Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 812 insertions, 0 deletions

diff --git a/clang-r353983/include/clang/Sema/Lookup.h b/clang-r353983/include/clang/Sema/Lookup.h
new file mode 100644
index 00000000..990005f1
--- /dev/null
+++ b/clang-r353983/include/clang/Sema/Lookup.h
@@ -0,0 +1,812 @@
+//===- Lookup.h - Classes for name lookup -----------------------*- C++ -*-===//
+//
+// 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 defines the LookupResult class, which is integral to
+// Sema's name-lookup subsystem.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_SEMA_LOOKUP_H
+#define LLVM_CLANG_SEMA_LOOKUP_H
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/DeclBase.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/DeclarationName.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/UnresolvedSet.h"
+#include "clang/Basic/LLVM.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/SourceLocation.h"
+#include "clang/Basic/Specifiers.h"
+#include "clang/Sema/Sema.h"
+#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Casting.h"
+#include <cassert>
+#include <utility>
+
+namespace clang {
+
+class CXXBasePaths;
+
+/// Represents the results of name lookup.
+///
+/// An instance of the LookupResult class captures the results of a
+/// single name lookup, which can return no result (nothing found),
+/// a single declaration, a set of overloaded functions, or an
+/// ambiguity. Use the getKind() method to determine which of these
+/// results occurred for a given lookup.
+class LookupResult {
+public:
+  enum LookupResultKind {
+    /// No entity found met the criteria.
+    NotFound = 0,
+
+    /// No entity found met the criteria within the current
+    /// instantiation,, but there were dependent base classes of the
+    /// current instantiation that could not be searched.
+    NotFoundInCurrentInstantiation,
+
+    /// Name lookup found a single declaration that met the
+    /// criteria.  getFoundDecl() will return this declaration.
+    Found,
+
+    /// Name lookup found a set of overloaded functions that
+    /// met the criteria.
+    FoundOverloaded,
+
+    /// Name lookup found an unresolvable value declaration
+    /// and cannot yet complete.  This only happens in C++ dependent
+    /// contexts with dependent using declarations.
+    FoundUnresolvedValue,
+
+    /// Name lookup results in an ambiguity; use
+    /// getAmbiguityKind to figure out what kind of ambiguity
+    /// we have.
+    Ambiguous
+  };
+
+  enum AmbiguityKind {
+    /// Name lookup results in an ambiguity because multiple
+    /// entities that meet the lookup criteria were found in
+    /// subobjects of different types. For example:
+    /// @code
+    /// struct A { void f(int); }
+    /// struct B { void f(double); }
+    /// struct C : A, B { };
+    /// void test(C c) {
+    ///   c.f(0); // error: A::f and B::f come from subobjects of different
+    ///           // types. overload resolution is not performed.
+    /// }
+    /// @endcode
+    AmbiguousBaseSubobjectTypes,
+
+    /// Name lookup results in an ambiguity because multiple
+    /// nonstatic entities that meet the lookup criteria were found
+    /// in different subobjects of the same type. For example:
+    /// @code
+    /// struct A { int x; };
+    /// struct B : A { };
+    /// struct C : A { };
+    /// struct D : B, C { };
+    /// int test(D d) {
+    ///   return d.x; // error: 'x' is found in two A subobjects (of B and C)
+    /// }
+    /// @endcode
+    AmbiguousBaseSubobjects,
+
+    /// Name lookup results in an ambiguity because multiple definitions
+    /// of entity that meet the lookup criteria were found in different
+    /// declaration contexts.
+    /// @code
+    /// namespace A {
+    ///   int i;
+    ///   namespace B { int i; }
+    ///   int test() {
+    ///     using namespace B;
+    ///     return i; // error 'i' is found in namespace A and A::B
+    ///    }
+    /// }
+    /// @endcode
+    AmbiguousReference,
+
+    /// Name lookup results in an ambiguity because an entity with a
+    /// tag name was hidden by an entity with an ordinary name from
+    /// a different context.
