//===- CXXInheritance.cpp - C++ Inheritance -------------------------------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file provides routines that help analyzing C++ inheritance hierarchies.

//

//===----------------------------------------------------------------------===//

#include "clang/AST/CXXInheritance.h"

#include "clang/AST/ASTContext.h"

#include "clang/AST/Decl.h"

#include "clang/AST/DeclBase.h"

#include "clang/AST/DeclCXX.h"

#include "clang/AST/DeclTemplate.h"

#include "clang/AST/RecordLayout.h"

#include "clang/AST/TemplateName.h"

#include "clang/AST/Type.h"

#include "clang/Basic/LLVM.h"

#include "llvm/ADT/DenseMap.h"

#include "llvm/ADT/STLExtras.h"

#include "llvm/ADT/SmallVector.h"

#include "llvm/ADT/iterator_range.h"

#include "llvm/Support/Casting.h"

#include <algorithm>

#include <utility>

#include <cassert>

#include <vector>

using namespace clang;

/// isAmbiguous - Determines whether the set of paths provided is

/// ambiguous, i.e., there are two or more paths that refer to

/// different base class subobjects of the same type. BaseType must be

/// an unqualified, canonical class type.

bool CXXBasePaths::isAmbiguous(CanQualType BaseType) {

  BaseType = BaseType.getUnqualifiedType();

  IsVirtBaseAndNumberNonVirtBases Subobjects = ClassSubobjects[BaseType];

  return Subobjects.NumberOfNonVirtBases + (Subobjects.IsVirtBase ? 1 : 0) > 1;

}

/// clear - Clear out all prior path information.

void CXXBasePaths::clear() {

  Paths.clear();

  ClassSubobjects.clear();

  VisitedDependentRecords.clear();

  ScratchPath.clear();

  DetectedVirtual = nullptr;

}

/// Swaps the contents of this CXXBasePaths structure with the

/// contents of Other.

void CXXBasePaths::swap(CXXBasePaths &Other) {

  std::swap(Origin, Other.Origin);

  Paths.swap(Other.Paths);

  ClassSubobjects.swap(Other.ClassSubobjects);

  VisitedDependentRecords.swap(Other.VisitedDependentRecords);

  std::swap(FindAmbiguities, Other.FindAmbiguities);

  std::swap(RecordPaths, Other.RecordPaths);

  std::swap(DetectVirtual, Other.DetectVirtual);

  std::swap(DetectedVirtual, Other.DetectedVirtual);

}

bool CXXRecordDecl::isDerivedFrom(const CXXRecordDecl *Base) const {

  CXXBasePaths Paths(/*FindAmbiguities=*/false, /*RecordPaths=*/false,

                     /*DetectVirtual=*/false);

  return isDerivedFrom(Base, Paths);

}

bool CXXRecordDecl::isDerivedFrom(const CXXRecordDecl *Base,

                                  CXXBasePaths &Paths) const {

  if (getCanonicalDecl() == Base->getCanonicalDecl())

    return false;

  Paths.setOrigin(const_cast<CXXRecordDecl*>(this));

  const CXXRecordDecl *BaseDecl = Base->getCanonicalDecl();

  return lookupInBases(

      [BaseDecl](const CXXBaseSpecifier *Specifier, CXXBasePath &Path) {

        return Specifier->getType()->getAsRecordDecl() &&

               FindBaseClass(Specifier, Path, BaseDecl);

      },

      Paths);

}

bool CXXRecordDecl::isVirtuallyDerivedFrom(const CXXRecordDecl *Base) const {

  if (!getNumVBases())

    return false;

  CXXBasePaths Paths(/*FindAmbiguities=*/false, /*RecordPaths=*/false,

                     /*DetectVirtual=*/false);

  if (getCanonicalDecl() == Base->getCanonicalDecl())

    return false;

