xref: /external/clang/lib/AST/Decl.cpp

//===--- Decl.cpp - Declaration AST Node Implementation -------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Decl subclasses.
//
//===----------------------------------------------------------------------===//

#include "clang/AST/Decl.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/TypeLoc.h"
#include "clang/AST/Stmt.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/PrettyPrinter.h"
#include "clang/AST/ASTMutationListener.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/Specifiers.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/Support/ErrorHandling.h"

#include <algorithm>

using namespace clang;

//===----------------------------------------------------------------------===//
// NamedDecl Implementation
//===----------------------------------------------------------------------===//

static llvm::Optional<Visibility> getVisibilityOf(const Decl *D) {
  // If this declaration has an explicit visibility attribute, use it.
  if (const VisibilityAttr *A = D->getAttr<VisibilityAttr>()) {
    switch (A->getVisibility()) {
    case VisibilityAttr::Default:
      return DefaultVisibility;
    case VisibilityAttr::Hidden:
      return HiddenVisibility;
    case VisibilityAttr::Protected:
      return ProtectedVisibility;
    }

    return DefaultVisibility;
  }

  // If we're on Mac OS X, an 'availability' for Mac OS X attribute
  // implies visibility(default).
  if (D->getASTContext().getTargetInfo().getTriple().isOSDarwin()) {
    for (specific_attr_iterator<AvailabilityAttr>
              A = D->specific_attr_begin<AvailabilityAttr>(),
           AEnd = D->specific_attr_end<AvailabilityAttr>();
         A != AEnd; ++A)
      if ((*A)->getPlatform()->getName().equals("macosx"))
        return DefaultVisibility;
  }

  return llvm::Optional<Visibility>();
}

typedef NamedDecl::LinkageInfo LinkageInfo;
typedef std::pair<Linkage,Visibility> LVPair;

static LVPair merge(LVPair L, LVPair R) {
  return LVPair(minLinkage(L.first, R.first),
                minVisibility(L.second, R.second));
}

static LVPair merge(LVPair L, LinkageInfo R) {
  return LVPair(minLinkage(L.first, R.linkage()),
                minVisibility(L.second, R.visibility()));
}

namespace {
/// Flags controlling the computation of linkage and visibility.
struct LVFlags {
  bool ConsiderGlobalVisibility;
  bool ConsiderVisibilityAttributes;
  bool ConsiderTemplateParameterTypes;

  LVFlags() : ConsiderGlobalVisibility(true),
              ConsiderVisibilityAttributes(true),
              ConsiderTemplateParameterTypes(true) {
  }

  /// \brief Returns a set of flags that is only useful for computing the
  /// linkage, not the visibility, of a declaration.
  static LVFlags CreateOnlyDeclLinkage() {
    LVFlags F;
    F.ConsiderGlobalVisibility = false;
    F.ConsiderVisibilityAttributes = false;
    F.ConsiderTemplateParameterTypes = false;
    return F;
  }

  /// Returns a set of flags, otherwise based on these, which ignores
  /// off all sources of visibility except template arguments.
  LVFlags onlyTemplateVisibility() const {
    LVFlags F = *this;
    F.ConsiderGlobalVisibility = false;
    F.ConsiderVisibilityAttributes = false;
    F.ConsiderTemplateParameterTypes = false;
    return F;
  }
};
} // end anonymous namespace

/// \brief Get the most restrictive linkage for the types in the given
/// template parameter list.
static LVPair
getLVForTemplateParameterList(const TemplateParameterList *Params) {
  LVPair LV(ExternalLinkage, DefaultVisibility);
  for (TemplateParameterList::const_iterator P = Params->begin(),
                                          PEnd = Params->end();
       P != PEnd; ++P) {
    if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(*P)) {
      if (NTTP->isExpandedParameterPack()) {
        for (unsigned I = 0, N = NTTP->getNumExpansionTypes(); I != N; ++I) {
          QualType T = NTTP->getExpansionType(I);
          if (!T->isDependentType())
            LV = merge(LV, T->getLinkageAndVisibility());
        }
        continue;
      }

      if (!NTTP->getType()->isDependentType()) {
        LV = merge(LV, NTTP->getType()->getLinkageAndVisibility());
        continue;
      }
    }

    if (TemplateTemplateParmDecl *TTP
                                   = dyn_cast<TemplateTemplateParmDecl>(*P)) {
      LV = merge(LV, getLVForTemplateParameterList(TTP->getTemplateParameters()));
    }
  }

  return LV;
}

/// getLVForDecl - Get the linkage and visibility for the given declaration.
static LinkageInfo getLVForDecl(const NamedDecl *D, LVFlags F);

/// \brief Get the most restrictive linkage for the types and
/// declarations in the given template argument list.
static LVPair getLVForTemplateArgumentList(const TemplateArgument *Args,
                                           unsigned NumArgs,
                                           LVFlags &F) {
  LVPair LV(ExternalLinkage, DefaultVisibility);

  for (unsigned I = 0; I != NumArgs; ++I) {
    switch (Args[I].getKind()) {
    case TemplateArgument::Null:
    case TemplateArgument::Integral:
    case TemplateArgument::Expression:
      break;

    case TemplateArgument::Type:
      LV = merge(LV, Args[I].getAsType()->getLinkageAndVisibility());
      break;

    case TemplateArgument::Declaration:
      // The decl can validly be null as the representation of nullptr
      // arguments, valid only in C++0x.
      if (Decl *D = Args[I].getAsDecl()) {
        if (NamedDecl *ND = dyn_cast<NamedDecl>(D))
          LV = merge(LV, getLVForDecl(ND, F));
      }
      break;

    case TemplateArgument::Template:
    case TemplateArgument::TemplateExpansion:
      if (TemplateDecl *Template
                = Args[I].getAsTemplateOrTemplatePattern().getAsTemplateDecl())
        LV = merge(LV, getLVForDecl(Template, F));
      break;

    case TemplateArgument::Pack:
      LV = merge(LV, getLVForTemplateArgumentList(Args[I].pack_begin(),
                                                  Args[I].pack_size(),
                                                  F));
      break;
    }
  }

  return LV;
}

static LVPair
getLVForTemplateArgumentList(const TemplateArgumentList &TArgs,
                             LVFlags &F) {
  return getLVForTemplateArgumentList(TArgs.data(), TArgs.size(), F);
}

static bool shouldConsiderTemplateLV(const FunctionDecl *fn,
                               const FunctionTemplateSpecializationInfo *spec) {
  return !(spec->isExplicitSpecialization() &&
           fn->hasAttr<VisibilityAttr>());
}

static bool shouldConsiderTemplateLV(const ClassTemplateSpecializationDecl *d) {
  return !(d->isExplicitSpecialization() && d->hasAttr<VisibilityAttr>());
}

static LinkageInfo getLVForNamespaceScopeDecl(const NamedDecl *D, LVFlags F) {
  assert(D->getDeclContext()->getRedeclContext()->isFileContext() &&
         "Not a name having namespace scope");
  ASTContext &Context = D->getASTContext();

  // C++ [basic.link]p3:
  //   A name having namespace scope (3.3.6) has internal linkage if it
  //   is the name of
  //     - an object, reference, function or function template that is
  //       explicitly declared static; or,
  // (This bullet corresponds to C99 6.2.2p3.)
  if (const VarDecl *Var = dyn_cast<VarDecl>(D)) {
    // Explicitly declared static.
    if (Var->getStorageClass() == SC_Static)
      return LinkageInfo::internal();

    // - an object or reference that is explicitly declared const
    //   and neither explicitly declared extern nor previously
    //   declared to have external linkage; or
    // (there is no equivalent in C99)
    if (Context.getLangOptions().CPlusPlus &&
        Var->getType().isConstant(Context) &&
        Var->getStorageClass() != SC_Extern &&
        Var->getStorageClass() != SC_PrivateExtern) {
      bool FoundExtern = false;
      for (const VarDecl *PrevVar = Var->getPreviousDeclaration();
           PrevVar && !FoundExtern;
           PrevVar = PrevVar->getPreviousDeclaration())
        if (isExternalLinkage(PrevVar->getLinkage()))
          FoundExtern = true;

      if (!FoundExtern)
        return LinkageInfo::internal();
    }
    if (Var->getStorageClass() == SC_None) {
      const VarDecl *PrevVar = Var->getPreviousDeclaration();
      for (; PrevVar; PrevVar = PrevVar->getPreviousDeclaration())
        if (PrevVar->getStorageClass() == SC_PrivateExtern)
          break;
        if (PrevVar)
          return PrevVar->getLinkageAndVisibility();
    }
  } else if (isa<FunctionDecl>(D) || isa<FunctionTemplateDecl>(D)) {
    // C++ [temp]p4:
    //   A non-member function template can have internal linkage; any
    //   other template name shall have external linkage.
    const FunctionDecl *Function = 0;
    if (const FunctionTemplateDecl *FunTmpl
                                        = dyn_cast<FunctionTemplateDecl>(D))
      Function = FunTmpl->getTemplatedDecl();
    else
      Function = cast<FunctionDecl>(D);

    // Explicitly declared static.
    if (Function->getStorageClass() == SC_Static)
      return LinkageInfo(InternalLinkage, DefaultVisibility, false);
  } else if (const FieldDecl *Field = dyn_cast<FieldDecl>(D)) {
    //   - a data member of an anonymous union.
    if (cast<RecordDecl>(Field->getDeclContext())->isAnonymousStructOrUnion())
      return LinkageInfo::internal();
  }

  if (D->isInAnonymousNamespace()) {
    const VarDecl *Var = dyn_cast<VarDecl>(D);
    const FunctionDecl *Func = dyn_cast<FunctionDecl>(D);
    if ((!Var || !Var->isExternC()) && (!Func || !Func->isExternC()))
      return LinkageInfo::uniqueExternal();
  }

  // Set up the defaults.

  // C99 6.2.2p5:
  //   If the declaration of an identifier for an object has file
  //   scope and no storage-class specifier, its linkage is
  //   external.
  LinkageInfo LV;

  if (F.ConsiderVisibilityAttributes) {
    if (llvm::Optional<Visibility> Vis = D->getExplicitVisibility()) {
      LV.setVisibility(*Vis, true);
      F.ConsiderGlobalVisibility = false;
    } else {
      // If we're declared in a namespace with a visibility attribute,
      // use that namespace's visibility, but don't call it explicit.
      for (const DeclContext *DC = D->getDeclContext();
           !isa<TranslationUnitDecl>(DC);
           DC = DC->getParent()) {
        if (!isa<NamespaceDecl>(DC)) continue;
        if (llvm::Optional<Visibility> Vis
                           = cast<NamespaceDecl>(DC)->getExplicitVisibility()) {
          LV.setVisibility(*Vis, false);
          F.ConsiderGlobalVisibility = false;
          break;
        }
      }
    }
  }

  // C++ [basic.link]p4:

  //   A name having namespace scope has external linkage if it is the
  //   name of
  //
  //     - an object or reference, unless it has internal linkage; or
  if (const VarDecl *Var = dyn_cast<VarDecl>(D)) {
    // GCC applies the following optimization to variables and static
    // data members, but not to functions:
    //
    // Modify the variable's LV by the LV of its type unless this is
    // C or extern "C".  This follows from [basic.link]p9:
    //   A type without linkage shall not be used as the type of a
    //   variable or function with external linkage unless
    //    - the entity has C language linkage, or
    //    - the entity is declared within an unnamed namespace, or
    //    - the entity is not used or is defined in the same
    //      translation unit.
    // and [basic.link]p10:
    //   ...the types specified by all declarations referring to a
    //   given variable or function shall be identical...
    // C does not have an equivalent rule.
    //
    // Ignore this if we've got an explicit attribute;  the user
    // probably knows what they're doing.
    //
    // Note that we don't want to make the variable non-external
    // because of this, but unique-external linkage suits us.
    if (Context.getLangOptions().CPlusPlus && !Var->isExternC()) {
      LVPair TypeLV = Var->getType()->getLinkageAndVisibility();
      if (TypeLV.first != ExternalLinkage)
        return LinkageInfo::uniqueExternal();
      if (!LV.visibilityExplicit())
        LV.mergeVisibility(TypeLV.second);
    }

    if (Var->getStorageClass() == SC_PrivateExtern)
      LV.setVisibility(HiddenVisibility, true);

    if (!Context.getLangOptions().CPlusPlus &&
        (Var->getStorageClass() == SC_Extern ||
         Var->getStorageClass() == SC_PrivateExtern)) {

