lib/IDE/CodeCompletion.cpp - third_party/swift - Git at Google

 //===--- CodeCompletion.cpp - Code completion implementation --------------===//
 //
 // This source file is part of the Swift.org open source project
 //
 // Copyright (c) 2014 - 2018 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//

 #include "swift/IDE/CodeCompletion.h"
 #include "CodeCompletionResultBuilder.h"
 #include "ExprContextAnalysis.h"
 #include "swift/AST/ASTPrinter.h"
 #include "swift/AST/ASTWalker.h"
 #include "swift/AST/Comment.h"
 #include "swift/AST/ImportCache.h"
 #include "swift/AST/Initializer.h"
 #include "swift/AST/GenericSignature.h"
 #include "swift/AST/LazyResolver.h"
 #include "swift/AST/NameLookup.h"
 #include "swift/AST/ParameterList.h"
 #include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/SourceFile.h"
 #include "swift/AST/SubstitutionMap.h"
 #include "swift/AST/USRGeneration.h"
 #include "swift/Basic/Defer.h"
 #include "swift/Basic/LLVM.h"
 #include "swift/ClangImporter/ClangImporter.h"
 #include "swift/ClangImporter/ClangModule.h"
 #include "swift/IDE/CodeCompletionCache.h"
 #include "swift/IDE/Utils.h"
 #include "swift/Parse/CodeCompletionCallbacks.h"
 #include "swift/Sema/IDETypeChecking.h"
 #include "swift/Syntax/SyntaxKind.h"
 #include "swift/Strings.h"
 #include "swift/Subsystems.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Attr.h"
 #include "clang/AST/Comment.h"
 #include "clang/AST/CommentVisitor.h"
 #include "clang/AST/Decl.h"
 #include "clang/Basic/Module.h"
 #include "clang/Index/USRGeneration.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/SaveAndRestore.h"
 #include <algorithm>
 #include <string>

 using namespace swift;
 using namespace ide;

 using CommandWordsPairs = std::vector<std::pair<StringRef, StringRef>>;

 enum CodeCompletionCommandKind {
   none,
   keyword,
   recommended,
   recommendedover,
   mutatingvariant,
   nonmutatingvariant,
 };

 CodeCompletionCommandKind getCommandKind(StringRef Command) {
 #define CHECK_CASE(KIND)                                                      \
   if (Command == #KIND)                                                       \
     return CodeCompletionCommandKind::KIND;
   CHECK_CASE(keyword);
   CHECK_CASE(recommended);
   CHECK_CASE(recommendedover);
   CHECK_CASE(mutatingvariant);
   CHECK_CASE(nonmutatingvariant);
 #undef CHECK_CASE
   return CodeCompletionCommandKind::none;
 }

 StringRef getCommandName(CodeCompletionCommandKind Kind) {
 #define CHECK_CASE(KIND)                                                    \
   if (CodeCompletionCommandKind::KIND == Kind) {                            \
     static std::string Name(#KIND);                                         \
     return Name;                                                            \
   }
   CHECK_CASE(keyword)
   CHECK_CASE(recommended)
   CHECK_CASE(recommendedover)
   CHECK_CASE(mutatingvariant);
   CHECK_CASE(nonmutatingvariant);
 #undef CHECK_CASE
   llvm_unreachable("Cannot handle this Kind.");
 }

 bool containsInterestedWords(StringRef Content, StringRef Splitter,
                              bool AllowWhitespace) {
   do {
     Content = Content.split(Splitter).second;
     Content = AllowWhitespace ? Content.trim() : Content;
 #define CHECK_CASE(KIND)                                                       \
 if (Content.startswith(#KIND))                                                 \
 return true;
     CHECK_CASE(keyword)
     CHECK_CASE(recommended)
     CHECK_CASE(recommendedover)
     CHECK_CASE(mutatingvariant);
     CHECK_CASE(nonmutatingvariant);
 #undef CHECK_CASE
   } while (!Content.empty());
   return false;
 }

 void splitTextByComma(StringRef Text, std::vector<StringRef>& Subs) {
   do {
     auto Pair = Text.split(',');
     auto Key = Pair.first.trim();
     if (!Key.empty())
       Subs.push_back(Key);
     Text = Pair.second;
   } while (!Text.empty());
 }

 namespace clang {
 namespace comments {
 class WordPairsArrangedViewer {
   ArrayRef<std::pair<StringRef, StringRef>> Content;
   std::vector<StringRef> ViewedText;
   std::vector<StringRef> Words;
   StringRef Key;

   bool isKeyViewed(StringRef K) {
     return std::find(ViewedText.begin(), ViewedText.end(), K) != ViewedText.end();
   }

 public:
   WordPairsArrangedViewer(ArrayRef<std::pair<StringRef, StringRef>> Content):
     Content(Content) {}

   bool hasNext() {
     Words.clear();
     bool Found = false;
     for (auto P : Content) {
       if (!Found && !isKeyViewed(P.first)) {
         Key = P.first;
         Found = true;
       }
       if (Found && P.first == Key)
         Words.push_back(P.second);
     }
     return Found;
   }

   std::pair<StringRef, ArrayRef<StringRef>> next() {
     bool HasNext = hasNext();
     (void) HasNext;
     assert(HasNext && "Have no more data.");
     ViewedText.push_back(Key);
     return std::make_pair(Key, llvm::makeArrayRef(Words));
   }
 };

 class ClangCommentExtractor : public ConstCommentVisitor<ClangCommentExtractor> {
   CommandWordsPairs &Words;
   const CommandTraits &Traits;
   std::vector<const Comment *> Parents;

   void visitChildren(const Comment* C) {
     Parents.push_back(C);
     for (auto It = C->child_begin(); It != C->child_end(); ++ It)
       visit(*It);
     Parents.pop_back();
   }

 public:
   ClangCommentExtractor(CommandWordsPairs &Words,
                         const CommandTraits &Traits) : Words(Words),
                                                        Traits(Traits) {}
 #define CHILD_VISIT(NAME) \
   void visit##NAME(const NAME *C) {\
     visitChildren(C);\
   }
   CHILD_VISIT(FullComment)
   CHILD_VISIT(ParagraphComment)
 #undef CHILD_VISIT

   void visitInlineCommandComment(const InlineCommandComment *C) {
     auto Command = C->getCommandName(Traits);
     auto CommandKind = getCommandKind(Command);
     if (CommandKind == CodeCompletionCommandKind::none)
       return;
     auto &Parent = Parents.back();
     for (auto CIT = std::find(Parent->child_begin(), Parent->child_end(), C) + 1;
          CIT != Parent->child_end(); CIT++) {
       if (auto TC = dyn_cast<TextComment>(*CIT)) {
         auto Text = TC->getText();
         std::vector<StringRef> Subs;
         splitTextByComma(Text, Subs);
         auto Kind = getCommandName(CommandKind);
         for (auto S : Subs)
           Words.push_back(std::make_pair(Kind, S));
       } else
         break;
     }
   }
 };

 void getClangDocKeyword(ClangImporter &Importer, const Decl *D,
                         CommandWordsPairs &Words) {
   ClangCommentExtractor Extractor(Words, Importer.getClangASTContext().
     getCommentCommandTraits());
   if (auto RC = Importer.getClangASTContext().getRawCommentForAnyRedecl(D)) {
     auto RT = RC->getRawText(Importer.getClangASTContext().getSourceManager());
     if (containsInterestedWords(RT, "@", /*AllowWhitespace*/false)) {
       FullComment* Comment = Importer.getClangASTContext().
         getLocalCommentForDeclUncached(D);
       Extractor.visit(Comment);
     }
   }
 }
 } // end namespace comments
 } // end namespace clang

 namespace swift {
 namespace markup {
 class SwiftDocWordExtractor : public MarkupASTWalker {
   CommandWordsPairs &Pairs;
   CodeCompletionCommandKind Kind;
 public:
   SwiftDocWordExtractor(CommandWordsPairs &Pairs) :
     Pairs(Pairs), Kind(CodeCompletionCommandKind::none) {}
   void visitKeywordField(const KeywordField *Field) override {
     Kind = CodeCompletionCommandKind::keyword;
   }
   void visitRecommendedField(const RecommendedField *Field) override {
     Kind = CodeCompletionCommandKind::recommended;
   }
   void visitRecommendedoverField(const RecommendedoverField *Field) override {
     Kind = CodeCompletionCommandKind::recommendedover;
   }
   void visitMutatingvariantField(const MutatingvariantField *Field) override {
     Kind = CodeCompletionCommandKind::mutatingvariant;
   }
   void visitNonmutatingvariantField(const NonmutatingvariantField *Field) override {
     Kind = CodeCompletionCommandKind::nonmutatingvariant;
   }
   void visitText(const Text *Text) override {
     if (Kind == CodeCompletionCommandKind::none)
       return;
     StringRef CommandName = getCommandName(Kind);
     std::vector<StringRef> Subs;
     splitTextByComma(Text->str(), Subs);
     for (auto S : Subs)
       Pairs.push_back(std::make_pair(CommandName, S));
   }
 };

 void getSwiftDocKeyword(const Decl* D, CommandWordsPairs &Words) {
   auto Interested = false;
   for (auto C : D->getRawComment().Comments) {
     if (containsInterestedWords(C.RawText, "-", /*AllowWhitespace*/true)) {
       Interested = true;
       break;
     }
   }
   if (!Interested)
     return;
   static swift::markup::MarkupContext MC;
   auto DC = getSingleDocComment(MC, D);
   if (!DC)
     return;
   SwiftDocWordExtractor Extractor(Words);
   for (auto Part : DC->getBodyNodes()) {
     switch (Part->getKind()) {
       case ASTNodeKind::KeywordField:
       case ASTNodeKind::RecommendedField:
       case ASTNodeKind::RecommendedoverField:
       case ASTNodeKind::MutatingvariantField:
       case ASTNodeKind::NonmutatingvariantField:
         Extractor.walk(Part);
         break;
       default:
         break;
     }
   }
 }
 } // end namespace markup
 } // end namespace swift

 using DeclFilter = std::function<bool(ValueDecl *, DeclVisibilityKind)>;
 static bool DefaultFilter(ValueDecl* VD, DeclVisibilityKind Kind) {
   return true;
 }
 static bool KeyPathFilter(ValueDecl* decl, DeclVisibilityKind) {
   return isa<TypeDecl>(decl) ||
          (isa<VarDecl>(decl) && decl->getDeclContext()->isTypeContext());
 }

 static bool SwiftKeyPathFilter(ValueDecl* decl, DeclVisibilityKind) {
   switch(decl->getKind()){
   case DeclKind::Var:
   case DeclKind::Subscript:
     return true;
   default:
     return false;
   }
 }

 std::string swift::ide::removeCodeCompletionTokens(
     StringRef Input, StringRef TokenName, unsigned *CompletionOffset) {
   assert(TokenName.size() >= 1);

   *CompletionOffset = ~0U;

   std::string CleanFile;
   CleanFile.reserve(Input.size());
   const std::string Token = std::string("#^") + TokenName.str() + "^#";

   for (const char *Ptr = Input.begin(), *End = Input.end();
        Ptr != End; ++Ptr) {
     const char C = *Ptr;
     if (C == '#' && Ptr <= End - Token.size() &&
         StringRef(Ptr, Token.size()) == Token) {
       Ptr += Token.size() - 1;
       *CompletionOffset = CleanFile.size();
       CleanFile += '\0';
       continue;
     }
     if (C == '#' && Ptr <= End - 2 && Ptr[1] == '^') {
       do {
         Ptr++;
       } while (Ptr < End && *Ptr != '#');
       if (Ptr == End)
         break;
       continue;
     }
     CleanFile += C;
   }
   return CleanFile;
 }

 CodeCompletionString::CodeCompletionString(ArrayRef<Chunk> Chunks) {
   std::uninitialized_copy(Chunks.begin(), Chunks.end(),
                           getTrailingObjects<Chunk>());
   NumChunks = Chunks.size();
 }

 CodeCompletionString *CodeCompletionString::create(llvm::BumpPtrAllocator &Allocator,
                                                    ArrayRef<Chunk> Chunks) {
   void *CCSMem = Allocator.Allocate(totalSizeToAlloc<Chunk>(Chunks.size()),
                                     alignof(CodeCompletionString));
   return new (CCSMem) CodeCompletionString(Chunks);
 }

 void CodeCompletionString::print(raw_ostream &OS) const {
   unsigned PrevNestingLevel = 0;
   for (auto C : getChunks()) {
     bool AnnotatedTextChunk = false;
     if (C.getNestingLevel() < PrevNestingLevel) {
       OS << "#}";
     }
     switch (C.getKind()) {
     using ChunkKind = Chunk::ChunkKind;
     case ChunkKind::AccessControlKeyword:
     case ChunkKind::DeclAttrKeyword:
     case ChunkKind::DeclAttrParamKeyword:
     case ChunkKind::OverrideKeyword:
     case ChunkKind::ThrowsKeyword:
     case ChunkKind::RethrowsKeyword:
     case ChunkKind::DeclIntroducer:
     case ChunkKind::Text:
     case ChunkKind::LeftParen:
     case ChunkKind::RightParen:
     case ChunkKind::LeftBracket:
     case ChunkKind::RightBracket:
     case ChunkKind::LeftAngle:
     case ChunkKind::RightAngle:
     case ChunkKind::Dot:
     case ChunkKind::Ellipsis:
     case ChunkKind::Comma:
     case ChunkKind::ExclamationMark:
     case ChunkKind::QuestionMark:
     case ChunkKind::Ampersand:
     case ChunkKind::Equal:
     case ChunkKind::Whitespace:
       AnnotatedTextChunk = C.isAnnotation();
       LLVM_FALLTHROUGH;
     case ChunkKind::CallParameterName:
     case ChunkKind::CallParameterInternalName:
     case ChunkKind::CallParameterColon:
     case ChunkKind::DeclAttrParamColon:
     case ChunkKind::CallParameterType:
     case ChunkKind::CallParameterClosureType:
     case ChunkKind::GenericParameterName:
       if (AnnotatedTextChunk)
         OS << "['";
       else if (C.getKind() == ChunkKind::CallParameterInternalName)
         OS << "(";
       else if (C.getKind() == ChunkKind::CallParameterClosureType)
         OS << "##";
       for (char Ch : C.getText()) {
         if (Ch == '\n')
           OS << "\\n";
         else
           OS << Ch;
       }
       if (AnnotatedTextChunk)
         OS << "']";
       else if (C.getKind() == ChunkKind::CallParameterInternalName)
         OS << ")";
       break;
     case ChunkKind::OptionalBegin:
     case ChunkKind::CallParameterBegin:
     case ChunkKind::GenericParameterBegin:
       OS << "{#";
       break;
     case ChunkKind::DynamicLookupMethodCallTail:
     case ChunkKind::OptionalMethodCallTail:
       OS << C.getText();
       break;
     case ChunkKind::TypeAnnotation:
       OS << "[#";
       OS << C.getText();
       OS << "#]";
       break;
     case ChunkKind::BraceStmtWithCursor:
       OS << " {|}";
       break;
     }
     PrevNestingLevel = C.getNestingLevel();
   }
   while (PrevNestingLevel > 0) {
     OS << "#}";
     PrevNestingLevel--;
   }
 }

 void CodeCompletionString::dump() const {
   print(llvm::errs());
 }

 CodeCompletionDeclKind
 CodeCompletionResult::getCodeCompletionDeclKind(const Decl *D) {
   switch (D->getKind()) {
   case DeclKind::Import:
   case DeclKind::Extension:
   case DeclKind::PatternBinding:
   case DeclKind::EnumCase:
   case DeclKind::TopLevelCode:
   case DeclKind::IfConfig:
   case DeclKind::PoundDiagnostic:
   case DeclKind::MissingMember:
   case DeclKind::OpaqueType:
     llvm_unreachable("not expecting such a declaration result");
   case DeclKind::Module:
     return CodeCompletionDeclKind::Module;
   case DeclKind::TypeAlias:
     return CodeCompletionDeclKind::TypeAlias;
   case DeclKind::AssociatedType:
     return CodeCompletionDeclKind::AssociatedType;
   case DeclKind::GenericTypeParam:
     return CodeCompletionDeclKind::GenericTypeParam;
   case DeclKind::Enum:
     return CodeCompletionDeclKind::Enum;
   case DeclKind::Struct:
     return CodeCompletionDeclKind::Struct;
   case DeclKind::Class:
     return CodeCompletionDeclKind::Class;
   case DeclKind::Protocol:
     return CodeCompletionDeclKind::Protocol;
   case DeclKind::Var:
   case DeclKind::Param: {
     auto DC = D->getDeclContext();
     if (DC->isTypeContext()) {
       if (cast<VarDecl>(D)->isStatic())
         return CodeCompletionDeclKind::StaticVar;
       else
         return CodeCompletionDeclKind::InstanceVar;
     }
     if (DC->isLocalContext())
       return CodeCompletionDeclKind::LocalVar;
     return CodeCompletionDeclKind::GlobalVar;
   }
   case DeclKind::Constructor:
     return CodeCompletionDeclKind::Constructor;
   case DeclKind::Destructor:
     return CodeCompletionDeclKind::Destructor;
   case DeclKind::Accessor:
   case DeclKind::Func: {
     auto DC = D->getDeclContext();
     auto FD = cast<FuncDecl>(D);
     if (DC->isTypeContext()) {
       if (FD->isStatic())
         return CodeCompletionDeclKind::StaticMethod;
       return CodeCompletionDeclKind::InstanceMethod;
     }
     if (FD->isOperator()) {
       if (auto op = FD->getOperatorDecl()) {
         switch (op->getKind()) {
         case DeclKind::PrefixOperator:
           return CodeCompletionDeclKind::PrefixOperatorFunction;
         case DeclKind::PostfixOperator:
           return CodeCompletionDeclKind::PostfixOperatorFunction;
         case DeclKind::InfixOperator:
           return CodeCompletionDeclKind::InfixOperatorFunction;
         default:
           llvm_unreachable("unexpected operator kind");
         }
       } else {
         return CodeCompletionDeclKind::InfixOperatorFunction;
       }
     }
     return CodeCompletionDeclKind::FreeFunction;
   }
   case DeclKind::InfixOperator:
     return CodeCompletionDeclKind::InfixOperatorFunction;
   case DeclKind::PrefixOperator:
     return CodeCompletionDeclKind::PrefixOperatorFunction;
   case DeclKind::PostfixOperator:
     return CodeCompletionDeclKind::PostfixOperatorFunction;
   case DeclKind::PrecedenceGroup:
     return CodeCompletionDeclKind::PrecedenceGroup;
   case DeclKind::EnumElement:
     return CodeCompletionDeclKind::EnumElement;
   case DeclKind::Subscript:
     return CodeCompletionDeclKind::Subscript;
   }
   llvm_unreachable("invalid DeclKind");
 }

 void CodeCompletionResult::print(raw_ostream &OS) const {
   llvm::SmallString<64> Prefix;
   switch (getKind()) {
   case ResultKind::Declaration:
     Prefix.append("Decl");
     switch (getAssociatedDeclKind()) {
     case CodeCompletionDeclKind::Class:
       Prefix.append("[Class]");
       break;
     case CodeCompletionDeclKind::Struct:
       Prefix.append("[Struct]");
       break;
     case CodeCompletionDeclKind::Enum:
       Prefix.append("[Enum]");
       break;
     case CodeCompletionDeclKind::EnumElement:
       Prefix.append("[EnumElement]");
       break;
     case CodeCompletionDeclKind::Protocol:
       Prefix.append("[Protocol]");
       break;
     case CodeCompletionDeclKind::TypeAlias:
       Prefix.append("[TypeAlias]");
       break;
     case CodeCompletionDeclKind::AssociatedType:
       Prefix.append("[AssociatedType]");
       break;
     case CodeCompletionDeclKind::GenericTypeParam:
       Prefix.append("[GenericTypeParam]");
       break;
     case CodeCompletionDeclKind::Constructor:
       Prefix.append("[Constructor]");
       break;
     case CodeCompletionDeclKind::Destructor:
       Prefix.append("[Destructor]");
       break;
     case CodeCompletionDeclKind::Subscript:
       Prefix.append("[Subscript]");
       break;
     case CodeCompletionDeclKind::StaticMethod:
       Prefix.append("[StaticMethod]");
       break;
     case CodeCompletionDeclKind::InstanceMethod:
       Prefix.append("[InstanceMethod]");
       break;
     case CodeCompletionDeclKind::PrefixOperatorFunction:
       Prefix.append("[PrefixOperatorFunction]");
       break;
     case CodeCompletionDeclKind::PostfixOperatorFunction:
       Prefix.append("[PostfixOperatorFunction]");
       break;
     case CodeCompletionDeclKind::InfixOperatorFunction:
       Prefix.append("[InfixOperatorFunction]");
       break;
     case CodeCompletionDeclKind::FreeFunction:
       Prefix.append("[FreeFunction]");
       break;
     case CodeCompletionDeclKind::StaticVar:
       Prefix.append("[StaticVar]");
       break;
     case CodeCompletionDeclKind::InstanceVar:
       Prefix.append("[InstanceVar]");
       break;
     case CodeCompletionDeclKind::LocalVar:
       Prefix.append("[LocalVar]");
       break;
     case CodeCompletionDeclKind::GlobalVar:
       Prefix.append("[GlobalVar]");
       break;
     case CodeCompletionDeclKind::Module:
       Prefix.append("[Module]");
       break;
     case CodeCompletionDeclKind::PrecedenceGroup:
       Prefix.append("[PrecedenceGroup]");
       break;
     }
     break;
   case ResultKind::Keyword:
     Prefix.append("Keyword");
     switch (getKeywordKind()) {
     case CodeCompletionKeywordKind::None:
       break;
 #define KEYWORD(X) case CodeCompletionKeywordKind::kw_##X: \
       Prefix.append("[" #X "]"); \
       break;
 #define POUND_KEYWORD(X) case CodeCompletionKeywordKind::pound_##X: \
       Prefix.append("[#" #X "]"); \
       break;
 #include "swift/Syntax/TokenKinds.def"
     }
     break;
   case ResultKind::Pattern:
     Prefix.append("Pattern");
     break;
   case ResultKind::Literal:
     Prefix.append("Literal");
     switch (getLiteralKind()) {
     case CodeCompletionLiteralKind::ArrayLiteral:
       Prefix.append("[Array]");
       break;
     case CodeCompletionLiteralKind::BooleanLiteral:
       Prefix.append("[Boolean]");
       break;
     case CodeCompletionLiteralKind::ColorLiteral:
       Prefix.append("[_Color]");
       break;
     case CodeCompletionLiteralKind::ImageLiteral:
       Prefix.append("[_Image]");
       break;
     case CodeCompletionLiteralKind::DictionaryLiteral:
       Prefix.append("[Dictionary]");
       break;
     case CodeCompletionLiteralKind::IntegerLiteral:
       Prefix.append("[Integer]");
       break;
     case CodeCompletionLiteralKind::NilLiteral:
       Prefix.append("[Nil]");
       break;
     case CodeCompletionLiteralKind::StringLiteral:
       Prefix.append("[String]");
       break;
     case CodeCompletionLiteralKind::Tuple:
       Prefix.append("[Tuple]");
       break;
     }
     break;
   case ResultKind::BuiltinOperator:
     Prefix.append("BuiltinOperator");
     break;
   }
   Prefix.append("/");
   switch (getSemanticContext()) {
   case SemanticContextKind::None:
     Prefix.append("None");
     break;
   case SemanticContextKind::ExpressionSpecific:
     Prefix.append("ExprSpecific");
     break;
   case SemanticContextKind::Local:
     Prefix.append("Local");
     break;
   case SemanticContextKind::CurrentNominal:
     Prefix.append("CurrNominal");
     break;
   case SemanticContextKind::Super:
     Prefix.append("Super");
     break;
   case SemanticContextKind::OutsideNominal:
     Prefix.append("OutNominal");
     break;
   case SemanticContextKind::CurrentModule:
     Prefix.append("CurrModule");
     break;
   case SemanticContextKind::OtherModule:
     Prefix.append("OtherModule");
     if (!ModuleName.empty())
       Prefix.append((Twine("[") + ModuleName + "]").str());
     break;
   }
   if (NotRecommended)
     Prefix.append("/NotRecommended");
   if (NumBytesToErase != 0) {
     Prefix.append("/Erase[");
     Prefix.append(Twine(NumBytesToErase).str());
     Prefix.append("]");
   }
   switch (TypeDistance) {
     case ExpectedTypeRelation::Invalid:
       Prefix.append("/TypeRelation[Invalid]");
       break;
     case ExpectedTypeRelation::Identical:
       Prefix.append("/TypeRelation[Identical]");
       break;
     case ExpectedTypeRelation::Convertible:
       Prefix.append("/TypeRelation[Convertible]");
       break;
     case ExpectedTypeRelation::Unrelated:
       break;
   }

   for (clang::comments::WordPairsArrangedViewer Viewer(DocWords);
        Viewer.hasNext();) {
     auto Pair = Viewer.next();
     Prefix.append("/");
     Prefix.append(Pair.first);
     Prefix.append("[");
     StringRef Sep = ", ";
     for (auto KW : Pair.second) {
       Prefix.append(KW);
       Prefix.append(Sep);
     }
     for (unsigned I = 0, N = Sep.size(); I < N; ++I)
       Prefix.pop_back();
     Prefix.append("]");
   }

   Prefix.append(": ");
   while (Prefix.size() < 36) {
     Prefix.append(" ");
   }
   OS << Prefix;
   CompletionString->print(OS);
 }

 void CodeCompletionResult::dump() const {
   print(llvm::errs());
 }

 static StringRef copyString(llvm::BumpPtrAllocator &Allocator,
                             StringRef Str) {
   char *Mem = Allocator.Allocate<char>(Str.size());
   std::copy(Str.begin(), Str.end(), Mem);
   return StringRef(Mem, Str.size());
 }

 static ArrayRef<StringRef> copyStringArray(llvm::BumpPtrAllocator &Allocator,
                                            ArrayRef<StringRef> Arr) {
   StringRef *Buff = Allocator.Allocate<StringRef>(Arr.size());
   std::copy(Arr.begin(), Arr.end(), Buff);
   return llvm::makeArrayRef(Buff, Arr.size());
 }

 static ArrayRef<std::pair<StringRef, StringRef>> copyStringPairArray(
     llvm::BumpPtrAllocator &Allocator,
     ArrayRef<std::pair<StringRef, StringRef>> Arr) {
   std::pair<StringRef, StringRef> *Buff = Allocator.Allocate<std::pair<StringRef,
     StringRef>>(Arr.size());
   std::copy(Arr.begin(), Arr.end(), Buff);
   return llvm::makeArrayRef(Buff, Arr.size());
 }

 void CodeCompletionResultBuilder::addChunkWithText(
     CodeCompletionString::Chunk::ChunkKind Kind, StringRef Text) {
   addChunkWithTextNoCopy(Kind, copyString(*Sink.Allocator, Text));
 }

 void CodeCompletionResultBuilder::setAssociatedDecl(const Decl *D) {
   assert(Kind == CodeCompletionResult::ResultKind::Declaration);
   AssociatedDecl = D;

   if (auto *ClangD = D->getClangDecl())
     CurrentModule = ClangD->getImportedOwningModule();
   // FIXME: macros
   // FIXME: imported header module

   if (!CurrentModule)
     CurrentModule = D->getModuleContext();

   if (D->getAttrs().getDeprecated(D->getASTContext()))
     setNotRecommended(CodeCompletionResult::Deprecated);
 }