  Paths.setOrigin(const_cast<CXXRecordDecl*>(this));

  const CXXRecordDecl *BaseDecl = Base->getCanonicalDecl();

  return lookupInBases(

      [BaseDecl](const CXXBaseSpecifier *Specifier, CXXBasePath &Path) {

        return FindVirtualBaseClass(Specifier, Path, BaseDecl);

      },

      Paths);

}

bool CXXRecordDecl::isProvablyNotDerivedFrom(const CXXRecordDecl *Base) const {

  const CXXRecordDecl *TargetDecl = Base->getCanonicalDecl();

  return forallBases([TargetDecl](const CXXRecordDecl *Base) {

    return Base->getCanonicalDecl() != TargetDecl;

  });

}

bool

CXXRecordDecl::isCurrentInstantiation(const DeclContext *CurContext) const {

  assert(isDependentContext());

  for (; !CurContext->isFileContext(); CurContext = CurContext->getParent())

    if (CurContext->Equals(this))

      return true;

  return false;

}

bool CXXRecordDecl::forallBases(ForallBasesCallback BaseMatches) const {

  SmallVector<const CXXRecordDecl*, 8> Queue;

  const CXXRecordDecl *Record = this;

  while (true) {

    for (const auto &I : Record->bases()) {

      const RecordType *Ty = I.getType()->getAs<RecordType>();

      if (!Ty)

        return false;

      CXXRecordDecl *Base =

            cast_or_null<CXXRecordDecl>(Ty->getDecl()->getDefinition());

      if (!Base ||

          (Base->isDependentContext() &&

           !Base->isCurrentInstantiation(Record))) {

        return false;

      }

      Queue.push_back(Base);

      if (!BaseMatches(Base))

        return false;

    }

    if (Queue.empty())

      break;

    Record = Queue.pop_back_val(); // not actually a queue.

  }

  return true;

}

bool CXXBasePaths::lookupInBases(ASTContext &Context,

                                 const CXXRecordDecl *Record,

                                 CXXRecordDecl::BaseMatchesCallback BaseMatches,

                                 bool LookupInDependent) {

  bool FoundPath = false;

  // The access of the path down to this record.

  AccessSpecifier AccessToHere = ScratchPath.Access;

  bool IsFirstStep = ScratchPath.empty();

  for (const auto &BaseSpec : Record->bases()) {

    // Find the record of the base class subobjects for this type.

    QualType BaseType =

        Context.getCanonicalType(BaseSpec.getType()).getUnqualifiedType();

    // C++ [temp.dep]p3:

    //   In the definition of a class template or a member of a class template,

    //   if a base class of the class template depends on a template-parameter,

    //   the base class scope is not examined during unqualified name lookup

    //   either at the point of definition of the class template or member or

    //   during an instantiation of the class tem- plate or member.

    if (!LookupInDependent && BaseType->isDependentType())

      continue;

    // Determine whether we need to visit this base class at all,

    // updating the count of subobjects appropriately.

    IsVirtBaseAndNumberNonVirtBases &Subobjects = ClassSubobjects[BaseType];

    bool VisitBase = true;

    bool SetVirtual = false;

    if (BaseSpec.isVirtual()) {

      VisitBase = !Subobjects.IsVirtBase;

      Subobjects.IsVirtBase = true;

      if (isDetectingVirtual() && DetectedVirtual == nullptr) {

        // If this is the first virtual we find, remember it. If it turns out

        // there is no base path here, we'll reset it later.

        DetectedVirtual = BaseType->getAs<RecordType>();

        SetVirtual = true;

      }

    } else {

      ++Subobjects.NumberOfNonVirtBases;

    }

    if (isRecordingPaths()) {

      // Add this base specifier to the current path.

      CXXBasePathElement Element;

      Element.Base = &BaseSpec;

      Element.Class = Record;

      if (BaseSpec.isVirtual())

        Element.SubobjectNumber = 0;

      else

        Element.SubobjectNumber = Subobjects.NumberOfNonVirtBases;

      ScratchPath.push_back(Element);

      // Calculate the "top-down" access to this base class.

