Export clang-format16 via ydblib project

6e6be3a95868fde888d801b7590af4044049563f

1 files changed, 1628 insertions, 0 deletions

diff --git a/contrib/libs/clang16/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp b/contrib/libs/clang16/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
new file mode 100644
index 0000000000..b4578385a1
--- /dev/null
+++ b/contrib/libs/clang16/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
@@ -0,0 +1,1628 @@
+//===- HTMLDiagnostics.cpp - HTML Diagnostics for Paths -------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the HTMLDiagnostics object.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclBase.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Analysis/IssueHash.h"
+#include "clang/Analysis/MacroExpansionContext.h"
+#include "clang/Analysis/PathDiagnostic.h"
+#include "clang/Basic/FileManager.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/Token.h"
+#include "clang/Rewrite/Core/HTMLRewrite.h"
+#include "clang/Rewrite/Core/Rewriter.h"
+#include "clang/StaticAnalyzer/Core/PathDiagnosticConsumers.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/Sequence.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cassert>
+#include <map>
+#include <memory>
+#include <set>
+#include <sstream>
+#include <string>
+#include <system_error>
+#include <utility>
+#include <vector>
+
+using namespace clang;
+using namespace ento;
+
+//===----------------------------------------------------------------------===//
+// Boilerplate.
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+class ArrowMap;
+
+class HTMLDiagnostics : public PathDiagnosticConsumer {
+  PathDiagnosticConsumerOptions DiagOpts;
+  std::string Directory;
+  bool createdDir = false;
+  bool noDir = false;
+  const Preprocessor &PP;
+  const bool SupportsCrossFileDiagnostics;
+
+public:
+  HTMLDiagnostics(PathDiagnosticConsumerOptions DiagOpts,
+                  const std::string &OutputDir, const Preprocessor &pp,
+                  bool supportsMultipleFiles)
+      : DiagOpts(std::move(DiagOpts)), Directory(OutputDir), PP(pp),
+        SupportsCrossFileDiagnostics(supportsMultipleFiles) {}
+
+  ~HTMLDiagnostics() override { FlushDiagnostics(nullptr); }
+
+  void FlushDiagnosticsImpl(std::vector<const PathDiagnostic *> &Diags,
+                            FilesMade *filesMade) override;
+
+  StringRef getName() const override { return "HTMLDiagnostics"; }
+
+  bool supportsCrossFileDiagnostics() const override {
+    return SupportsCrossFileDiagnostics;
+  }
+
+  unsigned ProcessMacroPiece(raw_ostream &os, const PathDiagnosticMacroPiece &P,
+                             unsigned num);
+
+  unsigned ProcessControlFlowPiece(Rewriter &R, FileID BugFileID,
+                                   const PathDiagnosticControlFlowPiece &P,
+                                   unsigned Number);
+
+  void HandlePiece(Rewriter &R, FileID BugFileID, const PathDiagnosticPiece &P,
+                   const std::vector<SourceRange> &PopUpRanges, unsigned num,
+                   unsigned max);
+
+  void HighlightRange(Rewriter &R, FileID BugFileID, SourceRange Range,
+                      const char *HighlightStart = "<span class=\"mrange\">",
+                      const char *HighlightEnd = "</span>");
+
+  void ReportDiag(const PathDiagnostic &D, FilesMade *filesMade);
+
+  // Generate the full HTML report
+  std::string GenerateHTML(const PathDiagnostic &D, Rewriter &R,
+                           const SourceManager &SMgr, const PathPieces &path,
+                           const char *declName);
+
+  // Add HTML header/footers to file specified by FID
+  void FinalizeHTML(const PathDiagnostic &D, Rewriter &R,
+                    const SourceManager &SMgr, const PathPieces &path,
+                    FileID FID, const FileEntry *Entry, const char *declName);
+
+  // Rewrite the file specified by FID with HTML formatting.
+  void RewriteFile(Rewriter &R, const PathPieces &path, FileID FID);
+
+  PathGenerationScheme getGenerationScheme() const override {
+    return Everything;
+  }
+
+private:
+  void addArrowSVGs(Rewriter &R, FileID BugFileID,
+                    const ArrowMap &ArrowIndices);
+
+  /// \return Javascript for displaying shortcuts help;
+  StringRef showHelpJavascript();
+
+  /// \return Javascript for navigating the HTML report using j/k keys.
+  StringRef generateKeyboardNavigationJavascript();
+
+  /// \return Javascript for drawing control-flow arrows.
+  StringRef generateArrowDrawingJavascript();
+
+  /// \return JavaScript for an option to only show relevant lines.
+  std::string showRelevantLinesJavascript(const PathDiagnostic &D,
+                                          const PathPieces &path);
+
+  /// Write executed lines from \p D in JSON format into \p os.
+  void dumpCoverageData(const PathDiagnostic &D, const PathPieces &path,
+                        llvm::raw_string_ostream &os);
+};
+
+bool isArrowPiece(const PathDiagnosticPiece &P) {
+  return isa<PathDiagnosticControlFlowPiece>(P) && P.getString().empty();
+}
+
+unsigned getPathSizeWithoutArrows(const PathPieces &Path) {
+  unsigned TotalPieces = Path.size();
+  unsigned TotalArrowPieces = llvm::count_if(
+      Path, [](const PathDiagnosticPieceRef &P) { return isArrowPiece(*P); });
+  return TotalPieces - TotalArrowPieces;
+}
+
+class ArrowMap : public std::vector<unsigned> {
+  using Base = std::vector<unsigned>;
+
+public:
+  ArrowMap(unsigned Size) : Base(Size, 0) {}
+  unsigned getTotalNumberOfArrows() const { return at(0); }
+};
+
+llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const ArrowMap &Indices) {
+  OS << "[ ";
+  llvm::interleave(Indices, OS, ",");
+  return OS << " ]";
+}
+
+} // namespace
+
+void ento::createHTMLDiagnosticConsumer(
+    PathDiagnosticConsumerOptions DiagOpts, PathDiagnosticConsumers &C,
+    const std::string &OutputDir, const Preprocessor &PP,
+    const cross_tu::CrossTranslationUnitContext &CTU,
+    const MacroExpansionContext &MacroExpansions) {
+
+  // FIXME: HTML is currently our default output type, but if the output
+  // directory isn't specified, it acts like if it was in the minimal text
+  // output mode. This doesn't make much sense, we should have the minimal text
+  // as our default. In the case of backward compatibility concerns, this could
+  // be preserved with -analyzer-config-compatibility-mode=true.
+  createTextMinimalPathDiagnosticConsumer(DiagOpts, C, OutputDir, PP, CTU,
+                                          MacroExpansions);
+
+  // TODO: Emit an error here.
+  if (OutputDir.empty())
+    return;
+
+  C.push_back(new HTMLDiagnostics(std::move(DiagOpts), OutputDir, PP, true));
+}
+
+void ento::createHTMLSingleFileDiagnosticConsumer(
+    PathDiagnosticConsumerOptions DiagOpts, PathDiagnosticConsumers &C,
+    const std::string &OutputDir, const Preprocessor &PP,
+    const cross_tu::CrossTranslationUnitContext &CTU,
+    const clang::MacroExpansionContext &MacroExpansions) {
+  createTextMinimalPathDiagnosticConsumer(DiagOpts, C, OutputDir, PP, CTU,
+                                          MacroExpansions);
+
+  // TODO: Emit an error here.