      // C99 6.2.2p4:
      //   For an identifier declared with the storage-class specifier
      //   extern in a scope in which a prior declaration of that
      //   identifier is visible, if the prior declaration specifies
      //   internal or external linkage, the linkage of the identifier
      //   at the later declaration is the same as the linkage
      //   specified at the prior declaration. If no prior declaration
      //   is visible, or if the prior declaration specifies no
      //   linkage, then the identifier has external linkage.
      if (const VarDecl *PrevVar = Var->getPreviousDeclaration()) {
        LinkageInfo PrevLV = getLVForDecl(PrevVar, F);
        if (PrevLV.linkage()) LV.setLinkage(PrevLV.linkage());
        LV.mergeVisibility(PrevLV);
      }
    }

  //     - a function, unless it has internal linkage; or
  } else if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
    // In theory, we can modify the function's LV by the LV of its
    // type unless it has C linkage (see comment above about variables
    // for justification).  In practice, GCC doesn't do this, so it's
    // just too painful to make work.

    if (Function->getStorageClass() == SC_PrivateExtern)
      LV.setVisibility(HiddenVisibility, true);

    // C99 6.2.2p5:
    //   If the declaration of an identifier for a function has no
    //   storage-class specifier, its linkage is determined exactly
    //   as if it were declared with the storage-class specifier
    //   extern.
    if (!Context.getLangOptions().CPlusPlus &&
        (Function->getStorageClass() == SC_Extern ||
         Function->getStorageClass() == SC_PrivateExtern ||
         Function->getStorageClass() == SC_None)) {
      // C99 6.2.2p4:
      //   For an identifier declared with the storage-class specifier
      //   extern in a scope in which a prior declaration of that
      //   identifier is visible, if the prior declaration specifies
      //   internal or external linkage, the linkage of the identifier
      //   at the later declaration is the same as the linkage
      //   specified at the prior declaration. If no prior declaration
      //   is visible, or if the prior declaration specifies no
      //   linkage, then the identifier has external linkage.
      if (const FunctionDecl *PrevFunc = Function->getPreviousDeclaration()) {
        LinkageInfo PrevLV = getLVForDecl(PrevFunc, F);
        if (PrevLV.linkage()) LV.setLinkage(PrevLV.linkage());
        LV.mergeVisibility(PrevLV);
      }
    }

    // In C++, then if the type of the function uses a type with
    // unique-external linkage, it's not legally usable from outside
    // this translation unit.  However, we should use the C linkage
    // rules instead for extern "C" declarations.
    if (Context.getLangOptions().CPlusPlus && !Function->isExternC() &&
        Function->getType()->getLinkage() == UniqueExternalLinkage)
      return LinkageInfo::uniqueExternal();

    // Consider LV from the template and the template arguments unless
    // this is an explicit specialization with a visibility attribute.
    if (FunctionTemplateSpecializationInfo *specInfo
                               = Function->getTemplateSpecializationInfo()) {
      if (shouldConsiderTemplateLV(Function, specInfo)) {
        LV.merge(getLVForDecl(specInfo->getTemplate(),
                              F.onlyTemplateVisibility()));
        const TemplateArgumentList &templateArgs = *specInfo->TemplateArguments;
        LV.merge(getLVForTemplateArgumentList(templateArgs, F));
      }
    }

  //     - a named class (Clause 9), or an unnamed class defined in a
  //       typedef declaration in which the class has the typedef name
  //       for linkage purposes (7.1.3); or
  //     - a named enumeration (7.2), or an unnamed enumeration
  //       defined in a typedef declaration in which the enumeration
  //       has the typedef name for linkage purposes (7.1.3); or
  } else if (const TagDecl *Tag = dyn_cast<TagDecl>(D)) {
    // Unnamed tags have no linkage.
    if (!Tag->getDeclName() && !Tag->getTypedefNameForAnonDecl())
      return LinkageInfo::none();

    // If this is a class template specialization, consider the
    // linkage of the template and template arguments.
    if (const ClassTemplateSpecializationDecl *spec
          = dyn_cast<ClassTemplateSpecializationDecl>(Tag)) {
      if (shouldConsiderTemplateLV(spec)) {
        // From the template.
        LV.merge(getLVForDecl(spec->getSpecializedTemplate(),
                              F.onlyTemplateVisibility()));

        // The arguments at which the template was instantiated.
        const TemplateArgumentList &TemplateArgs = spec->getTemplateArgs();
        LV.merge(getLVForTemplateArgumentList(TemplateArgs, F));
      }
    }

    // Consider -fvisibility unless the type has C linkage.
    if (F.ConsiderGlobalVisibility)
      F.ConsiderGlobalVisibility =
        (Context.getLangOptions().CPlusPlus &&
         !Tag->getDeclContext()->isExternCContext());

  //     - an enumerator belonging to an enumeration with external linkage;
  } else if (isa<EnumConstantDecl>(D)) {
    LinkageInfo EnumLV = getLVForDecl(cast<NamedDecl>(D->getDeclContext()), F);
    if (!isExternalLinkage(EnumLV.linkage()))
      return LinkageInfo::none();
    LV.merge(EnumLV);

  //     - a template, unless it is a function template that has
  //       internal linkage (Clause 14);
  } else if (const TemplateDecl *temp = dyn_cast<TemplateDecl>(D)) {
    if (F.ConsiderTemplateParameterTypes)
      LV.merge(getLVForTemplateParameterList(temp->getTemplateParameters()));

  //     - a namespace (7.3), unless it is declared within an unnamed
  //       namespace.
  } else if (isa<NamespaceDecl>(D) && !D->isInAnonymousNamespace()) {
    return LV;

  // By extension, we assign external linkage to Objective-C
  // interfaces.
  } else if (isa<ObjCInterfaceDecl>(D)) {
    // fallout

  // Everything not covered here has no linkage.
  } else {
    return LinkageInfo::none();
  }

  // If we ended up with non-external linkage, visibility should
  // always be default.
  if (LV.linkage() != ExternalLinkage)
    return LinkageInfo(LV.linkage(), DefaultVisibility, false);

  // If we didn't end up with hidden visibility, consider attributes
  // and -fvisibility.
  if (F.ConsiderGlobalVisibility)
    LV.mergeVisibility(Context.getLangOptions().getVisibilityMode());

  return LV;
}

static LinkageInfo getLVForClassMember(const NamedDecl *D, LVFlags F) {
  // Only certain class members have linkage.  Note that fields don't
  // really have linkage, but it's convenient to say they do for the
  // purposes of calculating linkage of pointer-to-data-member
  // template arguments.
  if (!(isa<CXXMethodDecl>(D) ||
        isa<VarDecl>(D) ||
        isa<FieldDecl>(D) ||
        (isa<TagDecl>(D) &&
         (D->getDeclName() || cast<TagDecl>(D)->getTypedefNameForAnonDecl()))))
    return LinkageInfo::none();

  LinkageInfo LV;

  // The flags we're going to use to compute the class's visibility.
  LVFlags ClassF = F;

  // If we have an explicit visibility attribute, merge that in.
  if (F.ConsiderVisibilityAttributes) {
    if (llvm::Optional<Visibility> Vis = D->getExplicitVisibility()) {
      LV.mergeVisibility(*Vis, true);

      // Ignore global visibility later, but not this attribute.
      F.ConsiderGlobalVisibility = false;

      // Ignore both global visibility and attributes when computing our
      // parent's visibility.
      ClassF = F.onlyTemplateVisibility();
    }
  }

  // Class members only have linkage if their class has external
  // linkage.
  LV.merge(getLVForDecl(cast<RecordDecl>(D->getDeclContext()), ClassF));
  if (!isExternalLinkage(LV.linkage()))
    return LinkageInfo::none();

  // If the class already has unique-external linkage, we can't improve.
  if (LV.linkage() == UniqueExternalLinkage)
    return LinkageInfo::uniqueExternal();

  if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(D)) {
    // If the type of the function uses a type with unique-external
    // linkage, it's not legally usable from outside this translation unit.
    if (MD->getType()->getLinkage() == UniqueExternalLinkage)
      return LinkageInfo::uniqueExternal();

    TemplateSpecializationKind TSK = TSK_Undeclared;

    // If this is a method template specialization, use the linkage for
    // the template parameters and arguments.
    if (FunctionTemplateSpecializationInfo *spec
           = MD->getTemplateSpecializationInfo()) {
      if (shouldConsiderTemplateLV(MD, spec)) {
        LV.merge(getLVForTemplateArgumentList(*spec->TemplateArguments, F));
        if (F.ConsiderTemplateParameterTypes)
          LV.merge(getLVForTemplateParameterList(
                              spec->getTemplate()->getTemplateParameters()));
      }

      TSK = spec->getTemplateSpecializationKind();
    } else if (MemberSpecializationInfo *MSI =
                 MD->getMemberSpecializationInfo()) {
      TSK = MSI->getTemplateSpecializationKind();
    }

    // If we're paying attention to global visibility, apply
    // -finline-visibility-hidden if this is an inline method.
    //
    // Note that ConsiderGlobalVisibility doesn't yet have information
    // about whether containing classes have visibility attributes,
    // and that's intentional.
    if (TSK != TSK_ExplicitInstantiationDeclaration &&
        F.ConsiderGlobalVisibility &&
        MD->getASTContext().getLangOptions().InlineVisibilityHidden) {
      // InlineVisibilityHidden only applies to definitions, and
      // isInlined() only gives meaningful answers on definitions
      // anyway.
      const FunctionDecl *Def = 0;
      if (MD->hasBody(Def) && Def->isInlined())
        LV.setVisibility(HiddenVisibility);
    }

    // Note that in contrast to basically every other situation, we
    // *do* apply -fvisibility to method declarations.

  } else if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) {
    if (const ClassTemplateSpecializationDecl *spec
        = dyn_cast<ClassTemplateSpecializationDecl>(RD)) {
      if (shouldConsiderTemplateLV(spec)) {
        // Merge template argument/parameter information for member
        // class template specializations.
        LV.merge(getLVForTemplateArgumentList(spec->getTemplateArgs(), F));
      if (F.ConsiderTemplateParameterTypes)
        LV.merge(getLVForTemplateParameterList(
                    spec->getSpecializedTemplate()->getTemplateParameters()));
      }
    }

  // Static data members.
  } else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
    // Modify the variable's linkage by its type, but ignore the
    // type's visibility unless it's a definition.
    LVPair TypeLV = VD->getType()->getLinkageAndVisibility();
    if (TypeLV.first != ExternalLinkage)
      LV.mergeLinkage(UniqueExternalLinkage);
    if (!LV.visibilityExplicit())
      LV.mergeVisibility(TypeLV.second);
  }

  F.ConsiderGlobalVisibility &= !LV.visibilityExplicit();

  // Apply -fvisibility if desired.
  if (F.ConsiderGlobalVisibility && LV.visibility() != HiddenVisibility) {
    LV.mergeVisibility(D->getASTContext().getLangOptions().getVisibilityMode());
  }

  return LV;
}

static void clearLinkageForClass(const CXXRecordDecl *record) {
  for (CXXRecordDecl::decl_iterator
         i = record->decls_begin(), e = record->decls_end(); i != e; ++i) {
    Decl *child = *i;
    if (isa<NamedDecl>(child))
      cast<NamedDecl>(child)->ClearLinkageCache();
  }
}

void NamedDecl::ClearLinkageCache() {
  // Note that we can't skip clearing the linkage of children just
  // because the parent doesn't have cached linkage:  we don't cache
  // when computing linkage for parent contexts.