+    /// @code
+    /// namespace A { struct Foo {}; }
+    /// namespace B { void Foo(); }
+    /// namespace C {
+    ///   using namespace A;
+    ///   using namespace B;
+    /// }
+    /// void test() {
+    ///   C::Foo(); // error: tag 'A::Foo' is hidden by an object in a
+    ///             // different namespace
+    /// }
+    /// @endcode
+    AmbiguousTagHiding
+  };
+
+  /// A little identifier for flagging temporary lookup results.
+  enum TemporaryToken {
+    Temporary
+  };
+
+  using iterator = UnresolvedSetImpl::iterator;
+
+  LookupResult(Sema &SemaRef, const DeclarationNameInfo &NameInfo,
+               Sema::LookupNameKind LookupKind,
+               Sema::RedeclarationKind Redecl = Sema::NotForRedeclaration)
+      : SemaPtr(&SemaRef), NameInfo(NameInfo), LookupKind(LookupKind),
+        Redecl(Redecl != Sema::NotForRedeclaration),
+        ExternalRedecl(Redecl == Sema::ForExternalRedeclaration),
+        Diagnose(Redecl == Sema::NotForRedeclaration) {
+    configure();
+  }
+
+  // TODO: consider whether this constructor should be restricted to take
+  // as input a const IdentifierInfo* (instead of Name),
+  // forcing other cases towards the constructor taking a DNInfo.
+  LookupResult(Sema &SemaRef, DeclarationName Name,
+               SourceLocation NameLoc, Sema::LookupNameKind LookupKind,
+               Sema::RedeclarationKind Redecl = Sema::NotForRedeclaration)
+      : SemaPtr(&SemaRef), NameInfo(Name, NameLoc), LookupKind(LookupKind),
+        Redecl(Redecl != Sema::NotForRedeclaration),
+        ExternalRedecl(Redecl == Sema::ForExternalRedeclaration),
+        Diagnose(Redecl == Sema::NotForRedeclaration) {
+    configure();
+  }
+
+  /// Creates a temporary lookup result, initializing its core data
+  /// using the information from another result.  Diagnostics are always
+  /// disabled.
+  LookupResult(TemporaryToken _, const LookupResult &Other)
+      : SemaPtr(Other.SemaPtr), NameInfo(Other.NameInfo),
+        LookupKind(Other.LookupKind), IDNS(Other.IDNS), Redecl(Other.Redecl),
+        ExternalRedecl(Other.ExternalRedecl), HideTags(Other.HideTags),
+        AllowHidden(Other.AllowHidden) {}
+
+  // FIXME: Remove these deleted methods once the default build includes
+  // -Wdeprecated.
+  LookupResult(const LookupResult &) = delete;
+  LookupResult &operator=(const LookupResult &) = delete;
+
+  LookupResult(LookupResult &&Other)
+      : ResultKind(std::move(Other.ResultKind)),
+        Ambiguity(std::move(Other.Ambiguity)), Decls(std::move(Other.Decls)),
+        Paths(std::move(Other.Paths)),
+        NamingClass(std::move(Other.NamingClass)),
+        BaseObjectType(std::move(Other.BaseObjectType)),
+        SemaPtr(std::move(Other.SemaPtr)), NameInfo(std::move(Other.NameInfo)),
+        NameContextRange(std::move(Other.NameContextRange)),
+        LookupKind(std::move(Other.LookupKind)), IDNS(std::move(Other.IDNS)),
+        Redecl(std::move(Other.Redecl)),
+        ExternalRedecl(std::move(Other.ExternalRedecl)),
+        HideTags(std::move(Other.HideTags)),
+        Diagnose(std::move(Other.Diagnose)),
+        AllowHidden(std::move(Other.AllowHidden)),
+        Shadowed(std::move(Other.Shadowed)) {
+    Other.Paths = nullptr;
+    Other.Diagnose = false;
+  }
+
+  LookupResult &operator=(LookupResult &&Other) {
+    ResultKind = std::move(Other.ResultKind);
+    Ambiguity = std::move(Other.Ambiguity);
+    Decls = std::move(Other.Decls);
+    Paths = std::move(Other.Paths);
+    NamingClass = std::move(Other.NamingClass);
+    BaseObjectType = std::move(Other.BaseObjectType);
+    SemaPtr = std::move(Other.SemaPtr);
+    NameInfo = std::move(Other.NameInfo);
+    NameContextRange = std::move(Other.NameContextRange);
+    LookupKind = std::move(Other.LookupKind);
+    IDNS = std::move(Other.IDNS);
+    Redecl = std::move(Other.Redecl);
+    ExternalRedecl = std::move(Other.ExternalRedecl);
+    HideTags = std::move(Other.HideTags);
+    Diagnose = std::move(Other.Diagnose);
+    AllowHidden = std::move(Other.AllowHidden);
+    Shadowed = std::move(Other.Shadowed);
+    Other.Paths = nullptr;
+    Other.Diagnose = false;
+    return *this;
+  }
+
+  ~LookupResult() {
+    if (Diagnose) diagnose();
+    if (Paths) deletePaths(Paths);
+  }
+
+  /// Gets the name info to look up.