+  if (OutputDir.empty())
+    return;
+
+  C.push_back(new HTMLDiagnostics(std::move(DiagOpts), OutputDir, PP, false));
+}
+
+void ento::createPlistHTMLDiagnosticConsumer(
+    PathDiagnosticConsumerOptions DiagOpts, PathDiagnosticConsumers &C,
+    const std::string &prefix, const Preprocessor &PP,
+    const cross_tu::CrossTranslationUnitContext &CTU,
+    const MacroExpansionContext &MacroExpansions) {
+  createHTMLDiagnosticConsumer(
+      DiagOpts, C, std::string(llvm::sys::path::parent_path(prefix)), PP, CTU,
+      MacroExpansions);
+  createPlistMultiFileDiagnosticConsumer(DiagOpts, C, prefix, PP, CTU,
+                                         MacroExpansions);
+  createTextMinimalPathDiagnosticConsumer(std::move(DiagOpts), C, prefix, PP,
+                                          CTU, MacroExpansions);
+}
+
+void ento::createSarifHTMLDiagnosticConsumer(
+    PathDiagnosticConsumerOptions DiagOpts, PathDiagnosticConsumers &C,
+    const std::string &sarif_file, const Preprocessor &PP,
+    const cross_tu::CrossTranslationUnitContext &CTU,
+    const MacroExpansionContext &MacroExpansions) {
+  createHTMLDiagnosticConsumer(
+      DiagOpts, C, std::string(llvm::sys::path::parent_path(sarif_file)), PP,
+      CTU, MacroExpansions);
+  createSarifDiagnosticConsumer(DiagOpts, C, sarif_file, PP, CTU,
+                                MacroExpansions);
+  createTextMinimalPathDiagnosticConsumer(std::move(DiagOpts), C, sarif_file,
+                                          PP, CTU, MacroExpansions);
+}
+
+//===----------------------------------------------------------------------===//
+// Report processing.
+//===----------------------------------------------------------------------===//
+
+void HTMLDiagnostics::FlushDiagnosticsImpl(
+  std::vector<const PathDiagnostic *> &Diags,
+  FilesMade *filesMade) {
+  for (const auto Diag : Diags)
+    ReportDiag(*Diag, filesMade);
+}
+
+static llvm::SmallString<32> getIssueHash(const PathDiagnostic &D,
+                                          const Preprocessor &PP) {
+  SourceManager &SMgr = PP.getSourceManager();
+  PathDiagnosticLocation UPDLoc = D.getUniqueingLoc();
+  FullSourceLoc L(SMgr.getExpansionLoc(UPDLoc.isValid()
+                                           ? UPDLoc.asLocation()
+                                           : D.getLocation().asLocation()),
+                  SMgr);
+  return getIssueHash(L, D.getCheckerName(), D.getBugType(),
+                      D.getDeclWithIssue(), PP.getLangOpts());
+}
+
+void HTMLDiagnostics::ReportDiag(const PathDiagnostic& D,
+                                 FilesMade *filesMade) {
+  // Create the HTML directory if it is missing.
+  if (!createdDir) {
+    createdDir = true;
+    if (std::error_code ec = llvm::sys::fs::create_directories(Directory)) {
+      llvm::errs() << "warning: could not create directory '"
+                   << Directory << "': " << ec.message() << '\n';
+      noDir = true;
+      return;
+    }
+  }
+
+  if (noDir)
+    return;
+
+  // First flatten out the entire path to make it easier to use.
+  PathPieces path = D.path.flatten(/*ShouldFlattenMacros=*/false);
+
+  // The path as already been prechecked that the path is non-empty.
+  assert(!path.empty());
+  const SourceManager &SMgr = path.front()->getLocation().getManager();
+
+  // Create a new rewriter to generate HTML.
+  Rewriter R(const_cast<SourceManager&>(SMgr), PP.getLangOpts());
+
+  // Get the function/method name
+  SmallString<128> declName("unknown");
+  int offsetDecl = 0;
+  if (const Decl *DeclWithIssue = D.getDeclWithIssue()) {
+      if (const auto *ND = dyn_cast<NamedDecl>(DeclWithIssue))
+          declName = ND->getDeclName().getAsString();
+
+      if (const Stmt *Body = DeclWithIssue->getBody()) {
+          // Retrieve the relative position of the declaration which will be used
+          // for the file name
+          FullSourceLoc L(
+              SMgr.getExpansionLoc(path.back()->getLocation().asLocation()),
+              SMgr);
+          FullSourceLoc FunL(SMgr.getExpansionLoc(Body->getBeginLoc()), SMgr);
+          offsetDecl = L.getExpansionLineNumber() - FunL.getExpansionLineNumber();
+      }
+  }
+
+  std::string report = GenerateHTML(D, R, SMgr, path, declName.c_str());
+  if (report.empty()) {
+    llvm::errs() << "warning: no diagnostics generated for main file.\n";
+    return;
+  }
+
+  // Create a path for the target HTML file.
+  int FD;
+
+  SmallString<128> FileNameStr;
+  llvm::raw_svector_ostream FileName(FileNameStr);
+  FileName << "report-";
+
+  // Historically, neither the stable report filename nor the unstable report
+  // filename were actually stable. That said, the stable report filename
+  // was more stable because it was mostly composed of information
+  // about the bug report instead of being completely random.
+  // Now both stable and unstable report filenames are in fact stable
+  // but the stable report filename is still more verbose.
+  if (DiagOpts.ShouldWriteVerboseReportFilename) {
+    // FIXME: This code relies on knowing what constitutes the issue hash.
+    // Otherwise deduplication won't work correctly.
+    FileID ReportFile =
+        path.back()->getLocation().asLocation().getExpansionLoc().getFileID();
+
+    const FileEntry *Entry = SMgr.getFileEntryForID(ReportFile);
+
+    FileName << llvm::sys::path::filename(Entry->getName()).str() << "-"
+             << declName.c_str() << "-" << offsetDecl << "-";
+  }
+
+  FileName << StringRef(getIssueHash(D, PP)).substr(0, 6).str() << ".html";
+
+  SmallString<128> ResultPath;
+  llvm::sys::path::append(ResultPath, Directory, FileName.str());
+  if (std::error_code EC = llvm::sys::fs::make_absolute(ResultPath)) {
+    llvm::errs() << "warning: could not make '" << ResultPath
+                 << "' absolute: " << EC.message() << '\n';
+    return;
+  }
+
+  if (std::error_code EC = llvm::sys::fs::openFileForReadWrite(
+          ResultPath, FD, llvm::sys::fs::CD_CreateNew,
+          llvm::sys::fs::OF_Text)) {
+    // Existence of the file corresponds to the situation where a different
+    // Clang instance has emitted a bug report with the same issue hash.
+    // This is an entirely normal situation that does not deserve a warning,
+    // as apart from hash collisions this can happen because the reports
+    // are in fact similar enough to be considered duplicates of each other.
+    if (EC != llvm::errc::file_exists) {
+      llvm::errs() << "warning: could not create file in '" << Directory
+                   << "': " << EC.message() << '\n';
+    }
+    return;
+  }
+
+  llvm::raw_fd_ostream os(FD, true);
+
+  if (filesMade)
+    filesMade->addDiagnostic(D, getName(),
+                             llvm::sys::path::filename(ResultPath));
+
+  // Emit the HTML to disk.
