llvm-project/clang/lib/Sema/SemaCXXScopeSpec.cpp

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//===--- SemaCXXScopeSpec.cpp - Semantic Analysis for C++ scope specifiers-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements C++ semantic analysis for scope specifiers.
//
//===----------------------------------------------------------------------===//
#include "Sema.h"
#include "Lookup.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ExprCXX.h"
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#include "clang/AST/NestedNameSpecifier.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Parse/DeclSpec.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
/// \brief Find the current instantiation that associated with the given type.
static CXXRecordDecl *
getCurrentInstantiationOf(ASTContext &Context, DeclContext *CurContext,
QualType T) {
if (T.isNull())
return 0;
T = Context.getCanonicalType(T).getUnqualifiedType();
for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
// If we've hit a namespace or the global scope, then the
// nested-name-specifier can't refer to the current instantiation.
if (Ctx->isFileContext())
return 0;
// Skip non-class contexts.
CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
if (!Record)
continue;
// If this record type is not dependent,
if (!Record->isDependentType())
return 0;
// C++ [temp.dep.type]p1:
//
// In the definition of a class template, a nested class of a
// class template, a member of a class template, or a member of a
// nested class of a class template, a name refers to the current
// instantiation if it is
// -- the injected-class-name (9) of the class template or
// nested class,
// -- in the definition of a primary class template, the name
// of the class template followed by the template argument
// list of the primary template (as described below)
// enclosed in <>,
// -- in the definition of a nested class of a class template,
// the name of the nested class referenced as a member of
// the current instantiation, or
// -- in the definition of a partial specialization, the name
// of the class template followed by the template argument
// list of the partial specialization enclosed in <>. If
// the nth template parameter is a parameter pack, the nth
// template argument is a pack expansion (14.6.3) whose
// pattern is the name of the parameter pack.
// (FIXME: parameter packs)
//
// All of these options come down to having the
// nested-name-specifier type that is equivalent to the
// injected-class-name of one of the types that is currently in
// our context.
if (Context.getCanonicalType(Context.getTypeDeclType(Record)) == T)
return Record;
if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate()) {
QualType InjectedClassName
= Template->getInjectedClassNameType(Context);
if (T == Context.getCanonicalType(InjectedClassName))
return Template->getTemplatedDecl();
}
// FIXME: check for class template partial specializations
}
return 0;
}
/// \brief Compute the DeclContext that is associated with the given type.
///
/// \param T the type for which we are attempting to find a DeclContext.
///
/// \returns the declaration context represented by the type T,
/// or NULL if the declaration context cannot be computed (e.g., because it is
/// dependent and not the current instantiation).
DeclContext *Sema::computeDeclContext(QualType T) {
if (const TagType *Tag = T->getAs<TagType>())
return Tag->getDecl();
return ::getCurrentInstantiationOf(Context, CurContext, T);
}
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/// \brief Compute the DeclContext that is associated with the given
/// scope specifier.
///
/// \param SS the C++ scope specifier as it appears in the source
///
/// \param EnteringContext when true, we will be entering the context of
/// this scope specifier, so we can retrieve the declaration context of a
/// class template or class template partial specialization even if it is
/// not the current instantiation.
///
/// \returns the declaration context represented by the scope specifier @p SS,
/// or NULL if the declaration context cannot be computed (e.g., because it is
/// dependent and not the current instantiation).
DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
bool EnteringContext) {
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if (!SS.isSet() || SS.isInvalid())
return 0;
NestedNameSpecifier *NNS
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
if (NNS->isDependent()) {
// If this nested-name-specifier refers to the current
// instantiation, return its DeclContext.
if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS))
return Record;
if (EnteringContext) {
if (const TemplateSpecializationType *SpecType
= dyn_cast_or_null<TemplateSpecializationType>(NNS->getAsType())) {
// We are entering the context of the nested name specifier, so try to
// match the nested name specifier to either a primary class template
// or a class template partial specialization.
if (ClassTemplateDecl *ClassTemplate
= dyn_cast_or_null<ClassTemplateDecl>(
SpecType->getTemplateName().getAsTemplateDecl())) {
QualType ContextType
= Context.getCanonicalType(QualType(SpecType, 0));
// If the type of the nested name specifier is the same as the
// injected class name of the named class template, we're entering
// into that class template definition.