 StringRef CodeCompletionContext::copyString(StringRef Str) {
   return ::copyString(*CurrentResults.Allocator, Str);
 }

 bool shouldCopyAssociatedUSRForDecl(const ValueDecl *VD) {
   // Avoid trying to generate a USR for some declaration types.
   if (isa<AbstractTypeParamDecl>(VD) && !isa<AssociatedTypeDecl>(VD))
     return false;
   if (isa<ParamDecl>(VD))
     return false;
   if (isa<ModuleDecl>(VD))
     return false;
   if (VD->hasClangNode() && !VD->getClangDecl())
     return false;

   return true;
 }

 template <typename FnTy>
 static void walkValueDeclAndOverriddenDecls(const Decl *D, const FnTy &Fn) {
   if (auto *VD = dyn_cast<ValueDecl>(D)) {
     Fn(VD);
     walkOverriddenDecls(VD, Fn);
   }
 }

 ArrayRef<StringRef> copyAssociatedUSRs(llvm::BumpPtrAllocator &Allocator,
                                        const Decl *D) {
   llvm::SmallVector<StringRef, 4> USRs;
   walkValueDeclAndOverriddenDecls(D, [&](llvm::PointerUnion<const ValueDecl*,
                                                   const clang::NamedDecl*> OD) {
     llvm::SmallString<128> SS;
     bool Ignored = true;
     if (auto *OVD = OD.dyn_cast<const ValueDecl*>()) {
       if (shouldCopyAssociatedUSRForDecl(OVD)) {
         llvm::raw_svector_ostream OS(SS);
         Ignored = printDeclUSR(OVD, OS);
       }
     } else if (auto *OND = OD.dyn_cast<const clang::NamedDecl*>()) {
       Ignored = clang::index::generateUSRForDecl(OND, SS);
     }

     if (!Ignored)
       USRs.push_back(copyString(Allocator, SS));
   });

   if (!USRs.empty())
     return copyStringArray(Allocator, USRs);

   return ArrayRef<StringRef>();
 }

 static CodeCompletionResult::ExpectedTypeRelation calculateTypeRelation(
                                                                 Type Ty,
                                                                 Type ExpectedTy,
                                                                 DeclContext *DC) {
   if (Ty.isNull() || ExpectedTy.isNull() ||
       Ty->is<ErrorType>() ||
       ExpectedTy->is<ErrorType>())
     return CodeCompletionResult::ExpectedTypeRelation::Unrelated;

   // Equality/Conversion of GenericTypeParameterType won't account for
   // requirements – ignore them
   if (!Ty->hasTypeParameter() && !ExpectedTy->hasTypeParameter()) {
     if (Ty->isEqual(ExpectedTy))
       return CodeCompletionResult::ExpectedTypeRelation::Identical;
     bool isAny = false;
     isAny |= ExpectedTy->isAny();
     isAny |= ExpectedTy->is<ArchetypeType>() &&
              !ExpectedTy->castTo<ArchetypeType>()->hasRequirements();

     if (!isAny && isConvertibleTo(Ty, ExpectedTy, /*openArchetypes=*/true, *DC))
       return CodeCompletionResult::ExpectedTypeRelation::Convertible;
   }
   if (auto FT = Ty->getAs<AnyFunctionType>()) {
     if (FT->getResult()->isVoid())
       return CodeCompletionResult::ExpectedTypeRelation::Invalid;
   }
   return CodeCompletionResult::ExpectedTypeRelation::Unrelated;
 }

 static CodeCompletionResult::ExpectedTypeRelation
 calculateTypeRelationForDecl(const Decl *D, Type ExpectedType,
                              bool IsImplicitlyCurriedInstanceMethod,
                              bool UseFuncResultType = true) {
   auto VD = dyn_cast<ValueDecl>(D);
   auto DC = D->getDeclContext();
   if (!VD)
     return CodeCompletionResult::ExpectedTypeRelation::Unrelated;

   if (auto FD = dyn_cast<AbstractFunctionDecl>(VD)) {
     auto funcType = FD->getInterfaceType()->getAs<AnyFunctionType>();
     if (DC->isTypeContext() && funcType && funcType->is<AnyFunctionType>() &&
         !IsImplicitlyCurriedInstanceMethod)
       funcType = funcType->getResult()->getAs<AnyFunctionType>();
     if (funcType) {
       funcType = funcType->removeArgumentLabels(1)->castTo<AnyFunctionType>();
       auto relation = calculateTypeRelation(funcType, ExpectedType, DC);
       if (UseFuncResultType)
         relation =
             std::max(relation, calculateTypeRelation(funcType->getResult(),
                                                      ExpectedType, DC));
       return relation;
     }
   }
   if (auto NTD = dyn_cast<NominalTypeDecl>(VD)) {
     return std::max(
         calculateTypeRelation(NTD->getInterfaceType(), ExpectedType, DC),
         calculateTypeRelation(NTD->getDeclaredInterfaceType(), ExpectedType, DC));
   }
   return calculateTypeRelation(VD->getInterfaceType(), ExpectedType, DC);
 }

 static CodeCompletionResult::ExpectedTypeRelation
 calculateMaxTypeRelationForDecl(
     const Decl *D, const ExpectedTypeContext &typeContext,
     bool IsImplicitlyCurriedInstanceMethod = false) {
   auto Result = CodeCompletionResult::ExpectedTypeRelation::Unrelated;
   for (auto Type : typeContext.possibleTypes) {
     // Do not use Void type context for a single-expression body, since the
     // implicit return does not constrain the expression.
     //
     //     { ... -> ()  in x } // x can be anything
     //
     // This behaves differently from explicit return, and from non-Void:
     //
     //     { ... -> Int in x }        // x must be Int
     //     { ... -> ()  in return x } // x must be Void
     if (typeContext.isSingleExpressionBody && Type->isVoid())
       continue;

     Result = std::max(Result, calculateTypeRelationForDecl(
                                   D, Type, IsImplicitlyCurriedInstanceMethod));

     // Map invalid -> unrelated when in a single-expression body, since the
     // input may be incomplete.
     if (typeContext.isSingleExpressionBody &&
         Result == CodeCompletionResult::ExpectedTypeRelation::Invalid)
       Result = CodeCompletionResult::ExpectedTypeRelation::Unrelated;
   }
   return Result;
 }

 CodeCompletionOperatorKind
 CodeCompletionResult::getCodeCompletionOperatorKind(StringRef name) {
   using CCOK = CodeCompletionOperatorKind;
   using OpPair = std::pair<StringRef, CCOK>;

   // This list must be kept in alphabetical order.
   static OpPair ops[] = {
       std::make_pair("!", CCOK::Bang),
       std::make_pair("!=", CCOK::NotEq),
       std::make_pair("!==", CCOK::NotEqEq),
       std::make_pair("%", CCOK::Modulo),
       std::make_pair("%=", CCOK::ModuloEq),
       std::make_pair("&", CCOK::Amp),
       std::make_pair("&&", CCOK::AmpAmp),
       std::make_pair("&*", CCOK::AmpStar),
       std::make_pair("&+", CCOK::AmpPlus),
       std::make_pair("&-", CCOK::AmpMinus),
       std::make_pair("&=", CCOK::AmpEq),
       std::make_pair("(", CCOK::LParen),
       std::make_pair("*", CCOK::Star),
       std::make_pair("*=", CCOK::StarEq),
       std::make_pair("+", CCOK::Plus),
       std::make_pair("+=", CCOK::PlusEq),
       std::make_pair("-", CCOK::Minus),
       std::make_pair("-=", CCOK::MinusEq),
       std::make_pair(".", CCOK::Dot),
       std::make_pair("...", CCOK::DotDotDot),
       std::make_pair("..<", CCOK::DotDotLess),
       std::make_pair("/", CCOK::Slash),
       std::make_pair("/=", CCOK::SlashEq),
       std::make_pair("<", CCOK::Less),
       std::make_pair("<<", CCOK::LessLess),
       std::make_pair("<<=", CCOK::LessLessEq),
       std::make_pair("<=", CCOK::LessEq),
       std::make_pair("=", CCOK::Eq),
       std::make_pair("==", CCOK::EqEq),
       std::make_pair("===", CCOK::EqEqEq),
       std::make_pair(">", CCOK::Greater),
       std::make_pair(">=", CCOK::GreaterEq),
       std::make_pair(">>", CCOK::GreaterGreater),
       std::make_pair(">>=", CCOK::GreaterGreaterEq),
       std::make_pair("?.", CCOK::QuestionDot),
       std::make_pair("^", CCOK::Caret),
       std::make_pair("^=", CCOK::CaretEq),
       std::make_pair("|", CCOK::Pipe),
       std::make_pair("|=", CCOK::PipeEq),
       std::make_pair("||", CCOK::PipePipe),
       std::make_pair("~=", CCOK::TildeEq),
   };
   static auto opsSize = sizeof(ops) / sizeof(ops[0]);

   auto I = std::lower_bound(
       ops, &ops[opsSize], std::make_pair(name, CCOK::None),
       [](const OpPair &a, const OpPair &b) { return a.first < b.first; });

   if (I == &ops[opsSize] || I->first != name)
     return CCOK::Unknown;
   return I->second;
 }

 static StringRef getOperatorName(CodeCompletionString *str) {
   return str->getFirstTextChunk(/*includeLeadingPunctuation=*/true);
 }

 CodeCompletionOperatorKind
 CodeCompletionResult::getCodeCompletionOperatorKind(CodeCompletionString *str) {
   return getCodeCompletionOperatorKind(getOperatorName(str));
 }

 CodeCompletionResult *CodeCompletionResultBuilder::takeResult() {
   auto *CCS = CodeCompletionString::create(*Sink.Allocator, Chunks);

   switch (Kind) {
   case CodeCompletionResult::ResultKind::Declaration: {
     StringRef BriefComment;
     auto MaybeClangNode = AssociatedDecl->getClangNode();
     if (MaybeClangNode) {
       if (auto *D = MaybeClangNode.getAsDecl()) {
         const auto &ClangContext = D->getASTContext();
         if (const clang::RawComment *RC =
                 ClangContext.getRawCommentForAnyRedecl(D))
           BriefComment = RC->getBriefText(ClangContext);
       }
     } else {
       BriefComment = AssociatedDecl->getBriefComment();
     }

     StringRef ModuleName;
     if (CurrentModule) {
       if (Sink.LastModule.first == CurrentModule.getOpaqueValue()) {
         ModuleName = Sink.LastModule.second;
       } else {
         if (auto *C = CurrentModule.dyn_cast<const clang::Module *>()) {
           ModuleName = copyString(*Sink.Allocator, C->getFullModuleName());
         } else {
           ModuleName = copyString(
               *Sink.Allocator,
               CurrentModule.get<const swift::ModuleDecl *>()->getName().str());
         }
         Sink.LastModule.first = CurrentModule.getOpaqueValue();
         Sink.LastModule.second = ModuleName;
       }
     }

     auto typeRelation = ExpectedTypeRelation;
     if (typeRelation == CodeCompletionResult::Unrelated)
       typeRelation =
           calculateMaxTypeRelationForDecl(AssociatedDecl, declTypeContext);

     if (typeRelation == CodeCompletionResult::Invalid) {
       IsNotRecommended = true;
       NotRecReason = CodeCompletionResult::NotRecommendedReason::TypeMismatch;
     }

     return new (*Sink.Allocator) CodeCompletionResult(
         SemanticContext, NumBytesToErase, CCS, AssociatedDecl, ModuleName,
         /*NotRecommended=*/IsNotRecommended, NotRecReason,
         copyString(*Sink.Allocator, BriefComment),
         copyAssociatedUSRs(*Sink.Allocator, AssociatedDecl),
         copyStringPairArray(*Sink.Allocator, CommentWords), typeRelation);
   }

   case CodeCompletionResult::ResultKind::Keyword:
     return new (*Sink.Allocator)
         CodeCompletionResult(KeywordKind, SemanticContext, NumBytesToErase,
                              CCS, ExpectedTypeRelation);

   case CodeCompletionResult::ResultKind::BuiltinOperator:
   case CodeCompletionResult::ResultKind::Pattern:
     return new (*Sink.Allocator) CodeCompletionResult(
         Kind, SemanticContext, NumBytesToErase, CCS, ExpectedTypeRelation);

   case CodeCompletionResult::ResultKind::Literal:
     assert(LiteralKind.hasValue());
     return new (*Sink.Allocator)
         CodeCompletionResult(*LiteralKind, SemanticContext, NumBytesToErase,
                              CCS, ExpectedTypeRelation);
   }

   llvm_unreachable("Unhandled CodeCompletionResult in switch.");
 }

 void CodeCompletionResultBuilder::finishResult() {
   if (!Cancelled)
     Sink.Results.push_back(takeResult());
 }


 MutableArrayRef<CodeCompletionResult *> CodeCompletionContext::takeResults() {
   // Copy pointers to the results.
   const size_t Count = CurrentResults.Results.size();
   CodeCompletionResult **Results =
       CurrentResults.Allocator->Allocate<CodeCompletionResult *>(Count);
   std::copy(CurrentResults.Results.begin(), CurrentResults.Results.end(),
             Results);
   CurrentResults.Results.clear();
   return MutableArrayRef<CodeCompletionResult *>(Results, Count);
 }

 Optional<unsigned> CodeCompletionString::getFirstTextChunkIndex(
     bool includeLeadingPunctuation) const {
   for (auto i : indices(getChunks())) {
     auto &C = getChunks()[i];
     switch (C.getKind()) {
     using ChunkKind = Chunk::ChunkKind;
     case ChunkKind::Text:
     case ChunkKind::CallParameterName:
     case ChunkKind::CallParameterInternalName:
     case ChunkKind::GenericParameterName:
     case ChunkKind::LeftParen:
     case ChunkKind::LeftBracket:
     case ChunkKind::Equal:
     case ChunkKind::DeclAttrParamKeyword:
     case ChunkKind::DeclAttrKeyword:
       return i;
     case ChunkKind::Dot:
     case ChunkKind::ExclamationMark:
     case ChunkKind::QuestionMark:
       if (includeLeadingPunctuation)
         return i;
       continue;
     case ChunkKind::RightParen:
     case ChunkKind::RightBracket:
     case ChunkKind::LeftAngle:
     case ChunkKind::RightAngle:
     case ChunkKind::Ellipsis:
     case ChunkKind::Comma:
     case ChunkKind::Ampersand:
     case ChunkKind::Whitespace:
     case ChunkKind::AccessControlKeyword:
     case ChunkKind::OverrideKeyword:
     case ChunkKind::ThrowsKeyword:
     case ChunkKind::RethrowsKeyword:
     case ChunkKind::DeclIntroducer:
     case ChunkKind::CallParameterColon:
     case ChunkKind::DeclAttrParamColon:
     case ChunkKind::CallParameterType:
     case ChunkKind::CallParameterClosureType:
     case ChunkKind::OptionalBegin:
     case ChunkKind::CallParameterBegin:
     case ChunkKind::GenericParameterBegin:
     case ChunkKind::DynamicLookupMethodCallTail:
     case ChunkKind::OptionalMethodCallTail:
     case ChunkKind::TypeAnnotation:
       continue;

     case ChunkKind::BraceStmtWithCursor:
       llvm_unreachable("should have already extracted the text");
     }
   }
   return None;
 }

 StringRef
 CodeCompletionString::getFirstTextChunk(bool includeLeadingPunctuation) const {
   Optional<unsigned> Idx = getFirstTextChunkIndex(includeLeadingPunctuation);
   if (Idx.hasValue())
     return getChunks()[*Idx].getText();
   return StringRef();
 }

 void CodeCompletionString::getName(raw_ostream &OS) const {
   auto FirstTextChunk = getFirstTextChunkIndex();
   int TextSize = 0;
   if (FirstTextChunk.hasValue()) {
     for (auto C : getChunks().slice(*FirstTextChunk)) {
       using ChunkKind = Chunk::ChunkKind;

       bool shouldPrint = !C.isAnnotation();
       switch (C.getKind()) {
       case ChunkKind::TypeAnnotation:
       case ChunkKind::CallParameterClosureType:
       case ChunkKind::DeclAttrParamColon:
       case ChunkKind::OptionalMethodCallTail:
         continue;
       case ChunkKind::ThrowsKeyword:
       case ChunkKind::RethrowsKeyword:
         shouldPrint = true; // Even when they're annotations.
         break;
       default:
         break;
       }

       if (C.hasText() && shouldPrint) {
         TextSize += C.getText().size();
         OS << C.getText();
       }
     }
   }
 }

 void CodeCompletionContext::sortCompletionResults(
     MutableArrayRef<CodeCompletionResult *> Results) {
   struct ResultAndName {
     CodeCompletionResult *result;
     std::string name;
   };

   // Caching the name of each field is important to avoid unnecessary calls to
   // CodeCompletionString::getName().
   std::vector<ResultAndName> nameCache(Results.size());
   for (unsigned i = 0, n = Results.size(); i < n; ++i) {
     auto *result = Results[i];
     nameCache[i].result = result;
     llvm::raw_string_ostream OS(nameCache[i].name);
     result->getCompletionString()->getName(OS);
     OS.flush();
   }

   // Sort nameCache, and then transform Results to return the pointers in order.
   std::sort(nameCache.begin(), nameCache.end(),
             [](const ResultAndName &LHS, const ResultAndName &RHS) {
     int Result = StringRef(LHS.name).compare_lower(RHS.name);
     // If the case insensitive comparison is equal, then secondary sort order
     // should be case sensitive.
     if (Result == 0)
       Result = LHS.name.compare(RHS.name);
     return Result < 0;
   });

   std::transform(nameCache.begin(), nameCache.end(), Results.begin(),
                  [](const ResultAndName &entry) { return entry.result; });
 }

 namespace {
 class CodeCompletionCallbacksImpl : public CodeCompletionCallbacks {
   CodeCompletionContext &CompletionContext;
   std::vector<RequestedCachedModule> RequestedModules;
   CodeCompletionConsumer &Consumer;
   CodeCompletionExpr *CodeCompleteTokenExpr = nullptr;
   CompletionKind Kind = CompletionKind::None;
   Expr *ParsedExpr = nullptr;
   SourceLoc DotLoc;
   DeclContext *CurDeclContext = nullptr;
   DeclAttrKind AttrKind;

   /// In situations when \c SyntaxKind hints or determines
   /// completions, i.e. a precedence group attribute, this
   /// can be set and used to control the code completion scenario.
   SyntaxKind SyntxKind;

   int AttrParamIndex;
   bool IsInSil = false;
   bool HasSpace = false;
   bool ShouldCompleteCallPatternAfterParen = true;
   bool PreferFunctionReferencesToCalls = false;
   bool AttTargetIsIndependent = false;
   Optional<DeclKind> AttTargetDK;
   Optional<StmtKind> ParentStmtKind;

   SmallVector<StringRef, 3> ParsedKeywords;
   SourceLoc introducerLoc;

   std::vector<std::pair<std::string, bool>> SubModuleNameVisibilityPairs;

   void addSuperKeyword(CodeCompletionResultSink &Sink) {
     auto *DC = CurDeclContext->getInnermostTypeContext();
     if (!DC)
       return;
     auto *CD = DC->getSelfClassDecl();
     if (!CD)
       return;
     Type ST = CD->getSuperclass();
     if (ST.isNull() || ST->is<ErrorType>())
       return;

     CodeCompletionResultBuilder Builder(Sink,
                                         CodeCompletionResult::ResultKind::Keyword,
                                         SemanticContextKind::CurrentNominal,
                                         {});
     Builder.setKeywordKind(CodeCompletionKeywordKind::kw_super);
     Builder.addTextChunk("super");
     Builder.addTypeAnnotation(ST.getString());
   }

   /// Set to true when we have delivered code completion results
   /// to the \c Consumer.
   bool DeliveredResults = false;


   Optional<std::pair<Type, ConcreteDeclRef>> typeCheckParsedExpr() {
     assert(ParsedExpr && "should have an expression");

     // Figure out the kind of type-check we'll be performing.
     auto CheckKind = CompletionTypeCheckKind::Normal;
     if (Kind == CompletionKind::KeyPathExprObjC)
       CheckKind = CompletionTypeCheckKind::KeyPath;

     // If we've already successfully type-checked the expression for some
     // reason, just return the type.
     // FIXME: if it's ErrorType but we've already typechecked we shouldn't
     // typecheck again. rdar://21466394
     if (CheckKind == CompletionTypeCheckKind::Normal &&
         ParsedExpr->getType() && !ParsedExpr->getType()->is<ErrorType>()) {
       auto refDecl = ParsedExpr->getReferencedDecl();
       auto exprTy = ParsedExpr->getType();
       if (!refDecl) {
         // FIXME: do this in the not-already-type-checked branch too?
         if (auto *apply = dyn_cast<SelfApplyExpr>(ParsedExpr)) {
           refDecl = apply->getFn()->getReferencedDecl();
         } else if (auto *apply = dyn_cast<ApplyExpr>(ParsedExpr)) {
           // If this is an IUO, use the underlying non-optional type instead
           auto fnDecl = apply->getFn()->getReferencedDecl();
           if (auto FD = fnDecl.getDecl()) {
             if (FD->isImplicitlyUnwrappedOptional()) {
               if (auto OT = exprTy->getOptionalObjectType())
                 exprTy = OT;
             }
           }
         }
       }
       return std::make_pair(exprTy, refDecl);
     }

     ConcreteDeclRef ReferencedDecl = nullptr;
     Expr *ModifiedExpr = ParsedExpr;
     if (auto T = getTypeOfCompletionContextExpr(P.Context, CurDeclContext,
                                                 CheckKind, ModifiedExpr,
                                                 ReferencedDecl)) {
       // FIXME: even though we don't apply the solution, the type checker may
       // modify the original expression. We should understand what effect that
       // may have on code completion.
       ParsedExpr = ModifiedExpr;

       return std::make_pair(*T, ReferencedDecl);
     }
     return None;
   }

   /// \returns true on success, false on failure.
   bool typecheckParsedType() {
     assert(ParsedTypeLoc.getTypeRepr() && "should have a TypeRepr");
     return !performTypeLocChecking(P.Context, ParsedTypeLoc,
                                    CurDeclContext, false);
   }

 public:
   CodeCompletionCallbacksImpl(Parser &P,
                               CodeCompletionContext &CompletionContext,
                               CodeCompletionConsumer &Consumer)
       : CodeCompletionCallbacks(P), CompletionContext(CompletionContext),
         Consumer(Consumer) {
   }

   void setAttrTargetDeclKind(Optional<DeclKind> DK) override {
     if (DK == DeclKind::PatternBinding)
       DK = DeclKind::Var;
     else if (DK == DeclKind::Param)
       // For params, consider the attribute is always for the decl.
       AttTargetIsIndependent = false;

     if (!AttTargetIsIndependent)
       AttTargetDK = DK;
   }

   void completeExpr() override;
   void completeDotExpr(Expr *E, SourceLoc DotLoc) override;
   void completeStmtOrExpr(CodeCompletionExpr *E) override;
   void completePostfixExprBeginning(CodeCompletionExpr *E) override;
   void completeForEachSequenceBeginning(CodeCompletionExpr *E) override;
   void completePostfixExpr(Expr *E, bool hasSpace) override;
   void completePostfixExprParen(Expr *E, Expr *CodeCompletionE) override;
   void completeExprKeyPath(KeyPathExpr *KPE, SourceLoc DotLoc) override;

   void completeTypeDeclResultBeginning() override;
   void completeTypeSimpleBeginning() override;
   void completeTypeIdentifierWithDot() override;
   void completeTypeIdentifierWithoutDot() override;

   void completeCaseStmtKeyword() override;
   void completeCaseStmtBeginning(CodeCompletionExpr *E) override;
   void completeDeclAttrBeginning(bool Sil, bool isIndependent) override;
   void completeDeclAttrParam(DeclAttrKind DK, int Index) override;
   void completeInPrecedenceGroup(SyntaxKind SK) override;
   void completeNominalMemberBeginning(
       SmallVectorImpl<StringRef> &Keywords, SourceLoc introducerLoc) override;
   void completeAccessorBeginning(CodeCompletionExpr *E) override;

   void completePoundAvailablePlatform() override;
   void completeImportDecl(std::vector<std::pair<Identifier, SourceLoc>> &Path) override;
   void completeUnresolvedMember(CodeCompletionExpr *E,
                                 SourceLoc DotLoc) override;
   void completeCallArg(CodeCompletionExpr *E, bool isFirst) override;
   void completeReturnStmt(CodeCompletionExpr *E) override;
   void completeYieldStmt(CodeCompletionExpr *E,
                          Optional<unsigned> yieldIndex) override;
   void completeAfterPoundExpr(CodeCompletionExpr *E,
                               Optional<StmtKind> ParentKind) override;
   void completeAfterPoundDirective() override;
   void completePlatformCondition() override;
   void completeGenericParams(TypeLoc TL) override;
   void completeAfterIfStmt(bool hasElse) override;

   void doneParsing() override;

 private:
   void addKeywords(CodeCompletionResultSink &Sink, bool MaybeFuncBody);
   void deliverCompletionResults();
 };
 } // end anonymous namespace

 void CodeCompletionCallbacksImpl::completeExpr() {
   if (DeliveredResults)
     return;

   Parser::ParserPositionRAII RestorePosition(P);
   P.restoreParserPosition(ExprBeginPosition);

   // FIXME: implement fallback code completion.