  HasCachedLinkage = 0;

  // If we're changing the linkage of a class, we need to reset the
  // linkage of child declarations, too.
  if (const CXXRecordDecl *record = dyn_cast<CXXRecordDecl>(this))
    clearLinkageForClass(record);

  if (ClassTemplateDecl *temp =
        dyn_cast<ClassTemplateDecl>(const_cast<NamedDecl*>(this))) {
    // Clear linkage for the template pattern.
    CXXRecordDecl *record = temp->getTemplatedDecl();
    record->HasCachedLinkage = 0;
    clearLinkageForClass(record);

    // We need to clear linkage for specializations, too.
    for (ClassTemplateDecl::spec_iterator
           i = temp->spec_begin(), e = temp->spec_end(); i != e; ++i)
      i->ClearLinkageCache();
  }

  // Clear cached linkage for function template decls, too.
  if (FunctionTemplateDecl *temp =
        dyn_cast<FunctionTemplateDecl>(const_cast<NamedDecl*>(this))) {
    temp->getTemplatedDecl()->ClearLinkageCache();
    for (FunctionTemplateDecl::spec_iterator
           i = temp->spec_begin(), e = temp->spec_end(); i != e; ++i)
      i->ClearLinkageCache();
  }

}

Linkage NamedDecl::getLinkage() const {
  if (HasCachedLinkage) {
    assert(Linkage(CachedLinkage) ==
             getLVForDecl(this, LVFlags::CreateOnlyDeclLinkage()).linkage());
    return Linkage(CachedLinkage);
  }

  CachedLinkage = getLVForDecl(this,
                               LVFlags::CreateOnlyDeclLinkage()).linkage();
  HasCachedLinkage = 1;
  return Linkage(CachedLinkage);
}

LinkageInfo NamedDecl::getLinkageAndVisibility() const {
  LinkageInfo LI = getLVForDecl(this, LVFlags());
  assert(!HasCachedLinkage || Linkage(CachedLinkage) == LI.linkage());
  HasCachedLinkage = 1;
  CachedLinkage = LI.linkage();
  return LI;
}

llvm::Optional<Visibility> NamedDecl::getExplicitVisibility() const {
  // Use the most recent declaration of a variable.
  if (const VarDecl *var = dyn_cast<VarDecl>(this))
    return getVisibilityOf(var->getMostRecentDeclaration());

  // Use the most recent declaration of a function, and also handle
  // function template specializations.
  if (const FunctionDecl *fn = dyn_cast<FunctionDecl>(this)) {
    if (llvm::Optional<Visibility> V
                            = getVisibilityOf(fn->getMostRecentDeclaration()))
      return V;

    // If the function is a specialization of a template with an
    // explicit visibility attribute, use that.
    if (FunctionTemplateSpecializationInfo *templateInfo
          = fn->getTemplateSpecializationInfo())
      return getVisibilityOf(templateInfo->getTemplate()->getTemplatedDecl());

    return llvm::Optional<Visibility>();
  }

  // Otherwise, just check the declaration itself first.
  if (llvm::Optional<Visibility> V = getVisibilityOf(this))
    return V;

  // If there wasn't explicit visibility there, and this is a
  // specialization of a class template, check for visibility
  // on the pattern.
  if (const ClassTemplateSpecializationDecl *spec
        = dyn_cast<ClassTemplateSpecializationDecl>(this))
    return getVisibilityOf(spec->getSpecializedTemplate()->getTemplatedDecl());

  return llvm::Optional<Visibility>();
}

static LinkageInfo getLVForDecl(const NamedDecl *D, LVFlags Flags) {
  // Objective-C: treat all Objective-C declarations as having external
  // linkage.
  switch (D->getKind()) {
    default:
      break;
    case Decl::TemplateTemplateParm: // count these as external
    case Decl::NonTypeTemplateParm:
    case Decl::ObjCAtDefsField:
    case Decl::ObjCCategory:
    case Decl::ObjCCategoryImpl:
    case Decl::ObjCCompatibleAlias:
    case Decl::ObjCForwardProtocol:
    case Decl::ObjCImplementation:
    case Decl::ObjCMethod:
    case Decl::ObjCProperty:
    case Decl::ObjCPropertyImpl:
    case Decl::ObjCProtocol:
      return LinkageInfo::external();
  }

  // Handle linkage for namespace-scope names.
  if (D->getDeclContext()->getRedeclContext()->isFileContext())
    return getLVForNamespaceScopeDecl(D, Flags);

  // C++ [basic.link]p5:
  //   In addition, a member function, static data member, a named
  //   class or enumeration of class scope, or an unnamed class or
  //   enumeration defined in a class-scope typedef declaration such
  //   that the class or enumeration has the typedef name for linkage
  //   purposes (7.1.3), has external linkage if the name of the class
  //   has external linkage.
  if (D->getDeclContext()->isRecord())
    return getLVForClassMember(D, Flags);

  // C++ [basic.link]p6:
  //   The name of a function declared in block scope and the name of
  //   an object declared by a block scope extern declaration have
  //   linkage. If there is a visible declaration of an entity with
  //   linkage having the same name and type, ignoring entities
  //   declared outside the innermost enclosing namespace scope, the
  //   block scope declaration declares that same entity and receives
  //   the linkage of the previous declaration. If there is more than
  //   one such matching entity, the program is ill-formed. Otherwise,
  //   if no matching entity is found, the block scope entity receives
  //   external linkage.
  if (D->getLexicalDeclContext()->isFunctionOrMethod()) {
    if (const FunctionDecl *Function = dyn_cast<FunctionDecl>(D)) {
      if (Function->isInAnonymousNamespace() && !Function->isExternC())
        return LinkageInfo::uniqueExternal();

      LinkageInfo LV;
      if (Flags.ConsiderVisibilityAttributes) {
        if (llvm::Optional<Visibility> Vis = Function->getExplicitVisibility())
          LV.setVisibility(*Vis);
      }

      if (const FunctionDecl *Prev = Function->getPreviousDeclaration()) {
        LinkageInfo PrevLV = getLVForDecl(Prev, Flags);
        if (PrevLV.linkage()) LV.setLinkage(PrevLV.linkage());
        LV.mergeVisibility(PrevLV);
      }

      return LV;
    }

    if (const VarDecl *Var = dyn_cast<VarDecl>(D))
      if (Var->getStorageClass() == SC_Extern ||
          Var->getStorageClass() == SC_PrivateExtern) {
        if (Var->isInAnonymousNamespace() && !Var->isExternC())
          return LinkageInfo::uniqueExternal();

        LinkageInfo LV;
        if (Var->getStorageClass() == SC_PrivateExtern)
          LV.setVisibility(HiddenVisibility);
        else if (Flags.ConsiderVisibilityAttributes) {
          if (llvm::Optional<Visibility> Vis = Var->getExplicitVisibility())
            LV.setVisibility(*Vis);
        }

        if (const VarDecl *Prev = Var->getPreviousDeclaration()) {
          LinkageInfo PrevLV = getLVForDecl(Prev, Flags);
          if (PrevLV.linkage()) LV.setLinkage(PrevLV.linkage());
          LV.mergeVisibility(PrevLV);
        }

        return LV;
      }
  }

  // C++ [basic.link]p6:
  //   Names not covered by these rules have no linkage.
  return LinkageInfo::none();
}

std::string NamedDecl::getQualifiedNameAsString() const {
  return getQualifiedNameAsString(getASTContext().getLangOptions());
}

std::string NamedDecl::getQualifiedNameAsString(const PrintingPolicy &P) const {
  const DeclContext *Ctx = getDeclContext();

  if (Ctx->isFunctionOrMethod())
    return getNameAsString();

  typedef SmallVector<const DeclContext *, 8> ContextsTy;
  ContextsTy Contexts;

  // Collect contexts.
  while (Ctx && isa<NamedDecl>(Ctx)) {
    Contexts.push_back(Ctx);
    Ctx = Ctx->getParent();
  };

  std::string QualName;
  llvm::raw_string_ostream OS(QualName);

  for (ContextsTy::reverse_iterator I = Contexts.rbegin(), E = Contexts.rend();
       I != E; ++I) {
    if (const ClassTemplateSpecializationDecl *Spec
          = dyn_cast<ClassTemplateSpecializationDecl>(*I)) {
      const TemplateArgumentList &TemplateArgs = Spec->getTemplateArgs();
      std::string TemplateArgsStr
        = TemplateSpecializationType::PrintTemplateArgumentList(
                                           TemplateArgs.data(),
                                           TemplateArgs.size(),
                                           P);
      OS << Spec->getName() << TemplateArgsStr;
    } else if (const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(*I)) {
      if (ND->isAnonymousNamespace())
        OS << "<anonymous namespace>";
      else
        OS << *ND;
    } else if (const RecordDecl *RD = dyn_cast<RecordDecl>(*I)) {
      if (!RD->getIdentifier())
        OS << "<anonymous " << RD->getKindName() << '>';
      else
        OS << *RD;
    } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
      const FunctionProtoType *FT = 0;
      if (FD->hasWrittenPrototype())
        FT = dyn_cast<FunctionProtoType>(FD->getType()->getAs<FunctionType>());

      OS << *FD << '(';
      if (FT) {
        unsigned NumParams = FD->getNumParams();
        for (unsigned i = 0; i < NumParams; ++i) {
          if (i)
            OS << ", ";
          std::string Param;
          FD->getParamDecl(i)->getType().getAsStringInternal(Param, P);
          OS << Param;
        }

        if (FT->isVariadic()) {
          if (NumParams > 0)
            OS << ", ";
          OS << "...";
        }
      }
      OS << ')';
    } else {
      OS << *cast<NamedDecl>(*I);
    }
    OS << "::";
  }

  if (getDeclName())
    OS << *this;
  else
    OS << "<anonymous>";

  return OS.str();
}

bool NamedDecl::declarationReplaces(NamedDecl *OldD) const {
  assert(getDeclName() == OldD->getDeclName() && "Declaration name mismatch");

  // UsingDirectiveDecl's are not really NamedDecl's, and all have same name.
  // We want to keep it, unless it nominates same namespace.
  if (getKind() == Decl::UsingDirective) {
    return cast<UsingDirectiveDecl>(this)->getNominatedNamespace()
             ->getOriginalNamespace() ==
           cast<UsingDirectiveDecl>(OldD)->getNominatedNamespace()
             ->getOriginalNamespace();
  }

  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(this))
    // For function declarations, we keep track of redeclarations.
    return FD->getPreviousDeclaration() == OldD;

  // For function templates, the underlying function declarations are linked.
  if (const FunctionTemplateDecl *FunctionTemplate
        = dyn_cast<FunctionTemplateDecl>(this))
    if (const FunctionTemplateDecl *OldFunctionTemplate
          = dyn_cast<FunctionTemplateDecl>(OldD))
      return FunctionTemplate->getTemplatedDecl()
               ->declarationReplaces(OldFunctionTemplate->getTemplatedDecl());

  // For method declarations, we keep track of redeclarations.
  if (isa<ObjCMethodDecl>(this))
    return false;

  if (isa<ObjCInterfaceDecl>(this) && isa<ObjCCompatibleAliasDecl>(OldD))
    return true;

  if (isa<UsingShadowDecl>(this) && isa<UsingShadowDecl>(OldD))
    return cast<UsingShadowDecl>(this)->getTargetDecl() ==
           cast<UsingShadowDecl>(OldD)->getTargetDecl();

  if (isa<UsingDecl>(this) && isa<UsingDecl>(OldD)) {
    ASTContext &Context = getASTContext();
    return Context.getCanonicalNestedNameSpecifier(
                                     cast<UsingDecl>(this)->getQualifier()) ==
           Context.getCanonicalNestedNameSpecifier(
                                        cast<UsingDecl>(OldD)->getQualifier());
  }

