/* Copyright 2017-2018 ccls Authors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/

#include "indexer.h"

#include "clang_tu.h"
#include "log.hh"
#include "platform.h"
#include "serializer.h"
using ccls::Intern;

#include <clang/AST/AST.h>
#include <clang/Frontend/ASTUnit.h>
#include <clang/Frontend/CompilerInstance.h>
#include <clang/Frontend/FrontendAction.h>
#include <clang/Index/IndexDataConsumer.h>
#include <clang/Index/IndexingAction.h>
#include <clang/Index/USRGeneration.h>
#include <clang/Lex/PreprocessorOptions.h>
#include <llvm/ADT/DenseSet.h>
#include <llvm/Support/CrashRecoveryContext.h>
#include <llvm/Support/Path.h>
#include <llvm/Support/Timer.h>
using namespace clang;
using llvm::Timer;

#include <algorithm>
#include <inttypes.h>
#include <limits.h>
#include <map>
#include <unordered_set>

namespace {

constexpr int kInitializerMaxLines = 3;

struct IndexParam {
  std::unordered_map<llvm::sys::fs::UniqueID, std::string> SeenUniqueID;
  std::unordered_map<std::string, FileContents> file_contents;
  std::unordered_map<std::string, int64_t> file2write_time;
  struct DeclInfo {
    Usr usr;
    std::string short_name;
    std::string qualified;
  };
  std::unordered_map<const Decl *, DeclInfo> Decl2Info;

  ASTUnit &Unit;
  ASTContext *Ctx;

  FileConsumer *file_consumer = nullptr;

  IndexParam(ASTUnit &Unit, FileConsumer *file_consumer)
      : Unit(Unit), file_consumer(file_consumer) {}

  IndexFile *ConsumeFile(const FileEntry &File) {
    IndexFile *db = file_consumer->TryConsumeFile(File, &file_contents);

    // If this is the first time we have seen the file (ignoring if we are
    // generating an index for it):
    auto [it, inserted] = SeenUniqueID.try_emplace(File.getUniqueID());
    if (inserted) {
      std::string file_name = FileName(File);
      it->second = file_name;

      // Set modification time.
      std::optional<int64_t> write_time = LastWriteTime(file_name);
      LOG_IF_S(ERROR, !write_time)
          << "failed to fetch write time for " << file_name;
      if (write_time)
        file2write_time[file_name] = *write_time;
    }

    return db;
  }
};

StringRef GetSourceInRange(const SourceManager &SM, const LangOptions &LangOpts,
                           SourceRange R) {
  SourceLocation BLoc = R.getBegin(), ELoc = R.getEnd();
  std::pair<FileID, unsigned> BInfo = SM.getDecomposedLoc(BLoc),
                              EInfo = SM.getDecomposedLoc(ELoc);
  bool invalid = false;
  StringRef Buf = SM.getBufferData(BInfo.first, &invalid);
  if (invalid)
    return "";
  return Buf.substr(BInfo.second,
                    EInfo.second +
                        Lexer::MeasureTokenLength(ELoc, SM, LangOpts) -
                        BInfo.second);
}

SymbolKind GetSymbolKind(const Decl *D) {
  switch (D->getKind()) {
  case Decl::TranslationUnit:
    return SymbolKind::File;
  case Decl::ObjCMethod:
  case Decl::FunctionTemplate:
  case Decl::Function:
  case Decl::CXXMethod:
  case Decl::CXXConstructor:
  case Decl::CXXConversion:
  case Decl::CXXDestructor:
    return SymbolKind::Func;
  case Decl::Namespace:
  case Decl::NamespaceAlias:
  case Decl::ObjCCategory:
  case Decl::ObjCInterface:
  case Decl::ObjCProtocol:
  case Decl::ClassTemplate:
  case Decl::TypeAliasTemplate:
  case Decl::TemplateTemplateParm:
  case Decl::Enum:
  case Decl::Record:
  case Decl::CXXRecord:
  case Decl::ClassTemplateSpecialization:
  case Decl::ClassTemplatePartialSpecialization:
  case Decl::TypeAlias:
  case Decl::Typedef:
  case Decl::UnresolvedUsingTypename:
    return SymbolKind::Type;
  case Decl::ObjCProperty:
  case Decl::VarTemplate:
  case Decl::Binding:
  case Decl::Field:
  case Decl::ObjCIvar:
  case Decl::Var:
  case Decl::ParmVar:
  case Decl::ImplicitParam:
  case Decl::Decomposition:
  case Decl::VarTemplateSpecialization:
  case Decl::VarTemplatePartialSpecialization:
  case Decl::EnumConstant:
  case Decl::UnresolvedUsingValue:
    return SymbolKind::Var;
  default:
    return SymbolKind::Invalid;
  }
}

LanguageId GetDeclLanguage(const Decl *D) {
  switch (D->getKind()) {
  default:
    return LanguageId::C;
  case Decl::ImplicitParam:
  case Decl::ObjCAtDefsField:
  case Decl::ObjCCategory:
  case Decl::ObjCCategoryImpl:
  case Decl::ObjCCompatibleAlias:
  case Decl::ObjCImplementation:
  case Decl::ObjCInterface:
  case Decl::ObjCIvar:
  case Decl::ObjCMethod:
  case Decl::ObjCProperty:
  case Decl::ObjCPropertyImpl:
  case Decl::ObjCProtocol:
  case Decl::ObjCTypeParam:
    return LanguageId::ObjC;
  case Decl::CXXConstructor:
  case Decl::CXXConversion:
  case Decl::CXXDestructor:
  case Decl::CXXMethod:
  case Decl::CXXRecord:
  case Decl::ClassTemplate:
  case Decl::ClassTemplatePartialSpecialization:
  case Decl::ClassTemplateSpecialization:
  case Decl::Friend:
  case Decl::FriendTemplate:
  case Decl::FunctionTemplate:
  case Decl::LinkageSpec:
  case Decl::Namespace:
  case Decl::NamespaceAlias:
  case Decl::NonTypeTemplateParm:
  case Decl::StaticAssert:
  case Decl::TemplateTemplateParm:
  case Decl::TemplateTypeParm:
  case Decl::UnresolvedUsingTypename:
  case Decl::UnresolvedUsingValue:
  case Decl::Using:
  case Decl::UsingDirective:
  case Decl::UsingShadow:
    return LanguageId::Cpp;
  }
}

