--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/lib/Parse/Parser.cpp	Thu Feb 13 15:10:13 2020 +0900
@@ -0,0 +1,2538 @@
+//===--- Parser.cpp - C Language Family Parser ----------------------------===//
+//
+// 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 implements the Parser interfaces.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Parse/Parser.h"
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/Parse/ParseDiagnostic.h"
+#include "clang/Parse/RAIIObjectsForParser.h"
+#include "clang/Sema/DeclSpec.h"
+#include "clang/Sema/ParsedTemplate.h"
+#include "clang/Sema/Scope.h"
+#include "llvm/Support/Path.h"
+using namespace clang;
+
+
+namespace {
+/// A comment handler that passes comments found by the preprocessor
+/// to the parser action.
+class ActionCommentHandler : public CommentHandler {
+  Sema &S;
+
+public:
+  explicit ActionCommentHandler(Sema &S) : S(S) { }
+
+  bool HandleComment(Preprocessor &PP, SourceRange Comment) override {
+    S.ActOnComment(Comment);
+    return false;
+  }
+};
+} // end anonymous namespace
+
+IdentifierInfo *Parser::getSEHExceptKeyword() {
+  // __except is accepted as a (contextual) keyword
+  if (!Ident__except && (getLangOpts().MicrosoftExt || getLangOpts().Borland))
+    Ident__except = PP.getIdentifierInfo("__except");
+
+  return Ident__except;
+}
+
+Parser::Parser(Preprocessor &pp, Sema &actions, bool skipFunctionBodies)
+  : PP(pp), Actions(actions), Diags(PP.getDiagnostics()),
+    GreaterThanIsOperator(true), ColonIsSacred(false),
+    InMessageExpression(false), TemplateParameterDepth(0),
+    ParsingInObjCContainer(false) {
+  SkipFunctionBodies = pp.isCodeCompletionEnabled() || skipFunctionBodies;
+  Tok.startToken();
+  Tok.setKind(tok::eof);
+  Actions.CurScope = nullptr;
+  NumCachedScopes = 0;
+  CurParsedObjCImpl = nullptr;
+
+  // Add #pragma handlers. These are removed and destroyed in the
+  // destructor.
+  initializePragmaHandlers();
+
+  CommentSemaHandler.reset(new ActionCommentHandler(actions));
+  PP.addCommentHandler(CommentSemaHandler.get());
+
+  PP.setCodeCompletionHandler(*this);
+}
+
+DiagnosticBuilder Parser::Diag(SourceLocation Loc, unsigned DiagID) {
+  return Diags.Report(Loc, DiagID);
+}
+
+DiagnosticBuilder Parser::Diag(const Token &Tok, unsigned DiagID) {
+  return Diag(Tok.getLocation(), DiagID);
+}
+
+/// Emits a diagnostic suggesting parentheses surrounding a
+/// given range.
+///
+/// \param Loc The location where we'll emit the diagnostic.
+/// \param DK The kind of diagnostic to emit.
+/// \param ParenRange Source range enclosing code that should be parenthesized.
+void Parser::SuggestParentheses(SourceLocation Loc, unsigned DK,
+                                SourceRange ParenRange) {
+  SourceLocation EndLoc = PP.getLocForEndOfToken(ParenRange.getEnd());
+  if (!ParenRange.getEnd().isFileID() || EndLoc.isInvalid()) {
+    // We can't display the parentheses, so just dig the
+    // warning/error and return.
+    Diag(Loc, DK);
+    return;
+  }
+
+  Diag(Loc, DK)
+    << FixItHint::CreateInsertion(ParenRange.getBegin(), "(")
+    << FixItHint::CreateInsertion(EndLoc, ")");
+}
+
+static bool IsCommonTypo(tok::TokenKind ExpectedTok, const Token &Tok) {
+  switch (ExpectedTok) {
+  case tok::semi:
+    return Tok.is(tok::colon) || Tok.is(tok::comma); // : or , for ;
+  default: return false;
+  }
+}
+
+bool Parser::ExpectAndConsume(tok::TokenKind ExpectedTok, unsigned DiagID,
+                              StringRef Msg) {
+  if (Tok.is(ExpectedTok) || Tok.is(tok::code_completion)) {
+    ConsumeAnyToken();
+    return false;
+  }
+
+  // Detect common single-character typos and resume.
+  if (IsCommonTypo(ExpectedTok, Tok)) {
+    SourceLocation Loc = Tok.getLocation();
+    {
+      DiagnosticBuilder DB = Diag(Loc, DiagID);
+      DB << FixItHint::CreateReplacement(
+                SourceRange(Loc), tok::getPunctuatorSpelling(ExpectedTok));
+      if (DiagID == diag::err_expected)
+        DB << ExpectedTok;
+      else if (DiagID == diag::err_expected_after)
+        DB << Msg << ExpectedTok;
+      else
+        DB << Msg;
+    }
+
+    // Pretend there wasn't a problem.
+    ConsumeAnyToken();
+    return false;
+  }
+
+  SourceLocation EndLoc = PP.getLocForEndOfToken(PrevTokLocation);
+  const char *Spelling = nullptr;
+  if (EndLoc.isValid())
+    Spelling = tok::getPunctuatorSpelling(ExpectedTok);
+
+  DiagnosticBuilder DB =
+      Spelling
+          ? Diag(EndLoc, DiagID) << FixItHint::CreateInsertion(EndLoc, Spelling)
+          : Diag(Tok, DiagID);
+  if (DiagID == diag::err_expected)
+    DB << ExpectedTok;
+  else if (DiagID == diag::err_expected_after)
+    DB << Msg << ExpectedTok;
+  else
+    DB << Msg;
+
+  return true;
+}
+
+bool Parser::ExpectAndConsumeSemi(unsigned DiagID) {
+  if (TryConsumeToken(tok::semi))
+    return false;
+
+  if (Tok.is(tok::code_completion)) {
+    handleUnexpectedCodeCompletionToken();
+    return false;
+  }
+
+  if ((Tok.is(tok::r_paren) || Tok.is(tok::r_square)) &&
+      NextToken().is(tok::semi)) {
+    Diag(Tok, diag::err_extraneous_token_before_semi)
+      << PP.getSpelling(Tok)
+      << FixItHint::CreateRemoval(Tok.getLocation());
+    ConsumeAnyToken(); // The ')' or ']'.
+    ConsumeToken(); // The ';'.
+    return false;
+  }
+
+  return ExpectAndConsume(tok::semi, DiagID);
+}
+
+void Parser::ConsumeExtraSemi(ExtraSemiKind Kind, DeclSpec::TST TST) {
+  if (!Tok.is(tok::semi)) return;
+
+  bool HadMultipleSemis = false;
+  SourceLocation StartLoc = Tok.getLocation();
+  SourceLocation EndLoc = Tok.getLocation();
+  ConsumeToken();
+
+  while ((Tok.is(tok::semi) && !Tok.isAtStartOfLine())) {
+    HadMultipleSemis = true;
+    EndLoc = Tok.getLocation();
+    ConsumeToken();
+  }
+
+  // C++11 allows extra semicolons at namespace scope, but not in any of the
+  // other contexts.
+  if (Kind == OutsideFunction && getLangOpts().CPlusPlus) {
+    if (getLangOpts().CPlusPlus11)
+      Diag(StartLoc, diag::warn_cxx98_compat_top_level_semi)
+          << FixItHint::CreateRemoval(SourceRange(StartLoc, EndLoc));
+    else
+      Diag(StartLoc, diag::ext_extra_semi_cxx11)
+          << FixItHint::CreateRemoval(SourceRange(StartLoc, EndLoc));
+    return;
+  }
+
+  if (Kind != AfterMemberFunctionDefinition || HadMultipleSemis)
+    Diag(StartLoc, diag::ext_extra_semi)
+        << Kind << DeclSpec::getSpecifierName(TST,
+                                    Actions.getASTContext().getPrintingPolicy())
+        << FixItHint::CreateRemoval(SourceRange(StartLoc, EndLoc));
+  else
+    // A single semicolon is valid after a member function definition.
+    Diag(StartLoc, diag::warn_extra_semi_after_mem_fn_def)
+      << FixItHint::CreateRemoval(SourceRange(StartLoc, EndLoc));
+}
+
+bool Parser::expectIdentifier() {
+  if (Tok.is(tok::identifier))
+    return false;
+  if (const auto *II = Tok.getIdentifierInfo()) {
+    if (II->isCPlusPlusKeyword(getLangOpts())) {
+      Diag(Tok, diag::err_expected_token_instead_of_objcxx_keyword)
+          << tok::identifier << Tok.getIdentifierInfo();
+      // Objective-C++: Recover by treating this keyword as a valid identifier.
+      return false;
+    }
+  }
+  Diag(Tok, diag::err_expected) << tok::identifier;
+  return true;
+}
+
+//===----------------------------------------------------------------------===//
+// Error recovery.
+//===----------------------------------------------------------------------===//
+
+static bool HasFlagsSet(Parser::SkipUntilFlags L, Parser::SkipUntilFlags R) {
+  return (static_cast<unsigned>(L) & static_cast<unsigned>(R)) != 0;
+}
+
+/// SkipUntil - Read tokens until we get to the specified token, then consume
+/// it (unless no flag StopBeforeMatch).  Because we cannot guarantee that the
+/// token will ever occur, this skips to the next token, or to some likely
+/// good stopping point.  If StopAtSemi is true, skipping will stop at a ';'
+/// character.
+///
+/// If SkipUntil finds the specified token, it returns true, otherwise it
+/// returns false.
+bool Parser::SkipUntil(ArrayRef<tok::TokenKind> Toks, SkipUntilFlags Flags) {
+  // We always want this function to skip at least one token if the first token
+  // isn't T and if not at EOF.
+  bool isFirstTokenSkipped = true;
+  while (1) {
+    // If we found one of the tokens, stop and return true.
+    for (unsigned i = 0, NumToks = Toks.size(); i != NumToks; ++i) {
+      if (Tok.is(Toks[i])) {
+        if (HasFlagsSet(Flags, StopBeforeMatch)) {
+          // Noop, don't consume the token.
+        } else {
+          ConsumeAnyToken();
+        }
+        return true;
+      }
+    }
+
+    // Important special case: The caller has given up and just wants us to
+    // skip the rest of the file. Do this without recursing, since we can
+    // get here precisely because the caller detected too much recursion.
+    if (Toks.size() == 1 && Toks[0] == tok::eof &&
+        !HasFlagsSet(Flags, StopAtSemi) &&
+        !HasFlagsSet(Flags, StopAtCodeCompletion)) {
+      while (Tok.isNot(tok::eof))
+        ConsumeAnyToken();
+      return true;
+    }
+
+    switch (Tok.getKind()) {
+    case tok::eof:
+      // Ran out of tokens.
+      return false;
+
+    case tok::annot_pragma_openmp:
+    case tok::annot_pragma_openmp_end:
+      // Stop before an OpenMP pragma boundary.
+      if (OpenMPDirectiveParsing)
+        return false;
+      ConsumeAnnotationToken();
+      break;
+    case tok::annot_module_begin:
+    case tok::annot_module_end:
+    case tok::annot_module_include:
+      // Stop before we change submodules. They generally indicate a "good"
+      // place to pick up parsing again (except in the special case where
+      // we're trying to skip to EOF).
+      return false;
+
+    case tok::code_completion:
+      if (!HasFlagsSet(Flags, StopAtCodeCompletion))
+        handleUnexpectedCodeCompletionToken();
+      return false;
+
+    case tok::l_paren:
+      // Recursively skip properly-nested parens.
+      ConsumeParen();
+      if (HasFlagsSet(Flags, StopAtCodeCompletion))
+        SkipUntil(tok::r_paren, StopAtCodeCompletion);
+      else
+        SkipUntil(tok::r_paren);
+      break;
+    case tok::l_square:
+      // Recursively skip properly-nested square brackets.
+      ConsumeBracket();
+      if (HasFlagsSet(Flags, StopAtCodeCompletion))
+        SkipUntil(tok::r_square, StopAtCodeCompletion);
+      else
+        SkipUntil(tok::r_square);
+      break;
+    case tok::l_brace:
+      // Recursively skip properly-nested braces.
+      ConsumeBrace();
+      if (HasFlagsSet(Flags, StopAtCodeCompletion))
+        SkipUntil(tok::r_brace, StopAtCodeCompletion);
+      else
+        SkipUntil(tok::r_brace);
+      break;
+    case tok::question:
+      // Recursively skip ? ... : pairs; these function as brackets. But
+      // still stop at a semicolon if requested.
+      ConsumeToken();
+      SkipUntil(tok::colon,
+                SkipUntilFlags(unsigned(Flags) &
+                               unsigned(StopAtCodeCompletion | StopAtSemi)));
+      break;
+
+    // Okay, we found a ']' or '}' or ')', which we think should be balanced.
+    // Since the user wasn't looking for this token (if they were, it would
+    // already be handled), this isn't balanced.  If there is a LHS token at a
+    // higher level, we will assume that this matches the unbalanced token
+    // and return it.  Otherwise, this is a spurious RHS token, which we skip.
+    case tok::r_paren:
+      if (ParenCount && !isFirstTokenSkipped)
+        return false;  // Matches something.