+  const DeclarationNameInfo &getLookupNameInfo() const {
+    return NameInfo;
+  }
+
+  /// Sets the name info to look up.
+  void setLookupNameInfo(const DeclarationNameInfo &NameInfo) {
+    this->NameInfo = NameInfo;
+  }
+
+  /// Gets the name to look up.
+  DeclarationName getLookupName() const {
+    return NameInfo.getName();
+  }
+
+  /// Sets the name to look up.
+  void setLookupName(DeclarationName Name) {
+    NameInfo.setName(Name);
+  }
+
+  /// Gets the kind of lookup to perform.
+  Sema::LookupNameKind getLookupKind() const {
+    return LookupKind;
+  }
+
+  /// True if this lookup is just looking for an existing declaration.
+  bool isForRedeclaration() const {
+    return Redecl;
+  }
+
+  /// True if this lookup is just looking for an existing declaration to link
+  /// against a declaration with external linkage.
+  bool isForExternalRedeclaration() const {
+    return ExternalRedecl;
+  }
+
+  Sema::RedeclarationKind redeclarationKind() const {
+    return ExternalRedecl ? Sema::ForExternalRedeclaration :
+           Redecl ? Sema::ForVisibleRedeclaration : Sema::NotForRedeclaration;
+  }
+
+  /// Specify whether hidden declarations are visible, e.g.,
+  /// for recovery reasons.
+  void setAllowHidden(bool AH) {
+    AllowHidden = AH;
+  }
+
+  /// Determine whether this lookup is permitted to see hidden
+  /// declarations, such as those in modules that have not yet been imported.
+  bool isHiddenDeclarationVisible(NamedDecl *ND) const {
+    return AllowHidden ||
+           (isForExternalRedeclaration() && ND->isExternallyDeclarable());
+  }
+
+  /// Sets whether tag declarations should be hidden by non-tag
+  /// declarations during resolution.  The default is true.
+  void setHideTags(bool Hide) {
+    HideTags = Hide;
+  }
+
+  bool isAmbiguous() const {
+    return getResultKind() == Ambiguous;
+  }
+
+  /// Determines if this names a single result which is not an
+  /// unresolved value using decl.  If so, it is safe to call
+  /// getFoundDecl().
+  bool isSingleResult() const {
+    return getResultKind() == Found;
+  }
+
+  /// Determines if the results are overloaded.
+  bool isOverloadedResult() const {
+    return getResultKind() == FoundOverloaded;
+  }
+
+  bool isUnresolvableResult() const {
+    return getResultKind() == FoundUnresolvedValue;
+  }
+
+  LookupResultKind getResultKind() const {
+    assert(sanity());
+    return ResultKind;
+  }
+
+  AmbiguityKind getAmbiguityKind() const {
+    assert(isAmbiguous());
+    return Ambiguity;
+  }
+
+  const UnresolvedSetImpl &asUnresolvedSet() const {
+    return Decls;
+  }
+
+  iterator begin() const { return iterator(Decls.begin()); }
+  iterator end() const { return iterator(Decls.end()); }
+
+  /// Return true if no decls were found
+  bool empty() const { return Decls.empty(); }
+
+  /// Return the base paths structure that's associated with
+  /// these results, or null if none is.