// clang/lib/AST/DeclPrinter.cpp
QualType GetBaseType(QualType T, bool deduce_auto) {
  QualType BaseType = T;
  while (!BaseType.isNull() && !BaseType->isSpecifierType()) {
    if (const PointerType *PTy = BaseType->getAs<PointerType>())
      BaseType = PTy->getPointeeType();
    else if (const BlockPointerType *BPy = BaseType->getAs<BlockPointerType>())
      BaseType = BPy->getPointeeType();
    else if (const ArrayType *ATy = dyn_cast<ArrayType>(BaseType))
      BaseType = ATy->getElementType();
    else if (const VectorType *VTy = BaseType->getAs<VectorType>())
      BaseType = VTy->getElementType();
    else if (const ReferenceType *RTy = BaseType->getAs<ReferenceType>())
      BaseType = RTy->getPointeeType();
    else if (const ParenType *PTy = BaseType->getAs<ParenType>())
      BaseType = PTy->desugar();
    else if (deduce_auto) {
      if (const AutoType *ATy = BaseType->getAs<AutoType>())
        BaseType = ATy->getDeducedType();
      else
        break;
    } else
      break;
  }
  return BaseType;
}

const Decl *GetTypeDecl(QualType T, bool *specialization = nullptr) {
  Decl *D = nullptr;
  T = GetBaseType(T.getUnqualifiedType(), true);
  const Type *TP = T.getTypePtrOrNull();
  if (!TP)
    return nullptr;

try_again:
  switch (TP->getTypeClass()) {
  case Type::Typedef:
    D = cast<TypedefType>(TP)->getDecl();
    break;
  case Type::ObjCObject:
    D = cast<ObjCObjectType>(TP)->getInterface();
    break;
  case Type::ObjCInterface:
    D = cast<ObjCInterfaceType>(TP)->getDecl();
    break;
  case Type::Record:
  case Type::Enum:
    D = cast<TagType>(TP)->getDecl();
    break;
  case Type::TemplateTypeParm:
    D = cast<TemplateTypeParmType>(TP)->getDecl();
    break;
  case Type::TemplateSpecialization:
    if (specialization)
      *specialization = true;
    if (const RecordType *Record = TP->getAs<RecordType>())
      D = Record->getDecl();
    else
      D = cast<TemplateSpecializationType>(TP)
              ->getTemplateName()
              .getAsTemplateDecl();
    break;

  case Type::Auto:
  case Type::DeducedTemplateSpecialization:
    TP = cast<DeducedType>(TP)->getDeducedType().getTypePtrOrNull();
    if (TP)
      goto try_again;
    break;

  case Type::InjectedClassName:
    D = cast<InjectedClassNameType>(TP)->getDecl();
    break;

    // FIXME: Template type parameters!

  case Type::Elaborated:
    TP = cast<ElaboratedType>(TP)->getNamedType().getTypePtrOrNull();
    goto try_again;

  default:
    break;
  }
  return D;
}

const Decl *GetSpecialized(const Decl *D) {
  if (!D)
    return D;
  Decl *Template = nullptr;
  if (const CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(D)) {
    if (const ClassTemplatePartialSpecializationDecl *PartialSpec =
            dyn_cast<ClassTemplatePartialSpecializationDecl>(CXXRecord))
      Template = PartialSpec->getSpecializedTemplate();
    else if (const ClassTemplateSpecializationDecl *ClassSpec =
                 dyn_cast<ClassTemplateSpecializationDecl>(CXXRecord)) {
      llvm::PointerUnion<ClassTemplateDecl *,
                         ClassTemplatePartialSpecializationDecl *>
          Result = ClassSpec->getSpecializedTemplateOrPartial();
      if (Result.is<ClassTemplateDecl *>())
        Template = Result.get<ClassTemplateDecl *>();
      else
        Template = Result.get<ClassTemplatePartialSpecializationDecl *>();

    } else
      Template = CXXRecord->getInstantiatedFromMemberClass();
  } else if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
    Template = Function->getPrimaryTemplate();
    if (!Template)
      Template = Function->getInstantiatedFromMemberFunction();
  } else if (const VarDecl *Var = dyn_cast<VarDecl>(D)) {
    if (Var->isStaticDataMember())
      Template = Var->getInstantiatedFromStaticDataMember();
  } else if (const RedeclarableTemplateDecl *Tmpl =
                 dyn_cast<RedeclarableTemplateDecl>(D))
    Template = Tmpl->getInstantiatedFromMemberTemplate();
  else
    return nullptr;
  return Template;
}

bool ValidateRecord(const RecordDecl *RD) {
  for (const auto *I : RD->fields()) {
    QualType FQT = I->getType();
    if (FQT->isIncompleteType() || FQT->isDependentType())
      return false;
    if (const RecordType *ChildType = I->getType()->getAs<RecordType>())
      if (const RecordDecl *Child = ChildType->getDecl())
        if (!ValidateRecord(Child))
          return false;
  }
  return true;
}

class IndexDataConsumer : public index::IndexDataConsumer {
public:
  ASTContext *Ctx;
  IndexParam &param;

  std::string GetComment(const Decl *D) {
    SourceManager &SM = Ctx->getSourceManager();
    const RawComment *RC = Ctx->getRawCommentForAnyRedecl(D);
    if (!RC)
      return "";
    StringRef Raw = RC->getRawText(Ctx->getSourceManager());
    SourceRange R = RC->getSourceRange();
    std::pair<FileID, unsigned> BInfo = SM.getDecomposedLoc(R.getBegin());
    unsigned start_column = SM.getLineNumber(BInfo.first, BInfo.second);
    std::string ret;
    int pad = -1;
    for (const char *p = Raw.data(), *E = Raw.end(); p < E;) {
      // The first line starts with a comment marker, but the rest needs
      // un-indenting.
      unsigned skip = start_column - 1;
      for (; skip > 0 && p < E && (*p == ' ' || *p == '\t'); p++)
        skip--;
      const char *q = p;
      while (q < E && *q != '\n')
        q++;
      if (q < E)
        q++;
      // A minimalist approach to skip Doxygen comment markers.
      // See https://www.stack.nl/~dimitri/doxygen/manual/docblocks.html
      if (pad < 0) {
        // First line, detect the length of comment marker and put into |pad|
        const char *begin = p;
        while (p < E && (*p == '/' || *p == '*' || *p == '-' || *p == '='))
          p++;
        if (p < E && (*p == '<' || *p == '!'))
          p++;
        if (p < E && *p == ' ')
          p++;
        if (p + 1 == q)
          p++;
        else
          pad = int(p - begin);
      } else {
        // Other lines, skip |pad| bytes
        int prefix = pad;
        while (prefix > 0 && p < E &&
               (*p == ' ' || *p == '/' || *p == '*' || *p == '<' || *p == '!'))
          prefix--, p++;
      }
      ret.insert(ret.end(), p, q);
      p = q;
    }
    while (ret.size() && isspace(ret.back()))
      ret.pop_back();
    if (EndsWith(ret, "*/")) {
      ret.resize(ret.size() - 2);
    } else if (EndsWith(ret, "\n/")) {
      ret.resize(ret.size() - 2);
    }
    while (ret.size() && isspace(ret.back()))
      ret.pop_back();
    return ret;
  }