+      ConsumeParen();
+      break;
+    case tok::r_square:
+      if (BracketCount && !isFirstTokenSkipped)
+        return false;  // Matches something.
+      ConsumeBracket();
+      break;
+    case tok::r_brace:
+      if (BraceCount && !isFirstTokenSkipped)
+        return false;  // Matches something.
+      ConsumeBrace();
+      break;
+
+    case tok::semi:
+      if (HasFlagsSet(Flags, StopAtSemi))
+        return false;
+      LLVM_FALLTHROUGH;
+    default:
+      // Skip this token.
+      ConsumeAnyToken();
+      break;
+    }
+    isFirstTokenSkipped = false;
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Scope manipulation
+//===----------------------------------------------------------------------===//
+
+/// EnterScope - Start a new scope.
+void Parser::EnterScope(unsigned ScopeFlags) {
+  if (NumCachedScopes) {
+    Scope *N = ScopeCache[--NumCachedScopes];
+    N->Init(getCurScope(), ScopeFlags);
+    Actions.CurScope = N;
+  } else {
+    Actions.CurScope = new Scope(getCurScope(), ScopeFlags, Diags);
+  }
+}
+
+/// ExitScope - Pop a scope off the scope stack.
+void Parser::ExitScope() {
+  assert(getCurScope() && "Scope imbalance!");
+
+  // Inform the actions module that this scope is going away if there are any
+  // decls in it.
+  Actions.ActOnPopScope(Tok.getLocation(), getCurScope());
+
+  Scope *OldScope = getCurScope();
+  Actions.CurScope = OldScope->getParent();
+
+  if (NumCachedScopes == ScopeCacheSize)
+    delete OldScope;
+  else
+    ScopeCache[NumCachedScopes++] = OldScope;
+}
+
+/// Set the flags for the current scope to ScopeFlags. If ManageFlags is false,
+/// this object does nothing.
+Parser::ParseScopeFlags::ParseScopeFlags(Parser *Self, unsigned ScopeFlags,
+                                 bool ManageFlags)
+  : CurScope(ManageFlags ? Self->getCurScope() : nullptr) {
+  if (CurScope) {
+    OldFlags = CurScope->getFlags();
+    CurScope->setFlags(ScopeFlags);
+  }
+}
+
+/// Restore the flags for the current scope to what they were before this
+/// object overrode them.
+Parser::ParseScopeFlags::~ParseScopeFlags() {
+  if (CurScope)
+    CurScope->setFlags(OldFlags);
+}
+
+
+//===----------------------------------------------------------------------===//
+// C99 6.9: External Definitions.
+//===----------------------------------------------------------------------===//
+
+Parser::~Parser() {
+  // If we still have scopes active, delete the scope tree.
+  delete getCurScope();
+  Actions.CurScope = nullptr;
+
+  // Free the scope cache.
+  for (unsigned i = 0, e = NumCachedScopes; i != e; ++i)
+    delete ScopeCache[i];
+
+  resetPragmaHandlers();
+
+  PP.removeCommentHandler(CommentSemaHandler.get());
+
+  PP.clearCodeCompletionHandler();
+
+  if (getLangOpts().DelayedTemplateParsing &&
+      !PP.isIncrementalProcessingEnabled() && !TemplateIds.empty()) {
+    // If an ASTConsumer parsed delay-parsed templates in their
+    // HandleTranslationUnit() method, TemplateIds created there were not
+    // guarded by a DestroyTemplateIdAnnotationsRAIIObj object in
+    // ParseTopLevelDecl(). Destroy them here.
+    DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(TemplateIds);
+  }
+
+  assert(TemplateIds.empty() && "Still alive TemplateIdAnnotations around?");
+}
+
+/// Initialize - Warm up the parser.
+///
+void Parser::Initialize() {
+  // Create the translation unit scope.  Install it as the current scope.
+  assert(getCurScope() == nullptr && "A scope is already active?");
+  EnterScope(Scope::DeclScope);
+  Actions.ActOnTranslationUnitScope(getCurScope());
+
+  // Initialization for Objective-C context sensitive keywords recognition.
+  // Referenced in Parser::ParseObjCTypeQualifierList.
+  if (getLangOpts().ObjC) {
+    ObjCTypeQuals[objc_in] = &PP.getIdentifierTable().get("in");
+    ObjCTypeQuals[objc_out] = &PP.getIdentifierTable().get("out");
+    ObjCTypeQuals[objc_inout] = &PP.getIdentifierTable().get("inout");
+    ObjCTypeQuals[objc_oneway] = &PP.getIdentifierTable().get("oneway");
+    ObjCTypeQuals[objc_bycopy] = &PP.getIdentifierTable().get("bycopy");
+    ObjCTypeQuals[objc_byref] = &PP.getIdentifierTable().get("byref");
+    ObjCTypeQuals[objc_nonnull] = &PP.getIdentifierTable().get("nonnull");
+    ObjCTypeQuals[objc_nullable] = &PP.getIdentifierTable().get("nullable");
+    ObjCTypeQuals[objc_null_unspecified]
+      = &PP.getIdentifierTable().get("null_unspecified");
+  }
+
+  Ident_instancetype = nullptr;
+  Ident_final = nullptr;
+  Ident_sealed = nullptr;
+  Ident_override = nullptr;
+  Ident_GNU_final = nullptr;
+  Ident_import = nullptr;
+  Ident_module = nullptr;
+
+  Ident_super = &PP.getIdentifierTable().get("super");
+
+  Ident_vector = nullptr;
+  Ident_bool = nullptr;
+  Ident_pixel = nullptr;
+  if (getLangOpts().AltiVec || getLangOpts().ZVector) {
+    Ident_vector = &PP.getIdentifierTable().get("vector");
+    Ident_bool = &PP.getIdentifierTable().get("bool");
+  }
+  if (getLangOpts().AltiVec)
+    Ident_pixel = &PP.getIdentifierTable().get("pixel");
+
+  Ident_introduced = nullptr;
+  Ident_deprecated = nullptr;
+  Ident_obsoleted = nullptr;
+  Ident_unavailable = nullptr;
+  Ident_strict = nullptr;
+  Ident_replacement = nullptr;
+
+  Ident_language = Ident_defined_in = Ident_generated_declaration = nullptr;
+
+  Ident__except = nullptr;
+
+  Ident__exception_code = Ident__exception_info = nullptr;
+  Ident__abnormal_termination = Ident___exception_code = nullptr;
+  Ident___exception_info = Ident___abnormal_termination = nullptr;
+  Ident_GetExceptionCode = Ident_GetExceptionInfo = nullptr;
+  Ident_AbnormalTermination = nullptr;
+
+  if(getLangOpts().Borland) {
+    Ident__exception_info        = PP.getIdentifierInfo("_exception_info");
+    Ident___exception_info       = PP.getIdentifierInfo("__exception_info");
+    Ident_GetExceptionInfo       = PP.getIdentifierInfo("GetExceptionInformation");
+    Ident__exception_code        = PP.getIdentifierInfo("_exception_code");
+    Ident___exception_code       = PP.getIdentifierInfo("__exception_code");
+    Ident_GetExceptionCode       = PP.getIdentifierInfo("GetExceptionCode");
+    Ident__abnormal_termination  = PP.getIdentifierInfo("_abnormal_termination");
+    Ident___abnormal_termination = PP.getIdentifierInfo("__abnormal_termination");
+    Ident_AbnormalTermination    = PP.getIdentifierInfo("AbnormalTermination");
+
+    PP.SetPoisonReason(Ident__exception_code,diag::err_seh___except_block);
+    PP.SetPoisonReason(Ident___exception_code,diag::err_seh___except_block);
+    PP.SetPoisonReason(Ident_GetExceptionCode,diag::err_seh___except_block);
+    PP.SetPoisonReason(Ident__exception_info,diag::err_seh___except_filter);
+    PP.SetPoisonReason(Ident___exception_info,diag::err_seh___except_filter);
+    PP.SetPoisonReason(Ident_GetExceptionInfo,diag::err_seh___except_filter);
+    PP.SetPoisonReason(Ident__abnormal_termination,diag::err_seh___finally_block);
+    PP.SetPoisonReason(Ident___abnormal_termination,diag::err_seh___finally_block);
+    PP.SetPoisonReason(Ident_AbnormalTermination,diag::err_seh___finally_block);
+  }
+
+  if (getLangOpts().CPlusPlusModules) {
+    Ident_import = PP.getIdentifierInfo("import");
+    Ident_module = PP.getIdentifierInfo("module");
+  }
+
+  Actions.Initialize();
+
+  // Prime the lexer look-ahead.
+  ConsumeToken();
+}
+
+void Parser::LateTemplateParserCleanupCallback(void *P) {
+  // While this RAII helper doesn't bracket any actual work, the destructor will
+  // clean up annotations that were created during ActOnEndOfTranslationUnit
+  // when incremental processing is enabled.
+  DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(((Parser *)P)->TemplateIds);
+}
+
+/// Parse the first top-level declaration in a translation unit.
+///
+///   translation-unit:
+/// [C]     external-declaration
+/// [C]     translation-unit external-declaration
+/// [C++]   top-level-declaration-seq[opt]
+/// [C++20] global-module-fragment[opt] module-declaration
+///                 top-level-declaration-seq[opt] private-module-fragment[opt]
+///
+/// Note that in C, it is an error if there is no first declaration.
+bool Parser::ParseFirstTopLevelDecl(DeclGroupPtrTy &Result) {
+  Actions.ActOnStartOfTranslationUnit();
+
+  // C11 6.9p1 says translation units must have at least one top-level
+  // declaration. C++ doesn't have this restriction. We also don't want to
+  // complain if we have a precompiled header, although technically if the PCH
+  // is empty we should still emit the (pedantic) diagnostic.
+  bool NoTopLevelDecls = ParseTopLevelDecl(Result, true);
+  if (NoTopLevelDecls && !Actions.getASTContext().getExternalSource() &&
+      !getLangOpts().CPlusPlus)
+    Diag(diag::ext_empty_translation_unit);
+
+  return NoTopLevelDecls;
+}
+
+/// ParseTopLevelDecl - Parse one top-level declaration, return whatever the
+/// action tells us to.  This returns true if the EOF was encountered.
+///
+///   top-level-declaration:
+///           declaration
+/// [C++20]   module-import-declaration
+bool Parser::ParseTopLevelDecl(DeclGroupPtrTy &Result, bool IsFirstDecl) {
+  DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(TemplateIds);
+
+  // Skip over the EOF token, flagging end of previous input for incremental
+  // processing
+  if (PP.isIncrementalProcessingEnabled() && Tok.is(tok::eof))
+    ConsumeToken();
+
+  Result = nullptr;
+  switch (Tok.getKind()) {
+  case tok::annot_pragma_unused:
+    HandlePragmaUnused();
+    return false;
+
+  case tok::kw_export:
+    switch (NextToken().getKind()) {
+    case tok::kw_module:
+      goto module_decl;
+
+    // Note: no need to handle kw_import here. We only form kw_import under
+    // the Modules TS, and in that case 'export import' is parsed as an
+    // export-declaration containing an import-declaration.
+
+    // Recognize context-sensitive C++20 'export module' and 'export import'
+    // declarations.
+    case tok::identifier: {
+      IdentifierInfo *II = NextToken().getIdentifierInfo();
+      if ((II == Ident_module || II == Ident_import) &&
+          GetLookAheadToken(2).isNot(tok::coloncolon)) {
+        if (II == Ident_module)
+          goto module_decl;
+        else
+          goto import_decl;
+      }
+      break;
+    }
+
+    default:
+      break;
+    }
+    break;
+
+  case tok::kw_module:
+  module_decl:
+    Result = ParseModuleDecl(IsFirstDecl);
+    return false;
+
+  // tok::kw_import is handled by ParseExternalDeclaration. (Under the Modules
+  // TS, an import can occur within an export block.)
+  import_decl: {
+    Decl *ImportDecl = ParseModuleImport(SourceLocation());
+    Result = Actions.ConvertDeclToDeclGroup(ImportDecl);
+    return false;
+  }
+
+  case tok::annot_module_include:
+    Actions.ActOnModuleInclude(Tok.getLocation(),
+                               reinterpret_cast<Module *>(
+                                   Tok.getAnnotationValue()));
+    ConsumeAnnotationToken();
+    return false;
+
+  case tok::annot_module_begin:
+    Actions.ActOnModuleBegin(Tok.getLocation(), reinterpret_cast<Module *>(
+                                                    Tok.getAnnotationValue()));
+    ConsumeAnnotationToken();
+    return false;
+
+  case tok::annot_module_end:
+    Actions.ActOnModuleEnd(Tok.getLocation(), reinterpret_cast<Module *>(
+                                                  Tok.getAnnotationValue()));
+    ConsumeAnnotationToken();
+    return false;
+
+  case tok::eof:
+    // Check whether -fmax-tokens= was reached.
+    if (PP.getMaxTokens() != 0 && PP.getTokenCount() > PP.getMaxTokens()) {
+      PP.Diag(Tok.getLocation(), diag::warn_max_tokens_total)
+          << PP.getTokenCount() << PP.getMaxTokens();
+      SourceLocation OverrideLoc = PP.getMaxTokensOverrideLoc();
+      if (OverrideLoc.isValid()) {
+        PP.Diag(OverrideLoc, diag::note_max_tokens_total_override);
+      }
+    }
+
+    // Late template parsing can begin.