  // For non-function declarations, if the declarations are of the
  // same kind then this must be a redeclaration, or semantic analysis
  // would not have given us the new declaration.
  return this->getKind() == OldD->getKind();
}

bool NamedDecl::hasLinkage() const {
  return getLinkage() != NoLinkage;
}

NamedDecl *NamedDecl::getUnderlyingDecl() {
  NamedDecl *ND = this;
  while (true) {
    if (UsingShadowDecl *UD = dyn_cast<UsingShadowDecl>(ND))
      ND = UD->getTargetDecl();
    else if (ObjCCompatibleAliasDecl *AD
              = dyn_cast<ObjCCompatibleAliasDecl>(ND))
      return AD->getClassInterface();
    else
      return ND;
  }
}

bool NamedDecl::isCXXInstanceMember() const {
  assert(isCXXClassMember() &&
         "checking whether non-member is instance member");

  const NamedDecl *D = this;
  if (isa<UsingShadowDecl>(D))
    D = cast<UsingShadowDecl>(D)->getTargetDecl();

  if (isa<FieldDecl>(D) || isa<IndirectFieldDecl>(D))
    return true;
  if (isa<CXXMethodDecl>(D))
    return cast<CXXMethodDecl>(D)->isInstance();
  if (isa<FunctionTemplateDecl>(D))
    return cast<CXXMethodDecl>(cast<FunctionTemplateDecl>(D)
                                 ->getTemplatedDecl())->isInstance();
  return false;
}

//===----------------------------------------------------------------------===//
// DeclaratorDecl Implementation
//===----------------------------------------------------------------------===//

template <typename DeclT>
static SourceLocation getTemplateOrInnerLocStart(const DeclT *decl) {
  if (decl->getNumTemplateParameterLists() > 0)
    return decl->getTemplateParameterList(0)->getTemplateLoc();
  else
    return decl->getInnerLocStart();
}

SourceLocation DeclaratorDecl::getTypeSpecStartLoc() const {
  TypeSourceInfo *TSI = getTypeSourceInfo();
  if (TSI) return TSI->getTypeLoc().getBeginLoc();
  return SourceLocation();
}

void DeclaratorDecl::setQualifierInfo(NestedNameSpecifierLoc QualifierLoc) {
  if (QualifierLoc) {
    // Make sure the extended decl info is allocated.
    if (!hasExtInfo()) {
      // Save (non-extended) type source info pointer.
      TypeSourceInfo *savedTInfo = DeclInfo.get<TypeSourceInfo*>();
      // Allocate external info struct.
      DeclInfo = new (getASTContext()) ExtInfo;
      // Restore savedTInfo into (extended) decl info.
      getExtInfo()->TInfo = savedTInfo;
    }
    // Set qualifier info.
    getExtInfo()->QualifierLoc = QualifierLoc;
  } else {
    // Here Qualifier == 0, i.e., we are removing the qualifier (if any).
    if (hasExtInfo()) {
      if (getExtInfo()->NumTemplParamLists == 0) {
        // Save type source info pointer.
        TypeSourceInfo *savedTInfo = getExtInfo()->TInfo;
        // Deallocate the extended decl info.
        getASTContext().Deallocate(getExtInfo());
        // Restore savedTInfo into (non-extended) decl info.
        DeclInfo = savedTInfo;
      }
      else
        getExtInfo()->QualifierLoc = QualifierLoc;
    }
  }
}

void
DeclaratorDecl::setTemplateParameterListsInfo(ASTContext &Context,
                                              unsigned NumTPLists,
                                              TemplateParameterList **TPLists) {
  assert(NumTPLists > 0);
  // Make sure the extended decl info is allocated.
  if (!hasExtInfo()) {
    // Save (non-extended) type source info pointer.
    TypeSourceInfo *savedTInfo = DeclInfo.get<TypeSourceInfo*>();
    // Allocate external info struct.
    DeclInfo = new (getASTContext()) ExtInfo;
    // Restore savedTInfo into (extended) decl info.
    getExtInfo()->TInfo = savedTInfo;
  }
  // Set the template parameter lists info.
  getExtInfo()->setTemplateParameterListsInfo(Context, NumTPLists, TPLists);
}

SourceLocation DeclaratorDecl::getOuterLocStart() const {
  return getTemplateOrInnerLocStart(this);
}

namespace {

// Helper function: returns true if QT is or contains a type
// having a postfix component.
bool typeIsPostfix(clang::QualType QT) {
  while (true) {
    const Type* T = QT.getTypePtr();
    switch (T->getTypeClass()) {
    default:
      return false;
    case Type::Pointer:
      QT = cast<PointerType>(T)->getPointeeType();
      break;
    case Type::BlockPointer:
      QT = cast<BlockPointerType>(T)->getPointeeType();
      break;
    case Type::MemberPointer:
      QT = cast<MemberPointerType>(T)->getPointeeType();
      break;
    case Type::LValueReference:
    case Type::RValueReference:
      QT = cast<ReferenceType>(T)->getPointeeType();
      break;
    case Type::PackExpansion:
      QT = cast<PackExpansionType>(T)->getPattern();
      break;
    case Type::Paren:
    case Type::ConstantArray:
    case Type::DependentSizedArray:
    case Type::IncompleteArray:
    case Type::VariableArray:
    case Type::FunctionProto:
    case Type::FunctionNoProto:
      return true;
    }
  }
}

} // namespace

SourceRange DeclaratorDecl::getSourceRange() const {
  SourceLocation RangeEnd = getLocation();
  if (TypeSourceInfo *TInfo = getTypeSourceInfo()) {
    if (typeIsPostfix(TInfo->getType()))
      RangeEnd = TInfo->getTypeLoc().getSourceRange().getEnd();
  }
  return SourceRange(getOuterLocStart(), RangeEnd);
}

void
QualifierInfo::setTemplateParameterListsInfo(ASTContext &Context,
                                             unsigned NumTPLists,
                                             TemplateParameterList **TPLists) {
  assert((NumTPLists == 0 || TPLists != 0) &&
         "Empty array of template parameters with positive size!");

  // Free previous template parameters (if any).
  if (NumTemplParamLists > 0) {
    Context.Deallocate(TemplParamLists);
    TemplParamLists = 0;
    NumTemplParamLists = 0;
  }
  // Set info on matched template parameter lists (if any).
  if (NumTPLists > 0) {
    TemplParamLists = new (Context) TemplateParameterList*[NumTPLists];
    NumTemplParamLists = NumTPLists;
    for (unsigned i = NumTPLists; i-- > 0; )
      TemplParamLists[i] = TPLists[i];
  }
}

//===----------------------------------------------------------------------===//
// VarDecl Implementation
//===----------------------------------------------------------------------===//

const char *VarDecl::getStorageClassSpecifierString(StorageClass SC) {
  switch (SC) {
  case SC_None:                 break;
  case SC_Auto:                 return "auto";
  case SC_Extern:               return "extern";
  case SC_OpenCLWorkGroupLocal: return "<<work-group-local>>";
  case SC_PrivateExtern:        return "__private_extern__";
  case SC_Register:             return "register";
  case SC_Static:               return "static";
  }

  llvm_unreachable("Invalid storage class");
  return 0;
}

VarDecl *VarDecl::Create(ASTContext &C, DeclContext *DC,
                         SourceLocation StartL, SourceLocation IdL,
                         IdentifierInfo *Id, QualType T, TypeSourceInfo *TInfo,
                         StorageClass S, StorageClass SCAsWritten) {
  return new (C) VarDecl(Var, DC, StartL, IdL, Id, T, TInfo, S, SCAsWritten);
}

void VarDecl::setStorageClass(StorageClass SC) {
  assert(isLegalForVariable(SC));
  if (getStorageClass() != SC)
    ClearLinkageCache();

  VarDeclBits.SClass = SC;
}

SourceRange VarDecl::getSourceRange() const {
  if (getInit())
    return SourceRange(getOuterLocStart(), getInit()->getLocEnd());
  return DeclaratorDecl::getSourceRange();
}

bool VarDecl::isExternC() const {
  ASTContext &Context = getASTContext();
  if (!Context.getLangOptions().CPlusPlus)
    return (getDeclContext()->isTranslationUnit() &&
            getStorageClass() != SC_Static) ||
      (getDeclContext()->isFunctionOrMethod() && hasExternalStorage());

  const DeclContext *DC = getDeclContext();
  if (DC->isFunctionOrMethod())
    return false;

  for (; !DC->isTranslationUnit(); DC = DC->getParent()) {
    if (const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(DC))  {
      if (Linkage->getLanguage() == LinkageSpecDecl::lang_c)
        return getStorageClass() != SC_Static;

      break;
    }

  }

  return false;
}

VarDecl *VarDecl::getCanonicalDecl() {
  return getFirstDeclaration();
}

VarDecl::DefinitionKind VarDecl::isThisDeclarationADefinition() const {
  // C++ [basic.def]p2:
  //   A declaration is a definition unless [...] it contains the 'extern'
  //   specifier or a linkage-specification and neither an initializer [...],
  //   it declares a static data member in a class declaration [...].
  // C++ [temp.expl.spec]p15:
  //   An explicit specialization of a static data member of a template is a
  //   definition if the declaration includes an initializer; otherwise, it is
  //   a declaration.
  if (isStaticDataMember()) {
    if (isOutOfLine() && (hasInit() ||
          getTemplateSpecializationKind() != TSK_ExplicitSpecialization))
      return Definition;
    else
      return DeclarationOnly;
  }
  // C99 6.7p5:
  //   A definition of an identifier is a declaration for that identifier that
  //   [...] causes storage to be reserved for that object.
  // Note: that applies for all non-file-scope objects.
  // C99 6.9.2p1:
  //   If the declaration of an identifier for an object has file scope and an
  //   initializer, the declaration is an external definition for the identifier
  if (hasInit())
    return Definition;
  // AST for 'extern "C" int foo;' is annotated with 'extern'.
  if (hasExternalStorage())
    return DeclarationOnly;

  if (getStorageClassAsWritten() == SC_Extern ||
       getStorageClassAsWritten() == SC_PrivateExtern) {
    for (const VarDecl *PrevVar = getPreviousDeclaration();
         PrevVar; PrevVar = PrevVar->getPreviousDeclaration()) {
      if (PrevVar->getLinkage() == InternalLinkage && PrevVar->hasInit())
        return DeclarationOnly;
    }
  }
  // C99 6.9.2p2:
  //   A declaration of an object that has file scope without an initializer,
  //   and without a storage class specifier or the scs 'static', constitutes
  //   a tentative definition.
  // No such thing in C++.
  if (!getASTContext().getLangOptions().CPlusPlus && isFileVarDecl())
    return TentativeDefinition;

  // What's left is (in C, block-scope) declarations without initializers or
  // external storage. These are definitions.
  return Definition;
}

VarDecl *VarDecl::getActingDefinition() {
  DefinitionKind Kind = isThisDeclarationADefinition();
  if (Kind != TentativeDefinition)
    return 0;

  VarDecl *LastTentative = 0;
  VarDecl *First = getFirstDeclaration();
  for (redecl_iterator I = First->redecls_begin(), E = First->redecls_end();
       I != E; ++I) {
    Kind = (*I)->isThisDeclarationADefinition();
    if (Kind == Definition)
      return 0;
    else if (Kind == TentativeDefinition)
      LastTentative = *I;
  }
  return LastTentative;
}

bool VarDecl::isTentativeDefinitionNow() const {
  DefinitionKind Kind = isThisDeclarationADefinition();
  if (Kind != TentativeDefinition)
    return false;

  for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) {
    if ((*I)->isThisDeclarationADefinition() == Definition)
      return false;
  }
  return true;
}

VarDecl *VarDecl::getDefinition() {
  VarDecl *First = getFirstDeclaration();
  for (redecl_iterator I = First->redecls_begin(), E = First->redecls_end();
       I != E; ++I) {
    if ((*I)->isThisDeclarationADefinition() == Definition)
      return *I;
  }
  return 0;
}

VarDecl::DefinitionKind VarDecl::hasDefinition() const {
  DefinitionKind Kind = DeclarationOnly;

  const VarDecl *First = getFirstDeclaration();
  for (redecl_iterator I = First->redecls_begin(), E = First->redecls_end();
       I != E; ++I)
    Kind = std::max(Kind, (*I)->isThisDeclarationADefinition());

  return Kind;
}

const Expr *VarDecl::getAnyInitializer(const VarDecl *&D) const {
  redecl_iterator I = redecls_begin(), E = redecls_end();
  while (I != E && !I->getInit())
    ++I;

  if (I != E) {
    D = *I;
    return I->getInit();
  }
  return 0;
}

bool VarDecl::isOutOfLine() const {
  if (Decl::isOutOfLine())
    return true;

  if (!isStaticDataMember())
    return false;