  Usr GetUsr(const Decl *D, IndexParam::DeclInfo **info = nullptr) const {
    D = D->getCanonicalDecl();
    auto [it, inserted] = param.Decl2Info.try_emplace(D);
    if (inserted) {
      SmallString<256> USR;
      index::generateUSRForDecl(D, USR);
      auto &info = it->second;
      info.usr = HashUsr(USR);
      if (auto *ND = dyn_cast<NamedDecl>(D)) {
        info.short_name = ND->getNameAsString();
        info.qualified = ND->getQualifiedNameAsString();
        SimplifyAnonymous(info.qualified);
      }
    }
    if (info)
      *info = &it->second;
    return it->second.usr;
  }

  Use GetUse(IndexFile *db, Range range, const DeclContext *DC,
             Role role) const {
    if (!DC)
      return Use{{range, 0, SymbolKind::File, role}};
    const Decl *D = cast<Decl>(DC);
    switch (GetSymbolKind(D)) {
    case SymbolKind::Func:
      return Use{{range, db->ToFunc(GetUsr(D)).usr, SymbolKind::Func, role}};
    case SymbolKind::Type:
      return Use{{range, db->ToType(GetUsr(D)).usr, SymbolKind::Type, role}};
    case SymbolKind::Var:
      return Use{{range, db->ToVar(GetUsr(D)).usr, SymbolKind::Var, role}};
    default:
      return Use{{range, 0, SymbolKind::File, role}};
    }
  }

  PrintingPolicy GetDefaultPolicy() const {
    PrintingPolicy PP(Ctx->getLangOpts());
    PP.AnonymousTagLocations = false;
    PP.TerseOutput = true;
    PP.PolishForDeclaration = true;
    PP.ConstantsAsWritten = true;
    PP.SuppressTagKeyword = true;
    PP.SuppressInitializers = true;
    PP.FullyQualifiedName = false;
    return PP;
  }

  static void SimplifyAnonymous(std::string &name) {
    for (std::string::size_type i = 0;;) {
      if ((i = name.find("(anonymous ", i)) == std::string::npos)
        break;
      i++;
      if (name.size() - i > 19 && name.compare(i + 10, 9, "namespace") == 0)
        name.replace(i, 19, "anon ns");
      else
        name.replace(i, 9, "anon");
    }
  }

  template <typename Def>
  void SetName(const Decl *D, std::string_view short_name,
               std::string_view qualified, Def &def) {
    SmallString<256> Str;
    llvm::raw_svector_ostream OS(Str);
    D->print(OS, GetDefaultPolicy());

    std::string name = OS.str();
    SimplifyAnonymous(name);
    auto i = name.find(short_name);
    if (short_name.size())
      while (i != std::string::npos && ((i && isalnum(name[i - 1])) ||
                                        isalnum(name[i + short_name.size()])))
        i = name.find(short_name, i + short_name.size());
    if (i == std::string::npos) {
      // e.g. operator type-parameter-1
      i = 0;
      def.short_name_offset = 0;
    } else if (short_name.size() && (!i || name[i - 1] != ':')) {
      name.replace(i, short_name.size(), qualified);
      def.short_name_offset = i + qualified.size() - short_name.size();
    } else {
      def.short_name_offset = i;
    }
    def.short_name_size = short_name.size();
    for (int paren = 0; i; i--) {
      // Skip parentheses in "(anon struct)::name"
      if (name[i - 1] == ')')
        paren++;
      else if (name[i - 1] == '(')
        paren--;
      else if (!(paren > 0 || isalnum(name[i - 1]) || name[i - 1] == '_' ||
                 name[i - 1] == ':'))
        break;
    }
    def.qual_name_offset = i;
    def.detailed_name = Intern(name);
  }

  void SetVarName(const Decl *D, std::string_view short_name,
                  std::string_view qualified, IndexVar::Def &def) {
    QualType T;
    const Expr *init = nullptr;
    bool binding = false;
    if (auto *VD = dyn_cast<VarDecl>(D)) {
      T = VD->getType();
      init = VD->getAnyInitializer();
      def.storage = VD->getStorageClass();
    } else if (auto *FD = dyn_cast<FieldDecl>(D)) {
      T = FD->getType();
      init = FD->getInClassInitializer();
    } else if (auto *BD = dyn_cast<BindingDecl>(D)) {
      T = BD->getType();
      binding = true;
    }
    auto BT = GetBaseType(T, false);
    if (!BT.isNull() && (binding || BT->getAs<AutoType>())) {
      SmallString<256> Str;
      llvm::raw_svector_ostream OS(Str);
      PrintingPolicy PP = GetDefaultPolicy();
      T.print(OS, PP);
      if (Str.size() &&
          (Str.back() != ' ' && Str.back() != '*' && Str.back() != '&'))
        Str += ' ';
      def.qual_name_offset = Str.size();
      def.short_name_offset = Str.size() + qualified.size() - short_name.size();
      def.short_name_size = short_name.size();
      Str += StringRef(qualified.data(), qualified.size());
      def.detailed_name = Intern(Str.str());
    } else {
      SetName(D, short_name, qualified, def);
    }
    if (init) {
      SourceManager &SM = Ctx->getSourceManager();
      const LangOptions &Lang = Ctx->getLangOpts();
      SourceRange R = SM.getExpansionRange(init->getSourceRange())
#if LLVM_VERSION_MAJOR >= 7
                          .getAsRange()
#endif
          ;
      SourceLocation L = D->getLocation();
      if (L.isMacroID() || !SM.isBeforeInTranslationUnit(L, R.getBegin()))
        return;
      StringRef Buf = GetSourceInRange(SM, Lang, R);
      Twine Init = Buf.count('\n') <= kInitializerMaxLines - 1
                       ? Buf.size() && Buf[0] == ':' ? Twine(" ", Buf)
                                                     : Twine(" = ", Buf)
                       : Twine();
      Twine T = def.detailed_name + Init;
      def.hover =
          def.storage == SC_Static && strncmp(def.detailed_name, "static ", 7)
              ? Intern(("static " + T).str())
              : Intern(T.str());
    }
  }