+    if (getLangOpts().DelayedTemplateParsing)
+      Actions.SetLateTemplateParser(LateTemplateParserCallback,
+                                    PP.isIncrementalProcessingEnabled() ?
+                                    LateTemplateParserCleanupCallback : nullptr,
+                                    this);
+    if (!PP.isIncrementalProcessingEnabled())
+      Actions.ActOnEndOfTranslationUnit();
+    //else don't tell Sema that we ended parsing: more input might come.
+    return true;
+
+  case tok::identifier:
+    // C++2a [basic.link]p3:
+    //   A token sequence beginning with 'export[opt] module' or
+    //   'export[opt] import' and not immediately followed by '::'
+    //   is never interpreted as the declaration of a top-level-declaration.
+    if ((Tok.getIdentifierInfo() == Ident_module ||
+         Tok.getIdentifierInfo() == Ident_import) &&
+        NextToken().isNot(tok::coloncolon)) {
+      if (Tok.getIdentifierInfo() == Ident_module)
+        goto module_decl;
+      else
+        goto import_decl;
+    }
+    break;
+
+  default:
+    break;
+  }
+
+  ParsedAttributesWithRange attrs(AttrFactory);
+  MaybeParseCXX11Attributes(attrs);
+
+  Result = ParseExternalDeclaration(attrs);
+  return false;
+}
+
+/// ParseExternalDeclaration:
+///
+///       external-declaration: [C99 6.9], declaration: [C++ dcl.dcl]
+///         function-definition
+///         declaration
+/// [GNU]   asm-definition
+/// [GNU]   __extension__ external-declaration
+/// [OBJC]  objc-class-definition
+/// [OBJC]  objc-class-declaration
+/// [OBJC]  objc-alias-declaration
+/// [OBJC]  objc-protocol-definition
+/// [OBJC]  objc-method-definition
+/// [OBJC]  @end
+/// [C++]   linkage-specification
+/// [GNU] asm-definition:
+///         simple-asm-expr ';'
+/// [C++11] empty-declaration
+/// [C++11] attribute-declaration
+///
+/// [C++11] empty-declaration:
+///           ';'
+///
+/// [C++0x/GNU] 'extern' 'template' declaration
+///
+/// [Modules-TS] module-import-declaration
+///
+Parser::DeclGroupPtrTy
+Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
+                                 ParsingDeclSpec *DS) {
+  DestroyTemplateIdAnnotationsRAIIObj CleanupRAII(TemplateIds);
+  ParenBraceBracketBalancer BalancerRAIIObj(*this);
+
+  if (PP.isCodeCompletionReached()) {
+    cutOffParsing();
+    return nullptr;
+  }
+
+  Decl *SingleDecl = nullptr;
+  switch (Tok.getKind()) {
+  case tok::annot_pragma_vis:
+    HandlePragmaVisibility();
+    return nullptr;
+  case tok::annot_pragma_pack:
+    HandlePragmaPack();
+    return nullptr;
+  case tok::annot_pragma_msstruct:
+    HandlePragmaMSStruct();
+    return nullptr;
+  case tok::annot_pragma_align:
+    HandlePragmaAlign();
+    return nullptr;
+  case tok::annot_pragma_weak:
+    HandlePragmaWeak();
+    return nullptr;
+  case tok::annot_pragma_weakalias:
+    HandlePragmaWeakAlias();
+    return nullptr;
+  case tok::annot_pragma_redefine_extname:
+    HandlePragmaRedefineExtname();
+    return nullptr;
+  case tok::annot_pragma_fp_contract:
+    HandlePragmaFPContract();
+    return nullptr;
+  case tok::annot_pragma_fenv_access:
+    HandlePragmaFEnvAccess();
+    return nullptr;
+  case tok::annot_pragma_fp:
+    HandlePragmaFP();
+    break;
+  case tok::annot_pragma_opencl_extension:
+    HandlePragmaOpenCLExtension();
+    return nullptr;
+  case tok::annot_pragma_openmp: {
+    AccessSpecifier AS = AS_none;
+    return ParseOpenMPDeclarativeDirectiveWithExtDecl(AS, attrs);
+  }
+  case tok::annot_pragma_ms_pointers_to_members:
+    HandlePragmaMSPointersToMembers();
+    return nullptr;
+  case tok::annot_pragma_ms_vtordisp:
+    HandlePragmaMSVtorDisp();
+    return nullptr;
+  case tok::annot_pragma_ms_pragma:
+    HandlePragmaMSPragma();
+    return nullptr;
+  case tok::annot_pragma_dump:
+    HandlePragmaDump();
+    return nullptr;
+  case tok::annot_pragma_attribute:
+    HandlePragmaAttribute();
+    return nullptr;
+  case tok::semi:
+    // Either a C++11 empty-declaration or attribute-declaration.
+    SingleDecl =
+        Actions.ActOnEmptyDeclaration(getCurScope(), attrs, Tok.getLocation());
+    ConsumeExtraSemi(OutsideFunction);
+    break;
+  case tok::r_brace:
+    Diag(Tok, diag::err_extraneous_closing_brace);
+    ConsumeBrace();
+    return nullptr;
+  case tok::eof:
+    Diag(Tok, diag::err_expected_external_declaration);
+    return nullptr;
+  case tok::kw___extension__: {
+    // __extension__ silences extension warnings in the subexpression.
+    ExtensionRAIIObject O(Diags);  // Use RAII to do this.
+    ConsumeToken();
+    return ParseExternalDeclaration(attrs);
+  }
+  case tok::kw_asm: {
+    ProhibitAttributes(attrs);
+
+    SourceLocation StartLoc = Tok.getLocation();
+    SourceLocation EndLoc;
+
+    ExprResult Result(ParseSimpleAsm(/*ForAsmLabel*/ false, &EndLoc));
+
+    // Check if GNU-style InlineAsm is disabled.
+    // Empty asm string is allowed because it will not introduce
+    // any assembly code.
+    if (!(getLangOpts().GNUAsm || Result.isInvalid())) {
+      const auto *SL = cast<StringLiteral>(Result.get());
+      if (!SL->getString().trim().empty())
+        Diag(StartLoc, diag::err_gnu_inline_asm_disabled);
+    }
+
+    ExpectAndConsume(tok::semi, diag::err_expected_after,
+                     "top-level asm block");
+
+    if (Result.isInvalid())
+      return nullptr;
+    SingleDecl = Actions.ActOnFileScopeAsmDecl(Result.get(), StartLoc, EndLoc);
+    break;
+  }
+  case tok::at:
+    return ParseObjCAtDirectives(attrs);
+  case tok::minus:
+  case tok::plus:
+    if (!getLangOpts().ObjC) {
+      Diag(Tok, diag::err_expected_external_declaration);
+      ConsumeToken();
+      return nullptr;
+    }
+    SingleDecl = ParseObjCMethodDefinition();
+    break;
+  case tok::code_completion:
+    if (CurParsedObjCImpl) {
+      // Code-complete Objective-C methods even without leading '-'/'+' prefix.
+      Actions.CodeCompleteObjCMethodDecl(getCurScope(),
+                                         /*IsInstanceMethod=*/None,
+                                         /*ReturnType=*/nullptr);
+    }
+    Actions.CodeCompleteOrdinaryName(
+        getCurScope(),
+        CurParsedObjCImpl ? Sema::PCC_ObjCImplementation : Sema::PCC_Namespace);
+    cutOffParsing();
+    return nullptr;
+  case tok::kw_import:
+    SingleDecl = ParseModuleImport(SourceLocation());
+    break;
+  case tok::kw_export:
+    if (getLangOpts().CPlusPlusModules || getLangOpts().ModulesTS) {
+      SingleDecl = ParseExportDeclaration();
+      break;
+    }
+    // This must be 'export template'. Parse it so we can diagnose our lack
+    // of support.
+    LLVM_FALLTHROUGH;
+  case tok::kw_using:
+  case tok::kw_namespace:
+  case tok::kw_typedef:
+  case tok::kw_template:
+  case tok::kw_static_assert:
+  case tok::kw__Static_assert:
+    // A function definition cannot start with any of these keywords.
+    {
+      SourceLocation DeclEnd;
+      return ParseDeclaration(DeclaratorContext::FileContext, DeclEnd, attrs);
+    }
+
+  case tok::kw_static:
+    // Parse (then ignore) 'static' prior to a template instantiation. This is
+    // a GCC extension that we intentionally do not support.
+    if (getLangOpts().CPlusPlus && NextToken().is(tok::kw_template)) {
+      Diag(ConsumeToken(), diag::warn_static_inline_explicit_inst_ignored)
+        << 0;
+      SourceLocation DeclEnd;
+      return ParseDeclaration(DeclaratorContext::FileContext, DeclEnd, attrs);
+    }
+    goto dont_know;
+
+  case tok::kw_inline:
+    if (getLangOpts().CPlusPlus) {
+      tok::TokenKind NextKind = NextToken().getKind();
+
+      // Inline namespaces. Allowed as an extension even in C++03.
+      if (NextKind == tok::kw_namespace) {
+        SourceLocation DeclEnd;
+        return ParseDeclaration(DeclaratorContext::FileContext, DeclEnd, attrs);
+      }
+
+      // Parse (then ignore) 'inline' prior to a template instantiation. This is
+      // a GCC extension that we intentionally do not support.
+      if (NextKind == tok::kw_template) {
+        Diag(ConsumeToken(), diag::warn_static_inline_explicit_inst_ignored)
+          << 1;
+        SourceLocation DeclEnd;
+        return ParseDeclaration(DeclaratorContext::FileContext, DeclEnd, attrs);
+      }
+    }
+    goto dont_know;
+
+  case tok::kw_extern:
+    if (getLangOpts().CPlusPlus && NextToken().is(tok::kw_template)) {
+      // Extern templates
+      SourceLocation ExternLoc = ConsumeToken();
+      SourceLocation TemplateLoc = ConsumeToken();
+      Diag(ExternLoc, getLangOpts().CPlusPlus11 ?
+             diag::warn_cxx98_compat_extern_template :
+             diag::ext_extern_template) << SourceRange(ExternLoc, TemplateLoc);
+      SourceLocation DeclEnd;
+      return Actions.ConvertDeclToDeclGroup(
+          ParseExplicitInstantiation(DeclaratorContext::FileContext, ExternLoc,
+                                     TemplateLoc, DeclEnd, attrs));
+    }
+    goto dont_know;
+
+  case tok::kw___if_exists:
+  case tok::kw___if_not_exists:
+    ParseMicrosoftIfExistsExternalDeclaration();
+    return nullptr;
+
+  case tok::kw_module:
+    Diag(Tok, diag::err_unexpected_module_decl);
+    SkipUntil(tok::semi);
+    return nullptr;
+
+  default:
+  dont_know:
+    if (Tok.isEditorPlaceholder()) {
+      ConsumeToken();
+      return nullptr;
+    }
+    // We can't tell whether this is a function-definition or declaration yet.
+    return ParseDeclarationOrFunctionDefinition(attrs, DS);
+  }
+
+  // This routine returns a DeclGroup, if the thing we parsed only contains a
+  // single decl, convert it now.
+  return Actions.ConvertDeclToDeclGroup(SingleDecl);
+}
+
+/// Determine whether the current token, if it occurs after a
+/// declarator, continues a declaration or declaration list.
+bool Parser::isDeclarationAfterDeclarator() {
+  // Check for '= delete' or '= default'
+  if (getLangOpts().CPlusPlus && Tok.is(tok::equal)) {
+    const Token &KW = NextToken();
+    if (KW.is(tok::kw_default) || KW.is(tok::kw_delete))
+      return false;
+  }
+
+  return Tok.is(tok::equal) ||      // int X()=  -> not a function def
+    Tok.is(tok::comma) ||           // int X(),  -> not a function def
+    Tok.is(tok::semi)  ||           // int X();  -> not a function def
+    Tok.is(tok::kw_asm) ||          // int X() __asm__ -> not a function def
+    Tok.is(tok::kw___attribute) ||  // int X() __attr__ -> not a function def
+    (getLangOpts().CPlusPlus &&
+     Tok.is(tok::l_paren));         // int X(0) -> not a function def [C++]
+}
+
+/// Determine whether the current token, if it occurs after a
+/// declarator, indicates the start of a function definition.
+bool Parser::isStartOfFunctionDefinition(const ParsingDeclarator &Declarator) {
+  assert(Declarator.isFunctionDeclarator() && "Isn't a function declarator");
+  if (Tok.is(tok::l_brace))   // int X() {}
+    return true;
+
+  // Handle K&R C argument lists: int X(f) int f; {}
+  if (!getLangOpts().CPlusPlus &&
+      Declarator.getFunctionTypeInfo().isKNRPrototype())
+    return isDeclarationSpecifier();
+
+  if (getLangOpts().CPlusPlus && Tok.is(tok::equal)) {
+    const Token &KW = NextToken();
+    return KW.is(tok::kw_default) || KW.is(tok::kw_delete);
+  }
+
+  return Tok.is(tok::colon) ||         // X() : Base() {} (used for ctors)
+         Tok.is(tok::kw_try);          // X() try { ... }
+}
+
+/// Parse either a function-definition or a declaration.  We can't tell which
+/// we have until we read up to the compound-statement in function-definition.