+  CXXBasePaths *getBasePaths() const {
+    return Paths;
+  }
+
+  /// Determine whether the given declaration is visible to the
+  /// program.
+  static bool isVisible(Sema &SemaRef, NamedDecl *D) {
+    // If this declaration is not hidden, it's visible.
+    if (!D->isHidden())
+      return true;
+
+    // During template instantiation, we can refer to hidden declarations, if
+    // they were visible in any module along the path of instantiation.
+    return isVisibleSlow(SemaRef, D);
+  }
+
+  /// Retrieve the accepted (re)declaration of the given declaration,
+  /// if there is one.
+  NamedDecl *getAcceptableDecl(NamedDecl *D) const {
+    if (!D->isInIdentifierNamespace(IDNS))
+      return nullptr;
+
+    if (isVisible(getSema(), D) || isHiddenDeclarationVisible(D))
+      return D;
+
+    return getAcceptableDeclSlow(D);
+  }
+
+private:
+  static bool isVisibleSlow(Sema &SemaRef, NamedDecl *D);
+  NamedDecl *getAcceptableDeclSlow(NamedDecl *D) const;
+
+public:
+  /// Returns the identifier namespace mask for this lookup.
+  unsigned getIdentifierNamespace() const {
+    return IDNS;
+  }
+
+  /// Returns whether these results arose from performing a
+  /// lookup into a class.
+  bool isClassLookup() const {
+    return NamingClass != nullptr;
+  }
+
+  /// Returns the 'naming class' for this lookup, i.e. the
+  /// class which was looked into to find these results.
+  ///
+  /// C++0x [class.access.base]p5:
+  ///   The access to a member is affected by the class in which the
+  ///   member is named. This naming class is the class in which the
+  ///   member name was looked up and found. [Note: this class can be
+  ///   explicit, e.g., when a qualified-id is used, or implicit,
+  ///   e.g., when a class member access operator (5.2.5) is used
+  ///   (including cases where an implicit "this->" is added). If both
+  ///   a class member access operator and a qualified-id are used to
+  ///   name the member (as in p->T::m), the class naming the member
+  ///   is the class named by the nested-name-specifier of the
+  ///   qualified-id (that is, T). -- end note ]
+  ///
+  /// This is set by the lookup routines when they find results in a class.
+  CXXRecordDecl *getNamingClass() const {
+    return NamingClass;
+  }
+
+  /// Sets the 'naming class' for this lookup.
+  void setNamingClass(CXXRecordDecl *Record) {
+    NamingClass = Record;
+  }
+
+  /// Returns the base object type associated with this lookup;
+  /// important for [class.protected].  Most lookups do not have an
+  /// associated base object.
+  QualType getBaseObjectType() const {
+    return BaseObjectType;
+  }
+
+  /// Sets the base object type for this lookup.
+  void setBaseObjectType(QualType T) {
+    BaseObjectType = T;
+  }
+
+  /// Add a declaration to these results with its natural access.
+  /// Does not test the acceptance criteria.
+  void addDecl(NamedDecl *D) {
+    addDecl(D, D->getAccess());
+  }
+
+  /// Add a declaration to these results with the given access.
+  /// Does not test the acceptance criteria.
+  void addDecl(NamedDecl *D, AccessSpecifier AS) {
+    Decls.addDecl(D, AS);
+    ResultKind = Found;
+  }
+
+  /// Add all the declarations from another set of lookup
+  /// results.
+  void addAllDecls(const LookupResult &Other) {
+    Decls.append(Other.Decls.begin(), Other.Decls.end());
+    ResultKind = Found;
+  }
+
+  /// Determine whether no result was found because we could not
+  /// search into dependent base classes of the current instantiation.
+  bool wasNotFoundInCurrentInstantiation() const {
+    return ResultKind == NotFoundInCurrentInstantiation;
+  }
+
+  /// Note that while no result was found in the current instantiation,
+  /// there were dependent base classes that could not be searched.