  void AddMacroUse(IndexFile *db, SourceManager &SM, Usr usr, SymbolKind kind,
                   SourceLocation Spell) const {
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(Spell));
    if (!FE)
      return;
    auto UID = FE->getUniqueID();
    auto [it, inserted] = db->uid2lid_and_path.try_emplace(UID);
    if (inserted) {
      it->second.first = db->uid2lid_and_path.size() - 1;
      SmallString<256> Path = FE->tryGetRealPathName();
      if (Path.empty())
        Path = FE->getName();
      if (!llvm::sys::path::is_absolute(Path) &&
          !SM.getFileManager().makeAbsolutePath(Path))
        return;
      it->second.second = Path.str();
    }
    Range spell =
        FromTokenRange(SM, Ctx->getLangOpts(), SourceRange(Spell, Spell));
    Use use{{spell, 0, SymbolKind::File, Role::Dynamic}, it->second.first};
    switch (kind) {
    case SymbolKind::Func:
      db->ToFunc(usr).uses.push_back(use);
      break;
    case SymbolKind::Type:
      db->ToType(usr).uses.push_back(use);
      break;
    case SymbolKind::Var:
      db->ToVar(usr).uses.push_back(use);
      break;
    default:
      llvm_unreachable("");
    }
  }

public:
  IndexDataConsumer(IndexParam &param) : param(param) {}
  void initialize(ASTContext &Ctx) override { this->Ctx = param.Ctx = &Ctx; }
  bool handleDeclOccurence(const Decl *D, index::SymbolRoleSet Roles,
                           ArrayRef<index::SymbolRelation> Relations,
#if LLVM_VERSION_MAJOR >= 7
                           SourceLocation Loc,
#else
                           FileID LocFID, unsigned LocOffset,
#endif
                           ASTNodeInfo ASTNode) override {
    SourceManager &SM = Ctx->getSourceManager();
    const LangOptions &Lang = Ctx->getLangOpts();
#if LLVM_VERSION_MAJOR < 7
    SourceLocation Loc;
    {
      const SrcMgr::SLocEntry &Entry = SM.getSLocEntry(LocFID);
      unsigned off = Entry.getOffset() + LocOffset;
      if (!Entry.isFile())
        off |= 1u << 31;
      Loc = SourceLocation::getFromRawEncoding(off);
    }
#else
    FileID LocFID;
#endif
    SourceLocation Spell = SM.getSpellingLoc(Loc);
    const FileEntry *FE;
    Range loc;
#if LLVM_VERSION_MAJOR < 7
    CharSourceRange R;
    if (SM.isMacroArgExpansion(Loc))
      R = CharSourceRange::getTokenRange(Spell);
    else {
      auto P = SM.getExpansionRange(Loc);
      R = CharSourceRange::getTokenRange(P.first, P.second);
    }
#else
    auto R = SM.isMacroArgExpansion(Loc) ? CharSourceRange::getTokenRange(Spell)
                                         : SM.getExpansionRange(Loc);
#endif
    loc = FromCharSourceRange(SM, Lang, R);
    LocFID = SM.getFileID(R.getBegin());
    FE = SM.getFileEntryForID(LocFID);
    if (!FE)
      return true;
    IndexFile *db = param.ConsumeFile(*FE);
    if (!db)
      return true;

    const Decl *OrigD = ASTNode.OrigD;
    const DeclContext *SemDC = OrigD->getDeclContext();
    const DeclContext *LexDC = ASTNode.ContainerDC;
    Role role = static_cast<Role>(Roles);
    db->language = std::max(db->language, GetDeclLanguage(OrigD));

    bool is_decl = Roles & uint32_t(index::SymbolRole::Declaration);
    bool is_def = Roles & uint32_t(index::SymbolRole::Definition);
    if (is_decl && D->getKind() == Decl::Binding)
      is_def = true;
    IndexFunc *func = nullptr;
    IndexType *type = nullptr;
    IndexVar *var = nullptr;
    SymbolKind kind = GetSymbolKind(D);
    IndexParam::DeclInfo *info;
    Usr usr = GetUsr(D, &info);