QualType Injected = ClassTemplate->getInjectedClassNameType(Context);
if (Context.hasSameType(Injected, ContextType))
return ClassTemplate->getTemplatedDecl();
// If the type of the nested name specifier is the same as the
// type of one of the class template's class template partial
// specializations, we're entering into the definition of that
// class template partial specialization.
if (ClassTemplatePartialSpecializationDecl *PartialSpec
= ClassTemplate->findPartialSpecialization(ContextType))
return PartialSpec;
}
} else if (const RecordType *RecordT
= dyn_cast_or_null<RecordType>(NNS->getAsType())) {
// The nested name specifier refers to a member of a class template.
return RecordT->getDecl();
}
}
return 0;
}
switch (NNS->getKind()) {
case NestedNameSpecifier::Identifier:
assert(false && "Dependent nested-name-specifier has no DeclContext");
break;
case NestedNameSpecifier::Namespace:
return NNS->getAsNamespace();
case NestedNameSpecifier::TypeSpec:
case NestedNameSpecifier::TypeSpecWithTemplate: {
if (const TagType *Tag = NNS->getAsType()->getAs<TagType>())
return Tag->getDecl();
break;
}
case NestedNameSpecifier::Global:
return Context.getTranslationUnitDecl();
}
return 0;
}
bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
if (!SS.isSet() || SS.isInvalid())
return false;
NestedNameSpecifier *NNS
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
return NNS->isDependent();
}
// \brief Determine whether this C++ scope specifier refers to an
// unknown specialization, i.e., a dependent type that is not the
// current instantiation.
bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
if (!isDependentScopeSpecifier(SS))
return false;
NestedNameSpecifier *NNS
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
return getCurrentInstantiationOf(NNS) == 0;
}
/// \brief If the given nested name specifier refers to the current
/// instantiation, return the declaration that corresponds to that
/// current instantiation (C++0x [temp.dep.type]p1).
///
/// \param NNS a dependent nested name specifier.
CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
assert(getLangOptions().CPlusPlus && "Only callable in C++");
assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
if (!NNS->getAsType())
return 0;
QualType T = QualType(NNS->getAsType(), 0);
return ::getCurrentInstantiationOf(Context, CurContext, T);
}
/// \brief Require that the context specified by SS be complete.
///
/// If SS refers to a type, this routine checks whether the type is
/// complete enough (or can be made complete enough) for name lookup
/// into the DeclContext. A type that is not yet completed can be
/// considered "complete enough" if it is a class/struct/union/enum
/// that is currently being defined. Or, if we have a type that names
/// a class template specialization that is not a complete type, we
/// will attempt to instantiate that class template.
bool Sema::RequireCompleteDeclContext(const CXXScopeSpec &SS) {
if (!SS.isSet() || SS.isInvalid())
return false;
DeclContext *DC = computeDeclContext(SS, true);
if (TagDecl *Tag = dyn_cast<TagDecl>(DC)) {
// If this is a dependent type, then we consider it complete.
if (Tag->isDependentContext())
return false;
// If we're currently defining this type, then lookup into the
// type is okay: don't complain that it isn't complete yet.
const TagType *TagT = Context.getTypeDeclType(Tag)->getAs<TagType>();
if (TagT->isBeingDefined())
return false;
// The type must be complete.
return RequireCompleteType(SS.getRange().getBegin(),
Context.getTypeDeclType(Tag),
PDiag(diag::err_incomplete_nested_name_spec)
<< SS.getRange());
}
return false;
}
/// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
/// global scope ('::').