+  void setNotFoundInCurrentInstantiation() {
+    assert(ResultKind == NotFound && Decls.empty());
+    ResultKind = NotFoundInCurrentInstantiation;
+  }
+
+  /// Determine whether the lookup result was shadowed by some other
+  /// declaration that lookup ignored.
+  bool isShadowed() const { return Shadowed; }
+
+  /// Note that we found and ignored a declaration while performing
+  /// lookup.
+  void setShadowed() { Shadowed = true; }
+
+  /// Resolves the result kind of the lookup, possibly hiding
+  /// decls.
+  ///
+  /// This should be called in any environment where lookup might
+  /// generate multiple lookup results.
+  void resolveKind();
+
+  /// Re-resolves the result kind of the lookup after a set of
+  /// removals has been performed.
+  void resolveKindAfterFilter() {
+    if (Decls.empty()) {
+      if (ResultKind != NotFoundInCurrentInstantiation)
+        ResultKind = NotFound;
+
+      if (Paths) {
+        deletePaths(Paths);
+        Paths = nullptr;
+      }
+    } else {
+      llvm::Optional<AmbiguityKind> SavedAK;
+      bool WasAmbiguous = false;
+      if (ResultKind == Ambiguous) {
+        SavedAK = Ambiguity;
+        WasAmbiguous = true;
+      }
+      ResultKind = Found;
+      resolveKind();
+
+      // If we didn't make the lookup unambiguous, restore the old
+      // ambiguity kind.
+      if (ResultKind == Ambiguous) {
+        (void)WasAmbiguous;
+        assert(WasAmbiguous);
+        Ambiguity = SavedAK.getValue();
+      } else if (Paths) {
+        deletePaths(Paths);
+        Paths = nullptr;
+      }
+    }
+  }
+
+  template <class DeclClass>
+  DeclClass *getAsSingle() const {
+    if (getResultKind() != Found) return nullptr;
+    return dyn_cast<DeclClass>(getFoundDecl());
+  }
+
+  /// Fetch the unique decl found by this lookup.  Asserts
+  /// that one was found.
+  ///
+  /// This is intended for users who have examined the result kind
+  /// and are certain that there is only one result.
+  NamedDecl *getFoundDecl() const {
+    assert(getResultKind() == Found
+           && "getFoundDecl called on non-unique result");
+    return (*begin())->getUnderlyingDecl();
+  }
+
+  /// Fetches a representative decl.  Useful for lazy diagnostics.
+  NamedDecl *getRepresentativeDecl() const {
+    assert(!Decls.empty() && "cannot get representative of empty set");
+    return *begin();
+  }
+
+  /// Asks if the result is a single tag decl.
+  bool isSingleTagDecl() const {
+    return getResultKind() == Found && isa<TagDecl>(getFoundDecl());
+  }
+
+  /// Make these results show that the name was found in
+  /// base classes of different types.
+  ///
+  /// The given paths object is copied and invalidated.
+  void setAmbiguousBaseSubobjectTypes(CXXBasePaths &P);
+
+  /// Make these results show that the name was found in
+  /// distinct base classes of the same type.
+  ///
+  /// The given paths object is copied and invalidated.
+  void setAmbiguousBaseSubobjects(CXXBasePaths &P);
+
+  /// Make these results show that the name was found in
+  /// different contexts and a tag decl was hidden by an ordinary
+  /// decl in a different context.
+  void setAmbiguousQualifiedTagHiding() {
+    setAmbiguous(AmbiguousTagHiding);
+  }
+
+  /// Clears out any current state.
+  LLVM_ATTRIBUTE_REINITIALIZES void clear() {
+    ResultKind = NotFound;
+    Decls.clear();
+    if (Paths) deletePaths(Paths);
+    Paths = nullptr;
+    NamingClass = nullptr;
+    Shadowed = false;
+  }
+
+  /// Clears out any current state and re-initializes for a
+  /// different kind of lookup.
+  void clear(Sema::LookupNameKind Kind) {
+    clear();
+    LookupKind = Kind;
+    configure();
+  }
+
+  /// Change this lookup's redeclaration kind.