      // The spec actually describes this bottom-up, but top-down is

      // equivalent because the definition works out as follows:

      // 1. Write down the access along each step in the inheritance

      //    chain, followed by the access of the decl itself.

      //    For example, in

      //      class A { public: int foo; };

      //      class B : protected A {};

      //      class C : public B {};

      //      class D : private C {};

      //    we would write:

      //      private public protected public

      // 2. If 'private' appears anywhere except far-left, access is denied.

      // 3. Otherwise, overall access is determined by the most restrictive

      //    access in the sequence.

      if (IsFirstStep)

        ScratchPath.Access = BaseSpec.getAccessSpecifier();

      else

        ScratchPath.Access = CXXRecordDecl::MergeAccess(AccessToHere,

                                                 BaseSpec.getAccessSpecifier());

    }

    // Track whether there's a path involving this specific base.

    bool FoundPathThroughBase = false;

    if (BaseMatches(&BaseSpec, ScratchPath)) {

      // We've found a path that terminates at this base.

      FoundPath = FoundPathThroughBase = true;

      if (isRecordingPaths()) {

        // We have a path. Make a copy of it before moving on.

        Paths.push_back(ScratchPath);

      } else if (!isFindingAmbiguities()) {

        // We found a path and we don't care about ambiguities;

        // return immediately.

        return FoundPath;

      }

    } else if (VisitBase) {

      CXXRecordDecl *BaseRecord;

      if (LookupInDependent) {

        BaseRecord = nullptr;

        const TemplateSpecializationType *TST =

            BaseSpec.getType()->getAs<TemplateSpecializationType>();

        if (!TST) {

          if (auto *RT = BaseSpec.getType()->getAs<RecordType>())

            BaseRecord = cast<CXXRecordDecl>(RT->getDecl());

        } else {

          TemplateName TN = TST->getTemplateName();

          if (auto *TD =

                  dyn_cast_or_null<ClassTemplateDecl>(TN.getAsTemplateDecl()))

            BaseRecord = TD->getTemplatedDecl();

        }

        if (BaseRecord) {

          if (!BaseRecord->hasDefinition() ||

              VisitedDependentRecords.count(BaseRecord)) {

            BaseRecord = nullptr;

          } else {

            VisitedDependentRecords.insert(BaseRecord);

          }

        }

      } else {

        BaseRecord = cast<CXXRecordDecl>(

            BaseSpec.getType()->castAs<RecordType>()->getDecl());

      }

      if (BaseRecord &&

          lookupInBases(Context, BaseRecord, BaseMatches, LookupInDependent)) {

        // C++ [class.member.lookup]p2:

        //   A member name f in one sub-object B hides a member name f in

        //   a sub-object A if A is a base class sub-object of B. Any

        //   declarations that are so hidden are eliminated from

        //   consideration.

        // There is a path to a base class that meets the criteria. If we're

        // not collecting paths or finding ambiguities, we're done.

        FoundPath = FoundPathThroughBase = true;

        if (!isFindingAmbiguities())

          return FoundPath;

      }

    }

    // Pop this base specifier off the current path (if we're

    // collecting paths).

    if (isRecordingPaths()) {

      ScratchPath.pop_back();

    }

    // If we set a virtual earlier, and this isn't a path, forget it again.

    if (SetVirtual && !FoundPathThroughBase) {

      DetectedVirtual = nullptr;

    }

  }

  // Reset the scratch path access.