Sema::CXXScopeTy *Sema::ActOnCXXGlobalScopeSpecifier(Scope *S,
SourceLocation CCLoc) {
return NestedNameSpecifier::GlobalSpecifier(Context);
}
/// \brief Determines whether the given declaration is an valid acceptable
/// result for name lookup of a nested-name-specifier.
bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD,
bool MayBePseudoDestructor) {
if (!SD)
return false;
// Namespace and namespace aliases are fine.
if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD))
return true;
if (!isa<TypeDecl>(SD))
return false;
// If this may be part of a pseudo-destructor expression, we'll
// accept any type.
if (MayBePseudoDestructor)
return true;
// Determine whether we have a class (or, in C++0x, an enum) or
// a typedef thereof. If so, build the nested-name-specifier.
QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
if (T->isDependentType())
return true;
else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(SD)) {
if (TD->getUnderlyingType()->isRecordType() ||
(Context.getLangOptions().CPlusPlus0x &&
TD->getUnderlyingType()->isEnumeralType()))
return true;
} else if (isa<RecordDecl>(SD) ||
(Context.getLangOptions().CPlusPlus0x && isa<EnumDecl>(SD)))
return true;
return false;
}
/// \brief If the given nested-name-specifier begins with a bare identifier
/// (e.g., Base::), perform name lookup for that identifier as a
/// nested-name-specifier within the given scope, and return the result of that
/// name lookup.
NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
if (!S || !NNS)
return 0;
while (NNS->getPrefix())
NNS = NNS->getPrefix();
if (NNS->getKind() != NestedNameSpecifier::Identifier)
return 0;
LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(),
LookupNestedNameSpecifierName);
LookupName(Found, S);
assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
if (!Found.isSingleResult())
return 0;
NamedDecl *Result = Found.getFoundDecl();
if (isAcceptableNestedNameSpecifier(Result, true))
return Result;
return 0;
}
/// \brief Build a new nested-name-specifier for "identifier::", as described
/// by ActOnCXXNestedNameSpecifier.
///
/// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
/// that it contains an extra parameter \p ScopeLookupResult, which provides
/// the result of name lookup within the scope of the nested-name-specifier
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/// that was computed at template definition time.
///
/// If ErrorRecoveryLookup is true, then this call is used to improve error
/// recovery. This means that it should not emit diagnostics, it should
/// just return null on failure. It also means it should only return a valid
/// scope if it *knows* that the result is correct. It should not return in a
/// dependent context, for example.
Sema::CXXScopeTy *Sema::BuildCXXNestedNameSpecifier(Scope *S,
const CXXScopeSpec &SS,
SourceLocation IdLoc,
SourceLocation CCLoc,
IdentifierInfo &II,
bool MayBePseudoDestructor,
QualType ObjectType,
NamedDecl *ScopeLookupResult,
bool EnteringContext,
bool ErrorRecoveryLookup) {
NestedNameSpecifier *Prefix
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
LookupResult Found(*this, &II, IdLoc, LookupNestedNameSpecifierName);
// Determine where to perform name lookup
DeclContext *LookupCtx = 0;
bool isDependent = false;
if (!ObjectType.isNull()) {
// This nested-name-specifier occurs in a member access expression, e.g.,
// x->B::f, and we are looking into the type of the object.
assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
LookupCtx = computeDeclContext(ObjectType);
isDependent = ObjectType->isDependentType();
} else if (SS.isSet()) {
// This nested-name-specifier occurs after another nested-name-specifier,
// so long into the context associated with the prior nested-name-specifier.
LookupCtx = computeDeclContext(SS, EnteringContext);
isDependent = isDependentScopeSpecifier(SS);
Found.setContextRange(SS.getRange());
}
bool ObjectTypeSearchedInScope = false;
if (LookupCtx) {
// Perform "qualified" name lookup into the declaration context we
// computed, which is either the type of the base of a member access
// expression or the declaration context associated with a prior
// nested-name-specifier.
// The declaration context must be complete.
if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS))
return 0;
LookupQualifiedName(Found, LookupCtx);
if (!ObjectType.isNull() && Found.empty()) {
// C++ [basic.lookup.classref]p4:
// If the id-expression in a class member access is a qualified-id of
// the form
//
// class-name-or-namespace-name::...