   deliverCompletionResults();
 }

 namespace {
 static bool isTopLevelContext(const DeclContext *DC) {
   for (; DC && DC->isLocalContext(); DC = DC->getParent()) {
     switch (DC->getContextKind()) {
     case DeclContextKind::TopLevelCodeDecl:
       return true;
     case DeclContextKind::AbstractFunctionDecl:
     case DeclContextKind::SubscriptDecl:
     case DeclContextKind::EnumElementDecl:
       return false;
     default:
       continue;
     }
   }
   return false;
 }

 static KnownProtocolKind
 protocolForLiteralKind(CodeCompletionLiteralKind kind) {
   switch (kind) {
   case CodeCompletionLiteralKind::ArrayLiteral:
     return KnownProtocolKind::ExpressibleByArrayLiteral;
   case CodeCompletionLiteralKind::BooleanLiteral:
     return KnownProtocolKind::ExpressibleByBooleanLiteral;
   case CodeCompletionLiteralKind::ColorLiteral:
     return KnownProtocolKind::ExpressibleByColorLiteral;
   case CodeCompletionLiteralKind::ImageLiteral:
     return KnownProtocolKind::ExpressibleByImageLiteral;
   case CodeCompletionLiteralKind::DictionaryLiteral:
     return KnownProtocolKind::ExpressibleByDictionaryLiteral;
   case CodeCompletionLiteralKind::IntegerLiteral:
     return KnownProtocolKind::ExpressibleByIntegerLiteral;
   case CodeCompletionLiteralKind::NilLiteral:
     return KnownProtocolKind::ExpressibleByNilLiteral;
   case CodeCompletionLiteralKind::StringLiteral:
     return KnownProtocolKind::ExpressibleByUnicodeScalarLiteral;
   case CodeCompletionLiteralKind::Tuple:
     llvm_unreachable("no such protocol kind");
   }

   llvm_unreachable("Unhandled CodeCompletionLiteralKind in switch.");
 }

 /// Whether funcType has a single argument (not including defaulted arguments)
 /// that is of type () -> ().
 static bool hasTrivialTrailingClosure(const FuncDecl *FD,
                                       AnyFunctionType *funcType) {
   ParameterListInfo paramInfo(funcType->getParams(), FD,
                               /*skipCurriedSelf*/ FD->hasCurriedSelf());

   if (paramInfo.size() - paramInfo.numNonDefaultedParameters() == 1) {
     auto param = funcType->getParams().back();
     if (!param.isAutoClosure()) {
       if (auto Fn = param.getOldType()->getAs<AnyFunctionType>()) {
         return Fn->getParams().empty() && Fn->getResult()->isVoid();
       }
     }
   }

   return false;
 }

 /// Build completions by doing visible decl lookup from a context.
 class CompletionLookup final : public swift::VisibleDeclConsumer {
   CodeCompletionResultSink &Sink;
   ASTContext &Ctx;
   const DeclContext *CurrDeclContext;
   ModuleDecl *CurrModule;
   ClangImporter *Importer;
   CodeCompletionContext *CompletionContext;

   enum class LookupKind {
     ValueExpr,
     ValueInDeclContext,
     EnumElement,
     Type,
     TypeInDeclContext,
     ImportFromModule
   };

   LookupKind Kind;

   /// Type of the user-provided expression for LookupKind::ValueExpr
   /// completions.
   Type ExprType;

   /// Whether the expr is of statically inferred metatype.
   bool IsStaticMetatype = false;

   /// User-provided base type for LookupKind::Type completions.
   Type BaseType;

   /// Expected types of the code completion expression.
   ExpectedTypeContext expectedTypeContext;

   bool HaveDot = false;
   bool IsUnwrappedOptional = false;
   SourceLoc DotLoc;
   bool NeedLeadingDot = false;

   bool NeedOptionalUnwrap = false;
   unsigned NumBytesToEraseForOptionalUnwrap = 0;

   bool HaveLParen = false;
   bool IsSuperRefExpr = false;
   bool IsSelfRefExpr = false;
   bool IsKeyPathExpr = false;
   bool IsSwiftKeyPathExpr = false;
   bool IsAfterSwiftKeyPathRoot = false;
   bool IsDynamicLookup = false;
   bool PreferFunctionReferencesToCalls = false;
   bool HaveLeadingSpace = false;

   bool IncludeInstanceMembers = false;

   /// True if we are code completing inside a static method.
   bool InsideStaticMethod = false;

   /// Innermost method that the code completion point is in.
   const AbstractFunctionDecl *CurrentMethod = nullptr;

   Optional<SemanticContextKind> ForcedSemanticContext = None;
   bool IsUnresolvedMember = false;

 public:
   bool FoundFunctionCalls = false;
   bool FoundFunctionsWithoutFirstKeyword = false;

 private:
   void foundFunction(const AbstractFunctionDecl *AFD) {
     FoundFunctionCalls = true;
     DeclName Name = AFD->getFullName();
     auto ArgNames = Name.getArgumentNames();
     if (ArgNames.empty())
       return;
     if (ArgNames[0].empty())
       FoundFunctionsWithoutFirstKeyword = true;
   }

   void foundFunction(const AnyFunctionType *AFT) {
     FoundFunctionCalls = true;
     auto Params = AFT->getParams();
     if (Params.empty())
       return;
     if (Params.size() == 1 && !Params[0].hasLabel()) {
       FoundFunctionsWithoutFirstKeyword = true;
       return;
     }
     if (!Params[0].hasLabel())
       FoundFunctionsWithoutFirstKeyword = true;
   }

   void setClangDeclKeywords(const ValueDecl *VD, CommandWordsPairs &Pairs,
                             CodeCompletionResultBuilder &Builder) {
     if (auto *CD = VD->getClangDecl()) {
       clang::comments::getClangDocKeyword(*Importer, CD, Pairs);
     } else {
       swift::markup::getSwiftDocKeyword(VD, Pairs);
     }
     Builder.addDeclDocCommentWords(llvm::makeArrayRef(Pairs));
   }

   bool shouldUseFunctionReference(AbstractFunctionDecl *D) {
     if (PreferFunctionReferencesToCalls)
       return true;
     bool isImplicitlyCurriedIM = isImplicitlyCurriedInstanceMethod(D);
     for (auto expectedType : expectedTypeContext.possibleTypes) {
       if (expectedType &&
           expectedType->lookThroughAllOptionalTypes()
               ->is<AnyFunctionType>() &&
           calculateTypeRelationForDecl(D, expectedType, isImplicitlyCurriedIM,
                                        /*UseFuncResultType=*/false) >=
               CodeCompletionResult::ExpectedTypeRelation::Convertible) {
         return true;
       }
     }
     return false;
   }

 public:
   struct RequestedResultsTy {
     const ModuleDecl *TheModule;
     bool OnlyTypes;
     bool OnlyPrecedenceGroups;
     bool NeedLeadingDot;

     static RequestedResultsTy fromModule(const ModuleDecl *TheModule) {
       return { TheModule, false, false, false };
     }

     RequestedResultsTy onlyTypes() const {
       return { TheModule, true, false, NeedLeadingDot };
     }

     RequestedResultsTy onlyPrecedenceGroups() const {
       assert(!OnlyTypes && "onlyTypes() already includes precedence groups");
       return { TheModule, false, true, false };
     }

     RequestedResultsTy needLeadingDot(bool NeedDot) const {
       return { TheModule, OnlyTypes, OnlyPrecedenceGroups, NeedDot };
     }

     static RequestedResultsTy toplevelResults() {
       return { nullptr, false, false, false };
     }
   };

   std::vector<RequestedResultsTy> RequestedCachedResults;

 public:
   CompletionLookup(CodeCompletionResultSink &Sink,
                    ASTContext &Ctx,
                    const DeclContext *CurrDeclContext,
                    CodeCompletionContext *CompletionContext = nullptr)
       : Sink(Sink), Ctx(Ctx), CurrDeclContext(CurrDeclContext),
         CurrModule(CurrDeclContext ? CurrDeclContext->getParentModule()
                                    : nullptr),
         Importer(static_cast<ClangImporter *>(CurrDeclContext->getASTContext().
           getClangModuleLoader())),
         CompletionContext(CompletionContext) {
     (void)createTypeChecker(Ctx);

     // Determine if we are doing code completion inside a static method.
     if (CurrDeclContext) {
       CurrentMethod = CurrDeclContext->getInnermostMethodContext();
       if (auto *FD = dyn_cast_or_null<FuncDecl>(CurrentMethod))
         InsideStaticMethod = FD->isStatic();
     }
   }

   void setHaveDot(SourceLoc DotLoc) {
     HaveDot = true;
     this->DotLoc = DotLoc;
   }

   void setIsUnwrappedOptional(bool value) {
     IsUnwrappedOptional = value;
   }

   void setIsStaticMetatype(bool value) {
     IsStaticMetatype = value;
   }

   void setExpectedTypes(ArrayRef<Type> Types, bool isSingleExpressionBody) {
     expectedTypeContext.isSingleExpressionBody = isSingleExpressionBody;
     expectedTypeContext.possibleTypes.clear();
     expectedTypeContext.possibleTypes.reserve(Types.size());
     for (auto T : Types)
       if (T)
         expectedTypeContext.possibleTypes.push_back(T);
   }

   CodeCompletionContext::TypeContextKind typeContextKind() const {
     if (expectedTypeContext.empty()) {
       return CodeCompletionContext::TypeContextKind::None;
     } else if (expectedTypeContext.isSingleExpressionBody) {
       return CodeCompletionContext::TypeContextKind::SingleExpressionBody;
     } else {
       return CodeCompletionContext::TypeContextKind::Required;
     }
   }

   bool needDot() const {
     return NeedLeadingDot;
   }

   void setHaveLParen(bool Value) {
     HaveLParen = Value;
   }

   void setIsSuperRefExpr() {
     IsSuperRefExpr = true;
   }

   void setIsSelfRefExpr(bool value) { IsSelfRefExpr = value; }

   void setIsKeyPathExpr() {
     IsKeyPathExpr = true;
   }

   void setIsSwiftKeyPathExpr(bool onRoot) {
     IsSwiftKeyPathExpr = true;
     IsAfterSwiftKeyPathRoot = onRoot;
   }

   void setIsDynamicLookup() {
     IsDynamicLookup = true;
   }

   void setPreferFunctionReferencesToCalls() {
     PreferFunctionReferencesToCalls = true;
   }

   void setHaveLeadingSpace(bool value) { HaveLeadingSpace = value; }

   void includeInstanceMembers() {
     IncludeInstanceMembers = true;
   }

   void addSubModuleNames(std::vector<std::pair<std::string, bool>>
       &SubModuleNameVisibilityPairs) {
     for (auto &Pair : SubModuleNameVisibilityPairs) {
       CodeCompletionResultBuilder Builder(Sink,
                                           CodeCompletionResult::ResultKind::
                                           Declaration,
                                           SemanticContextKind::OtherModule,
                                           expectedTypeContext);
       auto MD = ModuleDecl::create(Ctx.getIdentifier(Pair.first), Ctx);
       Builder.setAssociatedDecl(MD);
       Builder.addTextChunk(MD->getNameStr());
       Builder.addTypeAnnotation("Module");
       if (Pair.second)
         Builder.setNotRecommended(CodeCompletionResult::NotRecommendedReason::
                                     Redundant);
     }
   }

   void collectImportedModules(llvm::StringSet<> &ImportedModules) {
     ModuleDecl::ImportFilter ImportFilter;
     ImportFilter |= ModuleDecl::ImportFilterKind::Public;
     ImportFilter |= ModuleDecl::ImportFilterKind::Private;
     ImportFilter |= ModuleDecl::ImportFilterKind::ImplementationOnly;

     SmallVector<ModuleDecl::ImportedModule, 16> Imported;
     SmallVector<ModuleDecl::ImportedModule, 16> FurtherImported;
     CurrDeclContext->getParentSourceFile()->getImportedModules(Imported,
                                                                ImportFilter);
     while (!Imported.empty()) {
       ModuleDecl *MD = Imported.back().second;
       Imported.pop_back();
       if (!ImportedModules.insert(MD->getNameStr()).second)
         continue;
       FurtherImported.clear();
       MD->getImportedModules(FurtherImported,
                              ModuleDecl::ImportFilterKind::Public);
       Imported.append(FurtherImported.begin(), FurtherImported.end());
       for (auto SubMod : FurtherImported) {
         Imported.push_back(SubMod);
       }
     }
   }

   void addImportModuleNames() {
     SmallVector<Identifier, 0> ModuleNames;
     Ctx.getVisibleTopLevelModuleNames(ModuleNames);

     llvm::StringSet<> ImportedModules;
     collectImportedModules(ImportedModules);

     auto mainModuleName = CurrModule->getName();
     for (auto ModuleName : ModuleNames) {
       if (ModuleName.str().startswith("_") ||
           ModuleName == mainModuleName ||
           ModuleName == Ctx.SwiftShimsModuleName ||
           ModuleName.str() == SWIFT_ONONE_SUPPORT)
         continue;

       auto MD = ModuleDecl::create(ModuleName, Ctx);
       CodeCompletionResultBuilder Builder(
           Sink,
           CodeCompletionResult::ResultKind::Declaration,
           SemanticContextKind::OtherModule,
           expectedTypeContext);
       Builder.setAssociatedDecl(MD);
       Builder.addTextChunk(MD->getNameStr());
       Builder.addTypeAnnotation("Module");

       // Imported modules are not recommended.
       if (ImportedModules.count(MD->getNameStr()) != 0)
         Builder.setNotRecommended(
             CodeCompletionResult::NotRecommendedReason::Redundant);
     }
   }

   SemanticContextKind getSemanticContext(const Decl *D,
                                          DeclVisibilityKind Reason,
                                          DynamicLookupInfo dynamicLookupInfo) {
     if (ForcedSemanticContext)
       return *ForcedSemanticContext;

     if (IsUnresolvedMember) {
       if (isa<EnumElementDecl>(D)) {
         return SemanticContextKind::ExpressionSpecific;
       }
     }

     switch (Reason) {
     case DeclVisibilityKind::LocalVariable:
     case DeclVisibilityKind::FunctionParameter:
     case DeclVisibilityKind::GenericParameter:
       return SemanticContextKind::Local;

     case DeclVisibilityKind::MemberOfCurrentNominal:
       if (IsSuperRefExpr &&
           CurrentMethod && CurrentMethod->getOverriddenDecl() == D)
         return SemanticContextKind::ExpressionSpecific;
       return SemanticContextKind::CurrentNominal;

     case DeclVisibilityKind::MemberOfProtocolImplementedByCurrentNominal:
     case DeclVisibilityKind::MemberOfSuper:
       return SemanticContextKind::Super;

     case DeclVisibilityKind::MemberOfOutsideNominal:
       return SemanticContextKind::OutsideNominal;

     case DeclVisibilityKind::VisibleAtTopLevel:
       if (CurrDeclContext && D->getModuleContext() == CurrModule) {
         // Treat global variables from the same source file as local when
         // completing at top-level.
         if (isa<VarDecl>(D) && isTopLevelContext(CurrDeclContext) &&
             D->getDeclContext()->getParentSourceFile() ==
                 CurrDeclContext->getParentSourceFile()) {
           return SemanticContextKind::Local;
         } else {
           return SemanticContextKind::CurrentModule;
         }
       } else {
         return SemanticContextKind::OtherModule;
       }

     case DeclVisibilityKind::DynamicLookup:
       switch (dynamicLookupInfo.getKind()) {
       case DynamicLookupInfo::None:
         llvm_unreachable("invalid DynamicLookupInfo::Kind for dynamic lookup");

       case DynamicLookupInfo::AnyObject:
         // AnyObject results can come from different modules, including the
         // current module, but we always assign them the OtherModule semantic
         // context.  These declarations are uniqued by signature, so it is
         // totally random (determined by the hash function) which of the
         // equivalent declarations (across multiple modules) we will get.
         return SemanticContextKind::OtherModule;

       case DynamicLookupInfo::KeyPathDynamicMember:
         // Use the visibility of the underlying declaration.
         // FIXME: KeyPath<AnyObject, U> !?!?
         assert(dynamicLookupInfo.getKeyPathDynamicMember().originalVisibility !=
                DeclVisibilityKind::DynamicLookup);
         return getSemanticContext(
             D, dynamicLookupInfo.getKeyPathDynamicMember().originalVisibility,
             {});
       }
     }
     llvm_unreachable("unhandled kind");
   }

   void addValueBaseName(CodeCompletionResultBuilder &Builder,
                         DeclBaseName Name) {
     auto NameStr = Name.userFacingName();
     bool shouldEscapeKeywords;
     if (Name.isSpecial()) {
       // Special names (i.e. 'init') are always displayed as its user facing
       // name.
       shouldEscapeKeywords = false;
     } else if (ExprType) {
       // After dot. User can write any keyword after '.' except for `init` and
       // `self`. E.g. 'func `init`()' must be called by 'expr.`init`()'.
       shouldEscapeKeywords = NameStr == "self" || NameStr == "init";
     } else {
       // As primary expresson. We have to escape almost every keywords except
       // for 'self' and 'Self'.
       shouldEscapeKeywords = NameStr != "self" && NameStr != "Self";
     }

     if (!shouldEscapeKeywords) {
       Builder.addTextChunk(NameStr);
     } else {
       SmallString<16> buffer;
       Builder.addTextChunk(Builder.escapeKeyword(NameStr, true, buffer));
     }
   }

   void addLeadingDot(CodeCompletionResultBuilder &Builder) {
     if (NeedOptionalUnwrap) {
       Builder.setNumBytesToErase(NumBytesToEraseForOptionalUnwrap);
       Builder.addQuestionMark();
       Builder.addLeadingDot();
       return;
     }
     if (needDot())
       Builder.addLeadingDot();
   }

   void addTypeAnnotation(CodeCompletionResultBuilder &Builder, Type T) {
     T = T->getReferenceStorageReferent();
     if (T->isVoid()) {
       Builder.addTypeAnnotation("Void");
     } else {
       PrintOptions PO;
       PO.OpaqueReturnTypePrinting =
           PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
       Builder.addTypeAnnotation(T.getString(PO));
     }
   }

   void addTypeAnnotationForImplicitlyUnwrappedOptional(
       CodeCompletionResultBuilder &Builder, Type T,
       bool dynamicOrOptional = false) {

     std::string suffix;
     // FIXME: This retains previous behavior, but in reality the type of dynamic
     // lookups is IUO, not Optional as it is for the @optional attribute.
     if (dynamicOrOptional) {
       T = T->getOptionalObjectType();
       suffix = "?";
     }

     T = T->getReferenceStorageReferent();
     PrintOptions PO;
     PO.PrintOptionalAsImplicitlyUnwrapped = true;
     PO.OpaqueReturnTypePrinting =
         PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
     Builder.addTypeAnnotation(T.getString(PO) + suffix);
   }

   /// For printing in code completion results, replace archetypes with
   /// protocol compositions.
   ///
   /// FIXME: Perhaps this should be an option in PrintOptions instead.
   Type eraseArchetypes(Type type, GenericSignature genericSig) {
     if (!genericSig)
       return type;

     auto buildProtocolComposition = [&](ArrayRef<ProtocolDecl *> protos) -> Type {
       SmallVector<Type, 2> types;
       for (auto proto : protos)
         types.push_back(proto->getDeclaredInterfaceType());
       return ProtocolCompositionType::get(Ctx, types,
                                           /*HasExplicitAnyObject=*/false);
     };

     if (auto *genericFuncType = type->getAs<GenericFunctionType>()) {
       SmallVector<AnyFunctionType::Param, 8> erasedParams;
       for (const auto &param : genericFuncType->getParams()) {
         auto erasedTy = eraseArchetypes(param.getPlainType(), genericSig);
         erasedParams.emplace_back(erasedTy, param.getLabel(),
                                   param.getParameterFlags());
       }
       return GenericFunctionType::get(genericSig,
           erasedParams,
           eraseArchetypes(genericFuncType->getResult(), genericSig),
           genericFuncType->getExtInfo());
     }

     return type.transform([&](Type t) -> Type {
       // FIXME: Code completion should only deal with one or the other,
       // and not both.
       if (auto *archetypeType = t->getAs<ArchetypeType>()) {
         // Don't erase opaque archetype.
         if (isa<OpaqueTypeArchetypeType>(archetypeType))
           return t;

         auto protos = archetypeType->getConformsTo();
         if (!protos.empty())
           return buildProtocolComposition(protos);
       }

       if (t->isTypeParameter()) {
         auto protos = genericSig->getConformsTo(t);
         if (!protos.empty())
           return buildProtocolComposition(protos);
       }

       return t;
     });
   }

   Type getTypeOfMember(const ValueDecl *VD,
                        DynamicLookupInfo dynamicLookupInfo) {
     switch (dynamicLookupInfo.getKind()) {
     case DynamicLookupInfo::None:
       return getTypeOfMember(VD, this->ExprType);
     case DynamicLookupInfo::AnyObject:
       return getTypeOfMember(VD, Type());
     case DynamicLookupInfo::KeyPathDynamicMember: {
       auto &keyPathInfo = dynamicLookupInfo.getKeyPathDynamicMember();

       // Map the result of VD to keypath member lookup results.
       // Given:
       //   struct Wrapper<T> {
       //     subscript<U>(dynamicMember: KeyPath<T, U>) -> Wrapped<U> { get }
       //   }
       //   struct Circle {
       //     var center: Point { get }
       //     var radius: Length { get }
       //   }
       //
       // Consider 'Wrapper<Circle>.center'.
       //   'VD' is 'Circle.center' decl.
       //   'keyPathInfo.subscript' is 'Wrapper<T>.subscript' decl.
       //   'keyPathInfo.baseType' is 'Wrapper<Circle>' type.

       // FIXME: Handle nested keypath member lookup.
       // i.e. cases where 'ExprType' != 'keyPathInfo.baseType'.

       auto *SD = keyPathInfo.subscript;
       auto elementTy = SD->getElementTypeLoc().getType();
       if (!elementTy->hasTypeParameter())
         return elementTy;

       // Map is:
       //   { τ_0_0(T) => Circle
       //     τ_1_0(U) => U }
       auto subs = keyPathInfo.baseType->getMemberSubstitutions(SD);

       // If the keyPath result type has type parameters, that might affect the
       // subscript result type.
       auto keyPathResultTy = getResultTypeOfKeypathDynamicMember(SD)->
         mapTypeOutOfContext();
       if (keyPathResultTy->hasTypeParameter()) {
         auto keyPathRootTy = getRootTypeOfKeypathDynamicMember(SD).
           subst(QueryTypeSubstitutionMap{subs},
                 LookUpConformanceInModule(CurrModule));

         // The result type of the VD.
         // i.e. 'Circle.center' => 'Point'.
         auto innerResultTy = getTypeOfMember(VD, keyPathRootTy);

         if (auto paramTy = keyPathResultTy->getAs<GenericTypeParamType>()) {
           // Replace keyPath result type in the map with the inner result type.
           // i.e. Make the map as:
           //   { τ_0_0(T) => Circle
           //     τ_1_0(U) => Point }
           auto key =
               paramTy->getCanonicalType()->castTo<GenericTypeParamType>();
           subs[key] = innerResultTy;
         } else {
           // FIXME: Handle the case where the KeyPath result is generic.
           // e.g. 'subscript<U>(dynamicMember: KeyPath<T, Box<U>>) -> Bag<U>'
           // For now, just return the inner type.
           return innerResultTy;
         }
       }

       // Substitute the element type of the subscript using modified map.
       // i.e. 'Wrapped<U>' => 'Wrapped<Point>'.
       return elementTy.subst(QueryTypeSubstitutionMap{subs},
                              LookUpConformanceInModule(CurrModule));
     }
     }
     llvm_unreachable("Unhandled DynamicLookupInfo Kind in switch");
   }

   Type getTypeOfMember(const ValueDecl *VD, Type ExprType) {
     auto GenericSig = VD->getInnermostDeclContext()
         ->getGenericSignatureOfContext();

     Type T = VD->getInterfaceType();
     assert(!T.isNull());

     if (ExprType) {
       Type ContextTy = VD->getDeclContext()->getDeclaredInterfaceType();
       if (ContextTy) {
         // Look through lvalue types and metatypes
         Type MaybeNominalType = ExprType->getRValueType();

         if (auto Metatype = MaybeNominalType->getAs<MetatypeType>())
           MaybeNominalType = Metatype->getInstanceType();

         if (auto SelfType = MaybeNominalType->getAs<DynamicSelfType>())
           MaybeNominalType = SelfType->getSelfType();

         // For optional protocol requirements and dynamic dispatch,
         // strip off optionality from the base type, but only if
         // we're not actually completing a member of Optional.
         if (!ContextTy->getOptionalObjectType() &&
             MaybeNominalType->getOptionalObjectType())
           MaybeNominalType = MaybeNominalType->getOptionalObjectType();

         // For dynamic lookup don't substitute in the base type.
         if (MaybeNominalType->isAnyObject())
           return T;

         // FIXME: Sometimes ExprType is the type of the member here,
         // and not the type of the base. That is inconsistent and
         // should be cleaned up.
         if (!MaybeNominalType->mayHaveMembers())
           return T;

         // We can't do anything if the base type has unbound generic parameters.
         if (MaybeNominalType->hasUnboundGenericType())
           return T;

         // For everything else, substitute in the base type.
         auto Subs = MaybeNominalType->getMemberSubstitutionMap(CurrModule, VD);

         // Pass in DesugarMemberTypes so that we see the actual
         // concrete type witnesses instead of type alias types.
         T = T.subst(Subs, SubstFlags::DesugarMemberTypes);
       }
     }

     return eraseArchetypes(T, GenericSig);
   }

   Type getAssociatedTypeType(const AssociatedTypeDecl *ATD) {
     Type BaseTy = BaseType;
     if (!BaseTy)
       BaseTy = ExprType;
     if (!BaseTy && CurrDeclContext)
       BaseTy = CurrDeclContext->getInnermostTypeContext()
                    ->getDeclaredTypeInContext();
     if (BaseTy) {
       BaseTy = BaseTy->getInOutObjectType()->getMetatypeInstanceType();
       if (auto NTD = BaseTy->getAnyNominal()) {
         auto *Module = NTD->getParentModule();
         auto Conformance = Module->lookupConformance(
             BaseTy, ATD->getProtocol());
         if (Conformance && Conformance->isConcrete()) {
           return Conformance->getConcrete()
               ->getTypeWitness(const_cast<AssociatedTypeDecl *>(ATD));
         }
       }
     }
     return Type();
   }

   void addVarDeclRef(const VarDecl *VD, DeclVisibilityKind Reason,
                      DynamicLookupInfo dynamicLookupInfo) {
     if (!VD->hasName() ||
         !VD->isAccessibleFrom(CurrDeclContext) ||
         VD->shouldHideFromEditor())
       return;

     Identifier Name = VD->getName();
     assert(!Name.empty() && "name should not be empty");

     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(VD, Reason, dynamicLookupInfo), expectedTypeContext);
     Builder.setAssociatedDecl(VD);
     addLeadingDot(Builder);
     addValueBaseName(Builder, Name);
     setClangDeclKeywords(VD, Pairs, Builder);

     if (!VD->hasInterfaceType())
       return;

