basename.cpp, which includes Basename.h, which contains Code.
 void update(FileIndex &M, llvm::StringRef Basename, llvm::StringRef Code) {
   TestTU File;
   File.Filename = (Basename + ".cpp").str();
   File.HeaderFilename = (Basename + ".h").str();
   File.HeaderCode = std::string(Code);
   auto AST = File.build();
-  M.updatePreamble(File.Filename, AST.getASTContext(), AST.getPreprocessorPtr(),
-                   AST.getCanonicalIncludes());
+  M.updatePreamble(File.Filename, /*Version=*/nullptr, AST.getASTContext(),
+                   AST.getPreprocessorPtr(), AST.getCanonicalIncludes());
 }
 
 TEST(FileIndexTest, CustomizedURIScheme) {
   FileIndex M;
   update(M, "f", "class string {};");
 
   EXPECT_THAT(runFuzzyFind(M, ""), ElementsAre(DeclURI("unittest:///f.h")));
 }
TEST(FileIndexTest, RebuildWithPreamble) {
   bool IndexUpdated = false;
   buildPreamble(
       FooCpp, *CI, /*OldPreamble=*/nullptr, tooling::CompileCommand(), PI,
       /*StoreInMemory=*/true,
       [&](ASTContext &Ctx, std::shared_ptr<Preprocessor> PP,
           const CanonicalIncludes &CanonIncludes) {
         EXPECT_FALSE(IndexUpdated) << "Expected only a single index update";
         IndexUpdated = true;
-        Index.updatePreamble(FooCpp, Ctx, std::move(PP), CanonIncludes);
+        Index.updatePreamble(FooCpp, /*Version=*/nullptr, Ctx, std::move(PP),
+                             CanonIncludes);
       });
   ASSERT_TRUE(IndexUpdated);
 
   // Check the index contains symbols from the preamble, but not from the main
   // file.
   FuzzyFindRequest Req;
   Req.Query = "";
   Req.Scopes = {"", "ns_in_header::"};

 
 TEST(FileIndexTest, Relations) {
   TestTU TU;
   TU.Filename = "f.cpp";
   TU.HeaderFilename = "f.h";
   TU.HeaderCode = "class A {}; class B : public A {};";
   auto AST = TU.build();
   FileIndex Index;
-  Index.updatePreamble(TU.Filename, AST.getASTContext(),
+  Index.updatePreamble(TU.Filename, /*Version=*/nullptr, AST.getASTContext(),
                        AST.getPreprocessorPtr(), AST.getCanonicalIncludes());
   SymbolID A = findSymbol(TU.headerSymbols(), "A").ID;
   uint32_t Results = 0;
   RelationsRequest Req;
   Req.Subjects.insert(A);
   Req.Predicate = RelationKind::BaseOf;
   Index.relations(Req, [&](const SymbolID &, const Symbol &) { ++Results; });
   EXPECT_EQ(Results, 1u);

clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp

 }
 
 TEST(SemanticHighlighting, GeneratesHighlightsWhenFileChange) {
   class HighlightingsCounter : public ClangdServer::Callbacks {
   public:
     std::atomic<int> Count = {0};
 
     void onHighlightingsReady(
-        PathRef File, std::vector<HighlightingToken> Highlightings) override {
+        PathRef File, const llvm::json::Value &Version,
+        std::vector<HighlightingToken> Highlightings) override {
       ++Count;
     }
   };
 
   auto FooCpp = testPath("foo.cpp");
   MockFSProvider FS;
   FS.Files[FooCpp] = "";
 

clang-tools-extra/clangd/unittests/SyncAPI.h

 #include "ClangdServer.h"
 #include "index/Index.h"
 
 namespace clang {
 namespace clangd {
 
 // Calls addDocument and then blockUntilIdleForTest.
 void runAddDocument(ClangdServer &Server, PathRef File, StringRef Contents,
-                    WantDiagnostics WantDiags = WantDiagnostics::Auto);
+                    llvm::json::Value Version = nullptr,
+                    WantDiagnostics WantDiags = WantDiagnostics::Auto,
+                    bool ForceRebuild = false);
 
 llvm::Expected<CodeCompleteResult>
 runCodeComplete(ClangdServer &Server, PathRef File, Position Pos,
                 clangd::CodeCompleteOptions Opts);
 
 llvm::Expected<SignatureHelp> runSignatureHelp(ClangdServer &Server,
                                                PathRef File, Position Pos);
 

clang-tools-extra/clangd/unittests/SyncAPI.cpp

 //===--- SyncAPI.cpp - Sync version of ClangdServer's API --------*- C++-*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "SyncAPI.h"
 #include "index/Index.h"
 