+  os << report;
+}
+
+std::string HTMLDiagnostics::GenerateHTML(const PathDiagnostic& D, Rewriter &R,
+    const SourceManager& SMgr, const PathPieces& path, const char *declName) {
+  // Rewrite source files as HTML for every new file the path crosses
+  std::vector<FileID> FileIDs;
+  for (auto I : path) {
+    FileID FID = I->getLocation().asLocation().getExpansionLoc().getFileID();
+    if (llvm::is_contained(FileIDs, FID))
+      continue;
+
+    FileIDs.push_back(FID);
+    RewriteFile(R, path, FID);
+  }
+
+  if (SupportsCrossFileDiagnostics && FileIDs.size() > 1) {
+    // Prefix file names, anchor tags, and nav cursors to every file
+    for (auto I = FileIDs.begin(), E = FileIDs.end(); I != E; I++) {
+      std::string s;
+      llvm::raw_string_ostream os(s);
+
+      if (I != FileIDs.begin())
+        os << "<hr class=divider>\n";
+
+      os << "<div id=File" << I->getHashValue() << ">\n";
+
+      // Left nav arrow
+      if (I != FileIDs.begin())
+        os << "<div class=FileNav><a href=\"#File" << (I - 1)->getHashValue()
+           << "\">&#x2190;</a></div>";
+
+      os << "<h4 class=FileName>" << SMgr.getFileEntryForID(*I)->getName()
+         << "</h4>\n";
+
+      // Right nav arrow
+      if (I + 1 != E)
+        os << "<div class=FileNav><a href=\"#File" << (I + 1)->getHashValue()
+           << "\">&#x2192;</a></div>";
+
+      os << "</div>\n";
+
+      R.InsertTextBefore(SMgr.getLocForStartOfFile(*I), os.str());
+    }
+
+    // Append files to the main report file in the order they appear in the path
+    for (auto I : llvm::drop_begin(FileIDs)) {
+      std::string s;
+      llvm::raw_string_ostream os(s);
+
+      const RewriteBuffer *Buf = R.getRewriteBufferFor(I);
+      for (auto BI : *Buf)
+        os << BI;
+
+      R.InsertTextAfter(SMgr.getLocForEndOfFile(FileIDs[0]), os.str());
+    }
+  }
+
+  const RewriteBuffer *Buf = R.getRewriteBufferFor(FileIDs[0]);
+  if (!Buf)
+    return {};
+
+  // Add CSS, header, and footer.
+  FileID FID =
+      path.back()->getLocation().asLocation().getExpansionLoc().getFileID();
+  const FileEntry* Entry = SMgr.getFileEntryForID(FID);
+  FinalizeHTML(D, R, SMgr, path, FileIDs[0], Entry, declName);
+
+  std::string file;
+  llvm::raw_string_ostream os(file);
+  for (auto BI : *Buf)
+    os << BI;
+
+  return file;
+}
+
+void HTMLDiagnostics::dumpCoverageData(
+    const PathDiagnostic &D,
+    const PathPieces &path,
+    llvm::raw_string_ostream &os) {
+
+  const FilesToLineNumsMap &ExecutedLines = D.getExecutedLines();
+
+  os << "var relevant_lines = {";
+  for (auto I = ExecutedLines.begin(),
+            E = ExecutedLines.end(); I != E; ++I) {
+    if (I != ExecutedLines.begin())
+      os << ", ";
+
+    os << "\"" << I->first.getHashValue() << "\": {";
+    for (unsigned LineNo : I->second) {
+      if (LineNo != *(I->second.begin()))
+        os << ", ";
+
+      os << "\"" << LineNo << "\": 1";
+    }
+    os << "}";
+  }
+
+  os << "};";
+}
+
+std::string HTMLDiagnostics::showRelevantLinesJavascript(
+      const PathDiagnostic &D, const PathPieces &path) {
+  std::string s;
+  llvm::raw_string_ostream os(s);
+  os << "<script type='text/javascript'>\n";
+  dumpCoverageData(D, path, os);
+  os << R"<<<(
+
+var filterCounterexample = function (hide) {
+  var tables = document.getElementsByClassName("code");
+  for (var t=0; t<tables.length; t++) {
+    var table = tables[t];
+    var file_id = table.getAttribute("data-fileid");
+    var lines_in_fid = relevant_lines[file_id];
+    if (!lines_in_fid) {
+      lines_in_fid = {};
+    }
+    var lines = table.getElementsByClassName("codeline");
+    for (var i=0; i<lines.length; i++) {
+        var el = lines[i];
+        var lineNo = el.getAttribute("data-linenumber");
+        if (!lines_in_fid[lineNo]) {
+          if (hide) {
+            el.setAttribute("hidden", "");
+          } else {
+            el.removeAttribute("hidden");
+          }
+        }
+    }
+  }
+}
+
+window.addEventListener("keydown", function (event) {
+  if (event.defaultPrevented) {
+    return;
+  }
+  // SHIFT + S
+  if (event.shiftKey && event.keyCode == 83) {
+    var checked = document.getElementsByName("showCounterexample")[0].checked;
+    filterCounterexample(!checked);
+    document.getElementsByName("showCounterexample")[0].click();
+  } else {
+    return;
+  }
+  event.preventDefault();
+}, true);
+
+document.addEventListener("DOMContentLoaded", function() {
+    document.querySelector('input[name="showCounterexample"]').onchange=
+        function (event) {
+      filterCounterexample(this.checked);
+    };
+});
+</script>
+
+<form>
+    <input type="checkbox" name="showCounterexample" id="showCounterexample" />
+    <label for="showCounterexample">
+       Show only relevant lines
+    </label>
+    <input type="checkbox" name="showArrows"
+           id="showArrows" style="margin-left: 10px" />
+    <label for="showArrows">
+       Show control flow arrows
+    </label>
+</form>
+)<<<";
+
+  return s;
+}
+
+void HTMLDiagnostics::FinalizeHTML(const PathDiagnostic& D, Rewriter &R,
+    const SourceManager& SMgr, const PathPieces& path, FileID FID,
+    const FileEntry *Entry, const char *declName) {
+  // This is a cludge; basically we want to append either the full
+  // working directory if we have no directory information.  This is
+  // a work in progress.
+
+  llvm::SmallString<0> DirName;
+
+  if (llvm::sys::path::is_relative(Entry->getName())) {
+    llvm::sys::fs::current_path(DirName);
+    DirName += '/';
+  }
+
+  int LineNumber = path.back()->getLocation().asLocation().getExpansionLineNumber();
+  int ColumnNumber = path.back()->getLocation().asLocation().getExpansionColumnNumber();
+
+  R.InsertTextBefore(SMgr.getLocForStartOfFile(FID), showHelpJavascript());
+
+  R.InsertTextBefore(SMgr.getLocForStartOfFile(FID),
+                     generateKeyboardNavigationJavascript());
+
+  R.InsertTextBefore(SMgr.getLocForStartOfFile(FID),
+                     generateArrowDrawingJavascript());
+
+  // Checkbox and javascript for filtering the output to the counterexample.
+  R.InsertTextBefore(SMgr.getLocForStartOfFile(FID),
+                     showRelevantLinesJavascript(D, path));
+
+  // Add the name of the file as an <h1> tag.
+  {
+    std::string s;
+    llvm::raw_string_ostream os(s);
+
+    os << "<!-- REPORTHEADER -->\n"
+       << "<h3>Bug Summary</h3>\n<table class=\"simpletable\">\n"
+          "<tr><td class=\"rowname\">File:</td><td>"
+       << html::EscapeText(DirName)
+       << html::EscapeText(Entry->getName())
+       << "</td></tr>\n<tr><td class=\"rowname\">Warning:</td><td>"
+          "<a href=\"#EndPath\">line "
+       << LineNumber
+       << ", column "
+       << ColumnNumber
+       << "</a><br />"
+       << D.getVerboseDescription() << "</td></tr>\n";
+
+    // The navigation across the extra notes pieces.