  // If this static data member was instantiated from a static data member of
  // a class template, check whether that static data member was defined
  // out-of-line.
  if (VarDecl *VD = getInstantiatedFromStaticDataMember())
    return VD->isOutOfLine();

  return false;
}

VarDecl *VarDecl::getOutOfLineDefinition() {
  if (!isStaticDataMember())
    return 0;

  for (VarDecl::redecl_iterator RD = redecls_begin(), RDEnd = redecls_end();
       RD != RDEnd; ++RD) {
    if (RD->getLexicalDeclContext()->isFileContext())
      return *RD;
  }

  return 0;
}

void VarDecl::setInit(Expr *I) {
  if (EvaluatedStmt *Eval = Init.dyn_cast<EvaluatedStmt *>()) {
    Eval->~EvaluatedStmt();
    getASTContext().Deallocate(Eval);
  }

  Init = I;
}

bool VarDecl::extendsLifetimeOfTemporary() const {
  assert(getType()->isReferenceType() &&"Non-references never extend lifetime");

  const Expr *E = getInit();
  if (!E)
    return false;

  if (const ExprWithCleanups *Cleanups = dyn_cast<ExprWithCleanups>(E))
    E = Cleanups->getSubExpr();

  return isa<MaterializeTemporaryExpr>(E);
}

VarDecl *VarDecl::getInstantiatedFromStaticDataMember() const {
  if (MemberSpecializationInfo *MSI = getMemberSpecializationInfo())
    return cast<VarDecl>(MSI->getInstantiatedFrom());

  return 0;
}

TemplateSpecializationKind VarDecl::getTemplateSpecializationKind() const {
  if (MemberSpecializationInfo *MSI = getMemberSpecializationInfo())
    return MSI->getTemplateSpecializationKind();

  return TSK_Undeclared;
}

MemberSpecializationInfo *VarDecl::getMemberSpecializationInfo() const {
  return getASTContext().getInstantiatedFromStaticDataMember(this);
}

void VarDecl::setTemplateSpecializationKind(TemplateSpecializationKind TSK,
                                         SourceLocation PointOfInstantiation) {
  MemberSpecializationInfo *MSI = getMemberSpecializationInfo();
  assert(MSI && "Not an instantiated static data member?");
  MSI->setTemplateSpecializationKind(TSK);
  if (TSK != TSK_ExplicitSpecialization &&
      PointOfInstantiation.isValid() &&
      MSI->getPointOfInstantiation().isInvalid())
    MSI->setPointOfInstantiation(PointOfInstantiation);
}

//===----------------------------------------------------------------------===//
// ParmVarDecl Implementation
//===----------------------------------------------------------------------===//

ParmVarDecl *ParmVarDecl::Create(ASTContext &C, DeclContext *DC,
                                 SourceLocation StartLoc,
                                 SourceLocation IdLoc, IdentifierInfo *Id,
                                 QualType T, TypeSourceInfo *TInfo,
                                 StorageClass S, StorageClass SCAsWritten,
                                 Expr *DefArg) {
  return new (C) ParmVarDecl(ParmVar, DC, StartLoc, IdLoc, Id, T, TInfo,
                             S, SCAsWritten, DefArg);
}

SourceRange ParmVarDecl::getSourceRange() const {
  if (!hasInheritedDefaultArg()) {
    SourceRange ArgRange = getDefaultArgRange();
    if (ArgRange.isValid())
      return SourceRange(getOuterLocStart(), ArgRange.getEnd());
  }

  return DeclaratorDecl::getSourceRange();
}

Expr *ParmVarDecl::getDefaultArg() {
  assert(!hasUnparsedDefaultArg() && "Default argument is not yet parsed!");
  assert(!hasUninstantiatedDefaultArg() &&
         "Default argument is not yet instantiated!");

  Expr *Arg = getInit();
  if (ExprWithCleanups *E = dyn_cast_or_null<ExprWithCleanups>(Arg))
    return E->getSubExpr();

  return Arg;
}

unsigned ParmVarDecl::getNumDefaultArgTemporaries() const {
  if (const ExprWithCleanups *E = dyn_cast<ExprWithCleanups>(getInit()))
    return E->getNumTemporaries();

  return 0;
}

CXXTemporary *ParmVarDecl::getDefaultArgTemporary(unsigned i) {
  assert(getNumDefaultArgTemporaries() &&
         "Default arguments does not have any temporaries!");

  ExprWithCleanups *E = cast<ExprWithCleanups>(getInit());
  return E->getTemporary(i);
}

SourceRange ParmVarDecl::getDefaultArgRange() const {
  if (const Expr *E = getInit())
    return E->getSourceRange();

  if (hasUninstantiatedDefaultArg())
    return getUninstantiatedDefaultArg()->getSourceRange();

  return SourceRange();
}

bool ParmVarDecl::isParameterPack() const {
  return isa<PackExpansionType>(getType());
}

void ParmVarDecl::setParameterIndexLarge(unsigned parameterIndex) {
  getASTContext().setParameterIndex(this, parameterIndex);
  ParmVarDeclBits.ParameterIndex = ParameterIndexSentinel;
}

unsigned ParmVarDecl::getParameterIndexLarge() const {
  return getASTContext().getParameterIndex(this);
}

//===----------------------------------------------------------------------===//
// FunctionDecl Implementation
//===----------------------------------------------------------------------===//

void FunctionDecl::getNameForDiagnostic(std::string &S,
                                        const PrintingPolicy &Policy,
                                        bool Qualified) const {
  NamedDecl::getNameForDiagnostic(S, Policy, Qualified);
  const TemplateArgumentList *TemplateArgs = getTemplateSpecializationArgs();
  if (TemplateArgs)
    S += TemplateSpecializationType::PrintTemplateArgumentList(
                                                         TemplateArgs->data(),
                                                         TemplateArgs->size(),
                                                               Policy);

}

bool FunctionDecl::isVariadic() const {
  if (const FunctionProtoType *FT = getType()->getAs<FunctionProtoType>())
    return FT->isVariadic();
  return false;
}

bool FunctionDecl::hasBody(const FunctionDecl *&Definition) const {
  for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) {
    if (I->Body || I->IsLateTemplateParsed) {
      Definition = *I;
      return true;
    }
  }

  return false;
}

bool FunctionDecl::hasTrivialBody() const
{
  Stmt *S = getBody();
  if (!S) {
    // Since we don't have a body for this function, we don't know if it's
    // trivial or not.
    return false;
  }

  if (isa<CompoundStmt>(S) && cast<CompoundStmt>(S)->body_empty())
    return true;
  return false;
}

bool FunctionDecl::isDefined(const FunctionDecl *&Definition) const {
  for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) {
    if (I->IsDeleted || I->IsDefaulted || I->Body || I->IsLateTemplateParsed) {
      Definition = I->IsDeleted ? I->getCanonicalDecl() : *I;
      return true;
    }
  }

  return false;
}

Stmt *FunctionDecl::getBody(const FunctionDecl *&Definition) const {
  for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) {
    if (I->Body) {
      Definition = *I;
      return I->Body.get(getASTContext().getExternalSource());
    } else if (I->IsLateTemplateParsed) {
      Definition = *I;
      return 0;
    }
  }

  return 0;
}

void FunctionDecl::setBody(Stmt *B) {
  Body = B;
  if (B)
    EndRangeLoc = B->getLocEnd();
}

void FunctionDecl::setPure(bool P) {
  IsPure = P;
  if (P)
    if (CXXRecordDecl *Parent = dyn_cast<CXXRecordDecl>(getDeclContext()))
      Parent->markedVirtualFunctionPure();
}

bool FunctionDecl::isMain() const {
  const TranslationUnitDecl *tunit =
    dyn_cast<TranslationUnitDecl>(getDeclContext()->getRedeclContext());
  return tunit &&
         !tunit->getASTContext().getLangOptions().Freestanding &&
         getIdentifier() &&
         getIdentifier()->isStr("main");
}

bool FunctionDecl::isReservedGlobalPlacementOperator() const {
  assert(getDeclName().getNameKind() == DeclarationName::CXXOperatorName);
  assert(getDeclName().getCXXOverloadedOperator() == OO_New ||
         getDeclName().getCXXOverloadedOperator() == OO_Delete ||
         getDeclName().getCXXOverloadedOperator() == OO_Array_New ||
         getDeclName().getCXXOverloadedOperator() == OO_Array_Delete);

  if (isa<CXXRecordDecl>(getDeclContext())) return false;
  assert(getDeclContext()->getRedeclContext()->isTranslationUnit());

  const FunctionProtoType *proto = getType()->castAs<FunctionProtoType>();
  if (proto->getNumArgs() != 2 || proto->isVariadic()) return false;

  ASTContext &Context =
    cast<TranslationUnitDecl>(getDeclContext()->getRedeclContext())
      ->getASTContext();

  // The result type and first argument type are constant across all
  // these operators.  The second argument must be exactly void*.
  return (proto->getArgType(1).getCanonicalType() == Context.VoidPtrTy);
}

bool FunctionDecl::isExternC() const {
  ASTContext &Context = getASTContext();
  // In C, any non-static, non-overloadable function has external
  // linkage.
  if (!Context.getLangOptions().CPlusPlus)
    return getStorageClass() != SC_Static && !getAttr<OverloadableAttr>();

  const DeclContext *DC = getDeclContext();
  if (DC->isRecord())
    return false;

  for (; !DC->isTranslationUnit(); DC = DC->getParent()) {
    if (const LinkageSpecDecl *Linkage = dyn_cast<LinkageSpecDecl>(DC))  {
      if (Linkage->getLanguage() == LinkageSpecDecl::lang_c)
        return getStorageClass() != SC_Static &&
               !getAttr<OverloadableAttr>();

      break;
    }
  }

  return isMain();
}

bool FunctionDecl::isGlobal() const {
  if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(this))
    return Method->isStatic();

  if (getStorageClass() == SC_Static)
    return false;

  for (const DeclContext *DC = getDeclContext();
       DC->isNamespace();
       DC = DC->getParent()) {
    if (const NamespaceDecl *Namespace = cast<NamespaceDecl>(DC)) {
      if (!Namespace->getDeclName())
        return false;
      break;
    }
  }

  return true;
}

void
FunctionDecl::setPreviousDeclaration(FunctionDecl *PrevDecl) {
  redeclarable_base::setPreviousDeclaration(PrevDecl);

  if (FunctionTemplateDecl *FunTmpl = getDescribedFunctionTemplate()) {
    FunctionTemplateDecl *PrevFunTmpl
      = PrevDecl? PrevDecl->getDescribedFunctionTemplate() : 0;
    assert((!PrevDecl || PrevFunTmpl) && "Function/function template mismatch");
    FunTmpl->setPreviousDeclaration(PrevFunTmpl);
  }

  if (PrevDecl->IsInline)
    IsInline = true;
}

const FunctionDecl *FunctionDecl::getCanonicalDecl() const {
  return getFirstDeclaration();
}

FunctionDecl *FunctionDecl::getCanonicalDecl() {
  return getFirstDeclaration();
}

void FunctionDecl::setStorageClass(StorageClass SC) {
  assert(isLegalForFunction(SC));
  if (getStorageClass() != SC)
    ClearLinkageCache();

  SClass = SC;
}

/// \brief Returns a value indicating whether this function
/// corresponds to a builtin function.
///
/// The function corresponds to a built-in function if it is
/// declared at translation scope or within an extern "C" block and
/// its name matches with the name of a builtin. The returned value
/// will be 0 for functions that do not correspond to a builtin, a
/// value of type \c Builtin::ID if in the target-independent range
/// \c [1,Builtin::First), or a target-specific builtin value.
unsigned FunctionDecl::getBuiltinID() const {
  ASTContext &Context = getASTContext();
  if (!getIdentifier() || !getIdentifier()->getBuiltinID())
    return 0;

  unsigned BuiltinID = getIdentifier()->getBuiltinID();
  if (!Context.BuiltinInfo.isPredefinedLibFunction(BuiltinID))
    return BuiltinID;

  // This function has the name of a known C library
  // function. Determine whether it actually refers to the C library
  // function or whether it just has the same name.