    auto do_def_decl = [&](auto *entity) {
      if (is_def) {
        entity->def.spell = GetUse(db, loc, SemDC, role);
        SourceRange R = OrigD->getSourceRange();
        entity->def.extent =
            GetUse(db,
                   R.getBegin().isFileID()
                       ? FromTokenRange(SM, Lang, OrigD->getSourceRange())
                       : loc,
                   LexDC, Role::None);
      } else if (is_decl) {
        entity->declarations.push_back(GetUse(db, loc, LexDC, role));
      } else {
        entity->uses.push_back(GetUse(db, loc, LexDC, role));
        return;
      }
      if (entity->def.comments[0] == '\0' && g_config->index.comments)
        entity->def.comments = Intern(GetComment(OrigD));
    };
    switch (kind) {
    case SymbolKind::Invalid:
      LOG_S(INFO) << "Unhandled " << int(D->getKind()) << " " << info->qualified
                  << " in " << db->path << ":" << loc.start.line + 1;
      return true;
    case SymbolKind::File:
      return true;
    case SymbolKind::Func:
      func = &db->ToFunc(usr);
      // Span one more column to the left/right if D is CXXConstructor.
      if (!is_def && !is_decl && D->getKind() == Decl::CXXConstructor)
        role = Role(role | Role::Implicit);
      do_def_decl(func);
      if (Spell != Loc)
        AddMacroUse(db, SM, usr, SymbolKind::Func, Spell);
      if (func->def.detailed_name[0] == '\0')
        SetName(OrigD, info->short_name, info->qualified, func->def);
      if (is_def || is_decl) {
        const Decl *DC = cast<Decl>(SemDC);
        if (GetSymbolKind(DC) == SymbolKind::Type)
          db->ToType(GetUsr(DC)).def.funcs.push_back(usr);
      } else {
        const Decl *DC = cast<Decl>(LexDC);
        if (GetSymbolKind(DC) == SymbolKind::Func)
          db->ToFunc(GetUsr(DC))
              .def.callees.push_back({{loc, usr, SymbolKind::Func, role}});
      }
      break;
    case SymbolKind::Type:
      type = &db->ToType(usr);
      do_def_decl(type);
      if (Spell != Loc)
        AddMacroUse(db, SM, usr, SymbolKind::Type, Spell);
      if (type->def.detailed_name[0] == '\0')
        SetName(OrigD, info->short_name, info->qualified, type->def);
      if (is_def || is_decl) {
        const Decl *DC = cast<Decl>(SemDC);
        if (GetSymbolKind(DC) == SymbolKind::Type)
          db->ToType(GetUsr(DC)).def.types.push_back(usr);
      }
      break;
    case SymbolKind::Var:
      var = &db->ToVar(usr);
      do_def_decl(var);
      if (Spell != Loc)
        AddMacroUse(db, SM, usr, SymbolKind::Var, Spell);
      if (var->def.detailed_name[0] == '\0')
        SetVarName(OrigD, info->short_name, info->qualified, var->def);
      QualType T;
      if (auto *VD = dyn_cast<VarDecl>(D))
        T = VD->getType();
      else if (auto *FD = dyn_cast<FieldDecl>(D))
        T = FD->getType();
      if (is_def || is_decl) {
        const Decl *DC = cast<Decl>(SemDC);
        if (GetSymbolKind(DC) == SymbolKind::Func)
          db->ToFunc(GetUsr(DC)).def.vars.push_back(usr);
        else if (auto *ND = dyn_cast<NamespaceDecl>(SemDC))
          db->ToType(GetUsr(ND)).def.vars.emplace_back(usr, -1);
        if (!T.isNull()) {
          if (auto *BT = T->getAs<BuiltinType>()) {
            Usr usr1 = static_cast<Usr>(BT->getKind());
            var->def.type = usr1;
            db->ToType(usr1).instances.push_back(usr);
          } else {
            for (const Decl *D1 = GetTypeDecl(T); D1; D1 = GetSpecialized(D1)) {
              IndexParam::DeclInfo *info1;
              Usr usr1 = GetUsr(D1, &info1);
              auto it = db->usr2type.find(usr1);
              if (it != db->usr2type.end()) {
                var->def.type = usr1;
                it->second.instances.push_back(usr);
                break;
              }
              // e.g. TemplateTypeParmDecl is not handled by
              // handleDeclOccurence.
              SourceRange R1 = D1->getSourceRange();
              if (SM.getFileID(R1.getBegin()) == LocFID) {
                IndexType &type1 = db->ToType(usr1);
                SourceLocation L1 = D1->getLocation();
                type1.def.spell = GetUse(db, FromTokenRange(SM, Lang, {L1, L1}),
                                         SemDC, Role::Definition);
                type1.def.extent =
                    GetUse(db, FromTokenRange(SM, Lang, R1), LexDC, Role::None);
                type1.def.detailed_name = Intern(info1->short_name);
                type1.def.short_name_size = int16_t(info1->short_name.size());
                type1.def.kind = lsSymbolKind::TypeParameter;
                var->def.type = usr1;
                type1.instances.push_back(usr);
                break;
              }
            }
          }
        }
      } else if (!var->def.spell && var->declarations.empty()) {
        // e.g. lambda parameter
        SourceLocation L = OrigD->getLocation();
        if (SM.getFileID(L) == LocFID) {
          var->def.spell = GetUse(db, FromTokenRange(SM, Lang, {L, L}), SemDC,
                                  Role::Definition);
          var->def.extent =
              GetUse(db, FromTokenRange(SM, Lang, OrigD->getSourceRange()),
                     LexDC, Role::None);
        }
      }
      break;
    }

    switch (D->getKind()) {
    case Decl::Namespace:
      type->def.kind = lsSymbolKind::Namespace;
      if (OrigD->isFirstDecl()) {
        auto *ND = cast<NamespaceDecl>(OrigD);
        auto *ND1 = cast<Decl>(ND->getParent());
        if (isa<NamespaceDecl>(ND1)) {
          Usr usr1 = GetUsr(ND1);
          type->def.bases.push_back(usr1);
          db->ToType(usr1).derived.push_back(usr);
        }
      }
      break;
    case Decl::NamespaceAlias: {
      type->def.kind = lsSymbolKind::TypeAlias;
      auto *NAD = cast<NamespaceAliasDecl>(D);
      if (const NamespaceDecl *ND = NAD->getNamespace()) {
        Usr usr1 = GetUsr(ND);
        type->def.alias_of = usr1;
        (void)db->ToType(usr1);
      }
      break;
    }
    case Decl::ObjCCategory:
    case Decl::ObjCImplementation:
    case Decl::ObjCInterface:
    case Decl::ObjCProtocol:
      type->def.kind = lsSymbolKind::Interface;
      break;
    case Decl::ObjCMethod:
      func->def.kind = lsSymbolKind::Method;
      break;
    case Decl::ObjCProperty:
      var->def.kind = lsSymbolKind::Property;
      break;
    case Decl::ClassTemplate:
      type->def.kind = lsSymbolKind::Class;
      break;
    case Decl::FunctionTemplate:
      func->def.kind = lsSymbolKind::Function;
      break;
    case Decl::TypeAliasTemplate:
      type->def.kind = lsSymbolKind::TypeAlias;
      break;
    case Decl::VarTemplate:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::TemplateTemplateParm:
      type->def.kind = lsSymbolKind::TypeParameter;
      break;
    case Decl::Enum:
      type->def.kind = lsSymbolKind::Enum;
      break;
    case Decl::CXXRecord:
      if (is_def) {
        auto *RD = dyn_cast<CXXRecordDecl>(OrigD);
        if (RD && RD->hasDefinition()) {
          for (const CXXBaseSpecifier &Base : RD->bases()) {
            QualType T = Base.getType();
            const NamedDecl *BaseD = nullptr;
            if (auto *TDT = T->getAs<TypedefType>()) {
              BaseD = TDT->getDecl();
            } else if (auto *TST = T->getAs<TemplateSpecializationType>()) {
              BaseD = TST->getTemplateName().getAsTemplateDecl();
            } else if (auto *RT = T->getAs<RecordType>()) {
              BaseD = RT->getDecl();
            }
            if (BaseD) {
              Usr usr1 = GetUsr(BaseD);
              type->def.bases.push_back(usr1);
              db->ToType(usr1).derived.push_back(usr);
            }
          }
        }
      }
      [[fallthrough]];
    case Decl::Record:
      if (auto *RD = dyn_cast<RecordDecl>(OrigD)) {
        // spec has no Union, use Class
        type->def.kind = RD->getTagKind() == TTK_Struct ? lsSymbolKind::Struct
                                                        : lsSymbolKind::Class;
        if (is_def) {
          SmallVector<std::pair<const RecordDecl *, int>, 2> Stack{{RD, 0}};
          llvm::DenseSet<const RecordDecl *> Seen;
          Seen.insert(RD);
          while (Stack.size()) {
            int offset;
            std::tie(RD, offset) = Stack.back();
            Stack.pop_back();
            if (!RD->isCompleteDefinition() || RD->isDependentType() ||
                !ValidateRecord(RD))
              offset = -1;
            for (FieldDecl *FD : RD->fields()) {
              int offset1 = offset >= 0 ? offset + Ctx->getFieldOffset(FD) : -1;
              if (FD->getIdentifier())
                type->def.vars.emplace_back(GetUsr(FD), offset1);
              else if (const auto *RT1 = FD->getType()->getAs<RecordType>()) {
                if (const RecordDecl *RD1 = RT1->getDecl())
                  if (Seen.insert(RD1).second)
                    Stack.push_back({RD1, offset1});
              }
            }
          }
        }
      }
      break;
    case Decl::ClassTemplateSpecialization:
    case Decl::ClassTemplatePartialSpecialization:
      type->def.kind = lsSymbolKind::Class;
      if (is_def || is_decl) {
        if (auto *RD = dyn_cast<CXXRecordDecl>(D)) {
          Decl *D1 = nullptr;
          if (auto *SD = dyn_cast<ClassTemplatePartialSpecializationDecl>(RD))
            D1 = SD->getSpecializedTemplate();
          else if (auto *SD = dyn_cast<ClassTemplateSpecializationDecl>(RD)) {
            llvm::PointerUnion<ClassTemplateDecl *,
                               ClassTemplatePartialSpecializationDecl *>
                Result = SD->getSpecializedTemplateOrPartial();
            if (Result.is<ClassTemplateDecl *>())
              D1 = Result.get<ClassTemplateDecl *>();
            else
              D1 = Result.get<ClassTemplatePartialSpecializationDecl *>();