     // Add a type annotation.
     Type VarType = getTypeOfMember(VD, dynamicLookupInfo);
     if (auto *PD = dyn_cast<ParamDecl>(VD)) {
       if (Name != Ctx.Id_self && PD->isInOut()) {
         // It is useful to show inout for function parameters.
         // But for 'self' it is just noise.
         VarType = InOutType::get(VarType);
       }
     }
     auto DynamicOrOptional =
         IsDynamicLookup || VD->getAttrs().hasAttribute<OptionalAttr>();
     if (DynamicOrOptional) {
       // Values of properties that were found on a AnyObject have
       // Optional<T> type.  Same applies to optional members.
       VarType = OptionalType::get(VarType);
     }
     if (VD->isImplicitlyUnwrappedOptional())
       addTypeAnnotationForImplicitlyUnwrappedOptional(Builder, VarType,
                                                       DynamicOrOptional);
     else
       addTypeAnnotation(Builder, VarType);
   }

   static bool hasInterestingDefaultValues(const AbstractFunctionDecl *func) {
     if (!func) return false;

     for (auto param : *func->getParameters()) {
       switch (param->getDefaultArgumentKind()) {
       case DefaultArgumentKind::Normal:
       case DefaultArgumentKind::StoredProperty:
       case DefaultArgumentKind::Inherited: // FIXME: include this?
         return true;
       default:
         break;
       }
     }
     return false;
   }

   /// Build argument patterns for calling. Returns \c true if any content was
   /// added to \p Builder. If \p declParams is non-empty, the size must match
   /// with \p typeParams.
   bool addCallArgumentPatterns(CodeCompletionResultBuilder &Builder,
                                ArrayRef<AnyFunctionType::Param> typeParams,
                                ArrayRef<const ParamDecl *> declParams,
                                bool includeDefaultArgs = true) {
     assert(declParams.empty() || typeParams.size() == declParams.size());

     bool modifiedBuilder = false;

     // Determine whether we should skip this argument because it is defaulted.
     auto shouldSkipArg = [&](const ParamDecl *PD) -> bool {
       switch (PD->getDefaultArgumentKind()) {
       case DefaultArgumentKind::None:
         return false;

       case DefaultArgumentKind::Normal:
       case DefaultArgumentKind::StoredProperty:
       case DefaultArgumentKind::Inherited:
       case DefaultArgumentKind::NilLiteral:
       case DefaultArgumentKind::EmptyArray:
       case DefaultArgumentKind::EmptyDictionary:
         return !includeDefaultArgs;

       case DefaultArgumentKind::File:
       case DefaultArgumentKind::Line:
       case DefaultArgumentKind::Column:
       case DefaultArgumentKind::Function:
       case DefaultArgumentKind::DSOHandle:
         // Skip parameters that are defaulted to source location or other
         // caller context information.  Users typically don't want to specify
         // these parameters.
         return true;
       }

       llvm_unreachable("Unhandled DefaultArgumentKind in switch.");
     };

     bool NeedComma = false;
     // Iterate over each parameter.
     for (unsigned i = 0; i != typeParams.size(); ++i) {
       auto &typeParam = typeParams[i];

       Identifier argName;
       Identifier bodyName;
       bool isIUO = false;

       if (!declParams.empty()) {
         auto *PD = declParams[i];
         if (shouldSkipArg(PD))
           continue;
         argName = PD->getArgumentName();
         bodyName = PD->getParameterName();
         isIUO = PD->isImplicitlyUnwrappedOptional();
       } else {
         isIUO = false;
         argName = typeParam.getLabel();
       }

       bool isVariadic = typeParam.isVariadic();
       bool isInOut = typeParam.isInOut();
       bool isAutoclosure = typeParam.isAutoClosure();
       Type paramTy = typeParam.getPlainType();
       if (isVariadic)
         paramTy = ParamDecl::getVarargBaseTy(paramTy);

       if (NeedComma)
         Builder.addComma();

       Builder.addCallParameter(argName, bodyName, paramTy, isVariadic, isInOut,
                                isIUO, isAutoclosure);

       modifiedBuilder = true;
       NeedComma = true;
     }
     return modifiedBuilder;
   }

   /// Build argument patterns for calling. Returns \c true if any content was
   /// added to \p Builder. If \p Params is non-nullptr, \F
   bool addCallArgumentPatterns(CodeCompletionResultBuilder &Builder,
                                const AnyFunctionType *AFT,
                                const ParameterList *Params,
                                bool includeDefaultArgs = true) {
     ArrayRef<const ParamDecl *> declParams;
     if (Params)
       declParams = Params->getArray();
     return addCallArgumentPatterns(Builder, AFT->getParams(), declParams,
                                    includeDefaultArgs);
   }

   static void addThrows(CodeCompletionResultBuilder &Builder,
                         const AnyFunctionType *AFT,
                         const AbstractFunctionDecl *AFD) {
     if (AFD && AFD->getAttrs().hasAttribute<RethrowsAttr>())
       Builder.addAnnotatedRethrows();
     else if (AFT->throws())
       Builder.addAnnotatedThrows();
   }

   void addPoundAvailable(Optional<StmtKind> ParentKind) {
     if (ParentKind != StmtKind::If && ParentKind != StmtKind::Guard)
       return;
     CodeCompletionResultBuilder Builder(Sink, CodeCompletionResult::ResultKind::Keyword,
       SemanticContextKind::ExpressionSpecific, expectedTypeContext);
     Builder.addTextChunk("available");
     Builder.addLeftParen();
     Builder.addSimpleTypedParameter("Platform", /*IsVarArg=*/true);
     Builder.addComma();
     Builder.addTextChunk("*");
     Builder.addRightParen();
   }

   void addPoundSelector(bool needPound) {
     // #selector is only available when the Objective-C runtime is.
     if (!Ctx.LangOpts.EnableObjCInterop) return;

     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::None, {});
     if (needPound)
       Builder.addTextChunk("#selector");
     else
       Builder.addTextChunk("selector");
     Builder.addLeftParen();
     Builder.addSimpleTypedParameter("@objc method", /*IsVarArg=*/false);
     Builder.addRightParen();
     Builder.addTypeAnnotation("Selector");
     // This function is called only if the context type is 'Selector'.
     Builder.setExpectedTypeRelation(
         CodeCompletionResult::ExpectedTypeRelation::Identical);
   }

   void addPoundKeyPath(bool needPound) {
     // #keyPath is only available when the Objective-C runtime is.
     if (!Ctx.LangOpts.EnableObjCInterop) return;

     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::None, {});
     if (needPound)
       Builder.addTextChunk("#keyPath");
     else
       Builder.addTextChunk("keyPath");
     Builder.addLeftParen();
     Builder.addSimpleTypedParameter("@objc property sequence",
                                     /*IsVarArg=*/false);
     Builder.addRightParen();
     Builder.addTypeAnnotation("String");
     // This function is called only if the context type is 'String'.
     Builder.setExpectedTypeRelation(
         CodeCompletionResult::ExpectedTypeRelation::Identical);
   }

   SemanticContextKind getSemanticContextKind(const ValueDecl *VD) {
     // FIXME: to get the corect semantic context we need to know how lookup
     // would have found the VD. For now, just infer a reasonable semantics.

     if (!VD)
       return SemanticContextKind::CurrentModule;

     DeclContext *calleeDC = VD->getDeclContext();

     if (calleeDC->isTypeContext())
       // FIXME: We should distinguish CurrentNominal and Super. We need to
       // propagate the base type to do that.
       return SemanticContextKind::CurrentNominal;

     if (calleeDC->isLocalContext())
       return SemanticContextKind::Local;
     if (calleeDC->getParentModule() == CurrModule)
       return SemanticContextKind::CurrentModule;

     return SemanticContextKind::OtherModule;
   }

   void addSubscriptCallPattern(const AnyFunctionType *AFT,
                                const SubscriptDecl *SD) {
     foundFunction(AFT);
     auto genericSig =
         SD->getInnermostDeclContext()->getGenericSignatureOfContext();
     AFT = eraseArchetypes(const_cast<AnyFunctionType *>(AFT), genericSig)
               ->castTo<AnyFunctionType>();

     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContextKind(SD), expectedTypeContext);
     Builder.setAssociatedDecl(SD);
     setClangDeclKeywords(SD, Pairs, Builder);
     if (!HaveLParen)
       Builder.addLeftBracket();
     else
       Builder.addAnnotatedLeftBracket();
     addCallArgumentPatterns(Builder, AFT, SD->getIndices());
     if (!HaveLParen)
       Builder.addRightBracket();
     else
       Builder.addAnnotatedRightBracket();
     if (SD && SD->isImplicitlyUnwrappedOptional())
       addTypeAnnotationForImplicitlyUnwrappedOptional(Builder,
                                                       AFT->getResult());
     else
       addTypeAnnotation(Builder, AFT->getResult());
   }

   void addFunctionCallPattern(const AnyFunctionType *AFT,
                               const AbstractFunctionDecl *AFD = nullptr) {
     if (AFD) {
       auto genericSig =
           AFD->getInnermostDeclContext()->getGenericSignatureOfContext();
       AFT = eraseArchetypes(const_cast<AnyFunctionType *>(AFT), genericSig)
                 ->castTo<AnyFunctionType>();
     }

     // Add the pattern, possibly including any default arguments.
     auto addPattern = [&](ArrayRef<const ParamDecl *> declParams = {},
                           bool includeDefaultArgs = true) {
       CommandWordsPairs Pairs;
       CodeCompletionResultBuilder Builder(
           Sink,
           AFD ? CodeCompletionResult::ResultKind::Declaration
               : CodeCompletionResult::ResultKind::Pattern,
           getSemanticContextKind(AFD), expectedTypeContext);
       if (AFD) {
         Builder.setAssociatedDecl(AFD);
         setClangDeclKeywords(AFD, Pairs, Builder);
       }

       if (!HaveLParen)
         Builder.addLeftParen();
       else
         Builder.addAnnotatedLeftParen();

       addCallArgumentPatterns(Builder, AFT->getParams(), declParams,
                               includeDefaultArgs);

       // The rparen matches the lparen here so that we insert both or neither.
       if (!HaveLParen)
         Builder.addRightParen();
       else
         Builder.addAnnotatedRightParen();

       addThrows(Builder, AFT, AFD);

       if (AFD &&
           AFD->isImplicitlyUnwrappedOptional())
         addTypeAnnotationForImplicitlyUnwrappedOptional(Builder,
                                                         AFT->getResult());
       else
         addTypeAnnotation(Builder, AFT->getResult());
     };

     if (!AFD || !AFD->getInterfaceType() ||
         !AFD->getInterfaceType()->is<AnyFunctionType>()) {
       // Probably, calling closure type expression.
       foundFunction(AFT);
       addPattern();
       return;
     } else {
       // Calling function or method.
       foundFunction(AFD);

       // FIXME: Hack because we don't know we are calling instance
       // method or not. There's invariant that funcTy is derived from AFD.
       // Only if we are calling instance method on meta type, AFT is still
       // curried. So we should be able to detect that by comparing curried level
       // of AFT and the interface type of AFD.
       auto getCurriedLevel = [](const AnyFunctionType *funcTy) -> unsigned {
         unsigned level = 0;
         while ((funcTy = funcTy->getResult()->getAs<AnyFunctionType>()))
           ++level;
         return level;
       };
       bool isImplicitlyCurriedInstanceMethod =
           (AFD->hasImplicitSelfDecl() &&
            getCurriedLevel(AFT) ==
                getCurriedLevel(
                    AFD->getInterfaceType()->castTo<AnyFunctionType>()) &&
            // NOTE: shouldn't be necessary, but just in case curried level check
            // is insufficient.
            AFT->getParams().size() == 1 &&
            AFT->getParams()[0].getLabel().empty());

       if (isImplicitlyCurriedInstanceMethod) {
         addPattern({AFD->getImplicitSelfDecl()}, /*includeDefaultArgs=*/true);
       } else {
         if (hasInterestingDefaultValues(AFD))
           addPattern(AFD->getParameters()->getArray(),
                      /*includeDefaultArgs=*/false);
         addPattern(AFD->getParameters()->getArray(),
                    /*includeDefaultArgs=*/true);
       }
     }
   }

   bool isImplicitlyCurriedInstanceMethod(const AbstractFunctionDecl *FD) {
     switch (Kind) {
     case LookupKind::ValueExpr:
       return ExprType->is<AnyMetatypeType>() && !FD->isStatic();
     case LookupKind::ValueInDeclContext:
       if (InsideStaticMethod &&
           FD->getDeclContext() == CurrentMethod->getDeclContext() &&
           !FD->isStatic())
         return true;
       if (auto Init = dyn_cast<Initializer>(CurrDeclContext))
         return FD->getDeclContext() == Init->getParent() && !FD->isStatic();
       return false;
     case LookupKind::EnumElement:
     case LookupKind::Type:
     case LookupKind::TypeInDeclContext:
       llvm_unreachable("cannot have a method call while doing a "
                        "type completion");
     case LookupKind::ImportFromModule:
       return false;
     }

     llvm_unreachable("Unhandled LookupKind in switch.");
   }

   void addMethodCall(const FuncDecl *FD, DeclVisibilityKind Reason,
                      DynamicLookupInfo dynamicLookupInfo) {
     if (FD->getName().empty())
       return;

     // Suppress "sequenced" as a result, because it crashes completions.
     // TODO(TF-315): Fix properly and then remove this.
     if (FD->getName().str() == "sequenced")
       return;

     foundFunction(FD);

     Identifier Name = FD->getName();
     assert(!Name.empty() && "name should not be empty");

     Type FunctionType = getTypeOfMember(FD, dynamicLookupInfo);
     assert(FunctionType);

     auto AFT = FunctionType->getAs<AnyFunctionType>();

     bool IsImplicitlyCurriedInstanceMethod = false;
     if (FD->hasImplicitSelfDecl()) {
       IsImplicitlyCurriedInstanceMethod = isImplicitlyCurriedInstanceMethod(FD);

       // Strip off '(_ self: Self)' if needed.
       if (AFT && !IsImplicitlyCurriedInstanceMethod)
         AFT = AFT->getResult()->getAs<AnyFunctionType>();
     }

     bool trivialTrailingClosure = false;
     if (AFT && !IsImplicitlyCurriedInstanceMethod)
       trivialTrailingClosure = hasTrivialTrailingClosure(FD, AFT);

     // Add the method, possibly including any default arguments.
     auto addMethodImpl = [&](bool includeDefaultArgs = true,
                              bool trivialTrailingClosure = false) {
       CommandWordsPairs Pairs;
       CodeCompletionResultBuilder Builder(
           Sink, CodeCompletionResult::ResultKind::Declaration,
           getSemanticContext(FD, Reason, dynamicLookupInfo),
           expectedTypeContext);
       setClangDeclKeywords(FD, Pairs, Builder);
       Builder.setAssociatedDecl(FD);
       addLeadingDot(Builder);
       addValueBaseName(Builder, Name);
       if (IsDynamicLookup)
         Builder.addDynamicLookupMethodCallTail();
       else if (FD->getAttrs().hasAttribute<OptionalAttr>())
         Builder.addOptionalMethodCallTail();

       llvm::SmallString<32> TypeStr;

       if (!AFT) {
         llvm::raw_svector_ostream OS(TypeStr);
         FunctionType.print(OS);
         Builder.addTypeAnnotation(OS.str());
         return;
       }

       if (IsImplicitlyCurriedInstanceMethod) {
         Builder.addLeftParen();
         addCallArgumentPatterns(Builder, AFT->getParams(),
                                 {FD->getImplicitSelfDecl()},
                                 includeDefaultArgs);
         Builder.addRightParen();
       } else if (trivialTrailingClosure) {
         Builder.addBraceStmtWithCursor(" { code }");
         addThrows(Builder, AFT, FD);
       } else {
         Builder.addLeftParen();
         addCallArgumentPatterns(Builder, AFT, FD->getParameters(),
                                 includeDefaultArgs);
         Builder.addRightParen();
         addThrows(Builder, AFT, FD);
       }

       Type ResultType = AFT->getResult();

       // Build type annotation.
       {
         llvm::raw_svector_ostream OS(TypeStr);
         if (IsImplicitlyCurriedInstanceMethod) {
           auto *FnType = ResultType->castTo<AnyFunctionType>();
           AnyFunctionType::printParams(FnType->getParams(), OS);
           ResultType = FnType->getResult();
           OS << " -> ";
         }

         // What's left is the result type.
         if (ResultType->isVoid()) {
           OS << "Void";
         } else {
           // As we did with parameters in addParamPatternFromFunction,
           // for regular methods we'll print '!' after implicitly
           // unwrapped optional results.
           bool IsIUO =
               !IsImplicitlyCurriedInstanceMethod &&
               FD->isImplicitlyUnwrappedOptional();

           PrintOptions PO;
           PO.OpaqueReturnTypePrinting =
               PrintOptions::OpaqueReturnTypePrintingMode::WithoutOpaqueKeyword;
           PO.PrintOptionalAsImplicitlyUnwrapped = IsIUO;
           ResultType.print(OS, PO);
         }
       }
       Builder.addTypeAnnotation(TypeStr);
     };

     if (!AFT || IsImplicitlyCurriedInstanceMethod) {
       addMethodImpl();
     } else {
       if (trivialTrailingClosure)
         addMethodImpl(/*includeDefaultArgs=*/false,
                       /*trivialTrailingClosure=*/true);
       if (hasInterestingDefaultValues(FD))
         addMethodImpl(/*includeDefaultArgs=*/false);
       addMethodImpl(/*includeDefaultArgs=*/true);
     }
   }

   void addConstructorCall(const ConstructorDecl *CD, DeclVisibilityKind Reason,
                           DynamicLookupInfo dynamicLookupInfo,
                           Optional<Type> BaseType, Optional<Type> Result,
                           bool IsOnType = true,
                           Identifier addName = Identifier()) {
     foundFunction(CD);
     Type MemberType = getTypeOfMember(CD, BaseType.getValueOr(ExprType));
     AnyFunctionType *ConstructorType = nullptr;
     if (auto MemberFuncType = MemberType->getAs<AnyFunctionType>())
       ConstructorType = MemberFuncType->getResult()
                                       ->castTo<AnyFunctionType>();

     bool needInit = false;
     if (!IsOnType) {
       assert(addName.empty());
       needInit = true;
     } else if (addName.empty() && HaveDot) {
       needInit = true;
     }

     // If we won't be able to provide a result, bail out.
     if (!ConstructorType && addName.empty() && !needInit)
       return;

     // Add the constructor, possibly including any default arguments.
     auto addConstructorImpl = [&](bool includeDefaultArgs = true) {
       CommandWordsPairs Pairs;
       CodeCompletionResultBuilder Builder(
           Sink, CodeCompletionResult::ResultKind::Declaration,
           getSemanticContext(CD, Reason, dynamicLookupInfo),
           expectedTypeContext);
       setClangDeclKeywords(CD, Pairs, Builder);
       Builder.setAssociatedDecl(CD);
       if (needInit) {
         assert(addName.empty());
         addLeadingDot(Builder);
         Builder.addTextChunk("init");
       } else if (!addName.empty()) {
         Builder.addTextChunk(addName.str());
       }

       if (!ConstructorType) {
         addTypeAnnotation(Builder, MemberType);
         return;
       }

       if (!HaveLParen)
         Builder.addLeftParen();
       else
         Builder.addAnnotatedLeftParen();

       addCallArgumentPatterns(Builder, ConstructorType, CD->getParameters(),
                               includeDefaultArgs);

       // The rparen matches the lparen here so that we insert both or neither.
       if (!HaveLParen)
         Builder.addRightParen();
       else
         Builder.addAnnotatedRightParen();

       addThrows(Builder, ConstructorType, CD);

       if (CD->isImplicitlyUnwrappedOptional()) {
         addTypeAnnotationForImplicitlyUnwrappedOptional(
             Builder, Result.hasValue() ? Result.getValue()
                                        : ConstructorType->getResult());
       } else {
         addTypeAnnotation(Builder, Result.hasValue()
                                        ? Result.getValue()
                                        : ConstructorType->getResult());
       }
     };

     if (ConstructorType && hasInterestingDefaultValues(CD))
       addConstructorImpl(/*includeDefaultArgs*/ false);
     addConstructorImpl();
   }

   void addConstructorCallsForType(Type type, Identifier name,
                                   DeclVisibilityKind Reason,
                                   DynamicLookupInfo dynamicLookupInfo) {
     if (!Ctx.LangOpts.CodeCompleteInitsInPostfixExpr && !IsUnresolvedMember)
       return;

     assert(CurrDeclContext);
     SmallVector<ValueDecl *, 16> initializers;
     if (CurrDeclContext->lookupQualified(type, DeclBaseName::createConstructor(),
                                          NL_QualifiedDefault,
                                          initializers)) {
       for (auto *init : initializers) {
         if (init->shouldHideFromEditor())
           continue;
         if (IsUnresolvedMember &&
             cast<ConstructorDecl>(init)->isFailable() &&
             !cast<ConstructorDecl>(init)->isImplicitlyUnwrappedOptional()) {
           continue;
         }
         addConstructorCall(cast<ConstructorDecl>(init), Reason,
                            dynamicLookupInfo, type, None,
                            /*IsOnType=*/true, name);
       }
     }
   }

   void addSubscriptCall(const SubscriptDecl *SD, DeclVisibilityKind Reason,
                         DynamicLookupInfo dynamicLookupInfo) {
     // Don't add subscript call to unqualified completion.
     if (!ExprType)
       return;

     // Subscript after '.' is valid only after type part of Swift keypath
     // expression. (e.g. '\TyName.SubTy.[0])
     if (HaveDot && !IsAfterSwiftKeyPathRoot)
       return;

     auto subscriptType =
         getTypeOfMember(SD, dynamicLookupInfo)->getAs<AnyFunctionType>();
     if (!subscriptType)
       return;

     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(SD, Reason, dynamicLookupInfo), expectedTypeContext);
     Builder.setAssociatedDecl(SD);
     setClangDeclKeywords(SD, Pairs, Builder);

     // '\TyName#^TOKEN^#' requires leading dot.
     if (!HaveDot && IsAfterSwiftKeyPathRoot)
       Builder.addLeadingDot();

     if (NeedOptionalUnwrap) {
       Builder.setNumBytesToErase(NumBytesToEraseForOptionalUnwrap);
       Builder.addQuestionMark();
     }

     Builder.addLeftBracket();
     addCallArgumentPatterns(Builder, subscriptType, SD->getIndices(), true);
     Builder.addRightBracket();

     // Add a type annotation.
     Type resultTy = subscriptType->getResult();
     if (IsDynamicLookup) {
       // Values of properties that were found on a AnyObject have
       // Optional<T> type.
       resultTy = OptionalType::get(resultTy);
     }
     addTypeAnnotation(Builder, resultTy);
   }

   void addNominalTypeRef(const NominalTypeDecl *NTD, DeclVisibilityKind Reason,
                          DynamicLookupInfo dynamicLookupInfo) {
     if (IsUnresolvedMember)
       return;
     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(NTD, Reason, dynamicLookupInfo),
         expectedTypeContext);
     Builder.setAssociatedDecl(NTD);
     setClangDeclKeywords(NTD, Pairs, Builder);
     addLeadingDot(Builder);
     Builder.addTextChunk(NTD->getName().str());
     addTypeAnnotation(Builder, NTD->getDeclaredType());
   }

   void addTypeAliasRef(const TypeAliasDecl *TAD, DeclVisibilityKind Reason,
                        DynamicLookupInfo dynamicLookupInfo) {
     if (IsUnresolvedMember)
       return;
     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(TAD, Reason, dynamicLookupInfo),
         expectedTypeContext);
     Builder.setAssociatedDecl(TAD);
     setClangDeclKeywords(TAD, Pairs, Builder);
     addLeadingDot(Builder);
     Builder.addTextChunk(TAD->getName().str());
     if (auto underlyingType = TAD->getUnderlyingType()) {
       if (underlyingType->hasError()) {
         Type parentType;
         if (auto nominal = TAD->getDeclContext()->getSelfNominalTypeDecl()) {
           parentType = nominal->getDeclaredInterfaceType();
         }
         addTypeAnnotation(
                       Builder,
                       TypeAliasType::get(const_cast<TypeAliasDecl *>(TAD),
                                          parentType, SubstitutionMap(),
                                          underlyingType));

       } else {
         addTypeAnnotation(Builder, underlyingType);
       }
     }
   }

   void addGenericTypeParamRef(const GenericTypeParamDecl *GP,
                               DeclVisibilityKind Reason,
                               DynamicLookupInfo dynamicLookupInfo) {
     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(GP, Reason, dynamicLookupInfo), expectedTypeContext);
     setClangDeclKeywords(GP, Pairs, Builder);
     Builder.setAssociatedDecl(GP);
     addLeadingDot(Builder);
     Builder.addTextChunk(GP->getName().str());
     addTypeAnnotation(Builder, GP->getDeclaredInterfaceType());
   }

   void addAssociatedTypeRef(const AssociatedTypeDecl *AT,
                             DeclVisibilityKind Reason,
                             DynamicLookupInfo dynamicLookupInfo) {
     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(AT, Reason, dynamicLookupInfo), expectedTypeContext);
     setClangDeclKeywords(AT, Pairs, Builder);
     Builder.setAssociatedDecl(AT);
     addLeadingDot(Builder);
     Builder.addTextChunk(AT->getName().str());
     if (Type T = getAssociatedTypeType(AT))
       addTypeAnnotation(Builder, T);
   }

   void addPrecedenceGroupRef(PrecedenceGroupDecl *PGD) {
     auto semanticContext =
         getSemanticContext(PGD, DeclVisibilityKind::VisibleAtTopLevel, {});
     CodeCompletionResultBuilder builder(
       Sink, CodeCompletionResult::ResultKind::Declaration,
       semanticContext, {});

     builder.addTextChunk(PGD->getName().str());
     builder.setAssociatedDecl(PGD);
   };

   void addEnumElementRef(const EnumElementDecl *EED, DeclVisibilityKind Reason,
                          DynamicLookupInfo dynamicLookupInfo,
                          bool HasTypeContext) {
     if (!EED->hasName() ||
         !EED->isAccessibleFrom(CurrDeclContext) ||
         EED->shouldHideFromEditor())
       return;

     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         HasTypeContext ? SemanticContextKind::ExpressionSpecific
                        : getSemanticContext(EED, Reason, dynamicLookupInfo),
         expectedTypeContext);
     Builder.setAssociatedDecl(EED);
     setClangDeclKeywords(EED, Pairs, Builder);
     addLeadingDot(Builder);
     addValueBaseName(Builder, EED->getName());

     // Enum element is of function type; (Self.type) -> Self or
     // (Self.Type) -> (Args...) -> Self.
     Type EnumType = getTypeOfMember(EED, dynamicLookupInfo);
     if (EnumType->is<AnyFunctionType>())
       EnumType = EnumType->castTo<AnyFunctionType>()->getResult();

     if (EnumType->is<FunctionType>()) {
       Builder.addLeftParen();
       addCallArgumentPatterns(Builder, EnumType->castTo<FunctionType>(),
                               EED->getParameterList());
       Builder.addRightParen();