  // If this is a static function, it's not a builtin.
  if (getStorageClass() == SC_Static)
    return 0;

  // If this function is at translation-unit scope and we're not in
  // C++, it refers to the C library function.
  if (!Context.getLangOptions().CPlusPlus &&
      getDeclContext()->isTranslationUnit())
    return BuiltinID;

  // If the function is in an extern "C" linkage specification and is
  // not marked "overloadable", it's the real function.
  if (isa<LinkageSpecDecl>(getDeclContext()) &&
      cast<LinkageSpecDecl>(getDeclContext())->getLanguage()
        == LinkageSpecDecl::lang_c &&
      !getAttr<OverloadableAttr>())
    return BuiltinID;

  // Not a builtin
  return 0;
}


/// getNumParams - Return the number of parameters this function must have
/// based on its FunctionType.  This is the length of the ParamInfo array
/// after it has been created.
unsigned FunctionDecl::getNumParams() const {
  const FunctionType *FT = getType()->getAs<FunctionType>();
  if (isa<FunctionNoProtoType>(FT))
    return 0;
  return cast<FunctionProtoType>(FT)->getNumArgs();

}

void FunctionDecl::setParams(ASTContext &C,
                             llvm::ArrayRef<ParmVarDecl *> NewParamInfo) {
  assert(ParamInfo == 0 && "Already has param info!");
  assert(NewParamInfo.size() == getNumParams() && "Parameter count mismatch!");

  // Zero params -> null pointer.
  if (!NewParamInfo.empty()) {
    ParamInfo = new (C) ParmVarDecl*[NewParamInfo.size()];
    std::copy(NewParamInfo.begin(), NewParamInfo.end(), ParamInfo);
  }
}

/// getMinRequiredArguments - Returns the minimum number of arguments
/// needed to call this function. This may be fewer than the number of
/// function parameters, if some of the parameters have default
/// arguments (in C++) or the last parameter is a parameter pack.
unsigned FunctionDecl::getMinRequiredArguments() const {
  if (!getASTContext().getLangOptions().CPlusPlus)
    return getNumParams();

  unsigned NumRequiredArgs = getNumParams();

  // If the last parameter is a parameter pack, we don't need an argument for
  // it.
  if (NumRequiredArgs > 0 &&
      getParamDecl(NumRequiredArgs - 1)->isParameterPack())
    --NumRequiredArgs;

  // If this parameter has a default argument, we don't need an argument for
  // it.
  while (NumRequiredArgs > 0 &&
         getParamDecl(NumRequiredArgs-1)->hasDefaultArg())
    --NumRequiredArgs;

  // We might have parameter packs before the end. These can't be deduced,
  // but they can still handle multiple arguments.
  unsigned ArgIdx = NumRequiredArgs;
  while (ArgIdx > 0) {
    if (getParamDecl(ArgIdx - 1)->isParameterPack())
      NumRequiredArgs = ArgIdx;

    --ArgIdx;
  }

  return NumRequiredArgs;
}

bool FunctionDecl::isInlined() const {
  if (IsInline)
    return true;

  if (isa<CXXMethodDecl>(this)) {
    if (!isOutOfLine() || getCanonicalDecl()->isInlineSpecified())
      return true;
  }

  switch (getTemplateSpecializationKind()) {
  case TSK_Undeclared:
  case TSK_ExplicitSpecialization:
    return false;

  case TSK_ImplicitInstantiation:
  case TSK_ExplicitInstantiationDeclaration:
  case TSK_ExplicitInstantiationDefinition:
    // Handle below.
    break;
  }

  const FunctionDecl *PatternDecl = getTemplateInstantiationPattern();
  bool HasPattern = false;
  if (PatternDecl)
    HasPattern = PatternDecl->hasBody(PatternDecl);

  if (HasPattern && PatternDecl)
    return PatternDecl->isInlined();

  return false;
}

/// \brief For a function declaration in C or C++, determine whether this
/// declaration causes the definition to be externally visible.
///
/// Determines whether this is the first non-inline redeclaration of an inline
/// function in a language where "inline" does not normally require an
/// externally visible definition.
bool FunctionDecl::doesDeclarationForceExternallyVisibleDefinition() const {
  assert(!doesThisDeclarationHaveABody() &&
         "Must have a declaration without a body.");

  ASTContext &Context = getASTContext();

  // In C99 mode, a function may have an inline definition (causing it to
  // be deferred) then redeclared later.  As a special case, "extern inline"
  // is not required to produce an external symbol.
  if (Context.getLangOptions().GNUInline || !Context.getLangOptions().C99 ||
      Context.getLangOptions().CPlusPlus)
    return false;
  if (getLinkage() != ExternalLinkage || isInlineSpecified())
    return false;
  const FunctionDecl *Definition = 0;
  if (hasBody(Definition))
    return Definition->isInlined() &&
           Definition->isInlineDefinitionExternallyVisible();
  return false;
}

/// \brief For an inline function definition in C or C++, determine whether the
/// definition will be externally visible.
///
/// Inline function definitions are always available for inlining optimizations.
/// However, depending on the language dialect, declaration specifiers, and
/// attributes, the definition of an inline function may or may not be
/// "externally" visible to other translation units in the program.
///
/// In C99, inline definitions are not externally visible by default. However,
/// if even one of the global-scope declarations is marked "extern inline", the
/// inline definition becomes externally visible (C99 6.7.4p6).
///
/// In GNU89 mode, or if the gnu_inline attribute is attached to the function
/// definition, we use the GNU semantics for inline, which are nearly the
/// opposite of C99 semantics. In particular, "inline" by itself will create
/// an externally visible symbol, but "extern inline" will not create an
/// externally visible symbol.
bool FunctionDecl::isInlineDefinitionExternallyVisible() const {
  assert(doesThisDeclarationHaveABody() && "Must have the function definition");
  assert(isInlined() && "Function must be inline");
  ASTContext &Context = getASTContext();

  if (Context.getLangOptions().GNUInline || hasAttr<GNUInlineAttr>()) {
    // If it's not the case that both 'inline' and 'extern' are
    // specified on the definition, then this inline definition is
    // externally visible.
    if (!(isInlineSpecified() && getStorageClassAsWritten() == SC_Extern))
      return true;

    // If any declaration is 'inline' but not 'extern', then this definition
    // is externally visible.
    for (redecl_iterator Redecl = redecls_begin(), RedeclEnd = redecls_end();
         Redecl != RedeclEnd;
         ++Redecl) {
      if (Redecl->isInlineSpecified() &&
          Redecl->getStorageClassAsWritten() != SC_Extern)
        return true;
    }

    return false;
  }

  // C99 6.7.4p6:
  //   [...] If all of the file scope declarations for a function in a
  //   translation unit include the inline function specifier without extern,
  //   then the definition in that translation unit is an inline definition.
  for (redecl_iterator Redecl = redecls_begin(), RedeclEnd = redecls_end();
       Redecl != RedeclEnd;
       ++Redecl) {
    // Only consider file-scope declarations in this test.
    if (!Redecl->getLexicalDeclContext()->isTranslationUnit())
      continue;

    // Only consider explicit declarations; the presence of a builtin for a
    // libcall shouldn't affect whether a definition is externally visible.
    if (Redecl->isImplicit())
      continue;

    if (!Redecl->isInlineSpecified() || Redecl->getStorageClass() == SC_Extern)
      return true; // Not an inline definition
  }

  // C99 6.7.4p6:
  //   An inline definition does not provide an external definition for the
  //   function, and does not forbid an external definition in another
  //   translation unit.
  return false;
}

/// getOverloadedOperator - Which C++ overloaded operator this
/// function represents, if any.
OverloadedOperatorKind FunctionDecl::getOverloadedOperator() const {
  if (getDeclName().getNameKind() == DeclarationName::CXXOperatorName)
    return getDeclName().getCXXOverloadedOperator();
  else
    return OO_None;
}

/// getLiteralIdentifier - The literal suffix identifier this function
/// represents, if any.
const IdentifierInfo *FunctionDecl::getLiteralIdentifier() const {
  if (getDeclName().getNameKind() == DeclarationName::CXXLiteralOperatorName)
    return getDeclName().getCXXLiteralIdentifier();
  else
    return 0;
}

FunctionDecl::TemplatedKind FunctionDecl::getTemplatedKind() const {
  if (TemplateOrSpecialization.isNull())
    return TK_NonTemplate;
  if (TemplateOrSpecialization.is<FunctionTemplateDecl *>())
    return TK_FunctionTemplate;
  if (TemplateOrSpecialization.is<MemberSpecializationInfo *>())
    return TK_MemberSpecialization;
  if (TemplateOrSpecialization.is<FunctionTemplateSpecializationInfo *>())
    return TK_FunctionTemplateSpecialization;
  if (TemplateOrSpecialization.is
                               <DependentFunctionTemplateSpecializationInfo*>())
    return TK_DependentFunctionTemplateSpecialization;

  llvm_unreachable("Did we miss a TemplateOrSpecialization type?");
}

FunctionDecl *FunctionDecl::getInstantiatedFromMemberFunction() const {
  if (MemberSpecializationInfo *Info = getMemberSpecializationInfo())
    return cast<FunctionDecl>(Info->getInstantiatedFrom());

  return 0;
}

MemberSpecializationInfo *FunctionDecl::getMemberSpecializationInfo() const {
  return TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo*>();
}

void
FunctionDecl::setInstantiationOfMemberFunction(ASTContext &C,
                                               FunctionDecl *FD,
                                               TemplateSpecializationKind TSK) {
  assert(TemplateOrSpecialization.isNull() &&
         "Member function is already a specialization");
  MemberSpecializationInfo *Info
    = new (C) MemberSpecializationInfo(FD, TSK);
  TemplateOrSpecialization = Info;
}

bool FunctionDecl::isImplicitlyInstantiable() const {
  // If the function is invalid, it can't be implicitly instantiated.
  if (isInvalidDecl())
    return false;

  switch (getTemplateSpecializationKind()) {
  case TSK_Undeclared:
  case TSK_ExplicitInstantiationDefinition:
    return false;

  case TSK_ImplicitInstantiation:
    return true;

  // It is possible to instantiate TSK_ExplicitSpecialization kind
  // if the FunctionDecl has a class scope specialization pattern.
  case TSK_ExplicitSpecialization:
    return getClassScopeSpecializationPattern() != 0;

  case TSK_ExplicitInstantiationDeclaration:
    // Handled below.
    break;
  }

  // Find the actual template from which we will instantiate.
  const FunctionDecl *PatternDecl = getTemplateInstantiationPattern();
  bool HasPattern = false;
  if (PatternDecl)
    HasPattern = PatternDecl->hasBody(PatternDecl);

  // C++0x [temp.explicit]p9:
  //   Except for inline functions, other explicit instantiation declarations
  //   have the effect of suppressing the implicit instantiation of the entity
  //   to which they refer.
  if (!HasPattern || !PatternDecl)
    return true;

  return PatternDecl->isInlined();
}

FunctionDecl *FunctionDecl::getTemplateInstantiationPattern() const {
  // Handle class scope explicit specialization special case.
  if (getTemplateSpecializationKind() == TSK_ExplicitSpecialization)
    return getClassScopeSpecializationPattern();

  if (FunctionTemplateDecl *Primary = getPrimaryTemplate()) {
    while (Primary->getInstantiatedFromMemberTemplate()) {
      // If we have hit a point where the user provided a specialization of
      // this template, we're done looking.
      if (Primary->isMemberSpecialization())
        break;

      Primary = Primary->getInstantiatedFromMemberTemplate();
    }

    return Primary->getTemplatedDecl();
  }

  return getInstantiatedFromMemberFunction();
}

FunctionTemplateDecl *FunctionDecl::getPrimaryTemplate() const {
  if (FunctionTemplateSpecializationInfo *Info
        = TemplateOrSpecialization
            .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
    return Info->Template.getPointer();
  }
  return 0;
}