+    unsigned NumExtraPieces = 0;
+    for (const auto &Piece : path) {
+      if (const auto *P = dyn_cast<PathDiagnosticNotePiece>(Piece.get())) {
+        int LineNumber =
+            P->getLocation().asLocation().getExpansionLineNumber();
+        int ColumnNumber =
+            P->getLocation().asLocation().getExpansionColumnNumber();
+        os << "<tr><td class=\"rowname\">Note:</td><td>"
+           << "<a href=\"#Note" << NumExtraPieces << "\">line "
+           << LineNumber << ", column " << ColumnNumber << "</a><br />"
+           << P->getString() << "</td></tr>";
+        ++NumExtraPieces;
+      }
+    }
+
+    // Output any other meta data.
+
+    for (PathDiagnostic::meta_iterator I = D.meta_begin(), E = D.meta_end();
+         I != E; ++I) {
+      os << "<tr><td></td><td>" << html::EscapeText(*I) << "</td></tr>\n";
+    }
+
+    os << R"<<<(
+</table>
+<!-- REPORTSUMMARYEXTRA -->
+<h3>Annotated Source Code</h3>
+<p>Press <a href="#" onclick="toggleHelp(); return false;">'?'</a>
+   to see keyboard shortcuts</p>
+<input type="checkbox" class="spoilerhider" id="showinvocation" />
+<label for="showinvocation" >Show analyzer invocation</label>
+<div class="spoiler">clang -cc1 )<<<";
+    os << html::EscapeText(DiagOpts.ToolInvocation);
+    os << R"<<<(
+</div>
+<div id='tooltiphint' hidden="true">
+  <p>Keyboard shortcuts: </p>
+  <ul>
+    <li>Use 'j/k' keys for keyboard navigation</li>
+    <li>Use 'Shift+S' to show/hide relevant lines</li>
+    <li>Use '?' to toggle this window</li>
+  </ul>
+  <a href="#" onclick="toggleHelp(); return false;">Close</a>
+</div>
+)<<<";
+
+    R.InsertTextBefore(SMgr.getLocForStartOfFile(FID), os.str());
+  }
+
+  // Embed meta-data tags.
+  {
+    std::string s;
+    llvm::raw_string_ostream os(s);
+
+    StringRef BugDesc = D.getVerboseDescription();
+    if (!BugDesc.empty())
+      os << "\n<!-- BUGDESC " << BugDesc << " -->\n";
+
+    StringRef BugType = D.getBugType();
+    if (!BugType.empty())
+      os << "\n<!-- BUGTYPE " << BugType << " -->\n";
+
+    PathDiagnosticLocation UPDLoc = D.getUniqueingLoc();
+    FullSourceLoc L(SMgr.getExpansionLoc(UPDLoc.isValid()
+                                             ? UPDLoc.asLocation()
+                                             : D.getLocation().asLocation()),
+                    SMgr);
+
+    StringRef BugCategory = D.getCategory();
+    if (!BugCategory.empty())
+      os << "\n<!-- BUGCATEGORY " << BugCategory << " -->\n";
+
+    os << "\n<!-- BUGFILE " << DirName << Entry->getName() << " -->\n";
+
+    os << "\n<!-- FILENAME " << llvm::sys::path::filename(Entry->getName()) << " -->\n";
+
+    os  << "\n<!-- FUNCTIONNAME " <<  declName << " -->\n";
+
+    os << "\n<!-- ISSUEHASHCONTENTOFLINEINCONTEXT " << getIssueHash(D, PP)
+       << " -->\n";
+
+    os << "\n<!-- BUGLINE "
+       << LineNumber
+       << " -->\n";
+
+    os << "\n<!-- BUGCOLUMN "
+      << ColumnNumber
+      << " -->\n";
+
+    os << "\n<!-- BUGPATHLENGTH " << getPathSizeWithoutArrows(path) << " -->\n";
+
+    // Mark the end of the tags.
+    os << "\n<!-- BUGMETAEND -->\n";
+
+    // Insert the text.
+    R.InsertTextBefore(SMgr.getLocForStartOfFile(FID), os.str());
+  }
+
+  html::AddHeaderFooterInternalBuiltinCSS(R, FID, Entry->getName());
+}
+
+StringRef HTMLDiagnostics::showHelpJavascript() {
+  return R"<<<(
+<script type='text/javascript'>
+
+var toggleHelp = function() {
+    var hint = document.querySelector("#tooltiphint");
+    var attributeName = "hidden";
+    if (hint.hasAttribute(attributeName)) {
+      hint.removeAttribute(attributeName);
+    } else {
+      hint.setAttribute("hidden", "true");
+    }
+};
+window.addEventListener("keydown", function (event) {
+  if (event.defaultPrevented) {
+    return;
+  }
+  if (event.key == "?") {
+    toggleHelp();
+  } else {
+    return;
+  }
+  event.preventDefault();
+});
+</script>
+)<<<";
+}
+
+static bool shouldDisplayPopUpRange(const SourceRange &Range) {
+  return !(Range.getBegin().isMacroID() || Range.getEnd().isMacroID());
+}
+
+static void
+HandlePopUpPieceStartTag(Rewriter &R,
+                         const std::vector<SourceRange> &PopUpRanges) {
+  for (const auto &Range : PopUpRanges) {
+    if (!shouldDisplayPopUpRange(Range))
+      continue;
+
+    html::HighlightRange(R, Range.getBegin(), Range.getEnd(), "",
+                         "<table class='variable_popup'><tbody>",
+                         /*IsTokenRange=*/true);
+  }
+}
+
+static void HandlePopUpPieceEndTag(Rewriter &R,
+                                   const PathDiagnosticPopUpPiece &Piece,
+                                   std::vector<SourceRange> &PopUpRanges,
+                                   unsigned int LastReportedPieceIndex,
+                                   unsigned int PopUpPieceIndex) {
+  SmallString<256> Buf;
+  llvm::raw_svector_ostream Out(Buf);
+
+  SourceRange Range(Piece.getLocation().asRange());
+  if (!shouldDisplayPopUpRange(Range))
+    return;
+
+  // Write out the path indices with a right arrow and the message as a row.
+  Out << "<tr><td valign='top'><div class='PathIndex PathIndexPopUp'>"
+      << LastReportedPieceIndex;
+
+  // Also annotate the state transition with extra indices.
+  Out << '.' << PopUpPieceIndex;
+
+  Out << "</div></td><td>" << Piece.getString() << "</td></tr>";
+
+  // If no report made at this range mark the variable and add the end tags.
+  if (!llvm::is_contained(PopUpRanges, Range)) {
+    // Store that we create a report at this range.
+    PopUpRanges.push_back(Range);
+
+    Out << "</tbody></table></span>";
+    html::HighlightRange(R, Range.getBegin(), Range.getEnd(),
+                         "<span class='variable'>", Buf.c_str(),
+                         /*IsTokenRange=*/true);
+  } else {
+    // Otherwise inject just the new row at the end of the range.
+    html::HighlightRange(R, Range.getBegin(), Range.getEnd(), "", Buf.c_str(),
+                         /*IsTokenRange=*/true);
+  }
+}
+
+void HTMLDiagnostics::RewriteFile(Rewriter &R, const PathPieces &path,
+                                  FileID FID) {
+
+  // Process the path.
+  // Maintain the counts of extra note pieces separately.
+  unsigned TotalPieces = getPathSizeWithoutArrows(path);
+  unsigned TotalNotePieces =
+      llvm::count_if(path, [](const PathDiagnosticPieceRef &p) {
+        return isa<PathDiagnosticNotePiece>(*p);
+      });
+  unsigned PopUpPieceCount =
+      llvm::count_if(path, [](const PathDiagnosticPieceRef &p) {
+        return isa<PathDiagnosticPopUpPiece>(*p);
+      });
+
+  unsigned TotalRegularPieces = TotalPieces - TotalNotePieces - PopUpPieceCount;
+  unsigned NumRegularPieces = TotalRegularPieces;
+  unsigned NumNotePieces = TotalNotePieces;
+  unsigned NumberOfArrows = 0;
+  // Stores the count of the regular piece indices.