       // Extract result as the enum type.
       EnumType = EnumType->castTo<FunctionType>()->getResult();
     }

     addTypeAnnotation(Builder, EnumType);
   }

   void addKeyword(StringRef Name, Type TypeAnnotation = Type(),
                   SemanticContextKind SK = SemanticContextKind::None,
                   CodeCompletionKeywordKind KeyKind
                     = CodeCompletionKeywordKind::None,
                   unsigned NumBytesToErase = 0) {
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Keyword, SK,
         expectedTypeContext);
     addLeadingDot(Builder);
     Builder.addTextChunk(Name);
     Builder.setKeywordKind(KeyKind);
     if (TypeAnnotation)
       addTypeAnnotation(Builder, TypeAnnotation);
     if (NumBytesToErase > 0)
       Builder.setNumBytesToErase(NumBytesToErase);
   }

   void addKeyword(StringRef Name, StringRef TypeAnnotation,
                   CodeCompletionKeywordKind KeyKind
                     = CodeCompletionKeywordKind::None) {
     CodeCompletionResultBuilder Builder(
         Sink,
         CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::None, expectedTypeContext);
     addLeadingDot(Builder);
     Builder.addTextChunk(Name);
     Builder.setKeywordKind(KeyKind);
     if (!TypeAnnotation.empty())
       Builder.addTypeAnnotation(TypeAnnotation);
   }

   void addDeclAttrParamKeyword(StringRef Name, StringRef Annotation,
                              bool NeedSpecify) {
     CodeCompletionResultBuilder Builder(
         Sink,
         CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::None, expectedTypeContext);
     Builder.addDeclAttrParamKeyword(Name, Annotation, NeedSpecify);
   }

   void addDeclAttrKeyword(StringRef Name, StringRef Annotation) {
     CodeCompletionResultBuilder Builder(
         Sink,
         CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::None, expectedTypeContext);
     Builder.addDeclAttrKeyword(Name, Annotation);
   }

   /// Add the compound function name for the given function.
   void addCompoundFunctionName(AbstractFunctionDecl *AFD,
                                DeclVisibilityKind Reason,
                                DynamicLookupInfo dynamicLookupInfo) {
     CommandWordsPairs Pairs;
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         getSemanticContext(AFD, Reason, dynamicLookupInfo),
         expectedTypeContext);
     setClangDeclKeywords(AFD, Pairs, Builder);
     Builder.setAssociatedDecl(AFD);

     // Base name
     addLeadingDot(Builder);
     addValueBaseName(Builder, AFD->getBaseName());

     // Add the argument labels.
     auto ArgLabels = AFD->getFullName().getArgumentNames();
     if (!ArgLabels.empty()) {
       if (!HaveLParen)
         Builder.addLeftParen();
       else
         Builder.addAnnotatedLeftParen();

       for (auto ArgLabel : ArgLabels) {
         if (ArgLabel.empty())
           Builder.addTextChunk("_");
         else
           Builder.addTextChunk(ArgLabel.str());
         Builder.addTextChunk(":");
       }

       Builder.addRightParen();
     }
   }

   // Implement swift::VisibleDeclConsumer.
   void foundDecl(ValueDecl *D, DeclVisibilityKind Reason,
                  DynamicLookupInfo dynamicLookupInfo) override {
     if (D->shouldHideFromEditor())
       return;

     if (IsKeyPathExpr && !KeyPathFilter(D, Reason))
       return;

     if (IsSwiftKeyPathExpr && !SwiftKeyPathFilter(D, Reason))
       return;

     // FIXME(InterfaceTypeRequest): Remove this.
     (void)D->getInterfaceType();
     switch (Kind) {
     case LookupKind::ValueExpr:
       if (auto *CD = dyn_cast<ConstructorDecl>(D)) {
         // Do we want compound function names here?
         if (shouldUseFunctionReference(CD)) {
           addCompoundFunctionName(CD, Reason, dynamicLookupInfo);
           return;
         }

         if (auto MT = ExprType->getAs<AnyMetatypeType>()) {
           Type Ty = MT->getInstanceType();
           assert(Ty && "Cannot find instance type.");

           // If instance type is type alias, show users that the constructed
           // type is the typealias instead of the underlying type of the alias.
           Optional<Type> Result = None;
           if (!CD->getInterfaceType()->is<ErrorType>() &&
               isa<TypeAliasType>(Ty.getPointer()) &&
               Ty->getDesugaredType() ==
                 CD->getResultInterfaceType().getPointer()) {
             Result = Ty;
           }
           // If the expression type is not a static metatype or an archetype, the base
           // is not a type. Direct call syntax is illegal on values, so we only add
           // initializer completions if we do not have a left parenthesis and either
           // the initializer is required, the base type's instance type is not a class,
           // or this is a 'self' or 'super' reference.
           if (IsStaticMetatype || IsUnresolvedMember || Ty->is<ArchetypeType>())
             addConstructorCall(CD, Reason, dynamicLookupInfo, None, Result,
                                /*isOnType*/ true);
           else if ((IsSelfRefExpr || IsSuperRefExpr || !Ty->is<ClassType>() ||
                     CD->isRequired()) && !HaveLParen)
             addConstructorCall(CD, Reason, dynamicLookupInfo, None, Result,
                                /*isOnType*/ false);
           return;
         }
         if (!HaveLParen) {
           auto CDC = dyn_cast<ConstructorDecl>(CurrDeclContext);
           if (!CDC)
             return;
           // We do not want 'init' completions for 'self' in non-convenience
           // initializers and for 'super' in convenience initializers.
           if ((IsSelfRefExpr && CDC->isConvenienceInit()) ||
               ((IsSuperRefExpr && !CDC->isConvenienceInit())))
             addConstructorCall(CD, Reason, dynamicLookupInfo, None, None,
                                /*IsOnType=*/false);
         }
         return;
       }

       if (HaveLParen)
         return;

       LLVM_FALLTHROUGH;

     case LookupKind::ValueInDeclContext:
     case LookupKind::ImportFromModule:
       if (auto *VD = dyn_cast<VarDecl>(D)) {
         addVarDeclRef(VD, Reason, dynamicLookupInfo);
         return;
       }

       if (auto *FD = dyn_cast<FuncDecl>(D)) {
         // We cannot call operators with a postfix parenthesis syntax.
         if (FD->isBinaryOperator() || FD->isUnaryOperator())
           return;

         // We cannot call accessors.  We use VarDecls and SubscriptDecls to
         // produce completions that refer to getters and setters.
         if (isa<AccessorDecl>(FD))
           return;

         // Do we want compound function names here?
         if (shouldUseFunctionReference(FD)) {
           addCompoundFunctionName(FD, Reason, dynamicLookupInfo);
           return;
         }

         addMethodCall(FD, Reason, dynamicLookupInfo);
         return;
       }

       if (auto *NTD = dyn_cast<NominalTypeDecl>(D)) {
         addNominalTypeRef(NTD, Reason, dynamicLookupInfo);
         addConstructorCallsForType(NTD->getDeclaredInterfaceType(),
                                    NTD->getName(), Reason, dynamicLookupInfo);
         return;
       }

       if (auto *TAD = dyn_cast<TypeAliasDecl>(D)) {
         addTypeAliasRef(TAD, Reason, dynamicLookupInfo);
         auto type = TAD->mapTypeIntoContext(TAD->getDeclaredInterfaceType());
         if (type->mayHaveMembers())
           addConstructorCallsForType(type, TAD->getName(), Reason,
                                      dynamicLookupInfo);
         return;
       }

       if (auto *GP = dyn_cast<GenericTypeParamDecl>(D)) {
         addGenericTypeParamRef(GP, Reason, dynamicLookupInfo);
         for (auto *protocol : GP->getConformingProtocols())
           addConstructorCallsForType(protocol->getDeclaredInterfaceType(),
                                      GP->getName(), Reason, dynamicLookupInfo);
         return;
       }

       if (auto *AT = dyn_cast<AssociatedTypeDecl>(D)) {
         addAssociatedTypeRef(AT, Reason, dynamicLookupInfo);
         return;
       }

       if (auto *EED = dyn_cast<EnumElementDecl>(D)) {
         addEnumElementRef(EED, Reason, dynamicLookupInfo,
                           /*HasTypeContext=*/false);
         return;
       }

       // Swift key path allows .[0]
       if (auto *SD = dyn_cast<SubscriptDecl>(D)) {
         addSubscriptCall(SD, Reason, dynamicLookupInfo);
         return;
       }
       return;

     case LookupKind::EnumElement:
       handleEnumElement(D, Reason, dynamicLookupInfo);
       return;

     case LookupKind::Type:
     case LookupKind::TypeInDeclContext:
       if (auto *NTD = dyn_cast<NominalTypeDecl>(D)) {
         addNominalTypeRef(NTD, Reason, dynamicLookupInfo);
         return;
       }

       if (auto *TAD = dyn_cast<TypeAliasDecl>(D)) {
         addTypeAliasRef(TAD, Reason, dynamicLookupInfo);
         return;
       }

       if (auto *GP = dyn_cast<GenericTypeParamDecl>(D)) {
         addGenericTypeParamRef(GP, Reason, dynamicLookupInfo);
         return;
       }

       if (auto *AT = dyn_cast<AssociatedTypeDecl>(D)) {
         addAssociatedTypeRef(AT, Reason, dynamicLookupInfo);
         return;
       }

       return;
     }
   }

   bool handleEnumElement(ValueDecl *D, DeclVisibilityKind Reason,
                          DynamicLookupInfo dynamicLookupInfo) {
     if (auto *EED = dyn_cast<EnumElementDecl>(D)) {
       addEnumElementRef(EED, Reason, dynamicLookupInfo,
                         /*HasTypeContext=*/true);
       return true;
     } else if (auto *ED = dyn_cast<EnumDecl>(D)) {
       llvm::DenseSet<EnumElementDecl *> Elements;
       ED->getAllElements(Elements);
       for (auto *Ele : Elements) {
         addEnumElementRef(Ele, Reason, dynamicLookupInfo,
                           /*HasTypeContext=*/true);
       }
       return true;
     }
     return false;
   }

   bool tryTupleExprCompletions(Type ExprType) {
     auto *TT = ExprType->getAs<TupleType>();
     if (!TT)
       return false;

     unsigned Index = 0;
     for (auto TupleElt : TT->getElements()) {
       CodeCompletionResultBuilder Builder(
           Sink,
           CodeCompletionResult::ResultKind::Pattern,
           SemanticContextKind::CurrentNominal, expectedTypeContext);
       addLeadingDot(Builder);
       if (TupleElt.hasName()) {
         Builder.addTextChunk(TupleElt.getName().str());
       } else {
         llvm::SmallString<4> IndexStr;
         {
           llvm::raw_svector_ostream OS(IndexStr);
           OS << Index;
         }
         Builder.addTextChunk(IndexStr.str());
       }
       addTypeAnnotation(Builder, TupleElt.getType());
       Index++;
     }
     return true;
   }

   bool tryFunctionCallCompletions(Type ExprType, const ValueDecl *VD) {
     ExprType = ExprType->getRValueType();
     if (auto AFT = ExprType->getAs<AnyFunctionType>()) {
       if (auto *AFD = dyn_cast_or_null<AbstractFunctionDecl>(VD)) {
         addFunctionCallPattern(AFT, AFD);
       } else {
         addFunctionCallPattern(AFT);
       }
       return true;
     }
     return false;
   }

   bool tryModuleCompletions(Type ExprType) {
     if (auto MT = ExprType->getAs<ModuleType>()) {
       ModuleDecl *M = MT->getModule();
       if (CurrModule != M) {
         // Only use the cache if it is not the current module.
         RequestedCachedResults.push_back(
           RequestedResultsTy::fromModule(M).needLeadingDot(needDot()));
         return true;
       }
     }
     return false;
   }

   /// If the given ExprType is optional, this adds completions for the unwrapped
   /// type.
   ///
   /// \return true if the given type was Optional .
   bool tryUnwrappedCompletions(Type ExprType, bool isIUO) {
     // FIXME: consider types convertible to T?.

     ExprType = ExprType->getRValueType();
     // FIXME: We don't always pass down whether a type is from an
     // unforced IUO.
     if (isIUO) {
       if (Type Unwrapped = ExprType->getOptionalObjectType()) {
         lookupVisibleMemberDecls(*this, Unwrapped, CurrDeclContext,
                                  IncludeInstanceMembers);
         return true;
       }
       assert(IsUnwrappedOptional && "IUOs should be optional if not bound/forced");
       return false;
     }

     if (Type Unwrapped = ExprType->getOptionalObjectType()) {
       llvm::SaveAndRestore<bool> ChangeNeedOptionalUnwrap(NeedOptionalUnwrap,
                                                           true);
       if (DotLoc.isValid()) {
         NumBytesToEraseForOptionalUnwrap = Ctx.SourceMgr.getByteDistance(
             DotLoc, Ctx.SourceMgr.getCodeCompletionLoc());
       } else {
         NumBytesToEraseForOptionalUnwrap = 0;
       }
       if (NumBytesToEraseForOptionalUnwrap <=
           CodeCompletionResult::MaxNumBytesToErase) {
         if (!tryTupleExprCompletions(Unwrapped)) {
           lookupVisibleMemberDecls(*this, Unwrapped, CurrDeclContext,
                                    IncludeInstanceMembers);
         }
       }
       return true;
     }
     return false;
   }

   void getPostfixKeywordCompletions(Type ExprType, Expr *ParsedExpr) {
     if (IsSuperRefExpr)
       return;

     if (!ExprType->getAs<ModuleType>()) {
       addKeyword(getTokenText(tok::kw_self), ExprType->getRValueType(),
                  SemanticContextKind::CurrentNominal,
                  CodeCompletionKeywordKind::kw_self);
     }

     if (isa<TypeExpr>(ParsedExpr)) {
       if (auto *T = ExprType->getAs<AnyMetatypeType>()) {
         auto instanceTy = T->getInstanceType();
         if (instanceTy->isAnyExistentialType()) {
           addKeyword("Protocol", MetatypeType::get(instanceTy),
                      SemanticContextKind::CurrentNominal);
           addKeyword("Type", ExistentialMetatypeType::get(instanceTy),
                      SemanticContextKind::CurrentNominal);
         } else {
           addKeyword("Type", MetatypeType::get(instanceTy),
                      SemanticContextKind::CurrentNominal);
         }
       }
     }
   }

   void getValueExprCompletions(Type ExprType, ValueDecl *VD = nullptr) {
     Kind = LookupKind::ValueExpr;
     NeedLeadingDot = !HaveDot;

     ExprType = ExprType->getRValueType();
     assert(!ExprType->hasTypeParameter());

     this->ExprType = ExprType;

     // Open existential types, so that lookupVisibleMemberDecls() can properly
     // substitute them.
     bool WasOptional = false;
     if (auto OptionalType = ExprType->getOptionalObjectType()) {
       ExprType = OptionalType;
       WasOptional = true;
     }

     if (!ExprType->getMetatypeInstanceType()->isAnyObject())
       if (ExprType->isAnyExistentialType())
         ExprType = OpenedArchetypeType::getAny(ExprType);

     if (WasOptional)
       ExprType = OptionalType::get(ExprType);

     // Handle special cases
     bool isIUO = VD && VD->isImplicitlyUnwrappedOptional();
     if (tryFunctionCallCompletions(ExprType, VD))
       return;
     if (tryModuleCompletions(ExprType))
       return;
     if (tryTupleExprCompletions(ExprType))
       return;
     // Don't check/return so we still add the members of Optional itself below
     tryUnwrappedCompletions(ExprType, isIUO);

     lookupVisibleMemberDecls(*this, ExprType, CurrDeclContext,
                              IncludeInstanceMembers);
   }

   template <typename T>
   void collectOperatorsFromMap(SourceFile::OperatorMap<T> &map,
                                bool includePrivate,
                                std::vector<OperatorDecl *> &results) {
     for (auto &pair : map) {
       if (pair.second.getPointer() &&
           (pair.second.getInt() || includePrivate)) {
         results.push_back(pair.second.getPointer());
       }
     }
   }

   void collectOperatorsFrom(SourceFile *SF,
                             std::vector<OperatorDecl *> &results) {
     bool includePrivate = CurrDeclContext->getParentSourceFile() == SF;
     collectOperatorsFromMap(SF->PrefixOperators, includePrivate, results);
     collectOperatorsFromMap(SF->PostfixOperators, includePrivate, results);
     collectOperatorsFromMap(SF->InfixOperators, includePrivate, results);
   }

   void collectOperatorsFrom(LoadedFile *F,
                             std::vector<OperatorDecl *> &results) {
     SmallVector<Decl *, 64> topLevelDecls;
     F->getTopLevelDecls(topLevelDecls);
     for (auto D : topLevelDecls) {
       if (auto op = dyn_cast<OperatorDecl>(D))
         results.push_back(op);
     }
   }

   std::vector<OperatorDecl *> collectOperators() {
     std::vector<OperatorDecl *> results;
     assert(CurrDeclContext);
     for (auto import : namelookup::getAllImports(CurrDeclContext)) {
       for (auto fileUnit : import.second->getFiles()) {
         switch (fileUnit->getKind()) {
         case FileUnitKind::Builtin:
         case FileUnitKind::ClangModule:
         case FileUnitKind::DWARFModule:
           continue;
         case FileUnitKind::Source:
           collectOperatorsFrom(cast<SourceFile>(fileUnit), results);
           break;
         case FileUnitKind::SerializedAST:
           collectOperatorsFrom(cast<LoadedFile>(fileUnit), results);
           break;
         }
       }
     }
     return results;
   }

   void addPostfixBang(Type resultType) {
     CodeCompletionResultBuilder builder(
         Sink, CodeCompletionResult::ResultKind::BuiltinOperator,
         SemanticContextKind::None, {});
     // FIXME: we can't use the exclamation mark chunk kind, or it isn't
     // included in the completion name.
     builder.addTextChunk("!");
     assert(resultType);
     addTypeAnnotation(builder, resultType);
   }

   void addPostfixOperatorCompletion(OperatorDecl *op, Type resultType) {
     // FIXME: we should get the semantic context of the function, not the
     // operator decl.
     auto semanticContext =
         getSemanticContext(op, DeclVisibilityKind::VisibleAtTopLevel, {});
     CodeCompletionResultBuilder builder(
         Sink, CodeCompletionResult::ResultKind::Declaration, semanticContext,
         {});

     // FIXME: handle variable amounts of space.
     if (HaveLeadingSpace)
       builder.setNumBytesToErase(1);
     builder.setAssociatedDecl(op);
     builder.addTextChunk(op->getName().str());
     assert(resultType);
     addTypeAnnotation(builder, resultType);
   }

   void tryPostfixOperator(Expr *expr, PostfixOperatorDecl *op) {
     ConcreteDeclRef referencedDecl;
     FunctionType *funcTy = getTypeOfCompletionOperator(
         const_cast<DeclContext *>(CurrDeclContext), expr, op->getName(),
         DeclRefKind::PostfixOperator, referencedDecl);
     if (!funcTy)
       return;

     // TODO: Use referencedDecl (FuncDecl) instead of 'op' (OperatorDecl).
     addPostfixOperatorCompletion(op, funcTy->getResult());
   }

   void addAssignmentOperator(Type RHSType, Type resultType) {
     CodeCompletionResultBuilder builder(
         Sink, CodeCompletionResult::ResultKind::BuiltinOperator,
         SemanticContextKind::None, {});

     if (HaveLeadingSpace)
       builder.addAnnotatedWhitespace(" ");
     else
       builder.addWhitespace(" ");
     builder.addEqual();
     builder.addWhitespace(" ");
     assert(RHSType && resultType);
     builder.addCallParameter(Identifier(), Identifier(), RHSType,
                              /*IsVarArg*/ false, /*IsInOut*/ false,
                              /*isIUO*/ false, /*isAutoClosure*/ false);
     addTypeAnnotation(builder, resultType);
   }

   void addInfixOperatorCompletion(OperatorDecl *op, Type resultType,
                                   Type RHSType) {
     // FIXME: we should get the semantic context of the function, not the
     // operator decl.
     auto semanticContext =
         getSemanticContext(op, DeclVisibilityKind::VisibleAtTopLevel, {});
     CodeCompletionResultBuilder builder(
         Sink, CodeCompletionResult::ResultKind::Declaration, semanticContext,
         {});
     builder.setAssociatedDecl(op);

     if (HaveLeadingSpace)
       builder.addAnnotatedWhitespace(" ");
     else
       builder.addWhitespace(" ");
     builder.addTextChunk(op->getName().str());
     builder.addWhitespace(" ");
     if (RHSType)
       builder.addCallParameter(Identifier(), Identifier(), RHSType,
                                /*IsVarArg*/ false, /*IsInOut*/ false,
                                /*isIUO*/ false, /*isAutoClosure*/ false);
     if (resultType)
       addTypeAnnotation(builder, resultType);
   }

   void tryInfixOperatorCompletion(Expr *foldedExpr, InfixOperatorDecl *op) {
     ConcreteDeclRef referencedDecl;
     FunctionType *funcTy = getTypeOfCompletionOperator(
         const_cast<DeclContext *>(CurrDeclContext), foldedExpr, op->getName(),
         DeclRefKind::BinaryOperator, referencedDecl);
     if (!funcTy)
       return;

     Type lhsTy = funcTy->getParams()[0].getPlainType();
     Type rhsTy = funcTy->getParams()[1].getPlainType();
     Type resultTy = funcTy->getResult();

     // Don't complete optional operators on non-optional types.
     if (!lhsTy->getRValueType()->getOptionalObjectType()) {
       // 'T ?? T'
       if (op->getName().str() == "??")
         return;
       // 'T == nil'
       if (auto NT = rhsTy->getNominalOrBoundGenericNominal())
         if (NT->getName() ==
             CurrDeclContext->getASTContext().Id_OptionalNilComparisonType)
           return;
     }

     // If the right-hand side and result type are both type parameters, we're
     // not providing a useful completion.
     if (resultTy->isTypeParameter() && rhsTy->isTypeParameter())
       return;

     // TODO: Use referencedDecl (FuncDecl) instead of 'op' (OperatorDecl).
     addInfixOperatorCompletion(op, funcTy->getResult(),
                                funcTy->getParams()[1].getPlainType());
   }

   Expr *typeCheckLeadingSequence(Expr *LHS, ArrayRef<Expr *> leadingSequence) {
     if (leadingSequence.empty())
       return LHS;

     SourceRange sequenceRange(leadingSequence.front()->getStartLoc(),
                               LHS->getEndLoc());
     auto *expr = findParsedExpr(CurrDeclContext, sequenceRange);
     if (!expr)
       return LHS;

     if (expr->getType() && !expr->getType()->hasError())
       return expr;

     if (!typeCheckExpression(const_cast<DeclContext *>(CurrDeclContext), expr))
       return expr;
     return LHS;
   }

   void getOperatorCompletions(Expr *LHS, ArrayRef<Expr *> leadingSequence) {
     if (IsSuperRefExpr)
       return;

     Expr *foldedExpr = typeCheckLeadingSequence(LHS, leadingSequence);

     std::vector<OperatorDecl *> operators = collectOperators();
     // FIXME: this always chooses the first operator with the given name.
     llvm::DenseSet<Identifier> seenPostfixOperators;
     llvm::DenseSet<Identifier> seenInfixOperators;

     for (auto op : operators) {
       switch (op->getKind()) {
       case DeclKind::PrefixOperator:
         // Don't insert prefix operators in postfix position.
         // FIXME: where should these get completed?
         break;
       case DeclKind::PostfixOperator:
         if (seenPostfixOperators.insert(op->getName()).second)
           tryPostfixOperator(LHS, cast<PostfixOperatorDecl>(op));
         break;
       case DeclKind::InfixOperator:
         if (seenInfixOperators.insert(op->getName()).second)
           tryInfixOperatorCompletion(foldedExpr, cast<InfixOperatorDecl>(op));
         break;
       default:
         llvm_unreachable("unexpected operator kind");
       }
     }

     if (leadingSequence.empty() && LHS->getType() &&
         LHS->getType()->hasLValueType()) {
       addAssignmentOperator(LHS->getType()->getRValueType(),
                             CurrDeclContext->getASTContext().TheEmptyTupleType);
     }

     // FIXME: unify this with the ?.member completions.
     if (auto T = LHS->getType())
       if (auto ValueT = T->getRValueType()->getOptionalObjectType())
         addPostfixBang(ValueT);
   }

   void addTypeRelationFromProtocol(CodeCompletionResultBuilder &builder,
                                    CodeCompletionLiteralKind kind,
                                    StringRef defaultTypeName) {
     // Check for matching ExpectedTypes.
     auto *P = Ctx.getProtocol(protocolForLiteralKind(kind));
     for (auto T : expectedTypeContext.possibleTypes) {
       if (!T)
         continue;

       auto typeRelation = CodeCompletionResult::Identical;
       // Convert through optional types unless we're looking for a protocol
       // that Optional itself conforms to.
       if (kind != CodeCompletionLiteralKind::NilLiteral) {
         if (auto optionalObjT = T->getOptionalObjectType()) {
           T = optionalObjT;
           typeRelation = CodeCompletionResult::Convertible;
         }
       }

       // Check for conformance to the literal protocol.
       if (auto *NTD = T->getAnyNominal()) {
         SmallVector<ProtocolConformance *, 2> conformances;
         if (NTD->lookupConformance(CurrModule, P, conformances)) {
           addTypeAnnotation(builder, T);
           builder.setExpectedTypeRelation(typeRelation);
           return;
         }
       }
     }

     // Fallback to showing the default type.
     if (!defaultTypeName.empty())
       builder.addTypeAnnotation(defaultTypeName);
   }

   /// Add '#file', '#line', et at.
   void addPoundLiteralCompletions(bool needPound) {
     auto addFromProto = [&](StringRef name, CodeCompletionKeywordKind kwKind,
                             CodeCompletionLiteralKind literalKind,
                             StringRef defaultTypeName) {
       if (!needPound)
         name = name.substr(1);