FunctionDecl *FunctionDecl::getClassScopeSpecializationPattern() const {
    return getASTContext().getClassScopeSpecializationPattern(this);
}

const TemplateArgumentList *
FunctionDecl::getTemplateSpecializationArgs() const {
  if (FunctionTemplateSpecializationInfo *Info
        = TemplateOrSpecialization
            .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
    return Info->TemplateArguments;
  }
  return 0;
}

const ASTTemplateArgumentListInfo *
FunctionDecl::getTemplateSpecializationArgsAsWritten() const {
  if (FunctionTemplateSpecializationInfo *Info
        = TemplateOrSpecialization
            .dyn_cast<FunctionTemplateSpecializationInfo*>()) {
    return Info->TemplateArgumentsAsWritten;
  }
  return 0;
}

void
FunctionDecl::setFunctionTemplateSpecialization(ASTContext &C,
                                                FunctionTemplateDecl *Template,
                                     const TemplateArgumentList *TemplateArgs,
                                                void *InsertPos,
                                                TemplateSpecializationKind TSK,
                        const TemplateArgumentListInfo *TemplateArgsAsWritten,
                                          SourceLocation PointOfInstantiation) {
  assert(TSK != TSK_Undeclared &&
         "Must specify the type of function template specialization");
  FunctionTemplateSpecializationInfo *Info
    = TemplateOrSpecialization.dyn_cast<FunctionTemplateSpecializationInfo*>();
  if (!Info)
    Info = FunctionTemplateSpecializationInfo::Create(C, this, Template, TSK,
                                                      TemplateArgs,
                                                      TemplateArgsAsWritten,
                                                      PointOfInstantiation);
  TemplateOrSpecialization = Info;

  // Insert this function template specialization into the set of known
  // function template specializations.
  if (InsertPos)
    Template->addSpecialization(Info, InsertPos);
  else {
    // Try to insert the new node. If there is an existing node, leave it, the
    // set will contain the canonical decls while
    // FunctionTemplateDecl::findSpecialization will return
    // the most recent redeclarations.
    FunctionTemplateSpecializationInfo *Existing
      = Template->getSpecializations().GetOrInsertNode(Info);
    (void)Existing;
    assert((!Existing || Existing->Function->isCanonicalDecl()) &&
           "Set is supposed to only contain canonical decls");
  }
}

void
FunctionDecl::setDependentTemplateSpecialization(ASTContext &Context,
                                    const UnresolvedSetImpl &Templates,
                             const TemplateArgumentListInfo &TemplateArgs) {
  assert(TemplateOrSpecialization.isNull());
  size_t Size = sizeof(DependentFunctionTemplateSpecializationInfo);
  Size += Templates.size() * sizeof(FunctionTemplateDecl*);
  Size += TemplateArgs.size() * sizeof(TemplateArgumentLoc);
  void *Buffer = Context.Allocate(Size);
  DependentFunctionTemplateSpecializationInfo *Info =
    new (Buffer) DependentFunctionTemplateSpecializationInfo(Templates,
                                                             TemplateArgs);
  TemplateOrSpecialization = Info;
}

DependentFunctionTemplateSpecializationInfo::
DependentFunctionTemplateSpecializationInfo(const UnresolvedSetImpl &Ts,
                                      const TemplateArgumentListInfo &TArgs)
  : AngleLocs(TArgs.getLAngleLoc(), TArgs.getRAngleLoc()) {

  d.NumTemplates = Ts.size();
  d.NumArgs = TArgs.size();

  FunctionTemplateDecl **TsArray =
    const_cast<FunctionTemplateDecl**>(getTemplates());
  for (unsigned I = 0, E = Ts.size(); I != E; ++I)
    TsArray[I] = cast<FunctionTemplateDecl>(Ts[I]->getUnderlyingDecl());

  TemplateArgumentLoc *ArgsArray =
    const_cast<TemplateArgumentLoc*>(getTemplateArgs());
  for (unsigned I = 0, E = TArgs.size(); I != E; ++I)
    new (&ArgsArray[I]) TemplateArgumentLoc(TArgs[I]);
}

TemplateSpecializationKind FunctionDecl::getTemplateSpecializationKind() const {
  // For a function template specialization, query the specialization
  // information object.
  FunctionTemplateSpecializationInfo *FTSInfo
    = TemplateOrSpecialization.dyn_cast<FunctionTemplateSpecializationInfo*>();
  if (FTSInfo)
    return FTSInfo->getTemplateSpecializationKind();

  MemberSpecializationInfo *MSInfo
    = TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo*>();
  if (MSInfo)
    return MSInfo->getTemplateSpecializationKind();

  return TSK_Undeclared;
}

void
FunctionDecl::setTemplateSpecializationKind(TemplateSpecializationKind TSK,
                                          SourceLocation PointOfInstantiation) {
  if (FunctionTemplateSpecializationInfo *FTSInfo
        = TemplateOrSpecialization.dyn_cast<
                                    FunctionTemplateSpecializationInfo*>()) {
    FTSInfo->setTemplateSpecializationKind(TSK);
    if (TSK != TSK_ExplicitSpecialization &&
        PointOfInstantiation.isValid() &&
        FTSInfo->getPointOfInstantiation().isInvalid())
      FTSInfo->setPointOfInstantiation(PointOfInstantiation);
  } else if (MemberSpecializationInfo *MSInfo
             = TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo*>()) {
    MSInfo->setTemplateSpecializationKind(TSK);
    if (TSK != TSK_ExplicitSpecialization &&
        PointOfInstantiation.isValid() &&
        MSInfo->getPointOfInstantiation().isInvalid())
      MSInfo->setPointOfInstantiation(PointOfInstantiation);
  } else
    llvm_unreachable("Function cannot have a template specialization kind");
}

SourceLocation FunctionDecl::getPointOfInstantiation() const {
  if (FunctionTemplateSpecializationInfo *FTSInfo
        = TemplateOrSpecialization.dyn_cast<
                                        FunctionTemplateSpecializationInfo*>())
    return FTSInfo->getPointOfInstantiation();
  else if (MemberSpecializationInfo *MSInfo
             = TemplateOrSpecialization.dyn_cast<MemberSpecializationInfo*>())
    return MSInfo->getPointOfInstantiation();

  return SourceLocation();
}

bool FunctionDecl::isOutOfLine() const {
  if (Decl::isOutOfLine())
    return true;

  // If this function was instantiated from a member function of a
  // class template, check whether that member function was defined out-of-line.
  if (FunctionDecl *FD = getInstantiatedFromMemberFunction()) {
    const FunctionDecl *Definition;
    if (FD->hasBody(Definition))
      return Definition->isOutOfLine();
  }

  // If this function was instantiated from a function template,
  // check whether that function template was defined out-of-line.
  if (FunctionTemplateDecl *FunTmpl = getPrimaryTemplate()) {
    const FunctionDecl *Definition;
    if (FunTmpl->getTemplatedDecl()->hasBody(Definition))
      return Definition->isOutOfLine();
  }

  return false;
}

SourceRange FunctionDecl::getSourceRange() const {
  return SourceRange(getOuterLocStart(), EndRangeLoc);
}

//===----------------------------------------------------------------------===//
// FieldDecl Implementation
//===----------------------------------------------------------------------===//

FieldDecl *FieldDecl::Create(const ASTContext &C, DeclContext *DC,
                             SourceLocation StartLoc, SourceLocation IdLoc,
                             IdentifierInfo *Id, QualType T,
                             TypeSourceInfo *TInfo, Expr *BW, bool Mutable,
                             bool HasInit) {
  return new (C) FieldDecl(Decl::Field, DC, StartLoc, IdLoc, Id, T, TInfo,
                           BW, Mutable, HasInit);
}

bool FieldDecl::isAnonymousStructOrUnion() const {
  if (!isImplicit() || getDeclName())
    return false;

  if (const RecordType *Record = getType()->getAs<RecordType>())
    return Record->getDecl()->isAnonymousStructOrUnion();

  return false;
}

unsigned FieldDecl::getBitWidthValue(const ASTContext &Ctx) const {
  assert(isBitField() && "not a bitfield");
  Expr *BitWidth = InitializerOrBitWidth.getPointer();
  return BitWidth->EvaluateKnownConstInt(Ctx).getZExtValue();
}

unsigned FieldDecl::getFieldIndex() const {
  if (CachedFieldIndex) return CachedFieldIndex - 1;

  unsigned index = 0;
  const RecordDecl *RD = getParent();
  const FieldDecl *LastFD = 0;
  bool IsMsStruct = RD->hasAttr<MsStructAttr>();

  RecordDecl::field_iterator i = RD->field_begin(), e = RD->field_end();
  while (true) {
    assert(i != e && "failed to find field in parent!");
    if (*i == this)
      break;

    if (IsMsStruct) {
      // Zero-length bitfields following non-bitfield members are ignored.
      if (getASTContext().ZeroBitfieldFollowsNonBitfield((*i), LastFD)) {
        ++i;
        continue;
      }
      LastFD = (*i);
    }
    ++i;
    ++index;
  }

  CachedFieldIndex = index + 1;
  return index;
}

SourceRange FieldDecl::getSourceRange() const {
  if (const Expr *E = InitializerOrBitWidth.getPointer())
    return SourceRange(getInnerLocStart(), E->getLocEnd());
  return DeclaratorDecl::getSourceRange();
}

void FieldDecl::setInClassInitializer(Expr *Init) {
  assert(!InitializerOrBitWidth.getPointer() &&
         "bit width or initializer already set");
  InitializerOrBitWidth.setPointer(Init);
  InitializerOrBitWidth.setInt(0);
}

//===----------------------------------------------------------------------===//
// TagDecl Implementation
//===----------------------------------------------------------------------===//

SourceLocation TagDecl::getOuterLocStart() const {
  return getTemplateOrInnerLocStart(this);
}

SourceRange TagDecl::getSourceRange() const {
  SourceLocation E = RBraceLoc.isValid() ? RBraceLoc : getLocation();
  return SourceRange(getOuterLocStart(), E);
}

TagDecl* TagDecl::getCanonicalDecl() {
  return getFirstDeclaration();
}

void TagDecl::setTypedefNameForAnonDecl(TypedefNameDecl *TDD) {
  TypedefNameDeclOrQualifier = TDD;
  if (TypeForDecl)
    const_cast<Type*>(TypeForDecl)->ClearLinkageCache();
  ClearLinkageCache();
}

void TagDecl::startDefinition() {
  IsBeingDefined = true;

  if (isa<CXXRecordDecl>(this)) {
    CXXRecordDecl *D = cast<CXXRecordDecl>(this);
    struct CXXRecordDecl::DefinitionData *Data =
      new (getASTContext()) struct CXXRecordDecl::DefinitionData(D);
    for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I)
      cast<CXXRecordDecl>(*I)->DefinitionData = Data;
  }
}

void TagDecl::completeDefinition() {
  assert((!isa<CXXRecordDecl>(this) ||
          cast<CXXRecordDecl>(this)->hasDefinition()) &&
         "definition completed but not started");

  IsCompleteDefinition = true;
  IsBeingDefined = false;

  if (ASTMutationListener *L = getASTMutationListener())
    L->CompletedTagDefinition(this);
}

TagDecl *TagDecl::getDefinition() const {
  if (isCompleteDefinition())
    return const_cast<TagDecl *>(this);
  if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(this))
    return CXXRD->getDefinition();

  for (redecl_iterator R = redecls_begin(), REnd = redecls_end();
       R != REnd; ++R)
    if (R->isCompleteDefinition())
      return *R;

  return 0;
}

void TagDecl::setQualifierInfo(NestedNameSpecifierLoc QualifierLoc) {
  if (QualifierLoc) {
    // Make sure the extended qualifier info is allocated.
    if (!hasExtInfo())
      TypedefNameDeclOrQualifier = new (getASTContext()) ExtInfo;
    // Set qualifier info.
    getExtInfo()->QualifierLoc = QualifierLoc;
  } else {
    // Here Qualifier == 0, i.e., we are removing the qualifier (if any).
    if (hasExtInfo()) {
      if (getExtInfo()->NumTemplParamLists == 0) {
        getASTContext().Deallocate(getExtInfo());
        TypedefNameDeclOrQualifier = (TypedefNameDecl*) 0;
      }
      else
        getExtInfo()->QualifierLoc = QualifierLoc;
    }
  }
}

void TagDecl::setTemplateParameterListsInfo(ASTContext &Context,
                                            unsigned NumTPLists,
                                            TemplateParameterList **TPLists) {
  assert(NumTPLists > 0);
  // Make sure the extended decl info is allocated.
  if (!hasExtInfo())
    // Allocate external info struct.
    TypedefNameDeclOrQualifier = new (getASTContext()) ExtInfo;
  // Set the template parameter lists info.
  getExtInfo()->setTemplateParameterListsInfo(Context, NumTPLists, TPLists);
}