+/// TemplateParams, if non-NULL, provides the template parameters when we're
+/// parsing a C++ template-declaration.
+///
+///       function-definition: [C99 6.9.1]
+///         decl-specs      declarator declaration-list[opt] compound-statement
+/// [C90] function-definition: [C99 6.7.1] - implicit int result
+/// [C90]   decl-specs[opt] declarator declaration-list[opt] compound-statement
+///
+///       declaration: [C99 6.7]
+///         declaration-specifiers init-declarator-list[opt] ';'
+/// [!C99]  init-declarator-list ';'                   [TODO: warn in c99 mode]
+/// [OMP]   threadprivate-directive
+/// [OMP]   allocate-directive                         [TODO]
+///
+Parser::DeclGroupPtrTy
+Parser::ParseDeclOrFunctionDefInternal(ParsedAttributesWithRange &attrs,
+                                       ParsingDeclSpec &DS,
+                                       AccessSpecifier AS) {
+  MaybeParseMicrosoftAttributes(DS.getAttributes());
+  // Parse the common declaration-specifiers piece.
+  ParseDeclarationSpecifiers(DS, ParsedTemplateInfo(), AS,
+                             DeclSpecContext::DSC_top_level);
+
+  // If we had a free-standing type definition with a missing semicolon, we
+  // may get this far before the problem becomes obvious.
+  if (DS.hasTagDefinition() && DiagnoseMissingSemiAfterTagDefinition(
+                                   DS, AS, DeclSpecContext::DSC_top_level))
+    return nullptr;
+
+  // C99 6.7.2.3p6: Handle "struct-or-union identifier;", "enum { X };"
+  // declaration-specifiers init-declarator-list[opt] ';'
+  if (Tok.is(tok::semi)) {
+    auto LengthOfTSTToken = [](DeclSpec::TST TKind) {
+      assert(DeclSpec::isDeclRep(TKind));
+      switch(TKind) {
+      case DeclSpec::TST_class:
+        return 5;
+      case DeclSpec::TST_struct:
+        return 6;
+      case DeclSpec::TST_union:
+        return 5;
+      case DeclSpec::TST_enum:
+        return 4;
+      case DeclSpec::TST_interface:
+        return 9;
+      default:
+        llvm_unreachable("we only expect to get the length of the class/struct/union/enum");
+      }
+
+    };
+    // Suggest correct location to fix '[[attrib]] struct' to 'struct [[attrib]]'
+    SourceLocation CorrectLocationForAttributes =
+        DeclSpec::isDeclRep(DS.getTypeSpecType())
+            ? DS.getTypeSpecTypeLoc().getLocWithOffset(
+                  LengthOfTSTToken(DS.getTypeSpecType()))
+            : SourceLocation();
+    ProhibitAttributes(attrs, CorrectLocationForAttributes);
+    ConsumeToken();
+    RecordDecl *AnonRecord = nullptr;
+    Decl *TheDecl = Actions.ParsedFreeStandingDeclSpec(getCurScope(), AS_none,
+                                                       DS, AnonRecord);
+    DS.complete(TheDecl);
+    if (getLangOpts().OpenCL)
+      Actions.setCurrentOpenCLExtensionForDecl(TheDecl);
+    if (AnonRecord) {
+      Decl* decls[] = {AnonRecord, TheDecl};
+      return Actions.BuildDeclaratorGroup(decls);
+    }
+    return Actions.ConvertDeclToDeclGroup(TheDecl);
+  }
+
+  DS.takeAttributesFrom(attrs);
+
+  // ObjC2 allows prefix attributes on class interfaces and protocols.
+  // FIXME: This still needs better diagnostics. We should only accept
+  // attributes here, no types, etc.
+  if (getLangOpts().ObjC && Tok.is(tok::at)) {
+    SourceLocation AtLoc = ConsumeToken(); // the "@"
+    if (!Tok.isObjCAtKeyword(tok::objc_interface) &&
+        !Tok.isObjCAtKeyword(tok::objc_protocol) &&
+        !Tok.isObjCAtKeyword(tok::objc_implementation)) {
+      Diag(Tok, diag::err_objc_unexpected_attr);
+      SkipUntil(tok::semi);
+      return nullptr;
+    }
+
+    DS.abort();
+
+    const char *PrevSpec = nullptr;
+    unsigned DiagID;
+    if (DS.SetTypeSpecType(DeclSpec::TST_unspecified, AtLoc, PrevSpec, DiagID,
+                           Actions.getASTContext().getPrintingPolicy()))
+      Diag(AtLoc, DiagID) << PrevSpec;
+
+    if (Tok.isObjCAtKeyword(tok::objc_protocol))
+      return ParseObjCAtProtocolDeclaration(AtLoc, DS.getAttributes());
+
+    if (Tok.isObjCAtKeyword(tok::objc_implementation))
+      return ParseObjCAtImplementationDeclaration(AtLoc, DS.getAttributes());
+
+    return Actions.ConvertDeclToDeclGroup(
+            ParseObjCAtInterfaceDeclaration(AtLoc, DS.getAttributes()));
+  }
+
+  // If the declspec consisted only of 'extern' and we have a string
+  // literal following it, this must be a C++ linkage specifier like
+  // 'extern "C"'.
+  if (getLangOpts().CPlusPlus && isTokenStringLiteral() &&
+      DS.getStorageClassSpec() == DeclSpec::SCS_extern &&
+      DS.getParsedSpecifiers() == DeclSpec::PQ_StorageClassSpecifier) {
+    Decl *TheDecl = ParseLinkage(DS, DeclaratorContext::FileContext);
+    return Actions.ConvertDeclToDeclGroup(TheDecl);
+  }
+
+  return ParseDeclGroup(DS, DeclaratorContext::FileContext);
+}
+
+Parser::DeclGroupPtrTy
+Parser::ParseDeclarationOrFunctionDefinition(ParsedAttributesWithRange &attrs,
+                                             ParsingDeclSpec *DS,
+                                             AccessSpecifier AS) {
+  if (DS) {
+    return ParseDeclOrFunctionDefInternal(attrs, *DS, AS);
+  } else {
+    ParsingDeclSpec PDS(*this);
+    // Must temporarily exit the objective-c container scope for
+    // parsing c constructs and re-enter objc container scope
+    // afterwards.
+    ObjCDeclContextSwitch ObjCDC(*this);
+
+    return ParseDeclOrFunctionDefInternal(attrs, PDS, AS);
+  }
+}
+
+/// ParseFunctionDefinition - We parsed and verified that the specified
+/// Declarator is well formed.  If this is a K&R-style function, read the
+/// parameters declaration-list, then start the compound-statement.
+///
+///       function-definition: [C99 6.9.1]
+///         decl-specs      declarator declaration-list[opt] compound-statement
+/// [C90] function-definition: [C99 6.7.1] - implicit int result
+/// [C90]   decl-specs[opt] declarator declaration-list[opt] compound-statement
+/// [C++] function-definition: [C++ 8.4]
+///         decl-specifier-seq[opt] declarator ctor-initializer[opt]
+///         function-body
+/// [C++] function-definition: [C++ 8.4]
+///         decl-specifier-seq[opt] declarator function-try-block
+///
+Decl *Parser::ParseFunctionDefinition(ParsingDeclarator &D,
+                                      const ParsedTemplateInfo &TemplateInfo,
+                                      LateParsedAttrList *LateParsedAttrs) {
+  // Poison SEH identifiers so they are flagged as illegal in function bodies.
+  PoisonSEHIdentifiersRAIIObject PoisonSEHIdentifiers(*this, true);
+  const DeclaratorChunk::FunctionTypeInfo &FTI = D.getFunctionTypeInfo();
+  TemplateParameterDepthRAII CurTemplateDepthTracker(TemplateParameterDepth);
+
+  // If this is C90 and the declspecs were completely missing, fudge in an
+  // implicit int.  We do this here because this is the only place where
+  // declaration-specifiers are completely optional in the grammar.
+  if (getLangOpts().ImplicitInt && D.getDeclSpec().isEmpty()) {
+    const char *PrevSpec;
+    unsigned DiagID;
+    const PrintingPolicy &Policy = Actions.getASTContext().getPrintingPolicy();
+    D.getMutableDeclSpec().SetTypeSpecType(DeclSpec::TST_int,
+                                           D.getIdentifierLoc(),
+                                           PrevSpec, DiagID,
+                                           Policy);
+    D.SetRangeBegin(D.getDeclSpec().getSourceRange().getBegin());
+  }
+
+  // If this declaration was formed with a K&R-style identifier list for the
+  // arguments, parse declarations for all of the args next.
+  // int foo(a,b) int a; float b; {}
+  if (FTI.isKNRPrototype())
+    ParseKNRParamDeclarations(D);
+
+  // We should have either an opening brace or, in a C++ constructor,
+  // we may have a colon.
+  if (Tok.isNot(tok::l_brace) &&
+      (!getLangOpts().CPlusPlus ||
+       (Tok.isNot(tok::colon) && Tok.isNot(tok::kw_try) &&
+        Tok.isNot(tok::equal)))) {
+    Diag(Tok, diag::err_expected_fn_body);
+
+    // Skip over garbage, until we get to '{'.  Don't eat the '{'.
+    SkipUntil(tok::l_brace, StopAtSemi | StopBeforeMatch);
+
+    // If we didn't find the '{', bail out.
+    if (Tok.isNot(tok::l_brace))
+      return nullptr;
+  }
+
+  // Check to make sure that any normal attributes are allowed to be on
+  // a definition.  Late parsed attributes are checked at the end.
+  if (Tok.isNot(tok::equal)) {
+    for (const ParsedAttr &AL : D.getAttributes())
+      if (AL.isKnownToGCC() && !AL.isCXX11Attribute())
+        Diag(AL.getLoc(), diag::warn_attribute_on_function_definition) << AL;
+  }
+
+  // In delayed template parsing mode, for function template we consume the
+  // tokens and store them for late parsing at the end of the translation unit.
+  if (getLangOpts().DelayedTemplateParsing && Tok.isNot(tok::equal) &&
+      TemplateInfo.Kind == ParsedTemplateInfo::Template &&
+      Actions.canDelayFunctionBody(D)) {
+    MultiTemplateParamsArg TemplateParameterLists(*TemplateInfo.TemplateParams);
+
+    ParseScope BodyScope(this, Scope::FnScope | Scope::DeclScope |
+                                   Scope::CompoundStmtScope);
+    Scope *ParentScope = getCurScope()->getParent();
+
+    D.setFunctionDefinitionKind(FDK_Definition);
+    Decl *DP = Actions.HandleDeclarator(ParentScope, D,
+                                        TemplateParameterLists);
+    D.complete(DP);
+    D.getMutableDeclSpec().abort();
+
+    if (SkipFunctionBodies && (!DP || Actions.canSkipFunctionBody(DP)) &&
+        trySkippingFunctionBody()) {
+      BodyScope.Exit();
+      return Actions.ActOnSkippedFunctionBody(DP);
+    }
+
+    CachedTokens Toks;
+    LexTemplateFunctionForLateParsing(Toks);
+
+    if (DP) {
+      FunctionDecl *FnD = DP->getAsFunction();
+      Actions.CheckForFunctionRedefinition(FnD);
+      Actions.MarkAsLateParsedTemplate(FnD, DP, Toks);
+    }
+    return DP;
+  }
+  else if (CurParsedObjCImpl &&
+           !TemplateInfo.TemplateParams &&
+           (Tok.is(tok::l_brace) || Tok.is(tok::kw_try) ||
+            Tok.is(tok::colon)) &&
+      Actions.CurContext->isTranslationUnit()) {
+    ParseScope BodyScope(this, Scope::FnScope | Scope::DeclScope |
+                                   Scope::CompoundStmtScope);
+    Scope *ParentScope = getCurScope()->getParent();
+
+    D.setFunctionDefinitionKind(FDK_Definition);
+    Decl *FuncDecl = Actions.HandleDeclarator(ParentScope, D,
+                                              MultiTemplateParamsArg());
+    D.complete(FuncDecl);
+    D.getMutableDeclSpec().abort();
+    if (FuncDecl) {
+      // Consume the tokens and store them for later parsing.
+      StashAwayMethodOrFunctionBodyTokens(FuncDecl);
+      CurParsedObjCImpl->HasCFunction = true;
+      return FuncDecl;
+    }
+    // FIXME: Should we really fall through here?
+  }
+
+  // Enter a scope for the function body.
+  ParseScope BodyScope(this, Scope::FnScope | Scope::DeclScope |
+                                 Scope::CompoundStmtScope);
+
+  // Tell the actions module that we have entered a function definition with the
+  // specified Declarator for the function.
+  Sema::SkipBodyInfo SkipBody;
+  Decl *Res = Actions.ActOnStartOfFunctionDef(getCurScope(), D,
+                                              TemplateInfo.TemplateParams
+                                                  ? *TemplateInfo.TemplateParams
+                                                  : MultiTemplateParamsArg(),
+                                              &SkipBody);
+
+  if (SkipBody.ShouldSkip) {
+    SkipFunctionBody();
+    return Res;
+  }
+
+  // Break out of the ParsingDeclarator context before we parse the body.