       CodeCompletionResultBuilder builder(
           Sink, CodeCompletionResult::ResultKind::Keyword,
           SemanticContextKind::None, {});
       builder.setLiteralKind(literalKind);
       builder.setKeywordKind(kwKind);
       builder.addTextChunk(name);
       addTypeRelationFromProtocol(builder, literalKind, defaultTypeName);
     };

     addFromProto("#function", CodeCompletionKeywordKind::pound_function,
                  CodeCompletionLiteralKind::StringLiteral, "String");
     addFromProto("#file", CodeCompletionKeywordKind::pound_file,
                  CodeCompletionLiteralKind::StringLiteral, "String");
     addFromProto("#line", CodeCompletionKeywordKind::pound_line,
                  CodeCompletionLiteralKind::IntegerLiteral, "Int");
     addFromProto("#column", CodeCompletionKeywordKind::pound_column,
                  CodeCompletionLiteralKind::IntegerLiteral, "Int");

     addKeyword(needPound ? "#dsohandle" : "dsohandle", "UnsafeRawPointer",
                CodeCompletionKeywordKind::pound_dsohandle);
   }

   void addValueLiteralCompletions() {
     auto &context = CurrDeclContext->getASTContext();

     auto addFromProto = [&](
         CodeCompletionLiteralKind kind, StringRef defaultTypeName,
         llvm::function_ref<void(CodeCompletionResultBuilder &)> consumer,
         bool isKeyword = false) {

       CodeCompletionResultBuilder builder(Sink, CodeCompletionResult::Literal,
                                           SemanticContextKind::None, {});
       builder.setLiteralKind(kind);

       consumer(builder);
       addTypeRelationFromProtocol(builder, kind, defaultTypeName);
     };

     // FIXME: the pedantically correct way is to resolve Swift.*LiteralType.

     using LK = CodeCompletionLiteralKind;
     using Builder = CodeCompletionResultBuilder;

     // Add literal completions that conform to specific protocols.
     addFromProto(LK::IntegerLiteral, "Int", [](Builder &builder) {
       builder.addTextChunk("0");
     });
     addFromProto(LK::BooleanLiteral, "Bool", [](Builder &builder) {
       builder.addTextChunk("true");
     }, /*isKeyword=*/true);
     addFromProto(LK::BooleanLiteral, "Bool", [](Builder &builder) {
       builder.addTextChunk("false");
     }, /*isKeyword=*/true);
     addFromProto(LK::NilLiteral, "", [](Builder &builder) {
       builder.addTextChunk("nil");
     }, /*isKeyword=*/true);
     addFromProto(LK::StringLiteral, "String", [&](Builder &builder) {
       builder.addTextChunk("\"");
       builder.addSimpleNamedParameter("abc");
       builder.addTextChunk("\"");
     });
     addFromProto(LK::ArrayLiteral, "Array", [&](Builder &builder) {
       builder.addLeftBracket();
       builder.addSimpleNamedParameter("values");
       builder.addRightBracket();
     });
     addFromProto(LK::DictionaryLiteral, "Dictionary", [&](Builder &builder) {
       builder.addLeftBracket();
       builder.addSimpleNamedParameter("key");
       builder.addTextChunk(": ");
       builder.addSimpleNamedParameter("value");
       builder.addRightBracket();
     });

     auto floatType = context.getFloatDecl()->getDeclaredType();
     addFromProto(LK::ColorLiteral, "", [&](Builder &builder) {
       builder.addTextChunk("#colorLiteral");
       builder.addLeftParen();
       builder.addCallParameter(context.getIdentifier("red"), floatType,
                                /*IsVarArg*/ false, /*IsInOut*/ false,
                                /*isIUO*/ false, /*isAutoClosure*/ false);
       builder.addComma();
       builder.addCallParameter(context.getIdentifier("green"), floatType,
                                /*IsVarArg*/ false, /*IsInOut*/ false,
                                /*isIUO*/ false, /*isAutoClosure*/ false);
       builder.addComma();
       builder.addCallParameter(context.getIdentifier("blue"), floatType,
                                /*IsVarArg*/ false, /*IsInOut*/ false,
                                /*isIUO*/ false, /*isAutoClosure*/ false);
       builder.addComma();
       builder.addCallParameter(context.getIdentifier("alpha"), floatType,
                                /*IsVarArg*/ false, /*IsInOut*/ false,
                                /*isIUO*/ false, /*isAutoClosure*/ false);
       builder.addRightParen();
     });

     auto stringType = context.getStringDecl()->getDeclaredType();
     addFromProto(LK::ImageLiteral, "", [&](Builder &builder) {
       builder.addTextChunk("#imageLiteral");
       builder.addLeftParen();
       builder.addCallParameter(context.getIdentifier("resourceName"),
                                stringType, /*IsVarArg*/ false,
                                /*IsInOut*/ false, /*isIUO*/ false,
                                /*isAutoClosure*/ false);
       builder.addRightParen();
     });

     // Add tuple completion (item, item).
     {
       CodeCompletionResultBuilder builder(Sink, CodeCompletionResult::Literal,
                                           SemanticContextKind::None, {});
       builder.setLiteralKind(LK::Tuple);

       builder.addLeftParen();
       builder.addSimpleNamedParameter("values");
       builder.addRightParen();
       for (auto T : expectedTypeContext.possibleTypes) {
         if (T && T->is<TupleType>() && !T->isVoid()) {
           addTypeAnnotation(builder, T);
           builder.setExpectedTypeRelation(CodeCompletionResult::Identical);
           break;
         }
       }
     }
   }

   void addObjCPoundKeywordCompletions(bool needPound) {
     if (!Ctx.LangOpts.EnableObjCInterop)
       return;

     // If the expected type is ObjectiveC.Selector, add #selector. If
     // it's String, add #keyPath.
     bool addedSelector = false;
     bool addedKeyPath = false;

     for (auto T : expectedTypeContext.possibleTypes) {
       T = T->lookThroughAllOptionalTypes();
       if (auto structDecl = T->getStructOrBoundGenericStruct()) {
         if (!addedSelector && structDecl->getName() == Ctx.Id_Selector &&
             structDecl->getParentModule()->getName() == Ctx.Id_ObjectiveC) {
           addPoundSelector(needPound);
           if (addedKeyPath)
             break;
           addedSelector = true;
           continue;
         }
       }

       if (!addedKeyPath && T->getAnyNominal() == Ctx.getStringDecl()) {
         addPoundKeyPath(needPound);
         if (addedSelector)
           break;
         addedKeyPath = true;
         continue;
       }
     }
   }

   struct FilteredDeclConsumer : public swift::VisibleDeclConsumer {
     swift::VisibleDeclConsumer &Consumer;
     DeclFilter Filter;
     FilteredDeclConsumer(swift::VisibleDeclConsumer &Consumer,
                          DeclFilter Filter) : Consumer(Consumer), Filter(Filter) {}
     void foundDecl(ValueDecl *VD, DeclVisibilityKind Kind,
                    DynamicLookupInfo dynamicLookupInfo) override {
       if (Filter(VD, Kind))
         Consumer.foundDecl(VD, Kind, dynamicLookupInfo);
     }
   };

   void getValueCompletionsInDeclContext(SourceLoc Loc,
                                         DeclFilter Filter = DefaultFilter,
                                         bool IncludeTopLevel = false,
                                         bool RequestCache = true,
                                         bool LiteralCompletions = true) {
     ExprType = Type();
     Kind = LookupKind::ValueInDeclContext;
     NeedLeadingDot = false;
     FilteredDeclConsumer Consumer(*this, Filter);
     lookupVisibleDecls(Consumer, CurrDeclContext,
                        /*IncludeTopLevel=*/IncludeTopLevel, Loc);
     if (RequestCache)
       RequestedCachedResults.push_back(RequestedResultsTy::toplevelResults());

     // Manually add any expected nominal types from imported modules so that
     // they get their expected type relation. Don't include protocols, since
     // they can't be initialized from the type name.
     // FIXME: this does not include types that conform to an expected protocol.
     // FIXME: this creates duplicate results.
     for (auto T : expectedTypeContext.possibleTypes) {
       if (auto NT = T->getAs<NominalType>()) {
         if (auto NTD = NT->getDecl()) {
           if (!isa<ProtocolDecl>(NTD) &&
               NTD->getModuleContext() != CurrModule) {
             addNominalTypeRef(NT->getDecl(),
                               DeclVisibilityKind::VisibleAtTopLevel, {});
           }
         }
       }
     }

     if (CompletionContext) {
       // FIXME: this is an awful simplification that says all and only enums can
       // use implicit member syntax (leading dot). Computing the accurate answer
       // using lookup (e.g. getUnresolvedMemberCompletions) is too expensive,
       // and for some clients this approximation is good enough.
       CompletionContext->MayUseImplicitMemberExpr =
           std::any_of(expectedTypeContext.possibleTypes.begin(),
                       expectedTypeContext.possibleTypes.end(),
           [](Type T) {
             if (auto *NTD = T->getAnyNominal())
               return isa<EnumDecl>(NTD);
             return false;
           });
     }

     if (LiteralCompletions) {
       addValueLiteralCompletions();
       addPoundLiteralCompletions(/*needPound=*/true);
     }

     addObjCPoundKeywordCompletions(/*needPound=*/true);
   }

   void getUnresolvedMemberCompletions(Type T) {
     if (!T->mayHaveMembers())
       return;

     DeclContext *DC = const_cast<DeclContext *>(CurrDeclContext);

     // We can only say .foo where foo is a static member of the contextual
     // type and has the same type (or if the member is a function, then the
     // same result type) as the contextual type.
     FilteredDeclConsumer consumer(*this, [=](ValueDecl *VD,
                                              DeclVisibilityKind Reason) {
       return isReferenceableByImplicitMemberExpr(CurrModule, DC, T, VD);
     });

     auto baseType = MetatypeType::get(T);
     llvm::SaveAndRestore<LookupKind> SaveLook(Kind, LookupKind::ValueExpr);
     llvm::SaveAndRestore<Type> SaveType(ExprType, baseType);
     llvm::SaveAndRestore<bool> SaveUnresolved(IsUnresolvedMember, true);
     lookupVisibleMemberDecls(consumer, baseType, CurrDeclContext,
                              /*includeInstanceMembers=*/false);
   }

   void getUnresolvedMemberCompletions(ArrayRef<Type> Types) {
     NeedLeadingDot = !HaveDot;
     for (auto T : Types) {
       if (!T)
         continue;
       if (auto objT = T->getOptionalObjectType()) {
         // If this is optional type, perform completion for the object type.
         // i.e. 'let _: Enum??? = .enumMember' is legal.
         getUnresolvedMemberCompletions(objT->lookThroughAllOptionalTypes());

         // Add 'nil' keyword with erasing '.' instruction.
         unsigned bytesToErase = 0;
         auto &SM = CurrDeclContext->getASTContext().SourceMgr;
         if (DotLoc.isValid())
           bytesToErase = SM.getByteDistance(DotLoc, SM.getCodeCompletionLoc());
         addKeyword("nil", T, SemanticContextKind::ExpressionSpecific,
                    CodeCompletionKeywordKind::kw_nil, bytesToErase);
       }
       getUnresolvedMemberCompletions(T);
     }
   }

   void addArgNameCompletionResults(ArrayRef<StringRef> Names) {
     for (auto Name : Names) {
       CodeCompletionResultBuilder Builder(Sink,
                                           CodeCompletionResult::ResultKind::Keyword,
                                           SemanticContextKind::ExpressionSpecific, {});
       Builder.addTextChunk(Name);
       Builder.addCallParameterColon();
       Builder.addTypeAnnotation("Argument name");
     }
   }

   void getTypeCompletions(Type BaseType) {
     Kind = LookupKind::Type;
     this->BaseType = BaseType;
     NeedLeadingDot = !HaveDot;
     lookupVisibleMemberDecls(*this, MetatypeType::get(BaseType),
                              CurrDeclContext,
                              IncludeInstanceMembers);
     if (BaseType->isAnyExistentialType()) {
       addKeyword("Protocol", MetatypeType::get(BaseType));
       addKeyword("Type", ExistentialMetatypeType::get(BaseType));
     } else {
       addKeyword("Type", MetatypeType::get(BaseType));
     }
   }

   static bool canUseAttributeOnDecl(DeclAttrKind DAK, bool IsInSil,
                                     Optional<DeclKind> DK) {
     if (DeclAttribute::isUserInaccessible(DAK))
       return false;
     if (DeclAttribute::isDeclModifier(DAK))
       return false;
     if (DeclAttribute::shouldBeRejectedByParser(DAK))
       return false;
     if (!IsInSil && DeclAttribute::isSilOnly(DAK))
       return false;
     if (!DK.hasValue())
       return true;
     return DeclAttribute::canAttributeAppearOnDeclKind(DAK, DK.getValue());
   }

   void getAttributeDeclCompletions(bool IsInSil, Optional<DeclKind> DK) {
     // FIXME: also include user-defined attribute keywords
     StringRef TargetName = "Declaration";
     if (DK.hasValue()) {
       switch (DK.getValue()) {
 #define DECL(Id, ...)                                                         \
       case DeclKind::Id:                                                      \
         TargetName = #Id;                                                     \
         break;
 #include "swift/AST/DeclNodes.def"
       }
     }
     std::string Description = TargetName.str() + " Attribute";
 #define DECL_ATTR(KEYWORD, NAME, ...)                                         \
     if (canUseAttributeOnDecl(DAK_##NAME, IsInSil, DK))                       \
       addDeclAttrKeyword(#KEYWORD, Description);
 #include "swift/AST/Attr.def"
   }

   void getAttributeDeclParamCompletions(DeclAttrKind AttrKind, int ParamIndex) {
     if (AttrKind == DAK_Available) {
       if (ParamIndex == 0) {
         addDeclAttrParamKeyword("*", "Platform", false);
 #define AVAILABILITY_PLATFORM(X, PrettyName)                                  \
         addDeclAttrParamKeyword(#X, "Platform", false);
 #include "swift/AST/PlatformKinds.def"
       } else {
         addDeclAttrParamKeyword("unavailable", "", false);
         addDeclAttrParamKeyword("message", "Specify message", true);
         addDeclAttrParamKeyword("renamed", "Specify replacing name", true);
         addDeclAttrParamKeyword("introduced", "Specify version number", true);
         addDeclAttrParamKeyword("deprecated", "Specify version number", true);
       }
     }
   }

   void collectPrecedenceGroups() {
     assert(CurrDeclContext);

     if (CurrModule) {
       for (auto FU: CurrModule->getFiles()) {
         // We are looking through the current module,
         // inspect only source files.
         if (FU->getKind() != FileUnitKind::Source)
           continue;

         llvm::SmallVector<PrecedenceGroupDecl*, 4> results;
         cast<SourceFile>(FU)->getPrecedenceGroups(results);

         for (auto PG: results)
             addPrecedenceGroupRef(PG);
       }
     }
     for (auto Import : namelookup::getAllImports(CurrDeclContext)) {
       auto Module = Import.second;
       if (Module == CurrModule)
         continue;

       RequestedCachedResults.push_back(
         RequestedResultsTy::fromModule(Module).onlyPrecedenceGroups());
     }
   }

   void getPrecedenceGroupCompletions(SyntaxKind SK) {
     switch (SK) {
     case SyntaxKind::PrecedenceGroupAssociativity:
       addKeyword(getAssociativitySpelling(Associativity::None));
       addKeyword(getAssociativitySpelling(Associativity::Left));
       addKeyword(getAssociativitySpelling(Associativity::Right));
       break;
     case SyntaxKind::PrecedenceGroupAssignment:
       addKeyword(getTokenText(tok::kw_false), Type(), SemanticContextKind::None,
                  CodeCompletionKeywordKind::kw_false);
       addKeyword(getTokenText(tok::kw_true), Type(), SemanticContextKind::None,
                  CodeCompletionKeywordKind::kw_true);
       break;
     case SyntaxKind::PrecedenceGroupAttributeList:
       addKeyword("associativity");
       addKeyword("higherThan");
       addKeyword("lowerThan");
       addKeyword("assignment");
       break;
     case SyntaxKind::PrecedenceGroupRelation:
       collectPrecedenceGroups();
       break;
     default:
         llvm_unreachable("not a precedencegroup SyntaxKind");
     }
   }

   void getPoundAvailablePlatformCompletions() {

     // The platform names should be identical to those in @available.
     getAttributeDeclParamCompletions(DAK_Available, 0);
   }

   void getTypeCompletionsInDeclContext(SourceLoc Loc) {
     Kind = LookupKind::TypeInDeclContext;
     lookupVisibleDecls(*this, CurrDeclContext,
                        /*IncludeTopLevel=*/false, Loc);

     RequestedCachedResults.push_back(
       RequestedResultsTy::toplevelResults().onlyTypes());
   }

   void getToplevelCompletions(bool OnlyTypes) {
     Kind = OnlyTypes ? LookupKind::TypeInDeclContext
                      : LookupKind::ValueInDeclContext;
     NeedLeadingDot = false;
     AccessFilteringDeclConsumer FilteringConsumer(CurrDeclContext, *this);
     CurrModule->lookupVisibleDecls({}, FilteringConsumer,
                                    NLKind::UnqualifiedLookup);
   }

   void getVisibleDeclsOfModule(const ModuleDecl *TheModule,
                                ArrayRef<std::string> AccessPath,
                                bool ResultsHaveLeadingDot) {
     Kind = LookupKind::ImportFromModule;
     NeedLeadingDot = ResultsHaveLeadingDot;

     llvm::SmallVector<std::pair<Identifier, SourceLoc>, 1> LookupAccessPath;
     for (auto Piece : AccessPath) {
       LookupAccessPath.push_back(
           std::make_pair(Ctx.getIdentifier(Piece), SourceLoc()));
     }
     AccessFilteringDeclConsumer FilteringConsumer(CurrDeclContext, *this);
     TheModule->lookupVisibleDecls(LookupAccessPath, FilteringConsumer,
                                   NLKind::UnqualifiedLookup);

     llvm::SmallVector<PrecedenceGroupDecl*, 16> precedenceGroups;
     TheModule->getPrecedenceGroups(precedenceGroups);

     for (auto PGD: precedenceGroups)
       addPrecedenceGroupRef(PGD);
   }
 };

 class CompletionOverrideLookup : public swift::VisibleDeclConsumer {
   CodeCompletionResultSink &Sink;
   ASTContext &Ctx;
   const DeclContext *CurrDeclContext;
   SmallVectorImpl<StringRef> &ParsedKeywords;
   SourceLoc introducerLoc;

   bool hasFuncIntroducer = false;
   bool hasVarIntroducer = false;
   bool hasTypealiasIntroducer = false;
   bool hasInitializerModifier = false;
   bool hasAccessModifier = false;
   bool hasOverride = false;
   bool hasOverridabilityModifier = false;
   bool hasStaticOrClass = false;

 public:
   CompletionOverrideLookup(CodeCompletionResultSink &Sink, ASTContext &Ctx,
                            const DeclContext *CurrDeclContext,
                            SmallVectorImpl<StringRef> &ParsedKeywords,
                            SourceLoc introducerLoc)
       : Sink(Sink), Ctx(Ctx), CurrDeclContext(CurrDeclContext),
         ParsedKeywords(ParsedKeywords), introducerLoc(introducerLoc) {
     (void)createTypeChecker(Ctx);

     hasFuncIntroducer = isKeywordSpecified("func");
     hasVarIntroducer = isKeywordSpecified("var") ||
                        isKeywordSpecified("let");
     hasTypealiasIntroducer = isKeywordSpecified("typealias");
     hasInitializerModifier = isKeywordSpecified("required") ||
                              isKeywordSpecified("convenience");
     hasAccessModifier = isKeywordSpecified("private") ||
                         isKeywordSpecified("fileprivate") ||
                         isKeywordSpecified("internal") ||
                         isKeywordSpecified("public") ||
                         isKeywordSpecified("open");
     hasOverride = isKeywordSpecified("override");
     hasOverridabilityModifier = isKeywordSpecified("final") ||
                                 isKeywordSpecified("open");
     hasStaticOrClass = isKeywordSpecified(getTokenText(tok::kw_class)) ||
                        isKeywordSpecified(getTokenText(tok::kw_static));
   }

   bool isKeywordSpecified(StringRef Word) {
     return std::find(ParsedKeywords.begin(), ParsedKeywords.end(), Word)
       != ParsedKeywords.end();
   }

   bool missingOverride(DeclVisibilityKind Reason) {
     return !hasOverride && Reason == DeclVisibilityKind::MemberOfSuper &&
            !CurrDeclContext->getSelfProtocolDecl();
   }

   void addAccessControl(const ValueDecl *VD,
                         CodeCompletionResultBuilder &Builder) {
     assert(CurrDeclContext->getSelfNominalTypeDecl());
     auto AccessOfContext =
         CurrDeclContext->getSelfNominalTypeDecl()->getFormalAccess();
     auto Access = std::min(VD->getFormalAccess(), AccessOfContext);
     // Only emit 'public', not needed otherwise.
     if (Access >= AccessLevel::Public)
       Builder.addAccessControlKeyword(Access);
   }

   /// Return type if the result type if \p VD should be represented as opaque
   /// result type.
   TypeLoc getOpaqueResultTypeLoc(const ValueDecl *VD, DeclVisibilityKind Reason,
                                  DynamicLookupInfo dynamicLookupInfo) {
     if (Reason !=
         DeclVisibilityKind::MemberOfProtocolImplementedByCurrentNominal)
       return nullptr;

     auto currTy = CurrDeclContext->getDeclaredTypeInContext();
     if (!currTy)
       return nullptr;

     Type ResultT;
     if (auto *FD = dyn_cast<FuncDecl>(VD))
       ResultT = FD->getResultInterfaceType();
     else if (auto *SD = dyn_cast<SubscriptDecl>(VD))
       ResultT = SD->getElementInterfaceType();
     else if (auto *VarD = dyn_cast<VarDecl>(VD))
       ResultT = VarD->getInterfaceType();
     else
       return nullptr;

     if (!ResultT->is<DependentMemberType>())
       // The result is not associatedtype.
       return nullptr;

     // If associatedtype doesn't have conformance/superclass constraint, we
     // can't use opaque type.
     auto assocTyD = ResultT->castTo<DependentMemberType>()->getAssocType();
     if (!assocTyD->getInherited().size())
       return nullptr;

     // Try substitution to see if the associated type is resolved to concrete
     // type.
     auto substMap = currTy->getMemberSubstitutionMap(
         CurrDeclContext->getParentModule(), VD);
     ResultT = ResultT.subst(substMap);
     if (!ResultT || !ResultT->is<DependentMemberType>())
       // If resolved print it.
       return nullptr;

     return assocTyD->getInherited()[0];
   }

   void addValueOverride(const ValueDecl *VD, DeclVisibilityKind Reason,
                         DynamicLookupInfo dynamicLookupInfo,
                         CodeCompletionResultBuilder &Builder,
                         bool hasDeclIntroducer) {
     class DeclPrinter : public StreamPrinter {
       TypeLoc OpaqueBaseTy;

     public:
       using StreamPrinter::StreamPrinter;

       Optional<unsigned> NameOffset;

       DeclPrinter(raw_ostream &OS, TypeLoc OpaqueBaseTy)
           : StreamPrinter(OS), OpaqueBaseTy(OpaqueBaseTy) {}

       void printDeclLoc(const Decl *D) override {
         if (!NameOffset.hasValue())
           NameOffset = OS.tell();
       }

       // As for FuncDecl, SubscriptDecl, and VarDecl,
       void printDeclResultTypePre(ValueDecl *VD, TypeLoc &TL) override {
         if (!OpaqueBaseTy.isNull()) {
           OS << "some ";
           TL = OpaqueBaseTy;
         }
       }
     };

     llvm::SmallString<256> DeclStr;
     unsigned NameOffset = 0;
     {
       llvm::raw_svector_ostream OS(DeclStr);
       DeclPrinter Printer(
           OS, getOpaqueResultTypeLoc(VD, Reason, dynamicLookupInfo));
       PrintOptions Options;
       if (auto transformType = CurrDeclContext->getDeclaredTypeInContext())
         Options.setBaseType(transformType);
       Options.PrintImplicitAttrs = false;
       Options.ExclusiveAttrList.push_back(TAK_escaping);
       Options.ExclusiveAttrList.push_back(TAK_autoclosure);
       Options.PrintOverrideKeyword = false;
       Options.PrintPropertyAccessors = false;
       Options.PrintSubscriptAccessors = false;
       Options.PrintStaticKeyword = !hasStaticOrClass;
       VD->print(Printer, Options);
       NameOffset = Printer.NameOffset.getValue();
     }

     if (!hasDeclIntroducer && !hasAccessModifier)
       addAccessControl(VD, Builder);

     if (missingOverride(Reason)) {
       if (!hasDeclIntroducer)
         Builder.addOverrideKeyword();
       else {
         auto dist = Ctx.SourceMgr.getByteDistance(
             introducerLoc, Ctx.SourceMgr.getCodeCompletionLoc());
         Builder.setNumBytesToErase(dist);
         Builder.addOverrideKeyword();
         Builder.addDeclIntroducer(DeclStr.str().substr(0, NameOffset));
       }
     }

     if (!hasDeclIntroducer)
       Builder.addDeclIntroducer(DeclStr.str().substr(0, NameOffset));

     Builder.addTextChunk(DeclStr.str().substr(NameOffset));
   }

   void addMethodOverride(const FuncDecl *FD, DeclVisibilityKind Reason,
                          DynamicLookupInfo dynamicLookupInfo) {
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         SemanticContextKind::Super, {});
     Builder.setAssociatedDecl(FD);
     addValueOverride(FD, Reason, dynamicLookupInfo, Builder, hasFuncIntroducer);
     Builder.addBraceStmtWithCursor();
   }

   void addVarOverride(const VarDecl *VD, DeclVisibilityKind Reason,
                       DynamicLookupInfo dynamicLookupInfo) {
     // Overrides cannot use 'let', but if the 'override' keyword is specified
     // then the intention is clear, so provide the results anyway.  The compiler
     // can then provide an error telling you to use 'var' instead.
     // If we don't need override then it's a protocol requirement, so show it.
     if (missingOverride(Reason) && hasVarIntroducer &&
         isKeywordSpecified("let"))
       return;

     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         SemanticContextKind::Super, {});
     Builder.setAssociatedDecl(VD);
     addValueOverride(VD, Reason, dynamicLookupInfo, Builder, hasVarIntroducer);
   }

   void addSubscriptOverride(const SubscriptDecl *SD, DeclVisibilityKind Reason,
                             DynamicLookupInfo dynamicLookupInfo) {
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Declaration,
         SemanticContextKind::Super, {});
     Builder.setAssociatedDecl(SD);
     addValueOverride(SD, Reason, dynamicLookupInfo, Builder, false);
     Builder.addBraceStmtWithCursor();
   }

   void addTypeAlias(const AssociatedTypeDecl *ATD, DeclVisibilityKind Reason,
                     DynamicLookupInfo dynamicLookupInfo) {
     CodeCompletionResultBuilder Builder(Sink,
       CodeCompletionResult::ResultKind::Declaration,
       SemanticContextKind::Super, {});
     Builder.setAssociatedDecl(ATD);
     if (!hasTypealiasIntroducer && !hasAccessModifier)
       addAccessControl(ATD, Builder);
     if (!hasTypealiasIntroducer)
       Builder.addDeclIntroducer("typealias ");
     Builder.addTextChunk(ATD->getName().str());
     Builder.addTextChunk(" = ");
     Builder.addSimpleNamedParameter("Type");
   }

   void addConstructor(const ConstructorDecl *CD, DeclVisibilityKind Reason,
                       DynamicLookupInfo dynamicLookupInfo) {
     CodeCompletionResultBuilder Builder(
         Sink,
         CodeCompletionResult::ResultKind::Declaration,
         SemanticContextKind::Super, {});
     Builder.setAssociatedDecl(CD);

     if (!hasAccessModifier)
       addAccessControl(CD, Builder);

     if (missingOverride(Reason) && CD->isDesignatedInit() && !CD->isRequired())
       Builder.addOverrideKeyword();