+  std::map<int, int> IndexMap;
+  ArrowMap ArrowIndices(TotalRegularPieces + 1);
+
+  // Stores the different ranges where we have reported something.
+  std::vector<SourceRange> PopUpRanges;
+  for (const PathDiagnosticPieceRef &I : llvm::reverse(path)) {
+    const auto &Piece = *I.get();
+
+    if (isa<PathDiagnosticPopUpPiece>(Piece)) {
+      ++IndexMap[NumRegularPieces];
+    } else if (isa<PathDiagnosticNotePiece>(Piece)) {
+      // This adds diagnostic bubbles, but not navigation.
+      // Navigation through note pieces would be added later,
+      // as a separate pass through the piece list.
+      HandlePiece(R, FID, Piece, PopUpRanges, NumNotePieces, TotalNotePieces);
+      --NumNotePieces;
+
+    } else if (isArrowPiece(Piece)) {
+      NumberOfArrows = ProcessControlFlowPiece(
+          R, FID, cast<PathDiagnosticControlFlowPiece>(Piece), NumberOfArrows);
+      ArrowIndices[NumRegularPieces] = NumberOfArrows;
+
+    } else {
+      HandlePiece(R, FID, Piece, PopUpRanges, NumRegularPieces,
+                  TotalRegularPieces);
+      --NumRegularPieces;
+      ArrowIndices[NumRegularPieces] = ArrowIndices[NumRegularPieces + 1];
+    }
+  }
+  ArrowIndices[0] = NumberOfArrows;
+
+  // At this point ArrowIndices represent the following data structure:
+  //   [a_0, a_1, ..., a_N]
+  // where N is the number of events in the path.
+  //
+  // Then for every event with index i \in [0, N - 1], we can say that
+  // arrows with indices \in [a_(i+1), a_i) correspond to that event.
+  // We can say that because arrows with these indices appeared in the
+  // path in between the i-th and the (i+1)-th events.
+  assert(ArrowIndices.back() == 0 &&
+         "No arrows should be after the last event");
+  // This assertion also guarantees that all indices in are <= NumberOfArrows.
+  assert(llvm::is_sorted(ArrowIndices, std::greater<unsigned>()) &&
+         "Incorrect arrow indices map");
+
+  // Secondary indexing if we are having multiple pop-ups between two notes.
+  // (e.g. [(13) 'a' is 'true'];  [(13.1) 'b' is 'false'];  [(13.2) 'c' is...)
+  NumRegularPieces = TotalRegularPieces;
+  for (const PathDiagnosticPieceRef &I : llvm::reverse(path)) {
+    const auto &Piece = *I.get();
+
+    if (const auto *PopUpP = dyn_cast<PathDiagnosticPopUpPiece>(&Piece)) {
+      int PopUpPieceIndex = IndexMap[NumRegularPieces];
+
+      // Pop-up pieces needs the index of the last reported piece and its count
+      // how many times we report to handle multiple reports on the same range.
+      // This marks the variable, adds the </table> end tag and the message
+      // (list element) as a row. The <table> start tag will be added after the
+      // rows has been written out. Note: It stores every different range.
+      HandlePopUpPieceEndTag(R, *PopUpP, PopUpRanges, NumRegularPieces,
+                             PopUpPieceIndex);
+
+      if (PopUpPieceIndex > 0)
+        --IndexMap[NumRegularPieces];
+
+    } else if (!isa<PathDiagnosticNotePiece>(Piece) && !isArrowPiece(Piece)) {
+      --NumRegularPieces;
+    }
+  }
+
+  // Add the <table> start tag of pop-up pieces based on the stored ranges.
+  HandlePopUpPieceStartTag(R, PopUpRanges);
+
+  // Add line numbers, header, footer, etc.
+  html::EscapeText(R, FID);
+  html::AddLineNumbers(R, FID);
+
+  addArrowSVGs(R, FID, ArrowIndices);
+
+  // If we have a preprocessor, relex the file and syntax highlight.
+  // We might not have a preprocessor if we come from a deserialized AST file,
+  // for example.
+  html::SyntaxHighlight(R, FID, PP);
+  html::HighlightMacros(R, FID, PP);
+}
+
+void HTMLDiagnostics::HandlePiece(Rewriter &R, FileID BugFileID,
+                                  const PathDiagnosticPiece &P,
+                                  const std::vector<SourceRange> &PopUpRanges,
+                                  unsigned num, unsigned max) {
+  // For now, just draw a box above the line in question, and emit the
+  // warning.
+  FullSourceLoc Pos = P.getLocation().asLocation();
+
+  if (!Pos.isValid())
+    return;
+
+  SourceManager &SM = R.getSourceMgr();
+  assert(&Pos.getManager() == &SM && "SourceManagers are different!");
+  std::pair<FileID, unsigned> LPosInfo = SM.getDecomposedExpansionLoc(Pos);
+
+  if (LPosInfo.first != BugFileID)
+    return;
+
+  llvm::MemoryBufferRef Buf = SM.getBufferOrFake(LPosInfo.first);
+  const char *FileStart = Buf.getBufferStart();
+
+  // Compute the column number.  Rewind from the current position to the start
+  // of the line.
+  unsigned ColNo = SM.getColumnNumber(LPosInfo.first, LPosInfo.second);
+  const char *TokInstantiationPtr =Pos.getExpansionLoc().getCharacterData();
+  const char *LineStart = TokInstantiationPtr-ColNo;
+
+  // Compute LineEnd.
+  const char *LineEnd = TokInstantiationPtr;
+  const char *FileEnd = Buf.getBufferEnd();
+  while (*LineEnd != '\n' && LineEnd != FileEnd)
+    ++LineEnd;
+
+  // Compute the margin offset by counting tabs and non-tabs.
+  unsigned PosNo = 0;
+  for (const char* c = LineStart; c != TokInstantiationPtr; ++c)
+    PosNo += *c == '\t' ? 8 : 1;
+
+  // Create the html for the message.
+
+  const char *Kind = nullptr;
+  bool IsNote = false;
+  bool SuppressIndex = (max == 1);
+  switch (P.getKind()) {
+  case PathDiagnosticPiece::Event: Kind = "Event"; break;
+  case PathDiagnosticPiece::ControlFlow: Kind = "Control"; break;
+    // Setting Kind to "Control" is intentional.
+  case PathDiagnosticPiece::Macro: Kind = "Control"; break;
+  case PathDiagnosticPiece::Note:
+    Kind = "Note";
+    IsNote = true;
+    SuppressIndex = true;
+    break;
+  case PathDiagnosticPiece::Call:
+  case PathDiagnosticPiece::PopUp:
+    llvm_unreachable("Calls and extra notes should already be handled");
+  }
+
+  std::string sbuf;
+  llvm::raw_string_ostream os(sbuf);
+
+  os << "\n<tr><td class=\"num\"></td><td class=\"line\"><div id=\"";
+
+  if (IsNote)
+    os << "Note" << num;
+  else if (num == max)
+    os << "EndPath";
+  else
+    os << "Path" << num;
+
+  os << "\" class=\"msg";
+  if (Kind)
+    os << " msg" << Kind;
+  os << "\" style=\"margin-left:" << PosNo << "ex";
+
+  // Output a maximum size.