+  D.complete(Res);
+
+  // Break out of the ParsingDeclSpec context, too.  This const_cast is
+  // safe because we're always the sole owner.
+  D.getMutableDeclSpec().abort();
+
+  // With abbreviated function templates - we need to explicitly add depth to
+  // account for the implicit template parameter list induced by the template.
+  if (auto *Template = dyn_cast_or_null<FunctionTemplateDecl>(Res))
+    if (Template->isAbbreviated() &&
+        Template->getTemplateParameters()->getParam(0)->isImplicit())
+      // First template parameter is implicit - meaning no explicit template
+      // parameter list was specified.
+      CurTemplateDepthTracker.addDepth(1);
+
+  if (TryConsumeToken(tok::equal)) {
+    assert(getLangOpts().CPlusPlus && "Only C++ function definitions have '='");
+
+    bool Delete = false;
+    SourceLocation KWLoc;
+    if (TryConsumeToken(tok::kw_delete, KWLoc)) {
+      Diag(KWLoc, getLangOpts().CPlusPlus11
+                      ? diag::warn_cxx98_compat_defaulted_deleted_function
+                      : diag::ext_defaulted_deleted_function)
+        << 1 /* deleted */;
+      Actions.SetDeclDeleted(Res, KWLoc);
+      Delete = true;
+    } else if (TryConsumeToken(tok::kw_default, KWLoc)) {
+      Diag(KWLoc, getLangOpts().CPlusPlus11
+                      ? diag::warn_cxx98_compat_defaulted_deleted_function
+                      : diag::ext_defaulted_deleted_function)
+        << 0 /* defaulted */;
+      Actions.SetDeclDefaulted(Res, KWLoc);
+    } else {
+      llvm_unreachable("function definition after = not 'delete' or 'default'");
+    }
+
+    if (Tok.is(tok::comma)) {
+      Diag(KWLoc, diag::err_default_delete_in_multiple_declaration)
+        << Delete;
+      SkipUntil(tok::semi);
+    } else if (ExpectAndConsume(tok::semi, diag::err_expected_after,
+                                Delete ? "delete" : "default")) {
+      SkipUntil(tok::semi);
+    }
+
+    Stmt *GeneratedBody = Res ? Res->getBody() : nullptr;
+    Actions.ActOnFinishFunctionBody(Res, GeneratedBody, false);
+    return Res;
+  }
+
+  if (SkipFunctionBodies && (!Res || Actions.canSkipFunctionBody(Res)) &&
+      trySkippingFunctionBody()) {
+    BodyScope.Exit();
+    Actions.ActOnSkippedFunctionBody(Res);
+    return Actions.ActOnFinishFunctionBody(Res, nullptr, false);
+  }
+
+  if (Tok.is(tok::kw_try))
+    return ParseFunctionTryBlock(Res, BodyScope);
+
+  // If we have a colon, then we're probably parsing a C++
+  // ctor-initializer.
+  if (Tok.is(tok::colon)) {
+    ParseConstructorInitializer(Res);
+
+    // Recover from error.
+    if (!Tok.is(tok::l_brace)) {
+      BodyScope.Exit();
+      Actions.ActOnFinishFunctionBody(Res, nullptr);
+      return Res;
+    }
+  } else
+    Actions.ActOnDefaultCtorInitializers(Res);
+
+  // Late attributes are parsed in the same scope as the function body.
+  if (LateParsedAttrs)
+    ParseLexedAttributeList(*LateParsedAttrs, Res, false, true);
+
+  return ParseFunctionStatementBody(Res, BodyScope);
+}
+
+void Parser::SkipFunctionBody() {
+  if (Tok.is(tok::equal)) {
+    SkipUntil(tok::semi);
+    return;
+  }
+
+  bool IsFunctionTryBlock = Tok.is(tok::kw_try);
+  if (IsFunctionTryBlock)
+    ConsumeToken();
+
+  CachedTokens Skipped;
+  if (ConsumeAndStoreFunctionPrologue(Skipped))
+    SkipMalformedDecl();
+  else {
+    SkipUntil(tok::r_brace);
+    while (IsFunctionTryBlock && Tok.is(tok::kw_catch)) {
+      SkipUntil(tok::l_brace);
+      SkipUntil(tok::r_brace);
+    }
+  }
+}
+
+/// ParseKNRParamDeclarations - Parse 'declaration-list[opt]' which provides
+/// types for a function with a K&R-style identifier list for arguments.
+void Parser::ParseKNRParamDeclarations(Declarator &D) {
+  // We know that the top-level of this declarator is a function.
+  DeclaratorChunk::FunctionTypeInfo &FTI = D.getFunctionTypeInfo();
+
+  // Enter function-declaration scope, limiting any declarators to the
+  // function prototype scope, including parameter declarators.
+  ParseScope PrototypeScope(this, Scope::FunctionPrototypeScope |
+                            Scope::FunctionDeclarationScope | Scope::DeclScope);
+
+  // Read all the argument declarations.
+  while (isDeclarationSpecifier()) {
+    SourceLocation DSStart = Tok.getLocation();
+
+    // Parse the common declaration-specifiers piece.
+    DeclSpec DS(AttrFactory);
+    ParseDeclarationSpecifiers(DS);
+
+    // C99 6.9.1p6: 'each declaration in the declaration list shall have at
+    // least one declarator'.
+    // NOTE: GCC just makes this an ext-warn.  It's not clear what it does with
+    // the declarations though.  It's trivial to ignore them, really hard to do
+    // anything else with them.
+    if (TryConsumeToken(tok::semi)) {
+      Diag(DSStart, diag::err_declaration_does_not_declare_param);
+      continue;
+    }
+
+    // C99 6.9.1p6: Declarations shall contain no storage-class specifiers other
+    // than register.
+    if (DS.getStorageClassSpec() != DeclSpec::SCS_unspecified &&
+        DS.getStorageClassSpec() != DeclSpec::SCS_register) {
+      Diag(DS.getStorageClassSpecLoc(),
+           diag::err_invalid_storage_class_in_func_decl);
+      DS.ClearStorageClassSpecs();
+    }
+    if (DS.getThreadStorageClassSpec() != DeclSpec::TSCS_unspecified) {
+      Diag(DS.getThreadStorageClassSpecLoc(),
+           diag::err_invalid_storage_class_in_func_decl);
+      DS.ClearStorageClassSpecs();
+    }
+
+    // Parse the first declarator attached to this declspec.
+    Declarator ParmDeclarator(DS, DeclaratorContext::KNRTypeListContext);
+    ParseDeclarator(ParmDeclarator);
+
+    // Handle the full declarator list.
+    while (1) {
+      // If attributes are present, parse them.
+      MaybeParseGNUAttributes(ParmDeclarator);
+
+      // Ask the actions module to compute the type for this declarator.
+      Decl *Param =
+        Actions.ActOnParamDeclarator(getCurScope(), ParmDeclarator);
+
+      if (Param &&
+          // A missing identifier has already been diagnosed.
+          ParmDeclarator.getIdentifier()) {
+
+        // Scan the argument list looking for the correct param to apply this
+        // type.
+        for (unsigned i = 0; ; ++i) {
+          // C99 6.9.1p6: those declarators shall declare only identifiers from
+          // the identifier list.
+          if (i == FTI.NumParams) {
+            Diag(ParmDeclarator.getIdentifierLoc(), diag::err_no_matching_param)
+              << ParmDeclarator.getIdentifier();
+            break;
+          }
+
+          if (FTI.Params[i].Ident == ParmDeclarator.getIdentifier()) {
+            // Reject redefinitions of parameters.
+            if (FTI.Params[i].Param) {
+              Diag(ParmDeclarator.getIdentifierLoc(),
+                   diag::err_param_redefinition)
+                 << ParmDeclarator.getIdentifier();
+            } else {
+              FTI.Params[i].Param = Param;
+            }
+            break;
+          }
+        }
+      }
+
+      // If we don't have a comma, it is either the end of the list (a ';') or
+      // an error, bail out.
+      if (Tok.isNot(tok::comma))
+        break;
+
+      ParmDeclarator.clear();
+
+      // Consume the comma.
+      ParmDeclarator.setCommaLoc(ConsumeToken());
+
+      // Parse the next declarator.
+      ParseDeclarator(ParmDeclarator);
+    }
+
+    // Consume ';' and continue parsing.
+    if (!ExpectAndConsumeSemi(diag::err_expected_semi_declaration))
+      continue;
+
+    // Otherwise recover by skipping to next semi or mandatory function body.
+    if (SkipUntil(tok::l_brace, StopAtSemi | StopBeforeMatch))
+      break;
+    TryConsumeToken(tok::semi);
+  }
+
+  // The actions module must verify that all arguments were declared.
+  Actions.ActOnFinishKNRParamDeclarations(getCurScope(), D, Tok.getLocation());
+}
+
+
+/// ParseAsmStringLiteral - This is just a normal string-literal, but is not
+/// allowed to be a wide string, and is not subject to character translation.
+/// Unlike GCC, we also diagnose an empty string literal when parsing for an
+/// asm label as opposed to an asm statement, because such a construct does not
+/// behave well.
+///
+/// [GNU] asm-string-literal:
+///         string-literal
+///
+ExprResult Parser::ParseAsmStringLiteral(bool ForAsmLabel) {
+  if (!isTokenStringLiteral()) {
+    Diag(Tok, diag::err_expected_string_literal)
+      << /*Source='in...'*/0 << "'asm'";
+    return ExprError();
+  }
+
+  ExprResult AsmString(ParseStringLiteralExpression());
+  if (!AsmString.isInvalid()) {
+    const auto *SL = cast<StringLiteral>(AsmString.get());
+    if (!SL->isAscii()) {
+      Diag(Tok, diag::err_asm_operand_wide_string_literal)
+        << SL->isWide()
+        << SL->getSourceRange();
+      return ExprError();
+    }
+    if (ForAsmLabel && SL->getString().empty()) {
+      Diag(Tok, diag::err_asm_operand_wide_string_literal)
+          << 2 /* an empty */ << SL->getSourceRange();
+      return ExprError();
+    }
+  }
+  return AsmString;
+}
+
+/// ParseSimpleAsm
+///
+/// [GNU] simple-asm-expr:
+///         'asm' '(' asm-string-literal ')'
+///
+ExprResult Parser::ParseSimpleAsm(bool ForAsmLabel, SourceLocation *EndLoc) {
+  assert(Tok.is(tok::kw_asm) && "Not an asm!");
+  SourceLocation Loc = ConsumeToken();
+
+  if (Tok.is(tok::kw_volatile)) {
+    // Remove from the end of 'asm' to the end of 'volatile'.
+    SourceRange RemovalRange(PP.getLocForEndOfToken(Loc),
+                             PP.getLocForEndOfToken(Tok.getLocation()));
+
+    Diag(Tok, diag::warn_file_asm_volatile)
+      << FixItHint::CreateRemoval(RemovalRange);
+    ConsumeToken();
+  }
+
+  BalancedDelimiterTracker T(*this, tok::l_paren);
+  if (T.consumeOpen()) {
+    Diag(Tok, diag::err_expected_lparen_after) << "asm";
+    return ExprError();
+  }
+
+  ExprResult Result(ParseAsmStringLiteral(ForAsmLabel));
+
+  if (!Result.isInvalid()) {
+    // Close the paren and get the location of the end bracket
+    T.consumeClose();
+    if (EndLoc)
+      *EndLoc = T.getCloseLocation();
+  } else if (SkipUntil(tok::r_paren, StopAtSemi | StopBeforeMatch)) {
+    if (EndLoc)
+      *EndLoc = Tok.getLocation();
+    ConsumeParen();
+  }
+
+  return Result;
+}
+
+/// Get the TemplateIdAnnotation from the token and put it in the
+/// cleanup pool so that it gets destroyed when parsing the current top level
+/// declaration is finished.
+TemplateIdAnnotation *Parser::takeTemplateIdAnnotation(const Token &tok) {
+  assert(tok.is(tok::annot_template_id) && "Expected template-id token");
+  TemplateIdAnnotation *
+      Id = static_cast<TemplateIdAnnotation *>(tok.getAnnotationValue());
+  return Id;
+}
+
+void Parser::AnnotateScopeToken(CXXScopeSpec &SS, bool IsNewAnnotation) {
+  // Push the current token back into the token stream (or revert it if it is
+  // cached) and use an annotation scope token for current token.
+  if (PP.isBacktrackEnabled())
+    PP.RevertCachedTokens(1);
+  else
+    PP.EnterToken(Tok, /*IsReinject=*/true);
+  Tok.setKind(tok::annot_cxxscope);
+  Tok.setAnnotationValue(Actions.SaveNestedNameSpecifierAnnotation(SS));
+  Tok.setAnnotationRange(SS.getRange());
+
+  // In case the tokens were cached, have Preprocessor replace them
+  // with the annotation token.  We don't need to do this if we've
+  // just reverted back to a prior state.
+  if (IsNewAnnotation)
+    PP.AnnotateCachedTokens(Tok);
+}
+
+/// Attempt to classify the name at the current token position. This may
+/// form a type, scope or primary expression annotation, or replace the token
+/// with a typo-corrected keyword. This is only appropriate when the current
+/// name must refer to an entity which has already been declared.
+///
+/// \param CCC Indicates how to perform typo-correction for this name. If NULL,
+///        no typo correction will be performed.