          } else
            D1 = RD->getInstantiatedFromMemberClass();
          if (D1) {
            Usr usr1 = GetUsr(D1);
            type->def.bases.push_back(usr1);
            db->ToType(usr1).derived.push_back(usr);
          }
        }
      }
      break;
    case Decl::TypeAlias:
    case Decl::Typedef:
    case Decl::UnresolvedUsingTypename:
      type->def.kind = lsSymbolKind::TypeAlias;
      if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
        bool specialization = false;
        QualType T = TD->getUnderlyingType();
        if (const Decl *D1 = GetTypeDecl(T, &specialization)) {
          Usr usr1 = GetUsr(D1);
          IndexType &type1 = db->ToType(usr1);
          type->def.alias_of = usr1;
          // Not visited template<class T> struct B {typedef A<T> t;};
          if (specialization) {
            const TypeSourceInfo *TSI = TD->getTypeSourceInfo();
            SourceLocation L1 = TSI->getTypeLoc().getBeginLoc();
            if (SM.getFileID(L1) == LocFID) {
              Range loc1 = FromTokenRange(SM, Lang, {L1, L1});
              type1.uses.push_back(GetUse(db, loc1, LexDC, Role::Reference));
            }
          }
        }
      }
      break;
    case Decl::Binding:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::Field:
    case Decl::ObjCIvar:
      var->def.kind = lsSymbolKind::Field;
      break;
    case Decl::Function:
      func->def.kind = lsSymbolKind::Function;
      break;
    case Decl::CXXMethod: {
      const auto *MD = cast<CXXMethodDecl>(D);
      func->def.kind =
          MD->isStatic() ? lsSymbolKind::StaticMethod : lsSymbolKind::Method;
      if (is_def || is_decl) {
        if (auto *ND = dyn_cast<NamedDecl>(D)) {
          SmallVector<const NamedDecl *, 8> OverDecls;
          Ctx->getOverriddenMethods(ND, OverDecls);
          for (const auto *ND1 : OverDecls) {
            Usr usr1 = GetUsr(ND1);
            func->def.bases.push_back(usr1);
            db->ToFunc(usr1).derived.push_back(usr);
          }
        }
      }
      break;
    }
    case Decl::CXXConstructor:
    case Decl::CXXConversion:
      func->def.kind = lsSymbolKind::Constructor;
      break;
    case Decl::CXXDestructor:
      func->def.kind = lsSymbolKind::Method;
      break;
    case Decl::Var:
    case Decl::Decomposition:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::ImplicitParam:
    case Decl::ParmVar:
      // ccls extension
      var->def.kind = lsSymbolKind::Parameter;
      break;
    case Decl::VarTemplateSpecialization:
    case Decl::VarTemplatePartialSpecialization:
      var->def.kind = lsSymbolKind::Variable;
      break;
    case Decl::EnumConstant:
      var->def.kind = lsSymbolKind::EnumMember;
      // TODO Pretty printer may print =
      if (is_def && strchr(var->def.detailed_name, '=') == nullptr) {
        auto *ECD = cast<EnumConstantDecl>(D);
        const auto &Val = ECD->getInitVal();
        std::string init =
            " = " + (Val.isSigned() ? std::to_string(Val.getSExtValue())
                                    : std::to_string(Val.getZExtValue()));
        var->def.hover = Intern(var->def.detailed_name + init);
      }
      break;
    case Decl::UnresolvedUsingValue:
      var->def.kind = lsSymbolKind::Variable;
      break;
    default:
      LOG_S(INFO) << "Unhandled " << int(D->getKind());
      break;
    }
    return true;
  }
};

class IndexPPCallbacks : public PPCallbacks {
  SourceManager &SM;
  IndexParam &param;

  std::pair<StringRef, Usr> GetMacro(const Token &Tok) const {
    StringRef Name = Tok.getIdentifierInfo()->getName();
    SmallString<256> USR("@macro@");
    USR += Name;
    return {Name, HashUsr(USR)};
  }