 namespace clang {
 namespace clangd {
 
 void runAddDocument(ClangdServer &Server, PathRef File,
-                    llvm::StringRef Contents, WantDiagnostics WantDiags) {
-  Server.addDocument(File, Contents, WantDiags);
+                    llvm::StringRef Contents, llvm::json::Value Version,
+                    WantDiagnostics WantDiags, bool ForceRebuild) {
+  Server.addDocument(File, Contents, std::move(Version), WantDiags,
+                     ForceRebuild);
   if (!Server.blockUntilIdleForTest())
     llvm_unreachable("not idle after addDocument");
 }
 
 namespace {
 /// A helper that waits for async callbacks to fire and exposes their result in
 /// the output variable. Intended to be used in the following way:
 ///    T Result;

clang-tools-extra/clangd/unittests/TUSchedulerTests.cpp

 using ::testing::ElementsAre;
 using ::testing::Eq;
 using ::testing::Field;
 using ::testing::IsEmpty;
 using ::testing::Pointee;
 using ::testing::UnorderedElementsAre;
 
 MATCHER_P2(TUState, State, ActionName, "") {
-  return arg.Action.S == State && arg.Action.Name == ActionName;
+  if (arg.Action.S != State) {
+    *result_listener << "state is " << arg.Action.S;
+    return false;
+  }
+  if (arg.Action.Name != ActionName) {
+    *result_listener << "name is " << arg.Action.Name;
+    return false;
+  }
+  return true;
 }
 
 TUScheduler::Options optsForTest() {
   return TUScheduler::Options(ClangdServer::optsForTest());
 }
 
 class TUSchedulerTests : public ::testing::Test {
 protected:
   ParseInputs getInputs(PathRef File, std::string Contents) {
     ParseInputs Inputs;
     Inputs.CompileCommand = *CDB.getCompileCommand(File);
     Inputs.FS = buildTestFS(Files, Timestamps);
     Inputs.Contents = std::move(Contents);
     Inputs.Opts = ParseOptions();
     return Inputs;
   }
 
   void updateWithCallback(TUScheduler &S, PathRef File,
                           llvm::StringRef Contents, WantDiagnostics WD,
                           llvm::unique_function<void()> CB) {
+    updateWithCallback(S, File, getInputs(File, std::string(Contents)), WD,
+                       std::move(CB));
+  }
+
+  void updateWithCallback(TUScheduler &S, PathRef File, ParseInputs Inputs,
+                          WantDiagnostics WD,
+                          llvm::unique_function<void()> CB) {
     WithContextValue Ctx(llvm::make_scope_exit(std::move(CB)));
-    S.update(File, getInputs(File, std::string(Contents)), WD);
+    S.update(File, Inputs, WD);
   }
 
   static Key<llvm::unique_function<void(PathRef File, std::vector<Diag>)>>
       DiagsCallbackKey;
 
   /// A diagnostics callback that should be passed to TUScheduler when it's used
   /// in updateWithDiags.
   static std::unique_ptr<ParsingCallbacks> captureDiags() {
     class CaptureDiags : public ParsingCallbacks {
     public:
       void onMainAST(PathRef File, ParsedAST &AST, PublishFn Publish) override {
         reportDiagnostics(File, AST.getDiagnostics(), Publish);
       }
 
-      void onFailedAST(PathRef File, std::vector<Diag> Diags,
-                       PublishFn Publish) override {
+      void onFailedAST(PathRef File, const llvm::json::Value &Version,
+                       std::vector<Diag> Diags, PublishFn Publish) override {
         reportDiagnostics(File, Diags, Publish);
       }
 
     private:
       void reportDiagnostics(PathRef File, llvm::ArrayRef<Diag> Diags,
                              PublishFn Publish) {
         auto D = Context::current().get(DiagsCallbackKey);
         if (!D)
TEST_F(TUSchedulerTests, PreambleConsistency) {
   std::atomic<int> CallbackCount(0);
   {
     Notification InconsistentReadDone; // Must live longest.
     TUScheduler S(CDB, optsForTest());
     auto Path = testPath("foo.cpp");
     // Schedule two updates (A, B) and two preamble reads (stale, consistent).
     // The stale read should see A, and the consistent read should see B.
     // (We recognize the preambles by their included files).
-    updateWithCallback(S, Path, "#include <A>", WantDiagnostics::Yes, [&]() {
+    auto Inputs = getInputs(Path, "#include <A>");
+    Inputs.Version = "A";
+    updateWithCallback(S, Path, Inputs, WantDiagnostics::Yes, [&]() {
       // This callback runs in between the two preamble updates.
 
