void ExplicitConstructorCheck::check(const MatchFinder::MatchResult &Result) {
  const CXXConstructorDecl *Ctor =
      Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
  // Do not be confused: isExplicit means 'explicit' keyword is present,
  // isImplicit means that it's a compiler-generated constructor.
  if (Ctor->isOutOfLine() || Ctor->isImplicit() || Ctor->isDeleted() ||
      Ctor->getNumParams() == 0 || Ctor->getMinRequiredArguments() > 1)
    return;

  bool takesInitializerList = isStdInitializerList(
      Ctor->getParamDecl(0)->getType().getNonReferenceType());
  if (Ctor->isExplicit() &&
      (Ctor->isCopyOrMoveConstructor() || takesInitializerList)) {
    auto isKWExplicit = [](const Token &Tok) {
      return Tok.is(tok::raw_identifier) &&
             Tok.getRawIdentifier() == "explicit";
    };
    SourceRange ExplicitTokenRange =
        FindToken(*Result.SourceManager, Result.Context->getLangOpts(),
                  Ctor->getOuterLocStart(), Ctor->getLocEnd(), isKWExplicit);
    StringRef ConstructorDescription;
    if (Ctor->isMoveConstructor())
      ConstructorDescription = "move";
    else if (Ctor->isCopyConstructor())
      ConstructorDescription = "copy";
    else
      ConstructorDescription = "initializer-list";

    DiagnosticBuilder Diag =
        diag(Ctor->getLocation(),
             "%0 constructor should not be declared explicit")
        << ConstructorDescription;
    if (ExplicitTokenRange.isValid()) {
      Diag << FixItHint::CreateRemoval(
          CharSourceRange::getCharRange(ExplicitTokenRange));
    }
    return;
  }

  if (Ctor->isExplicit() || Ctor->isCopyOrMoveConstructor() ||
      takesInitializerList)
    return;

  bool SingleArgument =
      Ctor->getNumParams() == 1 && !Ctor->getParamDecl(0)->isParameterPack();
  SourceLocation Loc = Ctor->getLocation();
  diag(Loc,
       "%0 must be marked explicit to avoid unintentional implicit conversions")
      << (SingleArgument
              ? "single-argument constructors"
              : "constructors that are callable with a single argument")
      << FixItHint::CreateInsertion(Loc, "explicit ");
}
void ExplicitConstructorCheck::check(const MatchFinder::MatchResult &Result) {
  constexpr char WarningMessage[] =
      "%0 must be marked explicit to avoid unintentional implicit conversions";

  if (const auto *Conversion =
      Result.Nodes.getNodeAs<CXXConversionDecl>("conversion")) {
    if (Conversion->isOutOfLine())
      return;
    SourceLocation Loc = Conversion->getLocation();
    // Ignore all macros until we learn to ignore specific ones (e.g. used in
    // gmock to define matchers).
    if (Loc.isMacroID())
      return;
    diag(Loc, WarningMessage)
        << Conversion << FixItHint::CreateInsertion(Loc, "explicit ");
    return;
  }

  const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
  if (Ctor->isOutOfLine() || Ctor->getNumParams() == 0 ||
      Ctor->getMinRequiredArguments() > 1)
    return;

  bool takesInitializerList = isStdInitializerList(
      Ctor->getParamDecl(0)->getType().getNonReferenceType());
  if (Ctor->isExplicit() &&
      (Ctor->isCopyOrMoveConstructor() || takesInitializerList)) {
    auto isKWExplicit = [](const Token &Tok) {
      return Tok.is(tok::raw_identifier) &&
             Tok.getRawIdentifier() == "explicit";
    };
    SourceRange ExplicitTokenRange =
        FindToken(*Result.SourceManager, getLangOpts(),
                  Ctor->getOuterLocStart(), Ctor->getEndLoc(), isKWExplicit);
    StringRef ConstructorDescription;
    if (Ctor->isMoveConstructor())
      ConstructorDescription = "move";
    else if (Ctor->isCopyConstructor())
      ConstructorDescription = "copy";
    else
      ConstructorDescription = "initializer-list";

    auto Diag = diag(Ctor->getLocation(),
                     "%0 constructor should not be declared explicit")
                << ConstructorDescription;
    if (ExplicitTokenRange.isValid()) {
      Diag << FixItHint::CreateRemoval(
          CharSourceRange::getCharRange(ExplicitTokenRange));
    }
    return;
  }

  if (Ctor->isExplicit() || Ctor->isCopyOrMoveConstructor() ||
      takesInitializerList)
    return;

  bool SingleArgument =
      Ctor->getNumParams() == 1 && !Ctor->getParamDecl(0)->isParameterPack();
  SourceLocation Loc = Ctor->getLocation();
  diag(Loc, WarningMessage)
      << (SingleArgument
              ? "single-argument constructors"
              : "constructors that are callable with a single argument")
      << FixItHint::CreateInsertion(Loc, "explicit ");
}