  ScratchPath.Access = AccessToHere;

  return FoundPath;

}

bool CXXRecordDecl::lookupInBases(BaseMatchesCallback BaseMatches,

                                  CXXBasePaths &Paths,

                                  bool LookupInDependent) const {

  // If we didn't find anything, report that.

  if (!Paths.lookupInBases(getASTContext(), this, BaseMatches,

                           LookupInDependent))

    return false;

  // If we're not recording paths or we won't ever find ambiguities,

  // we're done.

  if (!Paths.isRecordingPaths() || !Paths.isFindingAmbiguities())

    return true;

  // C++ [class.member.lookup]p6:

  //   When virtual base classes are used, a hidden declaration can be

  //   reached along a path through the sub-object lattice that does

  //   not pass through the hiding declaration. This is not an

  //   ambiguity. The identical use with nonvirtual base classes is an

  //   ambiguity; in that case there is no unique instance of the name

  //   that hides all the others.

  //

  // FIXME: This is an O(N^2) algorithm, but DPG doesn't see an easy

  // way to make it any faster.

  Paths.Paths.remove_if([&Paths](const CXXBasePath &Path) {

    for (const CXXBasePathElement &PE : Path) {

      if (!PE.Base->isVirtual())

        continue;

      CXXRecordDecl *VBase = nullptr;

      if (const RecordType *Record = PE.Base->getType()->getAs<RecordType>())

        VBase = cast<CXXRecordDecl>(Record->getDecl());

      if (!VBase)

        break;

      // The declaration(s) we found along this path were found in a

      // subobject of a virtual base. Check whether this virtual

      // base is a subobject of any other path; if so, then the

      // declaration in this path are hidden by that patch.

      for (const CXXBasePath &HidingP : Paths) {

        CXXRecordDecl *HidingClass = nullptr;

        if (const RecordType *Record =

                HidingP.back().Base->getType()->getAs<RecordType>())

          HidingClass = cast<CXXRecordDecl>(Record->getDecl());

        if (!HidingClass)

          break;

        if (HidingClass->isVirtuallyDerivedFrom(VBase))

          return true;

      }

    }

    return false;

  });

  return true;

}

bool CXXRecordDecl::FindBaseClass(const CXXBaseSpecifier *Specifier,

                                  CXXBasePath &Path,

                                  const CXXRecordDecl *BaseRecord) {

  assert(BaseRecord->getCanonicalDecl() == BaseRecord &&

         "User data for FindBaseClass is not canonical!");

  return Specifier->getType()->castAs<RecordType>()->getDecl()

            ->getCanonicalDecl() == BaseRecord;

}

bool CXXRecordDecl::FindVirtualBaseClass(const CXXBaseSpecifier *Specifier,

                                         CXXBasePath &Path,

                                         const CXXRecordDecl *BaseRecord) {

  assert(BaseRecord->getCanonicalDecl() == BaseRecord &&

         "User data for FindBaseClass is not canonical!");

  return Specifier->isVirtual() &&

         Specifier->getType()->castAs<RecordType>()->getDecl()

            ->getCanonicalDecl() == BaseRecord;

}

static bool isOrdinaryMember(const NamedDecl *ND) {

  return ND->isInIdentifierNamespace(Decl::IDNS_Ordinary | Decl::IDNS_Tag |

                                     Decl::IDNS_Member);

}

static bool findOrdinaryMember(const CXXRecordDecl *RD, CXXBasePath &Path,

                               DeclarationName Name) {

  Path.Decls = RD->lookup(Name).begin();

  for (DeclContext::lookup_iterator I = Path.Decls, E = I.end(); I != E; ++I)

    if (isOrdinaryMember(*I))

      return true;

  return false;

}

bool CXXRecordDecl::hasMemberName(DeclarationName Name) const {

  CXXBasePath P;

  if (findOrdinaryMember(this, P, Name))

    return true;

  CXXBasePaths Paths(false, false, false);

  return lookupInBases(

      [Name](const CXXBaseSpecifier *Specifier, CXXBasePath &Path) {

        return findOrdinaryMember(Specifier->getType()->getAsCXXRecordDecl(),

                                  Path, Name);

      },

      Paths);