+  if (!isa<PathDiagnosticMacroPiece>(P)) {
+    // Get the string and determining its maximum substring.
+    const auto &Msg = P.getString();
+    unsigned max_token = 0;
+    unsigned cnt = 0;
+    unsigned len = Msg.size();
+
+    for (char C : Msg)
+      switch (C) {
+      default:
+        ++cnt;
+        continue;
+      case ' ':
+      case '\t':
+      case '\n':
+        if (cnt > max_token) max_token = cnt;
+        cnt = 0;
+      }
+
+    if (cnt > max_token)
+      max_token = cnt;
+
+    // Determine the approximate size of the message bubble in em.
+    unsigned em;
+    const unsigned max_line = 120;
+
+    if (max_token >= max_line)
+      em = max_token / 2;
+    else {
+      unsigned characters = max_line;
+      unsigned lines = len / max_line;
+
+      if (lines > 0) {
+        for (; characters > max_token; --characters)
+          if (len / characters > lines) {
+            ++characters;
+            break;
+          }
+      }
+
+      em = characters / 2;
+    }
+
+    if (em < max_line/2)
+      os << "; max-width:" << em << "em";
+  }
+  else
+    os << "; max-width:100em";
+
+  os << "\">";
+
+  if (!SuppressIndex) {
+    os << "<table class=\"msgT\"><tr><td valign=\"top\">";
+    os << "<div class=\"PathIndex";
+    if (Kind) os << " PathIndex" << Kind;
+    os << "\">" << num << "</div>";
+
+    if (num > 1) {
+      os << "</td><td><div class=\"PathNav\"><a href=\"#Path"
+         << (num - 1)
+         << "\" title=\"Previous event ("
+         << (num - 1)
+         << ")\">&#x2190;</a></div>";
+    }
+
+    os << "</td><td>";
+  }
+
+  if (const auto *MP = dyn_cast<PathDiagnosticMacroPiece>(&P)) {
+    os << "Within the expansion of the macro '";
+
+    // Get the name of the macro by relexing it.
+    {
+      FullSourceLoc L = MP->getLocation().asLocation().getExpansionLoc();
+      assert(L.isFileID());
+      StringRef BufferInfo = L.getBufferData();
+      std::pair<FileID, unsigned> LocInfo = L.getDecomposedLoc();
+      const char* MacroName = LocInfo.second + BufferInfo.data();
+      Lexer rawLexer(SM.getLocForStartOfFile(LocInfo.first), PP.getLangOpts(),
+                     BufferInfo.begin(), MacroName, BufferInfo.end());
+
+      Token TheTok;
+      rawLexer.LexFromRawLexer(TheTok);
+      for (unsigned i = 0, n = TheTok.getLength(); i < n; ++i)
+        os << MacroName[i];
+    }
+
+    os << "':\n";
+
+    if (!SuppressIndex) {
+      os << "</td>";
+      if (num < max) {
+        os << "<td><div class=\"PathNav\"><a href=\"#";
+        if (num == max - 1)
+          os << "EndPath";
+        else
+          os << "Path" << (num + 1);
+        os << "\" title=\"Next event ("
+        << (num + 1)
+        << ")\">&#x2192;</a></div></td>";
+      }
+
+      os << "</tr></table>";
+    }
+
+    // Within a macro piece.  Write out each event.
+    ProcessMacroPiece(os, *MP, 0);
+  }
+  else {
+    os << html::EscapeText(P.getString());
+
+    if (!SuppressIndex) {
+      os << "</td>";
+      if (num < max) {
+        os << "<td><div class=\"PathNav\"><a href=\"#";
+        if (num == max - 1)
+          os << "EndPath";
+        else
+          os << "Path" << (num + 1);
+        os << "\" title=\"Next event ("
+           << (num + 1)
+           << ")\">&#x2192;</a></div></td>";
+      }
+
+      os << "</tr></table>";
+    }
+  }
+
+  os << "</div></td></tr>";
+
+  // Insert the new html.
+  unsigned DisplayPos = LineEnd - FileStart;
+  SourceLocation Loc =
+    SM.getLocForStartOfFile(LPosInfo.first).getLocWithOffset(DisplayPos);
+
+  R.InsertTextBefore(Loc, os.str());
+
+  // Now highlight the ranges.
+  ArrayRef<SourceRange> Ranges = P.getRanges();
+  for (const auto &Range : Ranges) {
+    // If we have already highlighted the range as a pop-up there is no work.
+    if (llvm::is_contained(PopUpRanges, Range))
+      continue;
+
+    HighlightRange(R, LPosInfo.first, Range);
+  }
+}
+
+static void EmitAlphaCounter(raw_ostream &os, unsigned n) {
+  unsigned x = n % ('z' - 'a');
+  n /= 'z' - 'a';
+
+  if (n > 0)
+    EmitAlphaCounter(os, n);
+
+  os << char('a' + x);
+}
+
+unsigned HTMLDiagnostics::ProcessMacroPiece(raw_ostream &os,
+                                            const PathDiagnosticMacroPiece& P,
+                                            unsigned num) {
+  for (const auto &subPiece : P.subPieces) {
+    if (const auto *MP = dyn_cast<PathDiagnosticMacroPiece>(subPiece.get())) {
+      num = ProcessMacroPiece(os, *MP, num);
+      continue;
+    }
+
+    if (const auto *EP = dyn_cast<PathDiagnosticEventPiece>(subPiece.get())) {
+      os << "<div class=\"msg msgEvent\" style=\"width:94%; "
+            "margin-left:5px\">"
+            "<table class=\"msgT\"><tr>"
+            "<td valign=\"top\"><div class=\"PathIndex PathIndexEvent\">";
+      EmitAlphaCounter(os, num++);
+      os << "</div></td><td valign=\"top\">"
+         << html::EscapeText(EP->getString())
+         << "</td></tr></table></div>\n";
+    }
+  }
+
+  return num;
+}
+
+void HTMLDiagnostics::addArrowSVGs(Rewriter &R, FileID BugFileID,
+                                   const ArrowMap &ArrowIndices) {
+  std::string S;
+  llvm::raw_string_ostream OS(S);
+
+  OS << R"<<<(
+<style type="text/css">
+  svg {
+      position:absolute;
+      top:0;
+      left:0;
+      height:100%;
+      width:100%;
+      pointer-events: none;
+      overflow: visible
+  }
+  .arrow {
+      stroke-opacity: 0.2;
+      stroke-width: 1;
+      marker-end: url(#arrowhead);
+  }
+
+  .arrow.selected {
+      stroke-opacity: 0.6;
+      stroke-width: 2;
+      marker-end: url(#arrowheadSelected);
+  }
+
+  .arrowhead {
+      orient: auto;
+      stroke: none;
+      opacity: 0.6;
+      fill: blue;
+  }
+</style>
+<svg xmlns="http://www.w3.org/2000/svg">
+  <defs>
+    <marker id="arrowheadSelected" class="arrowhead" opacity="0.6"
+            viewBox="0 0 10 10" refX="3" refY="5"
+            markerWidth="4" markerHeight="4">
+      <path d="M 0 0 L 10 5 L 0 10 z" />
+    </marker>
+    <marker id="arrowhead" class="arrowhead" opacity="0.2"
+            viewBox="0 0 10 10" refX="3" refY="5"
+            markerWidth="4" markerHeight="4">
+      <path d="M 0 0 L 10 5 L 0 10 z" />
+    </marker>
+  </defs>