//
// the class-name-or-namespace-name following the . or -> operator is
// looked up both in the context of the entire postfix-expression and in
// the scope of the class of the object expression. If the name is found
// only in the scope of the class of the object expression, the name
// shall refer to a class-name. If the name is found only in the
// context of the entire postfix-expression, the name shall refer to a
// class-name or namespace-name. [...]
//
// Qualified name lookup into a class will not find a namespace-name,
// so we do not need to diagnoste that case specifically. However,
// this qualified name lookup may find nothing. In that case, perform
// unqualified name lookup in the given scope (if available) or
// reconstruct the result from when name lookup was performed at template
// definition time.
if (S)
LookupName(Found, S);
else if (ScopeLookupResult)
Found.addDecl(ScopeLookupResult);
ObjectTypeSearchedInScope = true;
}
} else if (isDependent) {
// Don't speculate if we're just trying to improve error recovery.
if (ErrorRecoveryLookup)
return 0;
// We were not able to compute the declaration context for a dependent
// base object type or prior nested-name-specifier, so this
// nested-name-specifier refers to an unknown specialization. Just build
// a dependent nested-name-specifier.
if (!Prefix)
return NestedNameSpecifier::Create(Context, &II);
return NestedNameSpecifier::Create(Context, Prefix, &II);
} else {
// Perform unqualified name lookup in the current scope.
LookupName(Found, S);
}
// FIXME: Deal with ambiguities cleanly.
if (Found.empty() && !ErrorRecoveryLookup) {
// We haven't found anything, and we're not recovering from a
// different kind of error, so look for typos.
DeclarationName Name = Found.getLookupName();
if (CorrectTypo(Found, S, &SS, LookupCtx, EnteringContext) &&
Found.isSingleResult() &&
isAcceptableNestedNameSpecifier(Found.getAsSingle<NamedDecl>(),
MayBePseudoDestructor)) {
if (LookupCtx)
Diag(Found.getNameLoc(), diag::err_no_member_suggest)
<< Name << LookupCtx << Found.getLookupName() << SS.getRange()
<< CodeModificationHint::CreateReplacement(Found.getNameLoc(),
Found.getLookupName().getAsString());
else
Diag(Found.getNameLoc(), diag::err_undeclared_var_use_suggest)
<< Name << Found.getLookupName()
<< CodeModificationHint::CreateReplacement(Found.getNameLoc(),
Found.getLookupName().getAsString());
if (NamedDecl *ND = Found.getAsSingle<NamedDecl>())
Diag(ND->getLocation(), diag::note_previous_decl)
<< ND->getDeclName();
} else
Found.clear();
}
NamedDecl *SD = Found.getAsSingle<NamedDecl>();
if (isAcceptableNestedNameSpecifier(SD, MayBePseudoDestructor)) {
if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) {
// C++ [basic.lookup.classref]p4:
// [...] If the name is found in both contexts, the
// class-name-or-namespace-name shall refer to the same entity.
//
// We already found the name in the scope of the object. Now, look
// into the current scope (the scope of the postfix-expression) to
// see if we can find the same name there. As above, if there is no
// scope, reconstruct the result from the template instantiation itself.
NamedDecl *OuterDecl;
if (S) {
LookupResult FoundOuter(*this, &II, IdLoc,
LookupNestedNameSpecifierName);
LookupName(FoundOuter, S);
OuterDecl = FoundOuter.getAsSingle<NamedDecl>();
} else
OuterDecl = ScopeLookupResult;
if (isAcceptableNestedNameSpecifier(OuterDecl, MayBePseudoDestructor) &&
OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
(!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
!Context.hasSameType(
Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
if (ErrorRecoveryLookup)
return 0;
Diag(IdLoc, diag::err_nested_name_member_ref_lookup_ambiguous)
<< &II;
Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
<< ObjectType;
Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope);
// Fall through so that we'll pick the name we found in the object
// type, since that's probably what the user wanted anyway.