}

static bool

findOrdinaryMemberInDependentClasses(const CXXBaseSpecifier *Specifier,

                                     CXXBasePath &Path, DeclarationName Name) {

  const TemplateSpecializationType *TST =

      Specifier->getType()->getAs<TemplateSpecializationType>();

  if (!TST) {

    auto *RT = Specifier->getType()->getAs<RecordType>();

    if (!RT)

      return false;

    return findOrdinaryMember(cast<CXXRecordDecl>(RT->getDecl()), Path, Name);

  }

  TemplateName TN = TST->getTemplateName();

  const auto *TD = dyn_cast_or_null<ClassTemplateDecl>(TN.getAsTemplateDecl());

  if (!TD)

    return false;

  CXXRecordDecl *RD = TD->getTemplatedDecl();

  if (!RD)

    return false;

  return findOrdinaryMember(RD, Path, Name);

}

std::vector<const NamedDecl *> CXXRecordDecl::lookupDependentName(

    DeclarationName Name,

    llvm::function_ref<bool(const NamedDecl *ND)> Filter) {

  std::vector<const NamedDecl *> Results;

  // Lookup in the class.

  bool AnyOrdinaryMembers = false;

  for (const NamedDecl *ND : lookup(Name)) {

    if (isOrdinaryMember(ND))

      AnyOrdinaryMembers = true;

    if (Filter(ND))

      Results.push_back(ND);

  }

  if (AnyOrdinaryMembers)

    return Results;

  // Perform lookup into our base classes.

  CXXBasePaths Paths;

  Paths.setOrigin(this);

  if (!lookupInBases(

          [&](const CXXBaseSpecifier *Specifier, CXXBasePath &Path) {

            return findOrdinaryMemberInDependentClasses(Specifier, Path, Name);

          },

          Paths, /*LookupInDependent=*/true))

    return Results;

  for (DeclContext::lookup_iterator I = Paths.front().Decls, E = I.end();

       I != E; ++I) {

    if (isOrdinaryMember(*I) && Filter(*I))

      Results.push_back(*I);

  }

  return Results;

}

void OverridingMethods::add(unsigned OverriddenSubobject,

                            UniqueVirtualMethod Overriding) {

  SmallVectorImpl<UniqueVirtualMethod> &SubobjectOverrides

    = Overrides[OverriddenSubobject];

  if (!llvm::is_contained(SubobjectOverrides, Overriding))

    SubobjectOverrides.push_back(Overriding);

}

void OverridingMethods::add(const OverridingMethods &Other) {

  for (const_iterator I = Other.begin(), IE = Other.end(); I != IE; ++I) {

    for (overriding_const_iterator M = I->second.begin(),

                                MEnd = I->second.end();

         M != MEnd;

         ++M)

      add(I->first, *M);

  }

}

void OverridingMethods::replaceAll(UniqueVirtualMethod Overriding) {

  for (iterator I = begin(), IEnd = end(); I != IEnd; ++I) {

    I->second.clear();

    I->second.push_back(Overriding);

  }

}

namespace {

class FinalOverriderCollector {

  /// The number of subobjects of a given class type that

  /// occur within the class hierarchy.

  llvm::DenseMap<const CXXRecordDecl *, unsigned> SubobjectCount;

  /// Overriders for each virtual base subobject.

  llvm::DenseMap<const CXXRecordDecl *, CXXFinalOverriderMap *> VirtualOverriders;

  CXXFinalOverriderMap FinalOverriders;

public:

  ~FinalOverriderCollector();

  void Collect(const CXXRecordDecl *RD, bool VirtualBase,

               const CXXRecordDecl *InVirtualSubobject,

               CXXFinalOverriderMap &Overriders);

};

} // namespace

void FinalOverriderCollector::Collect(const CXXRecordDecl *RD,

                                      bool VirtualBase,

                                      const CXXRecordDecl *InVirtualSubobject,

                                      CXXFinalOverriderMap &Overriders) {

  unsigned SubobjectNumber = 0;

  if (!VirtualBase)

    SubobjectNumber

      = ++SubobjectCount[cast<CXXRecordDecl>(RD->getCanonicalDecl())];

  for (const auto &Base : RD->bases()) {

    if (const RecordType *RT = Base.getType()->getAs<RecordType>()) {

      const CXXRecordDecl *BaseDecl = cast<CXXRecordDecl>(RT->getDecl());

      if (!BaseDecl->isPolymorphic())

        continue;

      if (Overriders.empty() && !Base.isVirtual()) {

        // There are no other overriders of virtual member functions,

        // so let the base class fill in our overriders for us.