+  <g id="arrows" fill="none" stroke="blue" visibility="hidden">
+)<<<";
+
+  for (unsigned Index : llvm::seq(0u, ArrowIndices.getTotalNumberOfArrows())) {
+    OS << "    <path class=\"arrow\" id=\"arrow" << Index << "\"/>\n";
+  }
+
+  OS << R"<<<(
+  </g>
+</svg>
+<script type='text/javascript'>
+const arrowIndices = )<<<";
+
+  OS << ArrowIndices << "\n</script>\n";
+
+  R.InsertTextBefore(R.getSourceMgr().getLocForStartOfFile(BugFileID),
+                     OS.str());
+}
+
+std::string getSpanBeginForControl(const char *ClassName, unsigned Index) {
+  std::string Result;
+  llvm::raw_string_ostream OS(Result);
+  OS << "<span id=\"" << ClassName << Index << "\">";
+  return Result;
+}
+
+std::string getSpanBeginForControlStart(unsigned Index) {
+  return getSpanBeginForControl("start", Index);
+}
+
+std::string getSpanBeginForControlEnd(unsigned Index) {
+  return getSpanBeginForControl("end", Index);
+}
+
+unsigned HTMLDiagnostics::ProcessControlFlowPiece(
+    Rewriter &R, FileID BugFileID, const PathDiagnosticControlFlowPiece &P,
+    unsigned Number) {
+  for (const PathDiagnosticLocationPair &LPair : P) {
+    std::string Start = getSpanBeginForControlStart(Number),
+                End = getSpanBeginForControlEnd(Number++);
+
+    HighlightRange(R, BugFileID, LPair.getStart().asRange().getBegin(),
+                   Start.c_str());
+    HighlightRange(R, BugFileID, LPair.getEnd().asRange().getBegin(),
+                   End.c_str());
+  }
+
+  return Number;
+}
+
+void HTMLDiagnostics::HighlightRange(Rewriter& R, FileID BugFileID,
+                                     SourceRange Range,
+                                     const char *HighlightStart,
+                                     const char *HighlightEnd) {
+  SourceManager &SM = R.getSourceMgr();
+  const LangOptions &LangOpts = R.getLangOpts();
+
+  SourceLocation InstantiationStart = SM.getExpansionLoc(Range.getBegin());
+  unsigned StartLineNo = SM.getExpansionLineNumber(InstantiationStart);
+
+  SourceLocation InstantiationEnd = SM.getExpansionLoc(Range.getEnd());
+  unsigned EndLineNo = SM.getExpansionLineNumber(InstantiationEnd);
+
+  if (EndLineNo < StartLineNo)
+    return;
+
+  if (SM.getFileID(InstantiationStart) != BugFileID ||
+      SM.getFileID(InstantiationEnd) != BugFileID)
+    return;
+
+  // Compute the column number of the end.
+  unsigned EndColNo = SM.getExpansionColumnNumber(InstantiationEnd);
+  unsigned OldEndColNo = EndColNo;
+
+  if (EndColNo) {
+    // Add in the length of the token, so that we cover multi-char tokens.
+    EndColNo += Lexer::MeasureTokenLength(Range.getEnd(), SM, LangOpts)-1;
+  }
+
+  // Highlight the range.  Make the span tag the outermost tag for the
+  // selected range.
+
+  SourceLocation E =
+    InstantiationEnd.getLocWithOffset(EndColNo - OldEndColNo);
+
+  html::HighlightRange(R, InstantiationStart, E, HighlightStart, HighlightEnd);
+}
+
+StringRef HTMLDiagnostics::generateKeyboardNavigationJavascript() {
+  return R"<<<(
+<script type='text/javascript'>
+var digitMatcher = new RegExp("[0-9]+");
+
+var querySelectorAllArray = function(selector) {
+  return Array.prototype.slice.call(
+    document.querySelectorAll(selector));
+}
+
+document.addEventListener("DOMContentLoaded", function() {
+    querySelectorAllArray(".PathNav > a").forEach(
+        function(currentValue, currentIndex) {
+            var hrefValue = currentValue.getAttribute("href");
+            currentValue.onclick = function() {
+                scrollTo(document.querySelector(hrefValue));
+                return false;
+            };
+        });
+});
+
+var findNum = function() {
+    var s = document.querySelector(".msg.selected");
+    if (!s || s.id == "EndPath") {
+        return 0;
+    }
+    var out = parseInt(digitMatcher.exec(s.id)[0]);
+    return out;
+};
+
+var classListAdd = function(el, theClass) {
+  if(!el.className.baseVal)
+    el.className += " " + theClass;
+  else
+    el.className.baseVal += " " + theClass;
+};
+
+var classListRemove = function(el, theClass) {
+  var className = (!el.className.baseVal) ?
+      el.className : el.className.baseVal;
+    className = className.replace(" " + theClass, "");
+  if(!el.className.baseVal)
+    el.className = className;
+  else
+    el.className.baseVal = className;
+};
+
+var scrollTo = function(el) {
+    querySelectorAllArray(".selected").forEach(function(s) {
+      classListRemove(s, "selected");
+    });
+    classListAdd(el, "selected");
+    window.scrollBy(0, el.getBoundingClientRect().top -
+        (window.innerHeight / 2));
+    highlightArrowsForSelectedEvent();
+};
+
+var move = function(num, up, numItems) {
+  if (num == 1 && up || num == numItems - 1 && !up) {
+    return 0;
+  } else if (num == 0 && up) {
+    return numItems - 1;
+  } else if (num == 0 && !up) {
+    return 1 % numItems;
+  }
+  return up ? num - 1 : num + 1;
+}
+
+var numToId = function(num) {
+  if (num == 0) {
+    return document.getElementById("EndPath")
+  }
+  return document.getElementById("Path" + num);
+};
+
+var navigateTo = function(up) {
+  var numItems = document.querySelectorAll(
+      ".line > .msgEvent, .line > .msgControl").length;
+  var currentSelected = findNum();
+  var newSelected = move(currentSelected, up, numItems);
+  var newEl = numToId(newSelected, numItems);
+
+  // Scroll element into center.
+  scrollTo(newEl);
+};
+
+window.addEventListener("keydown", function (event) {
+  if (event.defaultPrevented) {
+    return;
+  }
+  // key 'j'
+  if (event.keyCode == 74) {
+    navigateTo(/*up=*/false);
+  // key 'k'
+  } else if (event.keyCode == 75) {
+    navigateTo(/*up=*/true);
+  } else {
+    return;
+  }
+  event.preventDefault();
+}, true);
+</script>
+  )<<<";
+}
+
+StringRef HTMLDiagnostics::generateArrowDrawingJavascript() {
+  return R"<<<(
+<script type='text/javascript'>
+// Return range of numbers from a range [lower, upper).
+function range(lower, upper) {
+  var array = [];
+  for (var i = lower; i <= upper; ++i) {
+      array.push(i);
+  }
+  return array;
+}
+
+var getRelatedArrowIndices = function(pathId) {
+  // HTML numeration of events is a bit different than it is in the path.
+  // Everything is rotated one step to the right, so the last element
+  // (error diagnostic) has index 0.