     // Emit 'required' if we're in class context, 'required' is not specified,
     // and 1) this is a protocol conformance and the class is not final, or 2)
     // this is subclass and the initializer is marked as required.
     bool needRequired = false;
     auto C = CurrDeclContext->getSelfClassDecl();
     if (C && !isKeywordSpecified("required")) {
       if (Reason ==
             DeclVisibilityKind::MemberOfProtocolImplementedByCurrentNominal &&
           !C->isFinal())
         needRequired = true;
       else if (Reason == DeclVisibilityKind::MemberOfSuper && CD->isRequired())
         needRequired = true;
     }

     llvm::SmallString<256> DeclStr;
     if (needRequired)
       DeclStr += "required ";
     {
       llvm::raw_svector_ostream OS(DeclStr);
       PrintOptions Options;
       Options.PrintImplicitAttrs = false;
       Options.SkipAttributes = true;
       CD->print(OS, Options);
     }
     Builder.addTextChunk(DeclStr);
     Builder.addBraceStmtWithCursor();
   }

   // Implement swift::VisibleDeclConsumer.
   void foundDecl(ValueDecl *D, DeclVisibilityKind Reason,
                  DynamicLookupInfo dynamicLookupInfo) override {
     if (Reason == DeclVisibilityKind::MemberOfCurrentNominal)
       return;

     if (D->shouldHideFromEditor())
       return;

     if (D->isFinal() ||
         // A 'class' member with an initial value cannot be overriden either.
         (D->isStatic() && D->getAttrs().hasAttribute<HasInitialValueAttr>()))
       return;

     bool hasIntroducer = hasFuncIntroducer ||
                          hasVarIntroducer ||
                          hasTypealiasIntroducer;

     if (hasStaticOrClass && !D->isStatic())
       return;

     // As per the current convention, only instance members are
     // suggested if an introducer is not accompanied by a 'static' or
     // 'class' modifier.
     if (hasIntroducer && !hasStaticOrClass && D->isStatic())
       return;

     if (auto *FD = dyn_cast<FuncDecl>(D)) {
       // We cannot override operators as members.
       if (FD->isBinaryOperator() || FD->isUnaryOperator())
         return;

       // We cannot override individual accessors.
       if (isa<AccessorDecl>(FD))
         return;

       if (hasFuncIntroducer || (!hasIntroducer && !hasInitializerModifier))
         addMethodOverride(FD, Reason, dynamicLookupInfo);
       return;
     }

     if (auto *VD = dyn_cast<VarDecl>(D)) {
       if (hasVarIntroducer || (!hasIntroducer && !hasInitializerModifier))
         addVarOverride(VD, Reason, dynamicLookupInfo);
       return;
     }

     if (auto *SD = dyn_cast<SubscriptDecl>(D)) {
       if (!hasIntroducer && !hasInitializerModifier)
         addSubscriptOverride(SD, Reason, dynamicLookupInfo);
     }

     if (auto *CD = dyn_cast<ConstructorDecl>(D)) {
       if (!isa<ProtocolDecl>(CD->getDeclContext()))
         return;
       if (hasIntroducer || hasOverride || hasOverridabilityModifier ||
           hasStaticOrClass)
         return;
       if (CD->isRequired() || CD->isDesignatedInit())
         addConstructor(CD, Reason, dynamicLookupInfo);
       return;
     }
   }

   void addDesignatedInitializers(NominalTypeDecl *NTD) {
     if (hasFuncIntroducer || hasVarIntroducer || hasTypealiasIntroducer ||
         hasOverridabilityModifier || hasStaticOrClass)
       return;

     const auto *CD = dyn_cast<ClassDecl>(NTD);
     if (!CD)
       return;
     if (!CD->hasSuperclass())
       return;
     CD = CD->getSuperclassDecl();
     for (const auto *Member : CD->getMembers()) {
       const auto *Constructor = dyn_cast<ConstructorDecl>(Member);
       if (!Constructor)
         continue;
       if (Constructor->hasStubImplementation())
         continue;
       if (Constructor->isDesignatedInit())
         addConstructor(Constructor, DeclVisibilityKind::MemberOfSuper, {});
     }
   }

   void addAssociatedTypes(NominalTypeDecl *NTD) {
     if (!hasTypealiasIntroducer &&
         (hasFuncIntroducer || hasVarIntroducer || hasInitializerModifier ||
          hasOverride || hasOverridabilityModifier || hasStaticOrClass))
       return;

     for (auto Conformance : NTD->getAllConformances()) {
       auto Proto = Conformance->getProtocol();
       if (!Proto->isAccessibleFrom(CurrDeclContext))
         continue;
       for (auto *ATD : Proto->getAssociatedTypeMembers()) {
         // FIXME: Also exclude the type alias that has already been specified.
         if (!Conformance->hasTypeWitness(ATD) ||
             ATD->hasDefaultDefinitionType())
           continue;
         addTypeAlias(
             ATD,
             DeclVisibilityKind::MemberOfProtocolImplementedByCurrentNominal,
             {});
       }
     }
   }

   void getOverrideCompletions(SourceLoc Loc) {
     if (!CurrDeclContext->isTypeContext())
       return;
     if (isa<ProtocolDecl>(CurrDeclContext))
       return;

     Type CurrTy = CurrDeclContext->getSelfTypeInContext();
     auto *NTD = CurrDeclContext->getSelfNominalTypeDecl();
     if (CurrTy && !CurrTy->is<ErrorType>()) {
       // Look for overridable static members too.
       Type Meta = MetatypeType::get(CurrTy);
       lookupVisibleMemberDecls(*this, Meta, CurrDeclContext,
                                /*includeInstanceMembers=*/true);
       addDesignatedInitializers(NTD);
       addAssociatedTypes(NTD);
     }
   }
 };
 } // end anonymous namespace

 static void addSelectorModifierKeywords(CodeCompletionResultSink &sink) {
   auto addKeyword = [&](StringRef Name, CodeCompletionKeywordKind Kind) {
     CodeCompletionResultBuilder Builder(
                                   sink,
                                   CodeCompletionResult::ResultKind::Keyword,
                                   SemanticContextKind::None, {});
     Builder.setKeywordKind(Kind);
     Builder.addTextChunk(Name);
     Builder.addCallParameterColon();
     Builder.addSimpleTypedParameter("@objc property", /*IsVarArg=*/false);
   };

   addKeyword("getter", CodeCompletionKeywordKind::None);
   addKeyword("setter", CodeCompletionKeywordKind::None);
 }

 void CodeCompletionCallbacksImpl::completeDotExpr(Expr *E, SourceLoc DotLoc) {
   assert(P.Tok.is(tok::code_complete));

   // Don't produce any results in an enum element.
   if (InEnumElementRawValue)
     return;

   Kind = CompletionKind::DotExpr;
   if (ParseExprSelectorContext != ObjCSelectorContext::None) {
     PreferFunctionReferencesToCalls = true;
     CompleteExprSelectorContext = ParseExprSelectorContext;
   }

   ParsedExpr = E;
   this->DotLoc = DotLoc;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeStmtOrExpr(CodeCompletionExpr *E) {
   assert(P.Tok.is(tok::code_complete));
   Kind = CompletionKind::StmtOrExpr;
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
 }

 void CodeCompletionCallbacksImpl::completePostfixExprBeginning(CodeCompletionExpr *E) {
   assert(P.Tok.is(tok::code_complete));

   // Don't produce any results in an enum element.
   if (InEnumElementRawValue)
     return;

   Kind = CompletionKind::PostfixExprBeginning;
   if (ParseExprSelectorContext != ObjCSelectorContext::None) {
     PreferFunctionReferencesToCalls = true;
     CompleteExprSelectorContext = ParseExprSelectorContext;
     if (CompleteExprSelectorContext == ObjCSelectorContext::MethodSelector) {
       addSelectorModifierKeywords(CompletionContext.getResultSink());
     }
   }


   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
 }

 void CodeCompletionCallbacksImpl::completeForEachSequenceBeginning(
     CodeCompletionExpr *E) {
   assert(P.Tok.is(tok::code_complete));
   Kind = CompletionKind::ForEachSequence;
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
 }

 void CodeCompletionCallbacksImpl::completePostfixExpr(Expr *E, bool hasSpace) {
   assert(P.Tok.is(tok::code_complete));

   // Don't produce any results in an enum element.
   if (InEnumElementRawValue)
     return;

   HasSpace = hasSpace;
   Kind = CompletionKind::PostfixExpr;
   if (ParseExprSelectorContext != ObjCSelectorContext::None) {
     PreferFunctionReferencesToCalls = true;
     CompleteExprSelectorContext = ParseExprSelectorContext;
   }

   ParsedExpr = E;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completePostfixExprParen(Expr *E,
                                                            Expr *CodeCompletionE) {
   assert(P.Tok.is(tok::code_complete));

   // Don't produce any results in an enum element.
   if (InEnumElementRawValue)
     return;

   Kind = CompletionKind::PostfixExprParen;
   ParsedExpr = E;
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = static_cast<CodeCompletionExpr*>(CodeCompletionE);

   ShouldCompleteCallPatternAfterParen = true;
   if (Context.LangOpts.CodeCompleteCallPatternHeuristics) {
     // Lookahead one token to decide what kind of call completions to provide.
     // When it appears that there is already code for the call present, just
     // complete values and/or argument labels.  Otherwise give the entire call
     // pattern.
     Token next = P.peekToken();
     if (!next.isAtStartOfLine() && !next.is(tok::eof) && !next.is(tok::r_paren)) {
       ShouldCompleteCallPatternAfterParen = false;
     }
   }
 }

 void CodeCompletionCallbacksImpl::completeExprKeyPath(KeyPathExpr *KPE,
                                                       SourceLoc DotLoc) {
   Kind = (!KPE || KPE->isObjC()) ? CompletionKind::KeyPathExprObjC
                                  : CompletionKind::KeyPathExprSwift;
   ParsedExpr = KPE;
   this->DotLoc = DotLoc;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completePoundAvailablePlatform() {
   Kind = CompletionKind::PoundAvailablePlatform;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeTypeDeclResultBeginning() {
   Kind = CompletionKind::TypeDeclResultBeginning;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeTypeSimpleBeginning() {
   Kind = CompletionKind::TypeSimpleBeginning;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeDeclAttrParam(DeclAttrKind DK,
                                                         int Index) {
   Kind = CompletionKind::AttributeDeclParen;
   AttrKind = DK;
   AttrParamIndex = Index;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeDeclAttrBeginning(
     bool Sil, bool isIndependent) {
   Kind = CompletionKind::AttributeBegin;
   IsInSil = Sil;
   CurDeclContext = P.CurDeclContext;
   AttTargetIsIndependent = isIndependent;
 }

 void CodeCompletionCallbacksImpl::completeInPrecedenceGroup(SyntaxKind SK) {
   assert(P.Tok.is(tok::code_complete));

   SyntxKind = SK;
   Kind = CompletionKind::PrecedenceGroup;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeTypeIdentifierWithDot() {
   Kind = CompletionKind::TypeIdentifierWithDot;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeTypeIdentifierWithoutDot() {
   Kind = CompletionKind::TypeIdentifierWithoutDot;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeCaseStmtKeyword() {
   Kind = CompletionKind::CaseStmtKeyword;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeCaseStmtBeginning(CodeCompletionExpr *E) {
   assert(!InEnumElementRawValue);

   Kind = CompletionKind::CaseStmtBeginning;
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
 }

 void CodeCompletionCallbacksImpl::completeImportDecl(
     std::vector<std::pair<Identifier, SourceLoc>> &Path) {
   Kind = CompletionKind::Import;
   CurDeclContext = P.CurDeclContext;
   DotLoc = Path.empty() ? SourceLoc() : Path.back().second;
   if (DotLoc.isInvalid())
     return;
   auto Importer = static_cast<ClangImporter *>(CurDeclContext->getASTContext().
                                                getClangModuleLoader());
   std::vector<std::string> SubNames;
   Importer->collectSubModuleNames(Path, SubNames);
   ASTContext &Ctx = CurDeclContext->getASTContext();
   for (StringRef Sub : SubNames) {
     Path.push_back(std::make_pair(Ctx.getIdentifier(Sub), SourceLoc()));
     SubModuleNameVisibilityPairs.push_back(
       std::make_pair(Sub.str(), Ctx.getLoadedModule(Path)));
     Path.pop_back();
   }
 }

 void CodeCompletionCallbacksImpl::completeUnresolvedMember(CodeCompletionExpr *E,
     SourceLoc DotLoc) {
   Kind = CompletionKind::UnresolvedMember;
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
   this->DotLoc = DotLoc;
 }

 void CodeCompletionCallbacksImpl::completeCallArg(CodeCompletionExpr *E,
                                                   bool isFirst) {
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
   Kind = CompletionKind::CallArg;

   ShouldCompleteCallPatternAfterParen = false;
   if (isFirst) {
     ShouldCompleteCallPatternAfterParen = true;
     if (Context.LangOpts.CodeCompleteCallPatternHeuristics) {
       // Lookahead one token to decide what kind of call completions to provide.
       // When it appears that there is already code for the call present, just
       // complete values and/or argument labels.  Otherwise give the entire call
       // pattern.
       Token next = P.peekToken();
       if (!next.isAtStartOfLine() && !next.is(tok::eof) && !next.is(tok::r_paren)) {
         ShouldCompleteCallPatternAfterParen = false;
       }
     }
   }
 }

 void CodeCompletionCallbacksImpl::completeReturnStmt(CodeCompletionExpr *E) {
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
   Kind = CompletionKind::ReturnStmtExpr;
 }

 void CodeCompletionCallbacksImpl::completeYieldStmt(CodeCompletionExpr *E,
                                                     Optional<unsigned> index) {
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
   // TODO: use a different completion kind when completing without an index
   // in a multiple-value context.
   Kind = CompletionKind::YieldStmtExpr;
 }

 void CodeCompletionCallbacksImpl::completeAfterPoundExpr(
     CodeCompletionExpr *E, Optional<StmtKind> ParentKind) {
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
   Kind = CompletionKind::AfterPoundExpr;
   ParentStmtKind = ParentKind;
 }

 void CodeCompletionCallbacksImpl::completeAfterPoundDirective() {
   CurDeclContext = P.CurDeclContext;
   Kind = CompletionKind::AfterPoundDirective;
 }

 void CodeCompletionCallbacksImpl::completePlatformCondition() {
   CurDeclContext = P.CurDeclContext;
   Kind = CompletionKind::PlatformConditon;
 }

 void CodeCompletionCallbacksImpl::completeAfterIfStmt(bool hasElse) {
   CurDeclContext = P.CurDeclContext;
   if (hasElse) {
     Kind = CompletionKind::AfterIfStmtElse;
   } else {
     Kind = CompletionKind::StmtOrExpr;
   }
 }

 void CodeCompletionCallbacksImpl::completeGenericParams(TypeLoc TL) {
   CurDeclContext = P.CurDeclContext;
   Kind = CompletionKind::GenericParams;
   ParsedTypeLoc = TL;
 }

 void CodeCompletionCallbacksImpl::completeNominalMemberBeginning(
     SmallVectorImpl<StringRef> &Keywords, SourceLoc introducerLoc) {
   assert(!InEnumElementRawValue);
   this->introducerLoc = introducerLoc;
   ParsedKeywords.clear();
   ParsedKeywords.append(Keywords.begin(), Keywords.end());
   Kind = CompletionKind::NominalMemberBeginning;
   CurDeclContext = P.CurDeclContext;
 }

 void CodeCompletionCallbacksImpl::completeAccessorBeginning(
     CodeCompletionExpr *E) {
   Kind = CompletionKind::AccessorBeginning;
   CurDeclContext = P.CurDeclContext;
   CodeCompleteTokenExpr = E;
 }

 static bool isDynamicLookup(Type T) {
   return T->getRValueType()->isAnyObject();
 }

 static bool isClangSubModule(ModuleDecl *TheModule) {
   if (auto ClangMod = TheModule->findUnderlyingClangModule())
     return ClangMod->isSubModule();
   return false;
 }

 static void addKeyword(CodeCompletionResultSink &Sink, StringRef Name,
                        CodeCompletionKeywordKind Kind,
                        StringRef TypeAnnotation = "") {
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::None, {});
     Builder.setKeywordKind(Kind);
     Builder.addTextChunk(Name);
     if (!TypeAnnotation.empty())
       Builder.addTypeAnnotation(TypeAnnotation);
 }

 static void addDeclKeywords(CodeCompletionResultSink &Sink) {
   auto AddDeclKeyword = [&](StringRef Name, CodeCompletionKeywordKind Kind,
                         Optional<DeclAttrKind> DAK) {
     if (Name == "let" || Name == "var") {
       // Treat keywords that could be the start of a pattern specially.
       return;
     }

     // Remove user inaccessible keywords.
     if (DAK.hasValue() && DeclAttribute::isUserInaccessible(*DAK)) return;

     addKeyword(Sink, Name, Kind);
   };

 #define DECL_KEYWORD(kw) AddDeclKeyword(#kw, CodeCompletionKeywordKind::kw_##kw, None);
 #include "swift/Syntax/TokenKinds.def"

   // Context-sensitive keywords.
   auto AddCSKeyword = [&](StringRef Name, DeclAttrKind Kind) {
     AddDeclKeyword(Name, CodeCompletionKeywordKind::None, Kind);
   };

 #define CONTEXTUAL_CASE(KW, CLASS) AddCSKeyword(#KW, DAK_##CLASS);
 #define CONTEXTUAL_DECL_ATTR(KW, CLASS, ...) CONTEXTUAL_CASE(KW, CLASS)
 #define CONTEXTUAL_DECL_ATTR_ALIAS(KW, CLASS) CONTEXTUAL_CASE(KW, CLASS)
 #define CONTEXTUAL_SIMPLE_DECL_ATTR(KW, CLASS, ...) CONTEXTUAL_CASE(KW, CLASS)
 #include <swift/AST/Attr.def>
 #undef CONTEXTUAL_CASE

 }

 static void addStmtKeywords(CodeCompletionResultSink &Sink, bool MaybeFuncBody) {
   auto AddStmtKeyword = [&](StringRef Name, CodeCompletionKeywordKind Kind) {
     if (!MaybeFuncBody && Kind == CodeCompletionKeywordKind::kw_return)
       return;
     addKeyword(Sink, Name, Kind);
   };
 #define STMT_KEYWORD(kw) AddStmtKeyword(#kw, CodeCompletionKeywordKind::kw_##kw);
 #include "swift/Syntax/TokenKinds.def"
 }

 static void addCaseStmtKeywords(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "case", CodeCompletionKeywordKind::kw_case);
   addKeyword(Sink, "default", CodeCompletionKeywordKind::kw_default);
 }

 static void addLetVarKeywords(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "let", CodeCompletionKeywordKind::kw_let);
   addKeyword(Sink, "var", CodeCompletionKeywordKind::kw_var);
 }

 static void addAccessorKeywords(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "get", CodeCompletionKeywordKind::None);
   addKeyword(Sink, "set", CodeCompletionKeywordKind::None);
 }

 static void addObserverKeywords(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "willSet", CodeCompletionKeywordKind::None);
   addKeyword(Sink, "didSet", CodeCompletionKeywordKind::None);
 }

 static void addExprKeywords(CodeCompletionResultSink &Sink) {
   // Expr keywords.
   addKeyword(Sink, "try", CodeCompletionKeywordKind::kw_try);
   addKeyword(Sink, "try!", CodeCompletionKeywordKind::kw_try);
   addKeyword(Sink, "try?", CodeCompletionKeywordKind::kw_try);
 }

 static void addOpaqueTypeKeyword(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "some", CodeCompletionKeywordKind::None, "some");
 }

 static void addAnyTypeKeyword(CodeCompletionResultSink &Sink) {
   addKeyword(Sink, "Any", CodeCompletionKeywordKind::None, "Any");
 }

 void CodeCompletionCallbacksImpl::addKeywords(CodeCompletionResultSink &Sink,
                                               bool MaybeFuncBody) {
   switch (Kind) {
   case CompletionKind::None:
   case CompletionKind::DotExpr:
   case CompletionKind::AttributeDeclParen:
   case CompletionKind::AttributeBegin:
   case CompletionKind::PoundAvailablePlatform:
   case CompletionKind::Import:
   case CompletionKind::UnresolvedMember:
   case CompletionKind::CallArg:
   case CompletionKind::AfterPoundExpr:
   case CompletionKind::AfterPoundDirective:
   case CompletionKind::PlatformConditon:
   case CompletionKind::GenericParams:
   case CompletionKind::KeyPathExprObjC:
   case CompletionKind::KeyPathExprSwift:
   case CompletionKind::PrecedenceGroup:
     break;

   case CompletionKind::AccessorBeginning: {
     // TODO: Omit already declared or mutally exclusive accessors.
     //       E.g. If 'get' is already declared, emit 'set' only.
     addAccessorKeywords(Sink);

     // Only 'var' for non-protocol context can have 'willSet' and 'didSet'.
     assert(ParsedDecl);
     VarDecl *var = dyn_cast<VarDecl>(ParsedDecl);
     if (auto accessor = dyn_cast<AccessorDecl>(ParsedDecl))
       var = dyn_cast<VarDecl>(accessor->getStorage());
     if (var && !var->getDeclContext()->getSelfProtocolDecl())
       addObserverKeywords(Sink);

     if (!isa<AccessorDecl>(ParsedDecl))
       break;

     MaybeFuncBody = true;
     LLVM_FALLTHROUGH;
   }
   case CompletionKind::StmtOrExpr:
     addDeclKeywords(Sink);
     addStmtKeywords(Sink, MaybeFuncBody);
     LLVM_FALLTHROUGH;
   case CompletionKind::ReturnStmtExpr:
   case CompletionKind::YieldStmtExpr:
   case CompletionKind::PostfixExprBeginning:
   case CompletionKind::ForEachSequence:
     addSuperKeyword(Sink);
     addLetVarKeywords(Sink);
     addExprKeywords(Sink);
     addAnyTypeKeyword(Sink);
     break;

   case CompletionKind::CaseStmtKeyword:
     addCaseStmtKeywords(Sink);
     break;

   case CompletionKind::PostfixExpr:
   case CompletionKind::PostfixExprParen:
   case CompletionKind::CaseStmtBeginning:
   case CompletionKind::TypeIdentifierWithDot:
   case CompletionKind::TypeIdentifierWithoutDot:
     break;

   case CompletionKind::TypeDeclResultBeginning:
     if (!isa<ProtocolDecl>(CurDeclContext))
       if (CurDeclContext->isTypeContext() ||
           (ParsedDecl && isa<FuncDecl>(ParsedDecl)))
         addOpaqueTypeKeyword(Sink);

     LLVM_FALLTHROUGH;
   case CompletionKind::TypeSimpleBeginning:
     addAnyTypeKeyword(Sink);
     break;

   case CompletionKind::NominalMemberBeginning: {
     bool HasDeclIntroducer = llvm::find_if(ParsedKeywords,
                                            [this](const StringRef kw) {
       return llvm::StringSwitch<bool>(kw)
         .Case("associatedtype", true)
         .Case("class", !CurDeclContext || !isa<ClassDecl>(CurDeclContext))
         .Case("deinit", true)
         .Case("enum", true)
         .Case("extension", true)
         .Case("func", true)
         .Case("import", true)
         .Case("init", true)
         .Case("let", true)
         .Case("operator", true)
         .Case("precedencegroup", true)
         .Case("protocol", true)
         .Case("struct", true)
         .Case("subscript", true)
         .Case("typealias", true)
         .Case("var", true)
         .Default(false);
     }) != ParsedKeywords.end();
     if (!HasDeclIntroducer) {
       addDeclKeywords(Sink);
       addLetVarKeywords(Sink);
     }
     break;
   }

   case CompletionKind::AfterIfStmtElse:
     addKeyword(Sink, "if", CodeCompletionKeywordKind::kw_if);
     break;
   }
 }

 static void addPoundDirectives(CodeCompletionResultSink &Sink) {
   auto addWithName =
       [&](StringRef name, CodeCompletionKeywordKind K,
           llvm::function_ref<void(CodeCompletionResultBuilder &)> consumer =
               nullptr) {
         CodeCompletionResultBuilder Builder(Sink, CodeCompletionResult::Keyword,
                                             SemanticContextKind::None, {});
         Builder.addTextChunk(name);
         Builder.setKeywordKind(K);
         if (consumer)
           consumer(Builder);
       };

   addWithName("sourceLocation", CodeCompletionKeywordKind::pound_sourceLocation,
               [&] (CodeCompletionResultBuilder &Builder) {
     Builder.addLeftParen();
     Builder.addTextChunk("file");
     Builder.addCallParameterColon();
     Builder.addSimpleTypedParameter("String");
     Builder.addComma();
     Builder.addTextChunk("line");
     Builder.addCallParameterColon();
     Builder.addSimpleTypedParameter("Int");
     Builder.addRightParen();
   });
   addWithName("warning", CodeCompletionKeywordKind::pound_warning,
               [&] (CodeCompletionResultBuilder &Builder) {
     Builder.addLeftParen();
     Builder.addTextChunk("\"");
     Builder.addSimpleNamedParameter("message");
     Builder.addTextChunk("\"");
     Builder.addRightParen();
   });
   addWithName("error", CodeCompletionKeywordKind::pound_error,
               [&] (CodeCompletionResultBuilder &Builder) {
     Builder.addLeftParen();
     Builder.addTextChunk("\"");
     Builder.addSimpleNamedParameter("message");
     Builder.addTextChunk("\"");
     Builder.addRightParen();
   });

   addWithName("if ", CodeCompletionKeywordKind::pound_if,
               [&] (CodeCompletionResultBuilder &Builder) {
     Builder.addSimpleNamedParameter("condition");
   });

   // FIXME: These directives are only valid in conditional completion block.
   addWithName("elseif ", CodeCompletionKeywordKind::pound_elseif,
               [&] (CodeCompletionResultBuilder &Builder) {
     Builder.addSimpleNamedParameter("condition");
   });
   addWithName("else", CodeCompletionKeywordKind::pound_else);
   addWithName("endif", CodeCompletionKeywordKind::pound_endif);
 }