+  void setRedeclarationKind(Sema::RedeclarationKind RK) {
+    Redecl = (RK != Sema::NotForRedeclaration);
+    ExternalRedecl = (RK == Sema::ForExternalRedeclaration);
+    configure();
+  }
+
+  void dump();
+  void print(raw_ostream &);
+
+  /// Suppress the diagnostics that would normally fire because of this
+  /// lookup.  This happens during (e.g.) redeclaration lookups.
+  void suppressDiagnostics() {
+    Diagnose = false;
+  }
+
+  /// Determines whether this lookup is suppressing diagnostics.
+  bool isSuppressingDiagnostics() const {
+    return !Diagnose;
+  }
+
+  /// Sets a 'context' source range.
+  void setContextRange(SourceRange SR) {
+    NameContextRange = SR;
+  }
+
+  /// Gets the source range of the context of this name; for C++
+  /// qualified lookups, this is the source range of the scope
+  /// specifier.
+  SourceRange getContextRange() const {
+    return NameContextRange;
+  }
+
+  /// Gets the location of the identifier.  This isn't always defined:
+  /// sometimes we're doing lookups on synthesized names.
+  SourceLocation getNameLoc() const {
+    return NameInfo.getLoc();
+  }
+
+  /// Get the Sema object that this lookup result is searching
+  /// with.
+  Sema &getSema() const { return *SemaPtr; }
+
+  /// A class for iterating through a result set and possibly
+  /// filtering out results.  The results returned are possibly
+  /// sugared.
+  class Filter {
+    friend class LookupResult;
+
+    LookupResult &Results;
+    LookupResult::iterator I;
+    bool Changed = false;
+    bool CalledDone = false;
+
+    Filter(LookupResult &Results) : Results(Results), I(Results.begin()) {}
+
+  public:
+    Filter(Filter &&F)
+        : Results(F.Results), I(F.I), Changed(F.Changed),
+          CalledDone(F.CalledDone) {
+      F.CalledDone = true;
+    }
+
+    ~Filter() {
+      assert(CalledDone &&
+             "LookupResult::Filter destroyed without done() call");
+    }
+
+    bool hasNext() const {
+      return I != Results.end();
+    }
+
+    NamedDecl *next() {
+      assert(I != Results.end() && "next() called on empty filter");
+      return *I++;
+    }
+
+    /// Restart the iteration.
+    void restart() {
+      I = Results.begin();
+    }
+
+    /// Erase the last element returned from this iterator.
+    void erase() {
+      Results.Decls.erase(--I);
+      Changed = true;
+    }
+
+    /// Replaces the current entry with the given one, preserving the
+    /// access bits.
+    void replace(NamedDecl *D) {
+      Results.Decls.replace(I-1, D);
+      Changed = true;
+    }
+
+    /// Replaces the current entry with the given one.
+    void replace(NamedDecl *D, AccessSpecifier AS) {
+      Results.Decls.replace(I-1, D, AS);
+      Changed = true;
+    }
+
+    void done() {
+      assert(!CalledDone && "done() called twice");
+      CalledDone = true;
+
+      if (Changed)
+        Results.resolveKindAfterFilter();
+    }
+  };
+
+  /// Create a filter for this result set.
+  Filter makeFilter() {
+    return Filter(*this);
+  }
+
+  void setFindLocalExtern(bool FindLocalExtern) {
+    if (FindLocalExtern)
+      IDNS |= Decl::IDNS_LocalExtern;
+    else
+      IDNS &= ~Decl::IDNS_LocalExtern;
+  }
+
+private:
+  void diagnose() {
+    if (isAmbiguous())
+      getSema().DiagnoseAmbiguousLookup(*this);
+    else if (isClassLookup() && getSema().getLangOpts().AccessControl)
+      getSema().CheckLookupAccess(*this);
+  }
+
+  void setAmbiguous(AmbiguityKind AK) {
+    ResultKind = Ambiguous;
+    Ambiguity = AK;
+  }
+
+  void addDeclsFromBasePaths(const CXXBasePaths &P);
+  void configure();
+
+  // Sanity checks.