        Collect(BaseDecl, false, InVirtualSubobject, Overriders);

        continue;

      }

      // Collect all of the overridders from the base class subobject

      // and merge them into the set of overridders for this class.

      // For virtual base classes, populate or use the cached virtual

      // overrides so that we do not walk the virtual base class (and

      // its base classes) more than once.

      CXXFinalOverriderMap ComputedBaseOverriders;

      CXXFinalOverriderMap *BaseOverriders = &ComputedBaseOverriders;

      if (Base.isVirtual()) {

        CXXFinalOverriderMap *&MyVirtualOverriders = VirtualOverriders[BaseDecl];

        BaseOverriders = MyVirtualOverriders;

        if (!MyVirtualOverriders) {

          MyVirtualOverriders = new CXXFinalOverriderMap;

          // Collect may cause VirtualOverriders to reallocate, invalidating the

          // MyVirtualOverriders reference. Set BaseOverriders to the right

          // value now.

          BaseOverriders = MyVirtualOverriders;

          Collect(BaseDecl, true, BaseDecl, *MyVirtualOverriders);

        }

      } else

        Collect(BaseDecl, false, InVirtualSubobject, ComputedBaseOverriders);

      // Merge the overriders from this base class into our own set of

      // overriders.

      for (CXXFinalOverriderMap::iterator OM = BaseOverriders->begin(),

                               OMEnd = BaseOverriders->end();

           OM != OMEnd;

           ++OM) {

        const CXXMethodDecl *CanonOM = OM->first->getCanonicalDecl();

        Overriders[CanonOM].add(OM->second);

      }

    }

  }

  for (auto *M : RD->methods()) {

    // We only care about virtual methods.

    if (!M->isVirtual())

      continue;

    CXXMethodDecl *CanonM = M->getCanonicalDecl();

    using OverriddenMethodsRange =

        llvm::iterator_range<CXXMethodDecl::method_iterator>;

    OverriddenMethodsRange OverriddenMethods = CanonM->overridden_methods();

    if (OverriddenMethods.begin() == OverriddenMethods.end()) {

      // This is a new virtual function that does not override any

      // other virtual function. Add it to the map of virtual

      // functions for which we are tracking overridders.

      // C++ [class.virtual]p2:

      //   For convenience we say that any virtual function overrides itself.

      Overriders[CanonM].add(SubobjectNumber,

                             UniqueVirtualMethod(CanonM, SubobjectNumber,

                                                 InVirtualSubobject));

      continue;

    }

    // This virtual method overrides other virtual methods, so it does

    // not add any new slots into the set of overriders. Instead, we

    // replace entries in the set of overriders with the new

    // overrider. To do so, we dig down to the original virtual

    // functions using data recursion and update all of the methods it

    // overrides.

    SmallVector<OverriddenMethodsRange, 4> Stack(1, OverriddenMethods);

    while (!Stack.empty()) {

      for (const CXXMethodDecl *OM : Stack.pop_back_val()) {

        const CXXMethodDecl *CanonOM = OM->getCanonicalDecl();

        // C++ [class.virtual]p2:

        //   A virtual member function C::vf of a class object S is

        //   a final overrider unless the most derived class (1.8)

        //   of which S is a base class subobject (if any) declares

        //   or inherits another member function that overrides vf.

        //

        // Treating this object like the most derived class, we

        // replace any overrides from base classes with this

        // overriding virtual function.