//===----------------------------------------------------------------------===//
// EnumDecl Implementation
//===----------------------------------------------------------------------===//

EnumDecl *EnumDecl::Create(ASTContext &C, DeclContext *DC,
                           SourceLocation StartLoc, SourceLocation IdLoc,
                           IdentifierInfo *Id,
                           EnumDecl *PrevDecl, bool IsScoped,
                           bool IsScopedUsingClassTag, bool IsFixed) {
  EnumDecl *Enum = new (C) EnumDecl(DC, StartLoc, IdLoc, Id, PrevDecl,
                                    IsScoped, IsScopedUsingClassTag, IsFixed);
  C.getTypeDeclType(Enum, PrevDecl);
  return Enum;
}

EnumDecl *EnumDecl::Create(ASTContext &C, EmptyShell Empty) {
  return new (C) EnumDecl(0, SourceLocation(), SourceLocation(), 0, 0,
                          false, false, false);
}

void EnumDecl::completeDefinition(QualType NewType,
                                  QualType NewPromotionType,
                                  unsigned NumPositiveBits,
                                  unsigned NumNegativeBits) {
  assert(!isCompleteDefinition() && "Cannot redefine enums!");
  if (!IntegerType)
    IntegerType = NewType.getTypePtr();
  PromotionType = NewPromotionType;
  setNumPositiveBits(NumPositiveBits);
  setNumNegativeBits(NumNegativeBits);
  TagDecl::completeDefinition();
}

//===----------------------------------------------------------------------===//
// RecordDecl Implementation
//===----------------------------------------------------------------------===//

RecordDecl::RecordDecl(Kind DK, TagKind TK, DeclContext *DC,
                       SourceLocation StartLoc, SourceLocation IdLoc,
                       IdentifierInfo *Id, RecordDecl *PrevDecl)
  : TagDecl(DK, TK, DC, IdLoc, Id, PrevDecl, StartLoc) {
  HasFlexibleArrayMember = false;
  AnonymousStructOrUnion = false;
  HasObjectMember = false;
  LoadedFieldsFromExternalStorage = false;
  assert(classof(static_cast<Decl*>(this)) && "Invalid Kind!");
}

RecordDecl *RecordDecl::Create(const ASTContext &C, TagKind TK, DeclContext *DC,
                               SourceLocation StartLoc, SourceLocation IdLoc,
                               IdentifierInfo *Id, RecordDecl* PrevDecl) {
  RecordDecl* R = new (C) RecordDecl(Record, TK, DC, StartLoc, IdLoc, Id,
                                     PrevDecl);
  C.getTypeDeclType(R, PrevDecl);
  return R;
}

RecordDecl *RecordDecl::Create(const ASTContext &C, EmptyShell Empty) {
  return new (C) RecordDecl(Record, TTK_Struct, 0, SourceLocation(),
                            SourceLocation(), 0, 0);
}

bool RecordDecl::isInjectedClassName() const {
  return isImplicit() && getDeclName() && getDeclContext()->isRecord() &&
    cast<RecordDecl>(getDeclContext())->getDeclName() == getDeclName();
}

RecordDecl::field_iterator RecordDecl::field_begin() const {
  if (hasExternalLexicalStorage() && !LoadedFieldsFromExternalStorage)
    LoadFieldsFromExternalStorage();

  return field_iterator(decl_iterator(FirstDecl));
}

/// completeDefinition - Notes that the definition of this type is now
/// complete.
void RecordDecl::completeDefinition() {
  assert(!isCompleteDefinition() && "Cannot redefine record!");
  TagDecl::completeDefinition();
}

void RecordDecl::LoadFieldsFromExternalStorage() const {
  ExternalASTSource *Source = getASTContext().getExternalSource();
  assert(hasExternalLexicalStorage() && Source && "No external storage?");

  // Notify that we have a RecordDecl doing some initialization.
  ExternalASTSource::Deserializing TheFields(Source);

  SmallVector<Decl*, 64> Decls;
  LoadedFieldsFromExternalStorage = true;
  switch (Source->FindExternalLexicalDeclsBy<FieldDecl>(this, Decls)) {
  case ELR_Success:
    break;

  case ELR_AlreadyLoaded:
  case ELR_Failure:
    return;
  }

#ifndef NDEBUG
  // Check that all decls we got were FieldDecls.
  for (unsigned i=0, e=Decls.size(); i != e; ++i)
    assert(isa<FieldDecl>(Decls[i]));
#endif

  if (Decls.empty())
    return;

  llvm::tie(FirstDecl, LastDecl) = BuildDeclChain(Decls,
                                                 /*FieldsAlreadyLoaded=*/false);
}

//===----------------------------------------------------------------------===//
// BlockDecl Implementation
//===----------------------------------------------------------------------===//

void BlockDecl::setParams(llvm::ArrayRef<ParmVarDecl *> NewParamInfo) {
  assert(ParamInfo == 0 && "Already has param info!");

  // Zero params -> null pointer.
  if (!NewParamInfo.empty()) {
    NumParams = NewParamInfo.size();
    ParamInfo = new (getASTContext()) ParmVarDecl*[NewParamInfo.size()];
    std::copy(NewParamInfo.begin(), NewParamInfo.end(), ParamInfo);
  }
}

void BlockDecl::setCaptures(ASTContext &Context,
                            const Capture *begin,
                            const Capture *end,
                            bool capturesCXXThis) {
  CapturesCXXThis = capturesCXXThis;

  if (begin == end) {
    NumCaptures = 0;
    Captures = 0;
    return;
  }

  NumCaptures = end - begin;

  // Avoid new Capture[] because we don't want to provide a default
  // constructor.
  size_t allocationSize = NumCaptures * sizeof(Capture);
  void *buffer = Context.Allocate(allocationSize, /*alignment*/sizeof(void*));
  memcpy(buffer, begin, allocationSize);
  Captures = static_cast<Capture*>(buffer);
}

bool BlockDecl::capturesVariable(const VarDecl *variable) const {
  for (capture_const_iterator
         i = capture_begin(), e = capture_end(); i != e; ++i)
    // Only auto vars can be captured, so no redeclaration worries.
    if (i->getVariable() == variable)
      return true;

  return false;
}

SourceRange BlockDecl::getSourceRange() const {
  return SourceRange(getLocation(), Body? Body->getLocEnd() : getLocation());
}

//===----------------------------------------------------------------------===//
// Other Decl Allocation/Deallocation Method Implementations
//===----------------------------------------------------------------------===//

TranslationUnitDecl *TranslationUnitDecl::Create(ASTContext &C) {
  return new (C) TranslationUnitDecl(C);
}

LabelDecl *LabelDecl::Create(ASTContext &C, DeclContext *DC,
                             SourceLocation IdentL, IdentifierInfo *II) {
  return new (C) LabelDecl(DC, IdentL, II, 0, IdentL);
}

LabelDecl *LabelDecl::Create(ASTContext &C, DeclContext *DC,
                             SourceLocation IdentL, IdentifierInfo *II,
                             SourceLocation GnuLabelL) {
  assert(GnuLabelL != IdentL && "Use this only for GNU local labels");
  return new (C) LabelDecl(DC, IdentL, II, 0, GnuLabelL);
}


NamespaceDecl *NamespaceDecl::Create(ASTContext &C, DeclContext *DC,
                                     SourceLocation StartLoc,
                                     SourceLocation IdLoc, IdentifierInfo *Id) {
  return new (C) NamespaceDecl(DC, StartLoc, IdLoc, Id);
}

NamespaceDecl *NamespaceDecl::getNextNamespace() {
  return dyn_cast_or_null<NamespaceDecl>(
                       NextNamespace.get(getASTContext().getExternalSource()));
}

ImplicitParamDecl *ImplicitParamDecl::Create(ASTContext &C, DeclContext *DC,
                                             SourceLocation IdLoc,
                                             IdentifierInfo *Id,
                                             QualType Type) {
  return new (C) ImplicitParamDecl(DC, IdLoc, Id, Type);
}

FunctionDecl *FunctionDecl::Create(ASTContext &C, DeclContext *DC,
                                   SourceLocation StartLoc,
                                   const DeclarationNameInfo &NameInfo,
                                   QualType T, TypeSourceInfo *TInfo,
                                   StorageClass SC, StorageClass SCAsWritten,
                                   bool isInlineSpecified,
                                   bool hasWrittenPrototype,
                                   bool isConstexprSpecified) {
  FunctionDecl *New = new (C) FunctionDecl(Function, DC, StartLoc, NameInfo,
                                           T, TInfo, SC, SCAsWritten,
                                           isInlineSpecified,
                                           isConstexprSpecified);
  New->HasWrittenPrototype = hasWrittenPrototype;
  return New;
}

BlockDecl *BlockDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L) {
  return new (C) BlockDecl(DC, L);
}

EnumConstantDecl *EnumConstantDecl::Create(ASTContext &C, EnumDecl *CD,
                                           SourceLocation L,
                                           IdentifierInfo *Id, QualType T,
                                           Expr *E, const llvm::APSInt &V) {
  return new (C) EnumConstantDecl(CD, L, Id, T, E, V);
}

IndirectFieldDecl *
IndirectFieldDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L,
                          IdentifierInfo *Id, QualType T, NamedDecl **CH,
                          unsigned CHS) {
  return new (C) IndirectFieldDecl(DC, L, Id, T, CH, CHS);
}

SourceRange EnumConstantDecl::getSourceRange() const {
  SourceLocation End = getLocation();
  if (Init)
    End = Init->getLocEnd();
  return SourceRange(getLocation(), End);
}

TypedefDecl *TypedefDecl::Create(ASTContext &C, DeclContext *DC,
                                 SourceLocation StartLoc, SourceLocation IdLoc,
                                 IdentifierInfo *Id, TypeSourceInfo *TInfo) {
  return new (C) TypedefDecl(DC, StartLoc, IdLoc, Id, TInfo);
}

TypeAliasDecl *TypeAliasDecl::Create(ASTContext &C, DeclContext *DC,
                                     SourceLocation StartLoc,
                                     SourceLocation IdLoc, IdentifierInfo *Id,
                                     TypeSourceInfo *TInfo) {
  return new (C) TypeAliasDecl(DC, StartLoc, IdLoc, Id, TInfo);
}

SourceRange TypedefDecl::getSourceRange() const {
  SourceLocation RangeEnd = getLocation();
  if (TypeSourceInfo *TInfo = getTypeSourceInfo()) {
    if (typeIsPostfix(TInfo->getType()))
      RangeEnd = TInfo->getTypeLoc().getSourceRange().getEnd();
  }
  return SourceRange(getLocStart(), RangeEnd);
}

SourceRange TypeAliasDecl::getSourceRange() const {
  SourceLocation RangeEnd = getLocStart();
  if (TypeSourceInfo *TInfo = getTypeSourceInfo())
    RangeEnd = TInfo->getTypeLoc().getSourceRange().getEnd();
  return SourceRange(getLocStart(), RangeEnd);
}

FileScopeAsmDecl *FileScopeAsmDecl::Create(ASTContext &C, DeclContext *DC,
                                           StringLiteral *Str,
                                           SourceLocation AsmLoc,
                                           SourceLocation RParenLoc) {
  return new (C) FileScopeAsmDecl(DC, Str, AsmLoc, RParenLoc);
}