+  bool sanity() const;
+
+  bool sanityCheckUnresolved() const {
+    for (iterator I = begin(), E = end(); I != E; ++I)
+      if (isa<UnresolvedUsingValueDecl>((*I)->getUnderlyingDecl()))
+        return true;
+    return false;
+  }
+
+  static void deletePaths(CXXBasePaths *);
+
+  // Results.
+  LookupResultKind ResultKind = NotFound;
+  // ill-defined unless ambiguous. Still need to be initialized it will be
+  // copied/moved.
+  AmbiguityKind Ambiguity = {};
+  UnresolvedSet<8> Decls;
+  CXXBasePaths *Paths = nullptr;
+  CXXRecordDecl *NamingClass = nullptr;
+  QualType BaseObjectType;
+
+  // Parameters.
+  Sema *SemaPtr;
+  DeclarationNameInfo NameInfo;
+  SourceRange NameContextRange;
+  Sema::LookupNameKind LookupKind;
+  unsigned IDNS = 0; // set by configure()
+
+  bool Redecl;
+  bool ExternalRedecl;
+
+  /// True if tag declarations should be hidden if non-tags
+  ///   are present
+  bool HideTags = true;
+
+  bool Diagnose = false;
+
+  /// True if we should allow hidden declarations to be 'visible'.
+  bool AllowHidden = false;
+
+  /// True if the found declarations were shadowed by some other
+  /// declaration that we skipped. This only happens when \c LookupKind
+  /// is \c LookupRedeclarationWithLinkage.
+  bool Shadowed = false;
+};
+
+/// Consumes visible declarations found when searching for
+/// all visible names within a given scope or context.
+///
+/// This abstract class is meant to be subclassed by clients of \c
+/// Sema::LookupVisibleDecls(), each of which should override the \c
+/// FoundDecl() function to process declarations as they are found.
+class VisibleDeclConsumer {
+public:
+  /// Destroys the visible declaration consumer.
+  virtual ~VisibleDeclConsumer();
+
+  /// Determine whether hidden declarations (from unimported
+  /// modules) should be given to this consumer. By default, they
+  /// are not included.
+  virtual bool includeHiddenDecls() const;
+
+  /// Invoked each time \p Sema::LookupVisibleDecls() finds a
+  /// declaration visible from the current scope or context.
+  ///
+  /// \param ND the declaration found.
+  ///
+  /// \param Hiding a declaration that hides the declaration \p ND,
+  /// or NULL if no such declaration exists.
+  ///
+  /// \param Ctx the original context from which the lookup started.
+  ///
+  /// \param InBaseClass whether this declaration was found in base
+  /// class of the context we searched.
+  virtual void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
+                         bool InBaseClass) = 0;
+
+  /// Callback to inform the client that Sema entered into a new context
+  /// to find a visible declaration.
+  //
+  /// \param Ctx the context which Sema entered.
+  virtual void EnteredContext(DeclContext *Ctx) {}
+};
+
+/// A class for storing results from argument-dependent lookup.
+class ADLResult {
+private:
+  /// A map from canonical decls to the 'most recent' decl.
+  llvm::MapVector<NamedDecl*, NamedDecl*> Decls;
+
+  struct select_second {
+    NamedDecl *operator()(std::pair<NamedDecl*, NamedDecl*> P) const {
+      return P.second;
+    }
+  };
+
+public:
+  /// Adds a new ADL candidate to this map.
+  void insert(NamedDecl *D);
+
+  /// Removes any data associated with a given decl.
+  void erase(NamedDecl *D) {
+    Decls.erase(cast<NamedDecl>(D->getCanonicalDecl()));
+  }
+
+  using iterator =
+      llvm::mapped_iterator<decltype(Decls)::iterator, select_second>;
+
+  iterator begin() { return iterator(Decls.begin(), select_second()); }
+  iterator end() { return iterator(Decls.end(), select_second()); }
+};
+
+} // namespace clang
+
+#endif // LLVM_CLANG_SEMA_LOOKUP_H