        Overriders[CanonOM].replaceAll(

                               UniqueVirtualMethod(CanonM, SubobjectNumber,

                                                   InVirtualSubobject));

        auto OverriddenMethods = CanonOM->overridden_methods();

        if (OverriddenMethods.begin() == OverriddenMethods.end())

          continue;

        // Continue recursion to the methods that this virtual method

        // overrides.

        Stack.push_back(OverriddenMethods);

      }

    }

    // C++ [class.virtual]p2:

    //   For convenience we say that any virtual function overrides itself.

    Overriders[CanonM].add(SubobjectNumber,

                           UniqueVirtualMethod(CanonM, SubobjectNumber,

                                               InVirtualSubobject));

  }

}

FinalOverriderCollector::~FinalOverriderCollector() {

  for (llvm::DenseMap<const CXXRecordDecl *, CXXFinalOverriderMap *>::iterator

         VO = VirtualOverriders.begin(), VOEnd = VirtualOverriders.end();

       VO != VOEnd;

       ++VO)

    delete VO->second;

}

void

CXXRecordDecl::getFinalOverriders(CXXFinalOverriderMap &FinalOverriders) const {

  FinalOverriderCollector Collector;

  Collector.Collect(this, false, nullptr, FinalOverriders);

  // Weed out any final overriders that come from virtual base class

  // subobjects that were hidden by other subobjects along any path.

  // This is the final-overrider variant of C++ [class.member.lookup]p10.

  for (auto &OM : FinalOverriders) {

    for (auto &SO : OM.second) {

      SmallVectorImpl<UniqueVirtualMethod> &Overriding = SO.second;

      if (Overriding.size() < 2)

        continue;

      auto IsHidden = [&Overriding](const UniqueVirtualMethod &M) {

        if (!M.InVirtualSubobject)

          return false;

        // We have an overriding method in a virtual base class

        // subobject (or non-virtual base class subobject thereof);

        // determine whether there exists an other overriding method

        // in a base class subobject that hides the virtual base class

        // subobject.

        for (const UniqueVirtualMethod &OP : Overriding)

          if (&M != &OP &&

              OP.Method->getParent()->isVirtuallyDerivedFrom(

                  M.InVirtualSubobject))

            return true;

        return false;

      };

      // FIXME: IsHidden reads from Overriding from the middle of a remove_if

      // over the same sequence! Is this guaranteed to work?

      llvm::erase_if(Overriding, IsHidden);

    }

  }

}

static void

AddIndirectPrimaryBases(const CXXRecordDecl *RD, ASTContext &Context,

                        CXXIndirectPrimaryBaseSet& Bases) {

  // If the record has a virtual primary base class, add it to our set.

  const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD);

  if (Layout.isPrimaryBaseVirtual())

    Bases.insert(Layout.getPrimaryBase());

  for (const auto &I : RD->bases()) {

    assert(!I.getType()->isDependentType() &&

           "Cannot get indirect primary bases for class with dependent bases.");

    const CXXRecordDecl *BaseDecl =

      cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());

    // Only bases with virtual bases participate in computing the

    // indirect primary virtual base classes.

    if (BaseDecl->getNumVBases())

      AddIndirectPrimaryBases(BaseDecl, Context, Bases);

  }

}

void

CXXRecordDecl::getIndirectPrimaryBases(CXXIndirectPrimaryBaseSet& Bases) const {

  ASTContext &Context = getASTContext();

  if (!getNumVBases())

    return;

  for (const auto &I : bases()) {

    assert(!I.getType()->isDependentType() &&

           "Cannot get indirect primary bases for class with dependent bases.");

    const CXXRecordDecl *BaseDecl =

      cast<CXXRecordDecl>(I.getType()->castAs<RecordType>()->getDecl());

    // Only bases with virtual bases participate in computing the

    // indirect primary virtual base classes.

    if (BaseDecl->getNumVBases())

      AddIndirectPrimaryBases(BaseDecl, Context, Bases);

  }

}