       // This blocks update B, preventing it from winning the race
       // against the stale read.
       // If the first read was instead consistent, this would deadlock.
       InconsistentReadDone.wait();
       // This delays update B, preventing it from winning a race
       // against the consistent read. The consistent read sees B
       // only because it waits for it.
       // If the second read was stale, it would usually see A.
       std::this_thread::sleep_for(std::chrono::milliseconds(100));
     });
-    S.update(Path, getInputs(Path, "#include <B>"), WantDiagnostics::Yes);
+    Inputs.Contents = "#include <B>";
+    Inputs.Version = "B";
+    S.update(Path, Inputs, WantDiagnostics::Yes);
 
     S.runWithPreamble("StaleRead", Path, TUScheduler::Stale,
                       [&](Expected<InputsAndPreamble> Pre) {
                         ASSERT_TRUE(bool(Pre));
-                        assert(bool(Pre));
+                        EXPECT_EQ(Pre->Preamble->Version, "A");
                         EXPECT_THAT(includes(Pre->Preamble),
                                     ElementsAre("<A>"));
                         InconsistentReadDone.notify();
                         ++CallbackCount;
                       });
     S.runWithPreamble("ConsistentRead", Path, TUScheduler::Consistent,
                       [&](Expected<InputsAndPreamble> Pre) {
                         ASSERT_TRUE(bool(Pre));
+                        EXPECT_EQ(Pre->Preamble->Version, "B");
                         EXPECT_THAT(includes(Pre->Preamble),
                                     ElementsAre("<B>"));
                         ++CallbackCount;
                       });
   }
   EXPECT_EQ(2, CallbackCount);
 }
 
// Run TUScheduler and collect some stats.
     for (int FileI = 0; FileI < FilesCount; ++FileI) {
       for (int UpdateI = 0; UpdateI < UpdatesPerFile; ++UpdateI) {
         auto Contents = AllContents[(FileI + UpdateI) % AllContentsSize];
 
         auto File = Files[FileI];
         auto Inputs = getInputs(File, Contents.str());
         {
           WithContextValue WithNonce(NonceKey, ++Nonce);
+          Inputs.Version = Nonce;
           updateWithDiags(
               S, File, Inputs, WantDiagnostics::Auto,
               [File, Nonce, &Mut, &TotalUpdates](std::vector<Diag>) {
                 EXPECT_THAT(Context::current().get(NonceKey), Pointee(Nonce));
 
                 std::lock_guard<std::mutex> Lock(Mut);
                 ++TotalUpdates;
                 EXPECT_EQ(File, *TUScheduler::getFileBeingProcessedInContext());
               });
         }
         {
           WithContextValue WithNonce(NonceKey, ++Nonce);
           S.runWithAST(
               "CheckAST", File,
               [File, Inputs, Nonce, &Mut,
                &TotalASTReads](Expected<InputsAndAST> AST) {
                 EXPECT_THAT(Context::current().get(NonceKey), Pointee(Nonce));
 
                 ASSERT_TRUE((bool)AST);
                 EXPECT_EQ(AST->Inputs.FS, Inputs.FS);
                 EXPECT_EQ(AST->Inputs.Contents, Inputs.Contents);
+                EXPECT_EQ(AST->Inputs.Version, Inputs.Version);
+                EXPECT_EQ(AST->AST.version(), Inputs.Version);
 
                 std::lock_guard<std::mutex> Lock(Mut);
                 ++TotalASTReads;
                 EXPECT_EQ(File, *TUScheduler::getFileBeingProcessedInContext());
               });
         }
 
         {
S.run("props context", [&] {
     TaskRun.notify();
   });
   TaskRun.wait();
 }
 
 TEST_F(TUSchedulerTests, TUStatus) {
   class CaptureTUStatus : public ClangdServer::Callbacks {
   public:
-    void onDiagnosticsReady(PathRef File,
-                            std::vector<Diag> Diagnostics) override {}
-
     void onFileUpdated(PathRef File, const TUStatus &Status) override {
       std::lock_guard<std::mutex> Lock(Mutex);
       AllStatus.push_back(Status);
     }
 
     std::vector<TUStatus> allStatus() {
       std::lock_guard<std::mutex> Lock(Mutex);
       return AllStatus;
     }
 
   private:
     std::mutex Mutex;
     std::vector<TUStatus> AllStatus;
   } CaptureTUStatus;
   MockFSProvider FS;
   MockCompilationDatabase CDB;
   ClangdServer Server(CDB, FS, ClangdServer::optsForTest(), &CaptureTUStatus);
   Annotations Code("int m^ain () {}");
 