+Parser::AnnotatedNameKind
+Parser::TryAnnotateName(CorrectionCandidateCallback *CCC) {
+  assert(Tok.is(tok::identifier) || Tok.is(tok::annot_cxxscope));
+
+  const bool EnteringContext = false;
+  const bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
+
+  CXXScopeSpec SS;
+  if (getLangOpts().CPlusPlus &&
+      ParseOptionalCXXScopeSpecifier(SS, nullptr, EnteringContext))
+    return ANK_Error;
+
+  if (Tok.isNot(tok::identifier) || SS.isInvalid()) {
+    if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation))
+      return ANK_Error;
+    return ANK_Unresolved;
+  }
+
+  IdentifierInfo *Name = Tok.getIdentifierInfo();
+  SourceLocation NameLoc = Tok.getLocation();
+
+  // FIXME: Move the tentative declaration logic into ClassifyName so we can
+  // typo-correct to tentatively-declared identifiers.
+  if (isTentativelyDeclared(Name)) {
+    // Identifier has been tentatively declared, and thus cannot be resolved as
+    // an expression. Fall back to annotating it as a type.
+    if (TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation))
+      return ANK_Error;
+    return Tok.is(tok::annot_typename) ? ANK_Success : ANK_TentativeDecl;
+  }
+
+  Token Next = NextToken();
+
+  // Look up and classify the identifier. We don't perform any typo-correction
+  // after a scope specifier, because in general we can't recover from typos
+  // there (eg, after correcting 'A::template B<X>::C' [sic], we would need to
+  // jump back into scope specifier parsing).
+  Sema::NameClassification Classification = Actions.ClassifyName(
+      getCurScope(), SS, Name, NameLoc, Next, SS.isEmpty() ? CCC : nullptr);
+
+  // If name lookup found nothing and we guessed that this was a template name,
+  // double-check before committing to that interpretation. C++20 requires that
+  // we interpret this as a template-id if it can be, but if it can't be, then
+  // this is an error recovery case.
+  if (Classification.getKind() == Sema::NC_UndeclaredTemplate &&
+      isTemplateArgumentList(1) == TPResult::False) {
+    // It's not a template-id; re-classify without the '<' as a hint.
+    Token FakeNext = Next;
+    FakeNext.setKind(tok::unknown);
+    Classification =
+        Actions.ClassifyName(getCurScope(), SS, Name, NameLoc, FakeNext,
+                             SS.isEmpty() ? CCC : nullptr);
+  }
+
+  switch (Classification.getKind()) {
+  case Sema::NC_Error:
+    return ANK_Error;
+
+  case Sema::NC_Keyword:
+    // The identifier was typo-corrected to a keyword.
+    Tok.setIdentifierInfo(Name);
+    Tok.setKind(Name->getTokenID());
+    PP.TypoCorrectToken(Tok);
+    if (SS.isNotEmpty())
+      AnnotateScopeToken(SS, !WasScopeAnnotation);
+    // We've "annotated" this as a keyword.
+    return ANK_Success;
+
+  case Sema::NC_Unknown:
+    // It's not something we know about. Leave it unannotated.
+    break;
+
+  case Sema::NC_Type: {
+    SourceLocation BeginLoc = NameLoc;
+    if (SS.isNotEmpty())
+      BeginLoc = SS.getBeginLoc();
+
+    /// An Objective-C object type followed by '<' is a specialization of
+    /// a parameterized class type or a protocol-qualified type.
+    ParsedType Ty = Classification.getType();
+    if (getLangOpts().ObjC && NextToken().is(tok::less) &&
+        (Ty.get()->isObjCObjectType() ||
+         Ty.get()->isObjCObjectPointerType())) {
+      // Consume the name.
+      SourceLocation IdentifierLoc = ConsumeToken();
+      SourceLocation NewEndLoc;
+      TypeResult NewType
+          = parseObjCTypeArgsAndProtocolQualifiers(IdentifierLoc, Ty,
+                                                   /*consumeLastToken=*/false,
+                                                   NewEndLoc);
+      if (NewType.isUsable())
+        Ty = NewType.get();
+      else if (Tok.is(tok::eof)) // Nothing to do here, bail out...
+        return ANK_Error;
+    }
+
+    Tok.setKind(tok::annot_typename);
+    setTypeAnnotation(Tok, Ty);
+    Tok.setAnnotationEndLoc(Tok.getLocation());
+    Tok.setLocation(BeginLoc);
+    PP.AnnotateCachedTokens(Tok);
+    return ANK_Success;
+  }
+
+  case Sema::NC_ContextIndependentExpr:
+    Tok.setKind(tok::annot_primary_expr);
+    setExprAnnotation(Tok, Classification.getExpression());
+    Tok.setAnnotationEndLoc(NameLoc);
+    if (SS.isNotEmpty())
+      Tok.setLocation(SS.getBeginLoc());
+    PP.AnnotateCachedTokens(Tok);
+    return ANK_Success;
+
+  case Sema::NC_NonType:
+    Tok.setKind(tok::annot_non_type);
+    setNonTypeAnnotation(Tok, Classification.getNonTypeDecl());
+    Tok.setLocation(NameLoc);
+    Tok.setAnnotationEndLoc(NameLoc);
+    PP.AnnotateCachedTokens(Tok);
+    if (SS.isNotEmpty())
+      AnnotateScopeToken(SS, !WasScopeAnnotation);
+    return ANK_Success;
+
+  case Sema::NC_UndeclaredNonType:
+  case Sema::NC_DependentNonType:
+    Tok.setKind(Classification.getKind() == Sema::NC_UndeclaredNonType
+                    ? tok::annot_non_type_undeclared
+                    : tok::annot_non_type_dependent);
+    setIdentifierAnnotation(Tok, Name);
+    Tok.setLocation(NameLoc);
+    Tok.setAnnotationEndLoc(NameLoc);
+    PP.AnnotateCachedTokens(Tok);
+    if (SS.isNotEmpty())
+      AnnotateScopeToken(SS, !WasScopeAnnotation);
+    return ANK_Success;
+
+  case Sema::NC_TypeTemplate:
+    if (Next.isNot(tok::less)) {
+      // This may be a type template being used as a template template argument.
+      if (SS.isNotEmpty())
+        AnnotateScopeToken(SS, !WasScopeAnnotation);
+      return ANK_TemplateName;
+    }
+    LLVM_FALLTHROUGH;
+  case Sema::NC_VarTemplate:
+  case Sema::NC_FunctionTemplate:
+  case Sema::NC_UndeclaredTemplate: {
+    // We have a type, variable or function template followed by '<'.
+    ConsumeToken();
+    UnqualifiedId Id;
+    Id.setIdentifier(Name, NameLoc);
+    if (AnnotateTemplateIdToken(
+            TemplateTy::make(Classification.getTemplateName()),
+            Classification.getTemplateNameKind(), SS, SourceLocation(), Id))
+      return ANK_Error;
+    return ANK_Success;
+  }
+  case Sema::NC_Concept: {
+    UnqualifiedId Id;
+    Id.setIdentifier(Name, NameLoc);
+    if (Next.is(tok::less))
+      // We have a concept name followed by '<'. Consume the identifier token so
+      // we reach the '<' and annotate it.
+      ConsumeToken();
+    if (AnnotateTemplateIdToken(
+            TemplateTy::make(Classification.getTemplateName()),
+            Classification.getTemplateNameKind(), SS, SourceLocation(), Id,
+            /*AllowTypeAnnotation=*/false, /*TypeConstraint=*/true))
+      return ANK_Error;
+    return ANK_Success;
+  }
+  }
+
+  // Unable to classify the name, but maybe we can annotate a scope specifier.
+  if (SS.isNotEmpty())
+    AnnotateScopeToken(SS, !WasScopeAnnotation);
+  return ANK_Unresolved;
+}
+
+bool Parser::TryKeywordIdentFallback(bool DisableKeyword) {
+  assert(Tok.isNot(tok::identifier));
+  Diag(Tok, diag::ext_keyword_as_ident)
+    << PP.getSpelling(Tok)
+    << DisableKeyword;
+  if (DisableKeyword)
+    Tok.getIdentifierInfo()->revertTokenIDToIdentifier();
+  Tok.setKind(tok::identifier);
+  return true;
+}
+
+/// TryAnnotateTypeOrScopeToken - If the current token position is on a
+/// typename (possibly qualified in C++) or a C++ scope specifier not followed
+/// by a typename, TryAnnotateTypeOrScopeToken will replace one or more tokens
+/// with a single annotation token representing the typename or C++ scope
+/// respectively.
+/// This simplifies handling of C++ scope specifiers and allows efficient
+/// backtracking without the need to re-parse and resolve nested-names and
+/// typenames.
+/// It will mainly be called when we expect to treat identifiers as typenames
+/// (if they are typenames). For example, in C we do not expect identifiers
+/// inside expressions to be treated as typenames so it will not be called
+/// for expressions in C.
+/// The benefit for C/ObjC is that a typename will be annotated and
+/// Actions.getTypeName will not be needed to be called again (e.g. getTypeName
+/// will not be called twice, once to check whether we have a declaration
+/// specifier, and another one to get the actual type inside
+/// ParseDeclarationSpecifiers).
+///
+/// This returns true if an error occurred.
+///
+/// Note that this routine emits an error if you call it with ::new or ::delete
+/// as the current tokens, so only call it in contexts where these are invalid.
+bool Parser::TryAnnotateTypeOrScopeToken() {
+  assert((Tok.is(tok::identifier) || Tok.is(tok::coloncolon) ||
+          Tok.is(tok::kw_typename) || Tok.is(tok::annot_cxxscope) ||
+          Tok.is(tok::kw_decltype) || Tok.is(tok::annot_template_id) ||
+          Tok.is(tok::kw___super)) &&
+         "Cannot be a type or scope token!");
+
+  if (Tok.is(tok::kw_typename)) {
+    // MSVC lets you do stuff like:
+    //   typename typedef T_::D D;
+    //
+    // We will consume the typedef token here and put it back after we have
+    // parsed the first identifier, transforming it into something more like:
+    //   typename T_::D typedef D;
+    if (getLangOpts().MSVCCompat && NextToken().is(tok::kw_typedef)) {
+      Token TypedefToken;
+      PP.Lex(TypedefToken);
+      bool Result = TryAnnotateTypeOrScopeToken();
+      PP.EnterToken(Tok, /*IsReinject=*/true);
+      Tok = TypedefToken;
+      if (!Result)
+        Diag(Tok.getLocation(), diag::warn_expected_qualified_after_typename);
+      return Result;
+    }
+
+    // Parse a C++ typename-specifier, e.g., "typename T::type".
+    //
+    //   typename-specifier:
+    //     'typename' '::' [opt] nested-name-specifier identifier
+    //     'typename' '::' [opt] nested-name-specifier template [opt]
+    //            simple-template-id
+    SourceLocation TypenameLoc = ConsumeToken();
+    CXXScopeSpec SS;
+    if (ParseOptionalCXXScopeSpecifier(SS, /*ObjectType=*/nullptr,
+                                       /*EnteringContext=*/false, nullptr,
+                                       /*IsTypename*/ true))
+      return true;
+    if (SS.isEmpty()) {
+      if (Tok.is(tok::identifier) || Tok.is(tok::annot_template_id) ||
+          Tok.is(tok::annot_decltype)) {
+        // Attempt to recover by skipping the invalid 'typename'
+        if (Tok.is(tok::annot_decltype) ||
+            (!TryAnnotateTypeOrScopeToken() && Tok.isAnnotation())) {
+          unsigned DiagID = diag::err_expected_qualified_after_typename;
+          // MS compatibility: MSVC permits using known types with typename.
+          // e.g. "typedef typename T* pointer_type"
+          if (getLangOpts().MicrosoftExt)
+            DiagID = diag::warn_expected_qualified_after_typename;
+          Diag(Tok.getLocation(), DiagID);
+          return false;
+        }
+      }
+      if (Tok.isEditorPlaceholder())
+        return true;
+
+      Diag(Tok.getLocation(), diag::err_expected_qualified_after_typename);
+      return true;
+    }
+
+    TypeResult Ty;
+    if (Tok.is(tok::identifier)) {
+      // FIXME: check whether the next token is '<', first!
+      Ty = Actions.ActOnTypenameType(getCurScope(), TypenameLoc, SS,
+                                     *Tok.getIdentifierInfo(),
+                                     Tok.getLocation());
+    } else if (Tok.is(tok::annot_template_id)) {
+      TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
+      if (TemplateId->Kind != TNK_Type_template &&
+          TemplateId->Kind != TNK_Dependent_template_name &&
+          TemplateId->Kind != TNK_Undeclared_template) {
+        Diag(Tok, diag::err_typename_refers_to_non_type_template)
+          << Tok.getAnnotationRange();
+        return true;
+      }
+
+      ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
+                                         TemplateId->NumArgs);
+
+      Ty = Actions.ActOnTypenameType(getCurScope(), TypenameLoc, SS,
+                                     TemplateId->TemplateKWLoc,
+                                     TemplateId->Template,
+                                     TemplateId->Name,
+                                     TemplateId->TemplateNameLoc,
+                                     TemplateId->LAngleLoc,
+                                     TemplateArgsPtr,
+                                     TemplateId->RAngleLoc);
+    } else {
+      Diag(Tok, diag::err_expected_type_name_after_typename)
+        << SS.getRange();
+      return true;
+    }
+
+    SourceLocation EndLoc = Tok.getLastLoc();
+    Tok.setKind(tok::annot_typename);
+    setTypeAnnotation(Tok, Ty.isInvalid() ? nullptr : Ty.get());
+    Tok.setAnnotationEndLoc(EndLoc);
+    Tok.setLocation(TypenameLoc);
+    PP.AnnotateCachedTokens(Tok);
+    return false;
+  }
+
+  // Remembers whether the token was originally a scope annotation.