+  if (pathId == 0) {
+    // arrowIndices has at least 2 elements
+    pathId = arrowIndices.length - 1;
+  }
+
+  return range(arrowIndices[pathId], arrowIndices[pathId - 1]);
+}
+
+var highlightArrowsForSelectedEvent = function() {
+  const selectedNum = findNum();
+  const arrowIndicesToHighlight = getRelatedArrowIndices(selectedNum);
+  arrowIndicesToHighlight.forEach((index) => {
+    var arrow = document.querySelector("#arrow" + index);
+    if(arrow) {
+      classListAdd(arrow, "selected")
+    }
+  });
+}
+
+var getAbsoluteBoundingRect = function(element) {
+  const relative = element.getBoundingClientRect();
+  return {
+    left: relative.left + window.pageXOffset,
+    right: relative.right + window.pageXOffset,
+    top: relative.top + window.pageYOffset,
+    bottom: relative.bottom + window.pageYOffset,
+    height: relative.height,
+    width: relative.width
+  };
+}
+
+var drawArrow = function(index) {
+  // This function is based on the great answer from SO:
+  //   https://stackoverflow.com/a/39575674/11582326
+  var start = document.querySelector("#start" + index);
+  var end   = document.querySelector("#end" + index);
+  var arrow = document.querySelector("#arrow" + index);
+
+  var startRect = getAbsoluteBoundingRect(start);
+  var endRect   = getAbsoluteBoundingRect(end);
+
+  // It is an arrow from a token to itself, no need to visualize it.
+  if (startRect.top == endRect.top &&
+      startRect.left == endRect.left)
+    return;
+
+  // Each arrow is a very simple Bézier curve, with two nodes and
+  // two handles.  So, we need to calculate four points in the window:
+  //   * start node
+  var posStart    = { x: 0, y: 0 };
+  //   * end node
+  var posEnd      = { x: 0, y: 0 };
+  //   * handle for the start node
+  var startHandle = { x: 0, y: 0 };
+  //   * handle for the end node
+  var endHandle   = { x: 0, y: 0 };
+  // One can visualize it as follows:
+  //
+  //         start handle
+  //        /
+  //       X"""_.-""""X
+  //         .'        \
+  //        /           start node
+  //       |
+  //       |
+  //       |      end node
+  //        \    /
+  //         `->X
+  //        X-'
+  //         \
+  //          end handle
+  //
+  // NOTE: (0, 0) is the top left corner of the window.
+
+  // We have 3 similar, but still different scenarios to cover:
+  //
+  //   1. Two tokens on different lines.
+  //             -xxx
+  //           /
+  //           \
+  //             -> xxx
+  //      In this situation, we draw arrow on the left curving to the left.
+  //   2. Two tokens on the same line, and the destination is on the right.
+  //             ____
+  //            /    \
+  //           /      V
+  //        xxx        xxx
+  //      In this situation, we draw arrow above curving upwards.
+  //   3. Two tokens on the same line, and the destination is on the left.
+  //        xxx        xxx
+  //           ^      /
+  //            \____/
+  //      In this situation, we draw arrow below curving downwards.
+  const onDifferentLines = startRect.top <= endRect.top - 5 ||
+    startRect.top >= endRect.top + 5;
+  const leftToRight = startRect.left < endRect.left;
+
+  // NOTE: various magic constants are chosen empirically for
+  //       better positioning and look
+  if (onDifferentLines) {
+    // Case #1
+    const topToBottom = startRect.top < endRect.top;
+    posStart.x = startRect.left - 1;
+    // We don't want to start it at the top left corner of the token,
+    // it doesn't feel like this is where the arrow comes from.
+    // For this reason, we start it in the middle of the left side
+    // of the token.
+    posStart.y = startRect.top + startRect.height / 2;
+
+    // End node has arrow head and we give it a bit more space.
+    posEnd.x = endRect.left - 4;
+    posEnd.y = endRect.top;
+
+    // Utility object with x and y offsets for handles.
+    var curvature = {
+      // We want bottom-to-top arrow to curve a bit more, so it doesn't
+      // overlap much with top-to-bottom curves (much more frequent).
+      x: topToBottom ? 15 : 25,
+      y: Math.min((posEnd.y - posStart.y) / 3, 10)
+    }
+
+    // When destination is on the different line, we can make a
+    // curvier arrow because we have space for it.
+    // So, instead of using
+    //
+    //   startHandle.x = posStart.x - curvature.x
+    //   endHandle.x   = posEnd.x - curvature.x
+    //
+    // We use the leftmost of these two values for both handles.
+    startHandle.x = Math.min(posStart.x, posEnd.x) - curvature.x;
+    endHandle.x = startHandle.x;
+
+    // Curving downwards from the start node...
+    startHandle.y = posStart.y + curvature.y;
+    // ... and upwards from the end node.
+    endHandle.y = posEnd.y - curvature.y;
+
+  } else if (leftToRight) {
+    // Case #2
+    // Starting from the top right corner...
+    posStart.x = startRect.right - 1;
+    posStart.y = startRect.top;
+
+    // ...and ending at the top left corner of the end token.
+    posEnd.x = endRect.left + 1;
+    posEnd.y = endRect.top - 1;
+
+    // Utility object with x and y offsets for handles.
+    var curvature = {
+      x: Math.min((posEnd.x - posStart.x) / 3, 15),
+      y: 5
+    }
+
+    // Curving to the right...
+    startHandle.x = posStart.x + curvature.x;
+    // ... and upwards from the start node.
+    startHandle.y = posStart.y - curvature.y;
+
+    // And to the left...
+    endHandle.x = posEnd.x - curvature.x;
+    // ... and upwards from the end node.
+    endHandle.y = posEnd.y - curvature.y;
+
+  } else {
+    // Case #3
+    // Starting from the bottom right corner...
+    posStart.x = startRect.right;
+    posStart.y = startRect.bottom;
+
+    // ...and ending also at the bottom right corner, but of the end token.
+    posEnd.x = endRect.right - 1;
+    posEnd.y = endRect.bottom + 1;
+
+    // Utility object with x and y offsets for handles.
+    var curvature = {
+      x: Math.min((posStart.x - posEnd.x) / 3, 15),
+      y: 5
+    }
+
+    // Curving to the left...
+    startHandle.x = posStart.x - curvature.x;
+    // ... and downwards from the start node.
+    startHandle.y = posStart.y + curvature.y;
+
+    // And to the right...
+    endHandle.x = posEnd.x + curvature.x;
+    // ... and downwards from the end node.
+    endHandle.y = posEnd.y + curvature.y;
+  }
+
+  // Put it all together into a path.
+  // More information on the format:
+  //   https://developer.mozilla.org/en-US/docs/Web/SVG/Tutorial/Paths
+  var pathStr = "M" + posStart.x + "," + posStart.y + " " +
+    "C" + startHandle.x + "," + startHandle.y + " " +
+    endHandle.x + "," + endHandle.y + " " +
+    posEnd.x + "," + posEnd.y;
+
+  arrow.setAttribute("d", pathStr);
+};
+
+var drawArrows = function() {
+  const numOfArrows = document.querySelectorAll("path[id^=arrow]").length;
+  for (var i = 0; i < numOfArrows; ++i) {
+    drawArrow(i);
+  }
+}
+
+var toggleArrows = function(event) {
+  const arrows = document.querySelector("#arrows");
+  if (event.target.checked) {
+    arrows.setAttribute("visibility", "visible");
+  } else {
+    arrows.setAttribute("visibility", "hidden");
+  }
+}
+
+window.addEventListener("resize", drawArrows);
+document.addEventListener("DOMContentLoaded", function() {
+  // Whenever we show invocation, locations change, i.e. we
+  // need to redraw arrows.
+  document
+    .querySelector('input[id="showinvocation"]')
+    .addEventListener("click", drawArrows);
+  // Hiding irrelevant lines also should cause arrow rerender.
+  document
+    .querySelector('input[name="showCounterexample"]')
+    .addEventListener("change", drawArrows);
+  document
+    .querySelector('input[name="showArrows"]')
+    .addEventListener("change", toggleArrows);
+  drawArrows();
+  // Default highlighting for the last event.
+  highlightArrowsForSelectedEvent();
+});
+</script>
+  )<<<";
+}