public:
  IndexPPCallbacks(SourceManager &SM, IndexParam &param)
      : SM(SM), param(param) {}
  void InclusionDirective(SourceLocation HashLoc, const Token &Tok,
                          StringRef Included, bool IsAngled,
                          CharSourceRange FilenameRange, const FileEntry *File,
                          StringRef SearchPath, StringRef RelativePath,
                          const Module *Imported
#if LLVM_VERSION_MAJOR >= 7
                          ,
                          SrcMgr::CharacteristicKind FileType
#endif
                          ) override {
    if (!File)
      return;
    llvm::sys::fs::UniqueID UniqueID;
    auto spell = FromCharSourceRange(SM, param.Ctx->getLangOpts(),
                                     FilenameRange, &UniqueID);
    const FileEntry *FE =
        SM.getFileEntryForID(SM.getFileID(FilenameRange.getBegin()));
    if (!FE)
      return;
    if (IndexFile *db = param.ConsumeFile(*FE)) {
      std::string file_name = FileName(*File);
      if (file_name.size())
        db->includes.push_back({spell.start.line, std::move(file_name)});
    }
  }
  void MacroDefined(const Token &Tok, const MacroDirective *MD) override {
    llvm::sys::fs::UniqueID UniqueID;
    const LangOptions &Lang = param.Ctx->getLangOpts();
    SourceLocation L = MD->getLocation();
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(L));
    if (!FE)
      return;
    if (IndexFile *db = param.ConsumeFile(*FE)) {
      auto [Name, usr] = GetMacro(Tok);
      IndexVar &var = db->ToVar(usr);
      auto range = FromTokenRange(SM, Lang, {L, L}, &UniqueID);
      var.def.kind = lsSymbolKind::Macro;
      if (var.def.spell)
        var.declarations.push_back(*var.def.spell);
      var.def.spell = Use{{range, 0, SymbolKind::File, Role::Definition}};
      const MacroInfo *MI = MD->getMacroInfo();
      SourceRange R(MI->getDefinitionLoc(), MI->getDefinitionEndLoc());
      range = FromTokenRange(SM, param.Ctx->getLangOpts(), R);
      var.def.extent = Use{{range, 0, SymbolKind::File, Role::None}};
      if (var.def.detailed_name[0] == '\0') {
        var.def.detailed_name = Intern(Name);
        var.def.short_name_size = Name.size();
        StringRef Buf = GetSourceInRange(SM, Lang, R);
        var.def.hover =
            Intern(Buf.count('\n') <= kInitializerMaxLines - 1
                       ? Twine("#define ", GetSourceInRange(SM, Lang, R)).str()
                       : Twine("#define ", Name).str());
      }
    }
  }
  void MacroExpands(const Token &Tok, const MacroDefinition &MD, SourceRange R,
                    const MacroArgs *Args) override {
    llvm::sys::fs::UniqueID UniqueID;
    SourceLocation L = SM.getSpellingLoc(R.getBegin());
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(L));
    if (!FE)
      return;
    if (IndexFile *db = param.ConsumeFile(*FE)) {
      auto [Name, usr] = GetMacro(Tok);
      IndexVar &var = db->ToVar(usr);
      var.uses.push_back(
          {{FromTokenRange(SM, param.Ctx->getLangOpts(), {L, L}, &UniqueID), 0,
            SymbolKind::File, Role::Dynamic}});
    }
  }
  void MacroUndefined(const Token &Tok, const MacroDefinition &MD,
                      const MacroDirective *UD) override {
    if (UD) {
      SourceLocation L = UD->getLocation();
      MacroExpands(Tok, MD, {L, L}, nullptr);
    }
  }
  void SourceRangeSkipped(SourceRange Range, SourceLocation EndifLoc) override {
    llvm::sys::fs::UniqueID UniqueID;
    auto range = FromCharRange(SM, param.Ctx->getLangOpts(), Range, &UniqueID);
    const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(Range.getBegin()));
    if (IndexFile *db = param.ConsumeFile(*FE))
      db->skipped_ranges.push_back(range);
  }
};

class IndexFrontendAction : public ASTFrontendAction {
  IndexParam &param;

public:
  IndexFrontendAction(IndexParam &param) : param(param) {}
  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &CI,
                                                 StringRef InFile) override {
    Preprocessor &PP = CI.getPreprocessor();
    PP.addPPCallbacks(
        std::make_unique<IndexPPCallbacks>(PP.getSourceManager(), param));
    return std::make_unique<ASTConsumer>();
  }
};
} // namespace

const int IndexFile::kMajorVersion = 17;
const int IndexFile::kMinorVersion = 1;

IndexFile::IndexFile(llvm::sys::fs::UniqueID UniqueID, const std::string &path,
                     const std::string &contents)
    : UniqueID(UniqueID), path(path), file_contents(contents) {}

IndexFunc &IndexFile::ToFunc(Usr usr) {
  auto [it, inserted] = usr2func.try_emplace(usr);
  if (inserted)
    it->second.usr = usr;
  return it->second;
}

IndexType &IndexFile::ToType(Usr usr) {
  auto [it, inserted] = usr2type.try_emplace(usr);
  if (inserted)
    it->second.usr = usr;
  return it->second;
}

IndexVar &IndexFile::ToVar(Usr usr) {
  auto [it, inserted] = usr2var.try_emplace(usr);
  if (inserted)
    it->second.usr = usr;
  return it->second;
}

std::string IndexFile::ToString() {
  return ccls::Serialize(SerializeFormat::Json, *this);
}

template <typename T> void Uniquify(std::vector<T> &a) {
  std::unordered_set<T> seen;
  size_t n = 0;
  for (size_t i = 0; i < a.size(); i++)
    if (seen.insert(a[i]).second)
      a[n++] = a[i];
  a.resize(n);
}

namespace ccls::idx {
std::vector<std::unique_ptr<IndexFile>>
Index(VFS *vfs, const std::string &opt_wdir, const std::string &file,
      const std::vector<std::string> &args,
      const std::vector<FileContents> &file_contents) {
  if (!g_config->index.enabled)
    return {};

  std::vector<const char *> Args;
  for (auto &arg : args)
    Args.push_back(arg.c_str());
  auto PCHCO = std::make_shared<PCHContainerOperations>();
  IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
      CompilerInstance::createDiagnostics(new DiagnosticOptions));
  std::shared_ptr<CompilerInvocation> CI =
      createInvocationFromCommandLine(Args, Diags);
  if (!CI)
    return {};
  // -fparse-all-comments enables documentation in the indexer and in
  // code completion.
  if (g_config->index.comments > 1)
    CI->getLangOpts()->CommentOpts.ParseAllComments = true;
  CI->getLangOpts()->SpellChecking = false;
  {
    // FileSystemOptions& FSOpts = CI->getFileSystemOpts();
    // if (FSOpts.WorkingDir.empty())
    //   FSOpts.WorkingDir = opt_wdir;
    // HeaderSearchOptions &HSOpts = CI->getHeaderSearchOpts();
    // llvm::errs() << HSOpts.ResourceDir << "\n";
    // // lib/clang/7.0.0 is incorrect
    // if (HSOpts.ResourceDir.compare(0, 3, "lib") == 0 &&
    //     HSOpts.UseBuiltinIncludes)
    //   HSOpts.ResourceDir = g_config->clang.resourceDir;
  }

  std::vector<std::unique_ptr<llvm::MemoryBuffer>> BufOwner;
  for (auto &c : file_contents) {
    std::unique_ptr<llvm::MemoryBuffer> MB =
        llvm::MemoryBuffer::getMemBufferCopy(c.content, c.path);
    CI->getPreprocessorOpts().addRemappedFile(c.path, MB.get());
    BufOwner.push_back(std::move(MB));
  }

  auto Unit = ASTUnit::create(CI, Diags, true, true);
  if (!Unit)
    return {};