+  bool WasScopeAnnotation = Tok.is(tok::annot_cxxscope);
+
+  CXXScopeSpec SS;
+  if (getLangOpts().CPlusPlus)
+    if (ParseOptionalCXXScopeSpecifier(SS, nullptr, /*EnteringContext*/false))
+      return true;
+
+  return TryAnnotateTypeOrScopeTokenAfterScopeSpec(SS, !WasScopeAnnotation);
+}
+
+/// Try to annotate a type or scope token, having already parsed an
+/// optional scope specifier. \p IsNewScope should be \c true unless the scope
+/// specifier was extracted from an existing tok::annot_cxxscope annotation.
+bool Parser::TryAnnotateTypeOrScopeTokenAfterScopeSpec(CXXScopeSpec &SS,
+                                                       bool IsNewScope) {
+  if (Tok.is(tok::identifier)) {
+    // Determine whether the identifier is a type name.
+    if (ParsedType Ty = Actions.getTypeName(
+            *Tok.getIdentifierInfo(), Tok.getLocation(), getCurScope(), &SS,
+            false, NextToken().is(tok::period), nullptr,
+            /*IsCtorOrDtorName=*/false,
+            /*NonTrivialTypeSourceInfo*/true,
+            /*IsClassTemplateDeductionContext*/true)) {
+      SourceLocation BeginLoc = Tok.getLocation();
+      if (SS.isNotEmpty()) // it was a C++ qualified type name.
+        BeginLoc = SS.getBeginLoc();
+
+      /// An Objective-C object type followed by '<' is a specialization of
+      /// a parameterized class type or a protocol-qualified type.
+      if (getLangOpts().ObjC && NextToken().is(tok::less) &&
+          (Ty.get()->isObjCObjectType() ||
+           Ty.get()->isObjCObjectPointerType())) {
+        // Consume the name.
+        SourceLocation IdentifierLoc = ConsumeToken();
+        SourceLocation NewEndLoc;
+        TypeResult NewType
+          = parseObjCTypeArgsAndProtocolQualifiers(IdentifierLoc, Ty,
+                                                   /*consumeLastToken=*/false,
+                                                   NewEndLoc);
+        if (NewType.isUsable())
+          Ty = NewType.get();
+        else if (Tok.is(tok::eof)) // Nothing to do here, bail out...
+          return false;
+      }
+
+      // This is a typename. Replace the current token in-place with an
+      // annotation type token.
+      Tok.setKind(tok::annot_typename);
+      setTypeAnnotation(Tok, Ty);
+      Tok.setAnnotationEndLoc(Tok.getLocation());
+      Tok.setLocation(BeginLoc);
+
+      // In case the tokens were cached, have Preprocessor replace
+      // them with the annotation token.
+      PP.AnnotateCachedTokens(Tok);
+      return false;
+    }
+
+    if (!getLangOpts().CPlusPlus) {
+      // If we're in C, we can't have :: tokens at all (the lexer won't return
+      // them).  If the identifier is not a type, then it can't be scope either,
+      // just early exit.
+      return false;
+    }
+
+    // If this is a template-id, annotate with a template-id or type token.
+    // FIXME: This appears to be dead code. We already have formed template-id
+    // tokens when parsing the scope specifier; this can never form a new one.
+    if (NextToken().is(tok::less)) {
+      TemplateTy Template;
+      UnqualifiedId TemplateName;
+      TemplateName.setIdentifier(Tok.getIdentifierInfo(), Tok.getLocation());
+      bool MemberOfUnknownSpecialization;
+      if (TemplateNameKind TNK = Actions.isTemplateName(
+              getCurScope(), SS,
+              /*hasTemplateKeyword=*/false, TemplateName,
+              /*ObjectType=*/nullptr, /*EnteringContext*/false, Template,
+              MemberOfUnknownSpecialization)) {
+        // Only annotate an undeclared template name as a template-id if the
+        // following tokens have the form of a template argument list.
+        if (TNK != TNK_Undeclared_template ||
+            isTemplateArgumentList(1) != TPResult::False) {
+          // Consume the identifier.
+          ConsumeToken();
+          if (AnnotateTemplateIdToken(Template, TNK, SS, SourceLocation(),
+                                      TemplateName)) {
+            // If an unrecoverable error occurred, we need to return true here,
+            // because the token stream is in a damaged state.  We may not
+            // return a valid identifier.
+            return true;
+          }
+        }
+      }
+    }
+
+    // The current token, which is either an identifier or a
+    // template-id, is not part of the annotation. Fall through to
+    // push that token back into the stream and complete the C++ scope
+    // specifier annotation.
+  }
+
+  if (Tok.is(tok::annot_template_id)) {
+    TemplateIdAnnotation *TemplateId = takeTemplateIdAnnotation(Tok);
+    if (TemplateId->Kind == TNK_Type_template) {
+      // A template-id that refers to a type was parsed into a
+      // template-id annotation in a context where we weren't allowed
+      // to produce a type annotation token. Update the template-id
+      // annotation token to a type annotation token now.
+      AnnotateTemplateIdTokenAsType(SS);
+      return false;
+    }
+  }
+
+  if (SS.isEmpty())
+    return false;
+
+  // A C++ scope specifier that isn't followed by a typename.
+  AnnotateScopeToken(SS, IsNewScope);
+  return false;
+}
+
+/// TryAnnotateScopeToken - Like TryAnnotateTypeOrScopeToken but only
+/// annotates C++ scope specifiers and template-ids.  This returns
+/// true if there was an error that could not be recovered from.
+///
+/// Note that this routine emits an error if you call it with ::new or ::delete
+/// as the current tokens, so only call it in contexts where these are invalid.
+bool Parser::TryAnnotateCXXScopeToken(bool EnteringContext) {
+  assert(getLangOpts().CPlusPlus &&
+         "Call sites of this function should be guarded by checking for C++");
+  assert(MightBeCXXScopeToken() && "Cannot be a type or scope token!");
+
+  CXXScopeSpec SS;
+  if (ParseOptionalCXXScopeSpecifier(SS, nullptr, EnteringContext))
+    return true;
+  if (SS.isEmpty())
+    return false;
+
+  AnnotateScopeToken(SS, true);
+  return false;
+}
+
+bool Parser::isTokenEqualOrEqualTypo() {
+  tok::TokenKind Kind = Tok.getKind();
+  switch (Kind) {
+  default:
+    return false;
+  case tok::ampequal:            // &=
+  case tok::starequal:           // *=
+  case tok::plusequal:           // +=
+  case tok::minusequal:          // -=
+  case tok::exclaimequal:        // !=
+  case tok::slashequal:          // /=
+  case tok::percentequal:        // %=
+  case tok::lessequal:           // <=
+  case tok::lesslessequal:       // <<=
+  case tok::greaterequal:        // >=
+  case tok::greatergreaterequal: // >>=
+  case tok::caretequal:          // ^=
+  case tok::pipeequal:           // |=
+  case tok::equalequal:          // ==
+    Diag(Tok, diag::err_invalid_token_after_declarator_suggest_equal)
+        << Kind
+        << FixItHint::CreateReplacement(SourceRange(Tok.getLocation()), "=");
+    LLVM_FALLTHROUGH;
+  case tok::equal:
+    return true;
+  }
+}
+
+SourceLocation Parser::handleUnexpectedCodeCompletionToken() {
+  assert(Tok.is(tok::code_completion));
+  PrevTokLocation = Tok.getLocation();
+
+  for (Scope *S = getCurScope(); S; S = S->getParent()) {
+    if (S->getFlags() & Scope::FnScope) {
+      Actions.CodeCompleteOrdinaryName(getCurScope(),
+                                       Sema::PCC_RecoveryInFunction);
+      cutOffParsing();
+      return PrevTokLocation;
+    }
+
+    if (S->getFlags() & Scope::ClassScope) {
+      Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Class);
+      cutOffParsing();
+      return PrevTokLocation;
+    }
+  }
+
+  Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Namespace);
+  cutOffParsing();
+  return PrevTokLocation;
+}
+
+// Code-completion pass-through functions
+
+void Parser::CodeCompleteDirective(bool InConditional) {
+  Actions.CodeCompletePreprocessorDirective(InConditional);
+}
+
+void Parser::CodeCompleteInConditionalExclusion() {
+  Actions.CodeCompleteInPreprocessorConditionalExclusion(getCurScope());
+}
+
+void Parser::CodeCompleteMacroName(bool IsDefinition) {
+  Actions.CodeCompletePreprocessorMacroName(IsDefinition);
+}
+
+void Parser::CodeCompletePreprocessorExpression() {
+  Actions.CodeCompletePreprocessorExpression();
+}
+
+void Parser::CodeCompleteMacroArgument(IdentifierInfo *Macro,
+                                       MacroInfo *MacroInfo,
+                                       unsigned ArgumentIndex) {
+  Actions.CodeCompletePreprocessorMacroArgument(getCurScope(), Macro, MacroInfo,
+                                                ArgumentIndex);
+}
+
+void Parser::CodeCompleteIncludedFile(llvm::StringRef Dir, bool IsAngled) {
+  Actions.CodeCompleteIncludedFile(Dir, IsAngled);
+}
+
+void Parser::CodeCompleteNaturalLanguage() {
+  Actions.CodeCompleteNaturalLanguage();
+}
+
+bool Parser::ParseMicrosoftIfExistsCondition(IfExistsCondition& Result) {
+  assert((Tok.is(tok::kw___if_exists) || Tok.is(tok::kw___if_not_exists)) &&
+         "Expected '__if_exists' or '__if_not_exists'");
+  Result.IsIfExists = Tok.is(tok::kw___if_exists);
+  Result.KeywordLoc = ConsumeToken();
+
+  BalancedDelimiterTracker T(*this, tok::l_paren);
+  if (T.consumeOpen()) {
+    Diag(Tok, diag::err_expected_lparen_after)
+      << (Result.IsIfExists? "__if_exists" : "__if_not_exists");
+    return true;
+  }
+
+  // Parse nested-name-specifier.
+  if (getLangOpts().CPlusPlus)
+    ParseOptionalCXXScopeSpecifier(Result.SS, nullptr,
+                                   /*EnteringContext=*/false);
+
+  // Check nested-name specifier.
+  if (Result.SS.isInvalid()) {
+    T.skipToEnd();
+    return true;
+  }
+
+  // Parse the unqualified-id.
+  SourceLocation TemplateKWLoc; // FIXME: parsed, but unused.
+  if (ParseUnqualifiedId(
+          Result.SS, /*EnteringContext*/false, /*AllowDestructorName*/true,
+          /*AllowConstructorName*/true, /*AllowDeductionGuide*/false, nullptr,
+          &TemplateKWLoc, Result.Name)) {
+    T.skipToEnd();
+    return true;
+  }
+
+  if (T.consumeClose())
+    return true;
+
+  // Check if the symbol exists.
+  switch (Actions.CheckMicrosoftIfExistsSymbol(getCurScope(), Result.KeywordLoc,
+                                               Result.IsIfExists, Result.SS,
+                                               Result.Name)) {
+  case Sema::IER_Exists:
+    Result.Behavior = Result.IsIfExists ? IEB_Parse : IEB_Skip;
+    break;
+
+  case Sema::IER_DoesNotExist:
+    Result.Behavior = !Result.IsIfExists ? IEB_Parse : IEB_Skip;
+    break;
+
+  case Sema::IER_Dependent:
+    Result.Behavior = IEB_Dependent;
+    break;
+
+  case Sema::IER_Error:
+    return true;
+  }
+
+  return false;
+}
+
+void Parser::ParseMicrosoftIfExistsExternalDeclaration() {
+  IfExistsCondition Result;
+  if (ParseMicrosoftIfExistsCondition(Result))
+    return;
+
+  BalancedDelimiterTracker Braces(*this, tok::l_brace);
+  if (Braces.consumeOpen()) {
+    Diag(Tok, diag::err_expected) << tok::l_brace;
+    return;
+  }
+
+  switch (Result.Behavior) {
+  case IEB_Parse:
+    // Parse declarations below.
+    break;
+
+  case IEB_Dependent:
+    llvm_unreachable("Cannot have a dependent external declaration");
+
+  case IEB_Skip:
+    Braces.skipToEnd();
+    return;
+  }
+
+  // Parse the declarations.
+  // FIXME: Support module import within __if_exists?
+  while (Tok.isNot(tok::r_brace) && !isEofOrEom()) {
+    ParsedAttributesWithRange attrs(AttrFactory);
+    MaybeParseCXX11Attributes(attrs);
+    DeclGroupPtrTy Result = ParseExternalDeclaration(attrs);
+    if (Result && !getCurScope()->getParent())
+      Actions.getASTConsumer().HandleTopLevelDecl(Result.get());
+  }
+  Braces.consumeClose();
+}
+
+/// Parse a declaration beginning with the 'module' keyword or C++20
+/// context-sensitive keyword (optionally preceded by 'export').