 /// Add platform conditions used in '#if' and '#elseif' directives.
 static void addPlatformConditions(CodeCompletionResultSink &Sink) {
   auto addWithName =
       [&](StringRef Name,
           llvm::function_ref<void(CodeCompletionResultBuilder & Builder)>
               consumer) {
         CodeCompletionResultBuilder Builder(
             Sink, CodeCompletionResult::ResultKind::Pattern,
             SemanticContextKind::ExpressionSpecific, {});
         Builder.addTextChunk(Name);
         Builder.addLeftParen();
         consumer(Builder);
         Builder.addRightParen();
       };
   addWithName("os", [](CodeCompletionResultBuilder &Builder) {
     Builder.addSimpleNamedParameter("name");
   });
   addWithName("arch", [](CodeCompletionResultBuilder &Builder) {
     Builder.addSimpleNamedParameter("name");
   });
   addWithName("canImport", [](CodeCompletionResultBuilder &Builder) {
     Builder.addSimpleNamedParameter("module");
   });
   addWithName("targetEnvironment", [](CodeCompletionResultBuilder &Builder) {
     Builder.addTextChunk("simulator");
   });
   addWithName("swift", [](CodeCompletionResultBuilder &Builder) {
     Builder.addTextChunk(">=");
     Builder.addSimpleNamedParameter("version");
   });
   addWithName("swift", [](CodeCompletionResultBuilder &Builder) {
     Builder.addTextChunk("<");
     Builder.addSimpleNamedParameter("version");
   });
   addWithName("compiler", [](CodeCompletionResultBuilder &Builder) {
     Builder.addTextChunk(">=");
     Builder.addSimpleNamedParameter("version");
   });
   addWithName("compiler", [](CodeCompletionResultBuilder &Builder) {
     Builder.addTextChunk("<");
     Builder.addSimpleNamedParameter("version");
   });

   addKeyword(Sink, "true", CodeCompletionKeywordKind::kw_true, "Bool");
   addKeyword(Sink, "false", CodeCompletionKeywordKind::kw_false, "Bool");
 }

 /// Add flags specified by '-D' to completion results.
 static void addConditionalCompilationFlags(ASTContext &Ctx,
                                            CodeCompletionResultSink &Sink) {
   for (auto Flag : Ctx.LangOpts.getCustomConditionalCompilationFlags()) {
     // TODO: Should we filter out some flags?
     CodeCompletionResultBuilder Builder(
         Sink, CodeCompletionResult::ResultKind::Keyword,
         SemanticContextKind::ExpressionSpecific, {});
     Builder.addTextChunk(Flag);
   }
 }

 void CodeCompletionCallbacksImpl::doneParsing() {
   CompletionContext.CodeCompletionKind = Kind;

   if (Kind == CompletionKind::None) {
     return;
   }

   bool MaybeFuncBody = true;
   if (CurDeclContext) {
     auto *CD = CurDeclContext->getLocalContext();
     if (!CD || CD->getContextKind() == DeclContextKind::Initializer ||
         CD->getContextKind() == DeclContextKind::TopLevelCodeDecl)
       MaybeFuncBody = false;
   }
   // Add keywords even if type checking fails completely.
   addKeywords(CompletionContext.getResultSink(), MaybeFuncBody);

   if (auto *DC = dyn_cast_or_null<DeclContext>(ParsedDecl)) {
     if (DC->isChildContextOf(CurDeclContext))
       CurDeclContext = DC;
   }

   typeCheckContextUntil(
       CurDeclContext,
       CurDeclContext->getASTContext().SourceMgr.getCodeCompletionLoc());

   Optional<Type> ExprType;
   ConcreteDeclRef ReferencedDecl = nullptr;
   if (ParsedExpr) {
     if (auto *checkedExpr = findParsedExpr(CurDeclContext,
                                            ParsedExpr->getSourceRange())) {
       ParsedExpr = checkedExpr;
     }

     if (auto typechecked = typeCheckParsedExpr()) {
       ExprType = typechecked->first;
       ReferencedDecl = typechecked->second;
       ParsedExpr->setType(*ExprType);
     }

     if (!ExprType && Kind != CompletionKind::PostfixExprParen &&
         Kind != CompletionKind::CallArg &&
         Kind != CompletionKind::KeyPathExprObjC)
       return;
   }

   if (!ParsedTypeLoc.isNull() && !typecheckParsedType())
     return;

   CompletionLookup Lookup(CompletionContext.getResultSink(), P.Context,
                           CurDeclContext, &CompletionContext);
   if (ExprType) {
     Lookup.setIsStaticMetatype(ParsedExpr->isStaticallyDerivedMetatype());
   }
   if (auto *DRE = dyn_cast_or_null<DeclRefExpr>(ParsedExpr)) {
     Lookup.setIsSelfRefExpr(DRE->getDecl()->getFullName() == Context.Id_self);
   } else if (auto *SRE = dyn_cast_or_null<SuperRefExpr>(ParsedExpr)) {
     Lookup.setIsSuperRefExpr();
   }

   if (isInsideObjCSelector())
     Lookup.includeInstanceMembers();
   if (PreferFunctionReferencesToCalls)
     Lookup.setPreferFunctionReferencesToCalls();

   auto DoPostfixExprBeginning = [&] (){
     SourceLoc Loc = P.Context.SourceMgr.getCodeCompletionLoc();
     Lookup.getValueCompletionsInDeclContext(Loc);
   };

   switch (Kind) {
   case CompletionKind::None:
     llvm_unreachable("should be already handled");
     return;

   case CompletionKind::DotExpr: {
     Lookup.setHaveDot(DotLoc);

     if (isDynamicLookup(*ExprType))
       Lookup.setIsDynamicLookup();

     Lookup.getPostfixKeywordCompletions(*ExprType, ParsedExpr);

     if (isa<BindOptionalExpr>(ParsedExpr) || isa<ForceValueExpr>(ParsedExpr))
       Lookup.setIsUnwrappedOptional(true);

     ExprContextInfo ContextInfo(CurDeclContext, ParsedExpr);
     Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                             ContextInfo.isSingleExpressionBody());
     Lookup.getValueExprCompletions(*ExprType, ReferencedDecl.getDecl());
     break;
   }

   case CompletionKind::KeyPathExprSwift: {
     auto KPE = dyn_cast<KeyPathExpr>(ParsedExpr);
     auto BGT = (*ExprType)->getAs<BoundGenericType>();
     if (!KPE || !BGT || BGT->getGenericArgs().size() != 2)
       break;
     assert(!KPE->isObjC());

     if (DotLoc.isValid())
       Lookup.setHaveDot(DotLoc);

     bool OnRoot = !KPE->getComponents().front().isValid();
     Lookup.setIsSwiftKeyPathExpr(OnRoot);

     Type baseType = BGT->getGenericArgs()[OnRoot ? 0 : 1];
     if (OnRoot && baseType->is<UnresolvedType>()) {
       // Infer the root type of the keypath from the context type.
       ExprContextInfo ContextInfo(CurDeclContext, ParsedExpr);
       for (auto T : ContextInfo.getPossibleTypes()) {
         if (auto unwrapped = T->getOptionalObjectType())
           T = unwrapped;
         if (!T->getAnyNominal() || !T->getAnyNominal()->getKeyPathTypeKind() ||
             T->hasUnresolvedType() || !T->is<BoundGenericType>())
           continue;
         // Use the first KeyPath context type found.
         baseType = T->castTo<BoundGenericType>()->getGenericArgs()[0];
         break;
       }
     }
     if (!OnRoot && KPE->getComponents().back().getKind() ==
                        KeyPathExpr::Component::Kind::OptionalWrap) {
       // KeyPath expr with '?' (e.g. '\Ty.[0].prop?.another').
       // Althogh expected type is optional, we should unwrap it because it's
       // unwrapped.
       baseType = baseType->getOptionalObjectType();
     }

     Lookup.getValueExprCompletions(baseType);
     break;
   }

   case CompletionKind::StmtOrExpr:
   case CompletionKind::ForEachSequence:
   case CompletionKind::PostfixExprBeginning: {
     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);
     Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                             ContextInfo.isSingleExpressionBody());
     DoPostfixExprBeginning();
     break;
   }

   case CompletionKind::PostfixExpr: {
     Lookup.setHaveLeadingSpace(HasSpace);
     if (isDynamicLookup(*ExprType))
       Lookup.setIsDynamicLookup();
     Lookup.getValueExprCompletions(*ExprType, ReferencedDecl.getDecl());
     Lookup.getOperatorCompletions(ParsedExpr, leadingSequenceExprs);
     Lookup.getPostfixKeywordCompletions(*ExprType, ParsedExpr);
     break;
   }

   case CompletionKind::PostfixExprParen: {
     Lookup.setHaveLParen(true);

     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);

     if (ShouldCompleteCallPatternAfterParen) {
       ExprContextInfo ParentContextInfo(CurDeclContext, ParsedExpr);
       Lookup.setExpectedTypes(ParentContextInfo.getPossibleTypes(),
                               ParentContextInfo.isSingleExpressionBody());
       if (ExprType && ((*ExprType)->is<AnyFunctionType>() ||
                        (*ExprType)->is<AnyMetatypeType>())) {
         Lookup.getValueExprCompletions(*ExprType, ReferencedDecl.getDecl());
       } else {
         for (auto &typeAndDecl : ContextInfo.getPossibleCallees())
           Lookup.tryFunctionCallCompletions(typeAndDecl.first, typeAndDecl.second);
       }
     } else {
       // Add argument labels, then fallthrough to get values.
       Lookup.addArgNameCompletionResults(ContextInfo.getPossibleNames());
     }

     if (!Lookup.FoundFunctionCalls ||
         (Lookup.FoundFunctionCalls &&
          Lookup.FoundFunctionsWithoutFirstKeyword)) {
       Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                               ContextInfo.isSingleExpressionBody());
       Lookup.setHaveLParen(false);
       DoPostfixExprBeginning();
     }
     break;
   }

   case CompletionKind::KeyPathExprObjC: {
     if (DotLoc.isValid())
       Lookup.setHaveDot(DotLoc);
     Lookup.setIsKeyPathExpr();
     Lookup.includeInstanceMembers();

     if (ExprType) {
       if (isDynamicLookup(*ExprType))
         Lookup.setIsDynamicLookup();

       Lookup.getValueExprCompletions(*ExprType, ReferencedDecl.getDecl());
     } else {
       SourceLoc Loc = P.Context.SourceMgr.getCodeCompletionLoc();
       Lookup.getValueCompletionsInDeclContext(Loc, KeyPathFilter,
                                               false, true, false);
     }
     break;
   }

   case CompletionKind::TypeDeclResultBeginning:
   case CompletionKind::TypeSimpleBeginning: {
     Lookup.getTypeCompletionsInDeclContext(
         P.Context.SourceMgr.getCodeCompletionLoc());
     break;
   }

   case CompletionKind::TypeIdentifierWithDot: {
     Lookup.setHaveDot(SourceLoc());
     Lookup.getTypeCompletions(ParsedTypeLoc.getType());
     break;
   }

   case CompletionKind::TypeIdentifierWithoutDot: {
     Lookup.getTypeCompletions(ParsedTypeLoc.getType());
     break;
   }

   case CompletionKind::CaseStmtBeginning: {
     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);
     Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                             ContextInfo.isSingleExpressionBody());
     Lookup.getUnresolvedMemberCompletions(ContextInfo.getPossibleTypes());
     DoPostfixExprBeginning();
     break;
   }

   case CompletionKind::NominalMemberBeginning: {
     CompletionOverrideLookup OverrideLookup(CompletionContext.getResultSink(),
                                             P.Context, CurDeclContext,
                                             ParsedKeywords, introducerLoc);
     OverrideLookup.getOverrideCompletions(SourceLoc());
     break;
   }

   case CompletionKind::AccessorBeginning: {
     if (isa<AccessorDecl>(ParsedDecl)) {
       ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);
       Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                               ContextInfo.isSingleExpressionBody());
       DoPostfixExprBeginning();
     }
     break;
   }

   case CompletionKind::AttributeBegin: {
     Lookup.getAttributeDeclCompletions(IsInSil, AttTargetDK);

     // TypeName at attribute position after '@'.
     // - VarDecl: Property Wrappers.
     // - ParamDecl/VarDecl/FuncDecl: Function Buildres.
     if (!AttTargetDK || *AttTargetDK == DeclKind::Var ||
         *AttTargetDK == DeclKind::Param || *AttTargetDK == DeclKind::Func)
       Lookup.getTypeCompletionsInDeclContext(
           P.Context.SourceMgr.getCodeCompletionLoc());
     break;
   }
   case CompletionKind::AttributeDeclParen: {
     Lookup.getAttributeDeclParamCompletions(AttrKind, AttrParamIndex);
     break;
   }
   case CompletionKind::PoundAvailablePlatform: {
     Lookup.getPoundAvailablePlatformCompletions();
     break;
   }
   case CompletionKind::Import: {
     if (DotLoc.isValid())
       Lookup.addSubModuleNames(SubModuleNameVisibilityPairs);
     else
       Lookup.addImportModuleNames();
     break;
   }
   case CompletionKind::UnresolvedMember: {
     Lookup.setHaveDot(DotLoc);
     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);
     Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                             ContextInfo.isSingleExpressionBody());
     Lookup.getUnresolvedMemberCompletions(ContextInfo.getPossibleTypes());
     break;
   }
   case CompletionKind::CallArg : {
     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);

     bool shouldPerformGlobalCompletion = true;

     if (ShouldCompleteCallPatternAfterParen &&
         !ContextInfo.getPossibleCallees().empty()) {
       Lookup.setHaveLParen(true);
       for (auto &typeAndDecl : ContextInfo.getPossibleCallees()) {
         if (auto SD = dyn_cast_or_null<SubscriptDecl>(typeAndDecl.second)) {
           Lookup.addSubscriptCallPattern(typeAndDecl.first, SD);
         } else {
           Lookup.addFunctionCallPattern(
               typeAndDecl.first,
               dyn_cast_or_null<AbstractFunctionDecl>(typeAndDecl.second));
         }
       }
       Lookup.setHaveLParen(false);

       shouldPerformGlobalCompletion =
           !Lookup.FoundFunctionCalls ||
           (Lookup.FoundFunctionCalls &&
            Lookup.FoundFunctionsWithoutFirstKeyword);
     } else if (!ContextInfo.getPossibleNames().empty()) {
       Lookup.addArgNameCompletionResults(ContextInfo.getPossibleNames());

       shouldPerformGlobalCompletion = !ContextInfo.getPossibleTypes().empty();
     }

     if (shouldPerformGlobalCompletion) {
       Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                               ContextInfo.isSingleExpressionBody());
       DoPostfixExprBeginning();
     }
     break;
   }

   case CompletionKind::ReturnStmtExpr : {
     SourceLoc Loc = P.Context.SourceMgr.getCodeCompletionLoc();
     Lookup.setExpectedTypes(getReturnTypeFromContext(CurDeclContext),
                             /*isSingleExpressionBody*/ false);
     Lookup.getValueCompletionsInDeclContext(Loc);
     break;
   }

   case CompletionKind::YieldStmtExpr: {
     SourceLoc Loc = P.Context.SourceMgr.getCodeCompletionLoc();
     if (auto FD = dyn_cast<AccessorDecl>(CurDeclContext)) {
       if (FD->isCoroutine()) {
         // TODO: handle multi-value yields.
         Lookup.setExpectedTypes(FD->getStorage()->getValueInterfaceType(),
                                 /*isSingleExpressionBody*/ false);
       }
     }
     Lookup.getValueCompletionsInDeclContext(Loc);
     break;
   }

   case CompletionKind::AfterPoundExpr: {
     ExprContextInfo ContextInfo(CurDeclContext, CodeCompleteTokenExpr);
     Lookup.setExpectedTypes(ContextInfo.getPossibleTypes(),
                             ContextInfo.isSingleExpressionBody());

     Lookup.addPoundAvailable(ParentStmtKind);
     Lookup.addPoundLiteralCompletions(/*needPound=*/false);
     Lookup.addObjCPoundKeywordCompletions(/*needPound=*/false);
     break;
   }

   case CompletionKind::AfterPoundDirective: {
     addPoundDirectives(CompletionContext.getResultSink());
     // FIXME: Add pound expressions (e.g. '#selector()') if it's at statements
     // position.
     break;
   }

   case CompletionKind::PlatformConditon: {
     addPlatformConditions(CompletionContext.getResultSink());
     addConditionalCompilationFlags(CurDeclContext->getASTContext(),
                                    CompletionContext.getResultSink());
     break;
   }

   case CompletionKind::GenericParams:
     if (auto GT = ParsedTypeLoc.getType()->getAnyGeneric()) {
       if (auto Params = GT->getGenericParams()) {
         for (auto GP : Params->getParams()) {
           Lookup.addGenericTypeParamRef(
               GP, DeclVisibilityKind::GenericParameter, {});
         }
       }
     }
     break;
   case CompletionKind::PrecedenceGroup:
     Lookup.getPrecedenceGroupCompletions(SyntxKind);
     break;
   case CompletionKind::AfterIfStmtElse:
   case CompletionKind::CaseStmtKeyword:
     // Handled earlier by keyword completions.
     break;
   }

   for (auto &Request: Lookup.RequestedCachedResults) {
     // Use the current SourceFile as the DeclContext so that we can use it to
     // perform qualified lookup, and to get the correct visibility for
     // @testable imports.
     const SourceFile &SF = P.SF;

     llvm::DenseSet<CodeCompletionCache::Key> ImportsSeen;
     auto handleImport = [&](ModuleDecl::ImportedModule Import) {
       ModuleDecl *TheModule = Import.second;
       ModuleDecl::AccessPathTy Path = Import.first;
       if (TheModule->getFiles().empty())
         return;

       // Clang submodules are ignored and there's no lookup cost involved,
       // so just ignore them and don't put the empty results in the cache
       // because putting a lot of objects in the cache will push out
       // other lookups.
       if (isClangSubModule(TheModule))
         return;

       std::vector<std::string> AccessPath;
       for (auto Piece : Path) {
         AccessPath.push_back(Piece.first.str());
       }

       StringRef ModuleFilename = TheModule->getModuleFilename();
       // ModuleFilename can be empty if something strange happened during
       // module loading, for example, the module file is corrupted.
       if (!ModuleFilename.empty()) {
         auto &Ctx = TheModule->getASTContext();
         CodeCompletionCache::Key K{
           ModuleFilename, TheModule->getName().str(), AccessPath,
               Request.NeedLeadingDot,
               SF.hasTestableOrPrivateImport(
                   AccessLevel::Internal, TheModule,
                   SourceFile::ImportQueryKind::TestableOnly),
               SF.hasTestableOrPrivateImport(
                   AccessLevel::Internal, TheModule,
                   SourceFile::ImportQueryKind::PrivateOnly),
           Ctx.LangOpts.CodeCompleteInitsInPostfixExpr};

         using PairType = llvm::DenseSet<swift::ide::CodeCompletionCache::Key,
             llvm::DenseMapInfo<CodeCompletionCache::Key>>::iterator;
         std::pair<PairType, bool> Result = ImportsSeen.insert(K);
         if (!Result.second)
           return; // already handled.
         RequestedModules.push_back({std::move(K), TheModule,
           Request.OnlyTypes, Request.OnlyPrecedenceGroups});
       }
     };

     if (Request.TheModule) {
       // FIXME: actually check imports.
       for (auto Import : namelookup::getAllImports(Request.TheModule)) {
         handleImport(Import);
       }
     } else {
       // Add results from current module.
       Lookup.getToplevelCompletions(Request.OnlyTypes);

       // Add results for all imported modules.
       ModuleDecl::ImportFilter ImportFilter;
       ImportFilter |= ModuleDecl::ImportFilterKind::Public;
       ImportFilter |= ModuleDecl::ImportFilterKind::Private;
       ImportFilter |= ModuleDecl::ImportFilterKind::ImplementationOnly;
       SmallVector<ModuleDecl::ImportedModule, 4> Imports;
       auto *SF = CurDeclContext->getParentSourceFile();
       SF->getImportedModules(Imports, ImportFilter);

       for (auto Imported : Imports) {
         for (auto Import : namelookup::getAllImports(Imported.second))
           handleImport(Import);
       }
     }
   }
   Lookup.RequestedCachedResults.clear();

   CompletionContext.typeContextKind = Lookup.typeContextKind();

   deliverCompletionResults();
 }

 void CodeCompletionCallbacksImpl::deliverCompletionResults() {
   // Use the current SourceFile as the DeclContext so that we can use it to
   // perform qualified lookup, and to get the correct visibility for
   // @testable imports.
   DeclContext *DCForModules = &P.SF;

   Consumer.handleResultsAndModules(CompletionContext, RequestedModules,
                                    DCForModules);
   RequestedModules.clear();
   DeliveredResults = true;
 }

 void PrintingCodeCompletionConsumer::handleResults(
     MutableArrayRef<CodeCompletionResult *> Results) {
   unsigned NumResults = 0;
   for (auto Result : Results) {
     if (!IncludeKeywords && Result->getKind() == CodeCompletionResult::Keyword)
       continue;
     NumResults++;
   }
   if (NumResults == 0)
     return;

   OS << "Begin completions, " << NumResults << " items\n";
   for (auto Result : Results) {
     if (!IncludeKeywords && Result->getKind() == CodeCompletionResult::Keyword)
       continue;
     Result->print(OS);

     llvm::SmallString<64> Name;
     llvm::raw_svector_ostream NameOs(Name);
     Result->getCompletionString()->getName(NameOs);
     OS << "; name=" << Name;

     StringRef comment = Result->getBriefDocComment();
     if (IncludeComments && !comment.empty()) {
       OS << "; comment=" << comment;
     }

     OS << "\n";
   }
   OS << "End completions\n";
 }

 namespace {
 class CodeCompletionCallbacksFactoryImpl
     : public CodeCompletionCallbacksFactory {
   CodeCompletionContext &CompletionContext;
   CodeCompletionConsumer &Consumer;

 public:
   CodeCompletionCallbacksFactoryImpl(CodeCompletionContext &CompletionContext,
                                      CodeCompletionConsumer &Consumer)
       : CompletionContext(CompletionContext), Consumer(Consumer) {}

   CodeCompletionCallbacks *createCodeCompletionCallbacks(Parser &P) override {
     return new CodeCompletionCallbacksImpl(P, CompletionContext, Consumer);
   }
 };
 } // end anonymous namespace

 CodeCompletionCallbacksFactory *
 swift::ide::makeCodeCompletionCallbacksFactory(
     CodeCompletionContext &CompletionContext,
     CodeCompletionConsumer &Consumer) {
   return new CodeCompletionCallbacksFactoryImpl(CompletionContext, Consumer);
 }

 void swift::ide::lookupCodeCompletionResultsFromModule(
     CodeCompletionResultSink &targetSink, const ModuleDecl *module,
     ArrayRef<std::string> accessPath, bool needLeadingDot,
     const DeclContext *currDeclContext) {
   CompletionLookup Lookup(targetSink, module->getASTContext(), currDeclContext);
   Lookup.getVisibleDeclsOfModule(module, accessPath, needLeadingDot);
 }

 void swift::ide::copyCodeCompletionResults(CodeCompletionResultSink &targetSink,
                                            CodeCompletionResultSink &sourceSink,
                                            bool onlyTypes,
                                            bool onlyPrecedenceGroups) {

   // We will be adding foreign results (from another sink) into TargetSink.
   // TargetSink should have an owning pointer to the allocator that keeps the
   // results alive.
   targetSink.ForeignAllocators.push_back(sourceSink.Allocator);

   if (onlyTypes) {
     std::copy_if(sourceSink.Results.begin(), sourceSink.Results.end(),
                  std::back_inserter(targetSink.Results),
                  [](CodeCompletionResult *R) -> bool {
       if (R->getKind() != CodeCompletionResult::Declaration)
         return false;
       switch(R->getAssociatedDeclKind()) {
       case CodeCompletionDeclKind::Module:
       case CodeCompletionDeclKind::Class:
       case CodeCompletionDeclKind::Struct:
       case CodeCompletionDeclKind::Enum:
       case CodeCompletionDeclKind::Protocol:
       case CodeCompletionDeclKind::TypeAlias:
       case CodeCompletionDeclKind::AssociatedType:
       case CodeCompletionDeclKind::GenericTypeParam:
         return true;
       case CodeCompletionDeclKind::PrecedenceGroup:
       case CodeCompletionDeclKind::EnumElement:
       case CodeCompletionDeclKind::Constructor:
       case CodeCompletionDeclKind::Destructor:
       case CodeCompletionDeclKind::Subscript:
       case CodeCompletionDeclKind::StaticMethod:
       case CodeCompletionDeclKind::InstanceMethod:
       case CodeCompletionDeclKind::PrefixOperatorFunction:
       case CodeCompletionDeclKind::PostfixOperatorFunction:
       case CodeCompletionDeclKind::InfixOperatorFunction:
       case CodeCompletionDeclKind::FreeFunction:
       case CodeCompletionDeclKind::StaticVar:
       case CodeCompletionDeclKind::InstanceVar:
       case CodeCompletionDeclKind::LocalVar:
       case CodeCompletionDeclKind::GlobalVar:
         return false;
       }

       llvm_unreachable("Unhandled CodeCompletionDeclKind in switch.");
     });
   } else if (onlyPrecedenceGroups) {
     std::copy_if(sourceSink.Results.begin(), sourceSink.Results.end(),
                  std::back_inserter(targetSink.Results),
                  [](CodeCompletionResult *R) -> bool {
       return R->getAssociatedDeclKind() ==
                CodeCompletionDeclKind::PrecedenceGroup;
     });
   } else {
     targetSink.Results.insert(targetSink.Results.end(),
                               sourceSink.Results.begin(),
                               sourceSink.Results.end());
   }
 }

 void SimpleCachingCodeCompletionConsumer::handleResultsAndModules(
     CodeCompletionContext &context,
     ArrayRef<RequestedCachedModule> requestedModules,
     DeclContext *DCForModules) {
   for (auto &R : requestedModules) {
     // FIXME(thread-safety): lock the whole AST context.  We might load a
     // module.
     llvm::Optional<CodeCompletionCache::ValueRefCntPtr> V =
         context.Cache.get(R.Key);
     if (!V.hasValue()) {
       // No cached results found. Fill the cache.
       V = context.Cache.createValue();
       lookupCodeCompletionResultsFromModule(
           (*V)->Sink, R.TheModule, R.Key.AccessPath,
           R.Key.ResultsHaveLeadingDot, DCForModules);
       context.Cache.set(R.Key, *V);
     }
     assert(V.hasValue());
     copyCodeCompletionResults(context.getResultSink(), (*V)->Sink,
                               R.OnlyTypes, R.OnlyPrecedenceGroups);
   }

   handleResults(context.takeResults());
 }