  FileConsumer file_consumer(vfs, file);
  IndexParam param(*Unit, &file_consumer);
  auto DataConsumer = std::make_shared<IndexDataConsumer>(param);

  index::IndexingOptions IndexOpts;
  IndexOpts.SystemSymbolFilter =
      index::IndexingOptions::SystemSymbolFilterKind::All;
  IndexOpts.IndexFunctionLocals = true;
#if LLVM_VERSION_MAJOR >= 7
  IndexOpts.IndexImplicitInstantiation = true;
#endif

  std::unique_ptr<FrontendAction> IndexAction = createIndexingAction(
      DataConsumer, IndexOpts, std::make_unique<IndexFrontendAction>(param));

  DiagnosticErrorTrap DiagTrap(*Diags);
  llvm::CrashRecoveryContext CRC;
  auto compile = [&]() {
    ASTUnit::LoadFromCompilerInvocationAction(
        std::move(CI), PCHCO, Diags, IndexAction.get(), Unit.get(),
        /*Persistent=*/true, /*ResourceDir=*/"",
        /*OnlyLocalDecls=*/true,
        /*CaptureDiagnostics=*/true, 0, false, false,
        /*UserFilesAreVolatile=*/true);
  };
  if (!CRC.RunSafely(compile)) {
    LOG_S(ERROR) << "clang crashed for " << file;
    return {};
  }
  if (!Unit) {
    LOG_S(ERROR) << "failed to index " << file;
    return {};
  }

  const SourceManager &SM = Unit->getSourceManager();
  const FileEntry *FE = SM.getFileEntryForID(SM.getMainFileID());
  IndexFile *main_file = param.ConsumeFile(*FE);
  std::unordered_map<std::string, int> inc_to_line;
  if (main_file)
    for (auto &inc : main_file->includes)
      inc_to_line[inc.resolved_path] = inc.line;

  auto result = param.file_consumer->TakeLocalState();
  for (std::unique_ptr<IndexFile> &entry : result) {
    entry->import_file = file;
    entry->args = args;
    for (auto &[_, it] : entry->uid2lid_and_path)
      entry->lid2path.emplace_back(it.first, std::move(it.second));
    entry->uid2lid_and_path.clear();
    for (auto &it : entry->usr2func) {
      // e.g. declaration + out-of-line definition
      Uniquify(it.second.derived);
      Uniquify(it.second.uses);
    }
    for (auto &it : entry->usr2type) {
      Uniquify(it.second.derived);
      Uniquify(it.second.uses);
      // e.g. declaration + out-of-line definition
      Uniquify(it.second.def.bases);
      Uniquify(it.second.def.funcs);
    }
    for (auto &it : entry->usr2var)
      Uniquify(it.second.uses);

    if (main_file) {
      // If there are errors, show at least one at the include position.
      auto it = inc_to_line.find(entry->path);
      if (it != inc_to_line.end()) {
        int line = it->second;
        for (auto ls_diagnostic : entry->diagnostics_) {
          if (ls_diagnostic.severity != lsDiagnosticSeverity::Error)
            continue;
          ls_diagnostic.range =
              lsRange{lsPosition{line, 10}, lsPosition{line, 10}};
          main_file->diagnostics_.push_back(ls_diagnostic);
          break;
        }
      }
    }

    // Update file contents and modification time.
    entry->last_write_time = param.file2write_time[entry->path];

    // Update dependencies for the file. Do not include the file in its own
    // dependency set.
    for (auto &[_, path] : param.SeenUniqueID)
      if (path != entry->path && path != entry->import_file)
        entry->dependencies[path] = param.file2write_time[path];
  }

  return result;
}
} // namespace ccls::idx

// |SymbolRef| is serialized this way.
// |Use| also uses this though it has an extra field |file|,
// which is not used by Index* so it does not need to be serialized.
void Reflect(Reader &vis, Reference &v) {
  if (vis.Format() == SerializeFormat::Json) {
    std::string t = vis.GetString();
    char *s = const_cast<char *>(t.c_str());
    v.range = Range::FromString(s);
    s = strchr(s, '|');
    v.usr = strtoull(s + 1, &s, 10);
    v.kind = static_cast<SymbolKind>(strtol(s + 1, &s, 10));
    v.role = static_cast<Role>(strtol(s + 1, &s, 10));
  } else {
    Reflect(vis, v.range);
    Reflect(vis, v.usr);
    Reflect(vis, v.kind);
    Reflect(vis, v.role);
  }
}
void Reflect(Writer &vis, Reference &v) {
  if (vis.Format() == SerializeFormat::Json) {
    char buf[99];
    snprintf(buf, sizeof buf, "%s|%" PRIu64 "|%d|%d",
             v.range.ToString().c_str(), v.usr, int(v.kind), int(v.role));
    std::string s(buf);
    Reflect(vis, s);
  } else {
    Reflect(vis, v.range);
    Reflect(vis, v.usr);
    Reflect(vis, v.kind);
    Reflect(vis, v.role);
  }
}

void Reflect(Reader &vis, Use &v) {
  if (vis.Format() == SerializeFormat::Json) {
    std::string t = vis.GetString();
    char *s = const_cast<char *>(t.c_str());
    v.range = Range::FromString(s);
    s = strchr(s, '|');
    v.usr = strtoull(s + 1, &s, 10);
    v.kind = static_cast<SymbolKind>(strtol(s + 1, &s, 10));
    v.role = static_cast<Role>(strtol(s + 1, &s, 10));
    if (*s == '|')
      v.file_id = static_cast<int>(strtol(s + 1, &s, 10));
  } else {
    Reflect(vis, static_cast<Reference &>(v));
    Reflect(vis, v.file_id);
  }
}
void Reflect(Writer &vis, Use &v) {
  if (vis.Format() == SerializeFormat::Json) {
    char buf[99];
    if (v.file_id == -1)
      snprintf(buf, sizeof buf, "%s|%" PRIu64 "|%d|%d",
               v.range.ToString().c_str(), v.usr, int(v.kind), int(v.role));
    else
      snprintf(buf, sizeof buf, "%s|%" PRIu64 "|%d|%d|%d",
               v.range.ToString().c_str(), v.usr, int(v.kind), int(v.role),
               v.file_id);
    std::string s(buf);
    Reflect(vis, s);
  } else {
    Reflect(vis, static_cast<Reference &>(v));
    Reflect(vis, v.file_id);
  }
}