+///
+///   module-declaration:   [Modules TS + P0629R0]
+///     'export'[opt] 'module' module-name attribute-specifier-seq[opt] ';'
+///
+///   global-module-fragment:  [C++2a]
+///     'module' ';' top-level-declaration-seq[opt]
+///   module-declaration:      [C++2a]
+///     'export'[opt] 'module' module-name module-partition[opt]
+///            attribute-specifier-seq[opt] ';'
+///   private-module-fragment: [C++2a]
+///     'module' ':' 'private' ';' top-level-declaration-seq[opt]
+Parser::DeclGroupPtrTy Parser::ParseModuleDecl(bool IsFirstDecl) {
+  SourceLocation StartLoc = Tok.getLocation();
+
+  Sema::ModuleDeclKind MDK = TryConsumeToken(tok::kw_export)
+                                 ? Sema::ModuleDeclKind::Interface
+                                 : Sema::ModuleDeclKind::Implementation;
+
+  assert(
+      (Tok.is(tok::kw_module) ||
+       (Tok.is(tok::identifier) && Tok.getIdentifierInfo() == Ident_module)) &&
+      "not a module declaration");
+  SourceLocation ModuleLoc = ConsumeToken();
+
+  // Attributes appear after the module name, not before.
+  // FIXME: Suggest moving the attributes later with a fixit.
+  DiagnoseAndSkipCXX11Attributes();
+
+  // Parse a global-module-fragment, if present.
+  if (getLangOpts().CPlusPlusModules && Tok.is(tok::semi)) {
+    SourceLocation SemiLoc = ConsumeToken();
+    if (!IsFirstDecl) {
+      Diag(StartLoc, diag::err_global_module_introducer_not_at_start)
+        << SourceRange(StartLoc, SemiLoc);
+      return nullptr;
+    }
+    if (MDK == Sema::ModuleDeclKind::Interface) {
+      Diag(StartLoc, diag::err_module_fragment_exported)
+        << /*global*/0 << FixItHint::CreateRemoval(StartLoc);
+    }
+    return Actions.ActOnGlobalModuleFragmentDecl(ModuleLoc);
+  }
+
+  // Parse a private-module-fragment, if present.
+  if (getLangOpts().CPlusPlusModules && Tok.is(tok::colon) &&
+      NextToken().is(tok::kw_private)) {
+    if (MDK == Sema::ModuleDeclKind::Interface) {
+      Diag(StartLoc, diag::err_module_fragment_exported)
+        << /*private*/1 << FixItHint::CreateRemoval(StartLoc);
+    }
+    ConsumeToken();
+    SourceLocation PrivateLoc = ConsumeToken();
+    DiagnoseAndSkipCXX11Attributes();
+    ExpectAndConsumeSemi(diag::err_private_module_fragment_expected_semi);
+    return Actions.ActOnPrivateModuleFragmentDecl(ModuleLoc, PrivateLoc);
+  }
+
+  SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 2> Path;
+  if (ParseModuleName(ModuleLoc, Path, /*IsImport*/false))
+    return nullptr;
+
+  // Parse the optional module-partition.
+  if (Tok.is(tok::colon)) {
+    SourceLocation ColonLoc = ConsumeToken();
+    SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 2> Partition;
+    if (ParseModuleName(ModuleLoc, Partition, /*IsImport*/false))
+      return nullptr;
+
+    // FIXME: Support module partition declarations.
+    Diag(ColonLoc, diag::err_unsupported_module_partition)
+      << SourceRange(ColonLoc, Partition.back().second);
+    // Recover by parsing as a non-partition.
+  }
+
+  // We don't support any module attributes yet; just parse them and diagnose.
+  ParsedAttributesWithRange Attrs(AttrFactory);
+  MaybeParseCXX11Attributes(Attrs);
+  ProhibitCXX11Attributes(Attrs, diag::err_attribute_not_module_attr);
+
+  ExpectAndConsumeSemi(diag::err_module_expected_semi);
+
+  return Actions.ActOnModuleDecl(StartLoc, ModuleLoc, MDK, Path, IsFirstDecl);
+}
+
+/// Parse a module import declaration. This is essentially the same for
+/// Objective-C and the C++ Modules TS, except for the leading '@' (in ObjC)
+/// and the trailing optional attributes (in C++).
+///
+/// [ObjC]  @import declaration:
+///           '@' 'import' module-name ';'
+/// [ModTS] module-import-declaration:
+///           'import' module-name attribute-specifier-seq[opt] ';'
+/// [C++2a] module-import-declaration:
+///           'export'[opt] 'import' module-name
+///                   attribute-specifier-seq[opt] ';'
+///           'export'[opt] 'import' module-partition
+///                   attribute-specifier-seq[opt] ';'
+///           'export'[opt] 'import' header-name
+///                   attribute-specifier-seq[opt] ';'
+Decl *Parser::ParseModuleImport(SourceLocation AtLoc) {
+  SourceLocation StartLoc = AtLoc.isInvalid() ? Tok.getLocation() : AtLoc;
+
+  SourceLocation ExportLoc;
+  TryConsumeToken(tok::kw_export, ExportLoc);
+
+  assert((AtLoc.isInvalid() ? Tok.isOneOf(tok::kw_import, tok::identifier)
+                            : Tok.isObjCAtKeyword(tok::objc_import)) &&
+         "Improper start to module import");
+  bool IsObjCAtImport = Tok.isObjCAtKeyword(tok::objc_import);
+  SourceLocation ImportLoc = ConsumeToken();
+
+  SmallVector<std::pair<IdentifierInfo *, SourceLocation>, 2> Path;
+  Module *HeaderUnit = nullptr;
+
+  if (Tok.is(tok::header_name)) {
+    // This is a header import that the preprocessor decided we should skip
+    // because it was malformed in some way. Parse and ignore it; it's already
+    // been diagnosed.
+    ConsumeToken();
+  } else if (Tok.is(tok::annot_header_unit)) {
+    // This is a header import that the preprocessor mapped to a module import.
+    HeaderUnit = reinterpret_cast<Module *>(Tok.getAnnotationValue());
+    ConsumeAnnotationToken();
+  } else if (getLangOpts().CPlusPlusModules && Tok.is(tok::colon)) {
+    SourceLocation ColonLoc = ConsumeToken();
+    if (ParseModuleName(ImportLoc, Path, /*IsImport*/true))
+      return nullptr;
+
+    // FIXME: Support module partition import.
+    Diag(ColonLoc, diag::err_unsupported_module_partition)
+      << SourceRange(ColonLoc, Path.back().second);
+    return nullptr;
+  } else {
+    if (ParseModuleName(ImportLoc, Path, /*IsImport*/true))
+      return nullptr;
+  }
+
+  ParsedAttributesWithRange Attrs(AttrFactory);
+  MaybeParseCXX11Attributes(Attrs);
+  // We don't support any module import attributes yet.
+  ProhibitCXX11Attributes(Attrs, diag::err_attribute_not_import_attr);
+
+  if (PP.hadModuleLoaderFatalFailure()) {
+    // With a fatal failure in the module loader, we abort parsing.
+    cutOffParsing();
+    return nullptr;
+  }
+
+  DeclResult Import;
+  if (HeaderUnit)
+    Import =
+        Actions.ActOnModuleImport(StartLoc, ExportLoc, ImportLoc, HeaderUnit);
+  else if (!Path.empty())
+    Import = Actions.ActOnModuleImport(StartLoc, ExportLoc, ImportLoc, Path);
+  ExpectAndConsumeSemi(diag::err_module_expected_semi);
+  if (Import.isInvalid())
+    return nullptr;
+
+  // Using '@import' in framework headers requires modules to be enabled so that
+  // the header is parseable. Emit a warning to make the user aware.
+  if (IsObjCAtImport && AtLoc.isValid()) {
+    auto &SrcMgr = PP.getSourceManager();
+    auto *FE = SrcMgr.getFileEntryForID(SrcMgr.getFileID(AtLoc));
+    if (FE && llvm::sys::path::parent_path(FE->getDir()->getName())
+                  .endswith(".framework"))
+      Diags.Report(AtLoc, diag::warn_atimport_in_framework_header);
+  }
+
+  return Import.get();
+}
+
+/// Parse a C++ Modules TS / Objective-C module name (both forms use the same
+/// grammar).
+///
+///         module-name:
+///           module-name-qualifier[opt] identifier
+///         module-name-qualifier:
+///           module-name-qualifier[opt] identifier '.'
+bool Parser::ParseModuleName(
+    SourceLocation UseLoc,
+    SmallVectorImpl<std::pair<IdentifierInfo *, SourceLocation>> &Path,
+    bool IsImport) {
+  // Parse the module path.
+  while (true) {
+    if (!Tok.is(tok::identifier)) {
+      if (Tok.is(tok::code_completion)) {
+        Actions.CodeCompleteModuleImport(UseLoc, Path);
+        cutOffParsing();
+        return true;
+      }
+
+      Diag(Tok, diag::err_module_expected_ident) << IsImport;
+      SkipUntil(tok::semi);
+      return true;
+    }
+
+    // Record this part of the module path.
+    Path.push_back(std::make_pair(Tok.getIdentifierInfo(), Tok.getLocation()));
+    ConsumeToken();
+
+    if (Tok.isNot(tok::period))
+      return false;
+
+    ConsumeToken();
+  }
+}
+
+/// Try recover parser when module annotation appears where it must not
+/// be found.
+/// \returns false if the recover was successful and parsing may be continued, or
+/// true if parser must bail out to top level and handle the token there.
+bool Parser::parseMisplacedModuleImport() {
+  while (true) {
+    switch (Tok.getKind()) {
+    case tok::annot_module_end:
+      // If we recovered from a misplaced module begin, we expect to hit a
+      // misplaced module end too. Stay in the current context when this
+      // happens.
+      if (MisplacedModuleBeginCount) {
+        --MisplacedModuleBeginCount;
+        Actions.ActOnModuleEnd(Tok.getLocation(),
+                               reinterpret_cast<Module *>(
+                                   Tok.getAnnotationValue()));
+        ConsumeAnnotationToken();
+        continue;
+      }
+      // Inform caller that recovery failed, the error must be handled at upper
+      // level. This will generate the desired "missing '}' at end of module"
+      // diagnostics on the way out.
+      return true;
+    case tok::annot_module_begin:
+      // Recover by entering the module (Sema will diagnose).
+      Actions.ActOnModuleBegin(Tok.getLocation(),
+                               reinterpret_cast<Module *>(
+                                   Tok.getAnnotationValue()));
+      ConsumeAnnotationToken();
+      ++MisplacedModuleBeginCount;
+      continue;
+    case tok::annot_module_include:
+      // Module import found where it should not be, for instance, inside a
+      // namespace. Recover by importing the module.
+      Actions.ActOnModuleInclude(Tok.getLocation(),
+                                 reinterpret_cast<Module *>(
+                                     Tok.getAnnotationValue()));
+      ConsumeAnnotationToken();
+      // If there is another module import, process it.
+      continue;
+    default:
+      return false;
+    }
+  }
+  return false;
+}
+
+bool BalancedDelimiterTracker::diagnoseOverflow() {
+  P.Diag(P.Tok, diag::err_bracket_depth_exceeded)
+    << P.getLangOpts().BracketDepth;
+  P.Diag(P.Tok, diag::note_bracket_depth);
+  P.cutOffParsing();
+  return true;
+}
+
+bool BalancedDelimiterTracker::expectAndConsume(unsigned DiagID,
+                                                const char *Msg,
+                                                tok::TokenKind SkipToTok) {
+  LOpen = P.Tok.getLocation();
+  if (P.ExpectAndConsume(Kind, DiagID, Msg)) {
+    if (SkipToTok != tok::unknown)
+      P.SkipUntil(SkipToTok, Parser::StopAtSemi);
+    return true;
+  }
+
+  if (getDepth() < P.getLangOpts().BracketDepth)
+    return false;
+
+  return diagnoseOverflow();
+}
+
+bool BalancedDelimiterTracker::diagnoseMissingClose() {
+  assert(!P.Tok.is(Close) && "Should have consumed closing delimiter");
+
+  if (P.Tok.is(tok::annot_module_end))
+    P.Diag(P.Tok, diag::err_missing_before_module_end) << Close;
+  else
+    P.Diag(P.Tok, diag::err_expected) << Close;
+  P.Diag(LOpen, diag::note_matching) << Kind;
+
+  // If we're not already at some kind of closing bracket, skip to our closing
+  // token.
+  if (P.Tok.isNot(tok::r_paren) && P.Tok.isNot(tok::r_brace) &&
+      P.Tok.isNot(tok::r_square) &&
+      P.SkipUntil(Close, FinalToken,
+                  Parser::StopAtSemi | Parser::StopBeforeMatch) &&
+      P.Tok.is(Close))
+    LClose = P.ConsumeAnyToken();
+  return true;
+}
+
+void BalancedDelimiterTracker::skipToEnd() {
+  P.SkipUntil(Close, Parser::StopBeforeMatch);
+  consumeClose();
+}