   // We schedule the following tasks in the queue:
   //   [Update] [GoToDefinition]
-  Server.addDocument(testPath("foo.cpp"), Code.code(), WantDiagnostics::Yes);
+  Server.addDocument(testPath("foo.cpp"), Code.code(), 1, WantDiagnostics::Yes);
   Server.locateSymbolAt(testPath("foo.cpp"), Code.point(),
                         [](Expected<std::vector<LocatedSymbol>> Result) {
                           ASSERT_TRUE((bool)Result);
                         });
 
   ASSERT_TRUE(Server.blockUntilIdleForTest());
 
   EXPECT_THAT(CaptureTUStatus.allStatus(),
               ElementsAre(
                   // Statuses of "Update" action.
-                  TUState(TUAction::RunningAction, "Update"),
-                  TUState(TUAction::BuildingPreamble, "Update"),
-                  TUState(TUAction::BuildingFile, "Update"),
+                  TUState(TUAction::RunningAction, "Update (1)"),
+                  TUState(TUAction::BuildingPreamble, "Update (1)"),
+                  TUState(TUAction::BuildingFile, "Update (1)"),
 
                   // Statuses of "Definitions" action
                   TUState(TUAction::RunningAction, "Definitions"),
                   TUState(TUAction::Idle, /*No action*/ "")));
 }
 
 TEST_F(TUSchedulerTests, CommandLineErrors) {
   // We should see errors from command-line parsing inside the main file.

clang-tools-extra/clangd/unittests/TestTU.cpp

for (const auto &D : AST->getDiagnostics())
         break; // Just report first error for simplicity.
       }
   }
   return std::move(*AST);
 }
 
 SymbolSlab TestTU::headerSymbols() const {
   auto AST = build();
-  return std::get<0>(indexHeaderSymbols(AST.getASTContext(),
-                                        AST.getPreprocessorPtr(),
-                                        AST.getCanonicalIncludes()));
+  return std::get<0>(
+      indexHeaderSymbols(/*Version=*/nullptr, AST.getASTContext(),
+                         AST.getPreprocessorPtr(), AST.getCanonicalIncludes()));
 }
 
 std::unique_ptr<SymbolIndex> TestTU::index() const {
   auto AST = build();
   auto Idx = std::make_unique<FileIndex>(/*UseDex=*/true);
-  Idx->updatePreamble(Filename, AST.getASTContext(), AST.getPreprocessorPtr(),
-                      AST.getCanonicalIncludes());
+  Idx->updatePreamble(Filename, /*Version=*/nullptr, AST.getASTContext(),
+                      AST.getPreprocessorPtr(), AST.getCanonicalIncludes());
   Idx->updateMain(Filename, AST);
   return std::move(Idx);
 }
 
 const Symbol &findSymbol(const SymbolSlab &Slab, llvm::StringRef QName) {
   const Symbol *Result = nullptr;
   for (const Symbol &S : Slab) {
     if (QName != (S.Scope + S.Name).str())

clang-tools-extra/clangd/unittests/XRefsTests.cpp

TEST(LocateSymbol, WithPreamble) {
 
   runAddDocument(Server, FooCpp, FooWithHeader.code());
   // LocateSymbol goes to a #include file: the result comes from the preamble.
   EXPECT_THAT(
       cantFail(runLocateSymbolAt(Server, FooCpp, FooWithHeader.point())),
       ElementsAre(Sym("foo.h", FooHeader.range())));
 
   // Only preamble is built, and no AST is built in this request.
-  Server.addDocument(FooCpp, FooWithoutHeader.code(), WantDiagnostics::No);
+  Server.addDocument(FooCpp, FooWithoutHeader.code(), nullptr,
+                     WantDiagnostics::No);
   // We build AST here, and it should use the latest preamble rather than the
   // stale one.
   EXPECT_THAT(
       cantFail(runLocateSymbolAt(Server, FooCpp, FooWithoutHeader.point())),
       ElementsAre(Sym("foo", FooWithoutHeader.range())));
 
   // Reset test environment.
   runAddDocument(Server, FooCpp, FooWithHeader.code());
   // Both preamble and AST are built in this request.
-  Server.addDocument(FooCpp, FooWithoutHeader.code(), WantDiagnostics::Yes);
+  Server.addDocument(FooCpp, FooWithoutHeader.code(), nullptr,
+                     WantDiagnostics::Yes);
   // Use the AST being built in above request.
   EXPECT_THAT(
       cantFail(runLocateSymbolAt(Server, FooCpp, FooWithoutHeader.point())),
       ElementsAre(Sym("foo", FooWithoutHeader.range())));
 }
 
 TEST(FindReferences, WithinAST) {
   const char *Tests[] = {