}
}
if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD))
return NestedNameSpecifier::Create(Context, Prefix, Namespace);
// FIXME: It would be nice to maintain the namespace alias name, then
// see through that alias when resolving the nested-name-specifier down to
// a declaration context.
if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD))
return NestedNameSpecifier::Create(Context, Prefix,
Alias->getNamespace());
QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
return NestedNameSpecifier::Create(Context, Prefix, false,
T.getTypePtr());
}
// Otherwise, we have an error case. If we don't want diagnostics, just
// return an error now.
if (ErrorRecoveryLookup)
return 0;
// If we didn't find anything during our lookup, try again with
// ordinary name lookup, which can help us produce better error
// messages.
if (Found.empty()) {
Found.clear(LookupOrdinaryName);
LookupName(Found, S);
}
unsigned DiagID;
if (!Found.empty())
DiagID = diag::err_expected_class_or_namespace;
else if (SS.isSet()) {
Diag(IdLoc, diag::err_no_member) << &II << LookupCtx << SS.getRange();
return 0;
} else
DiagID = diag::err_undeclared_var_use;
if (SS.isSet())
Diag(IdLoc, DiagID) << &II << SS.getRange();
else
Diag(IdLoc, DiagID) << &II;
return 0;
}
/// ActOnCXXNestedNameSpecifier - Called during parsing of a
/// nested-name-specifier. e.g. for "foo::bar::" we parsed "foo::" and now
/// we want to resolve "bar::". 'SS' is empty or the previously parsed
/// nested-name part ("foo::"), 'IdLoc' is the source location of 'bar',
/// 'CCLoc' is the location of '::' and 'II' is the identifier for 'bar'.
/// Returns a CXXScopeTy* object representing the C++ scope.
Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
const CXXScopeSpec &SS,
SourceLocation IdLoc,
SourceLocation CCLoc,
IdentifierInfo &II,
bool MayBePseudoDestructor,
TypeTy *ObjectTypePtr,
bool EnteringContext) {
return BuildCXXNestedNameSpecifier(S, SS, IdLoc, CCLoc, II,
MayBePseudoDestructor,
QualType::getFromOpaquePtr(ObjectTypePtr),
/*ScopeLookupResult=*/0, EnteringContext,
false);
}
/// IsInvalidUnlessNestedName - This method is used for error recovery
/// purposes to determine whether the specified identifier is only valid as
/// a nested name specifier, for example a namespace name. It is
/// conservatively correct to always return false from this method.
///
/// The arguments are the same as those passed to ActOnCXXNestedNameSpecifier.
bool Sema::IsInvalidUnlessNestedName(Scope *S, const CXXScopeSpec &SS,
IdentifierInfo &II,
bool MayBePseudoDestructor,
TypeTy *ObjectType,
bool EnteringContext) {
return BuildCXXNestedNameSpecifier(S, SS, SourceLocation(), SourceLocation(),
II, MayBePseudoDestructor,
QualType::getFromOpaquePtr(ObjectType),
/*ScopeLookupResult=*/0, EnteringContext,
true);
}
Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
const CXXScopeSpec &SS,
TypeTy *Ty,
SourceRange TypeRange,
SourceLocation CCLoc,
bool MayBePseudoDestructor) {
NestedNameSpecifier *Prefix
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
QualType T = GetTypeFromParser(Ty);
return NestedNameSpecifier::Create(Context, Prefix, /*FIXME:*/false,
T.getTypePtr());
}
bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
NestedNameSpecifier *Qualifier =
static_cast<NestedNameSpecifier*>(SS.getScopeRep());
// There are only two places a well-formed program may qualify a
// declarator: first, when defining a namespace or class member
// out-of-line, and second, when naming an explicitly-qualified
// friend function. The latter case is governed by
// C++03 [basic.lookup.unqual]p10:
// In a friend declaration naming a member function, a name used
// in the function declarator and not part of a template-argument
// in a template-id is first looked up in the scope of the member
// function's class. If it is not found, or if the name is part of
// a template-argument in a template-id, the look up is as
// described for unqualified names in the definition of the class
// granting friendship.
// i.e. we don't push a scope unless it's a class member.
switch (Qualifier->getKind()) {
case NestedNameSpecifier::Global:
case NestedNameSpecifier::Namespace:
// These are always namespace scopes. We never want to enter a
// namespace scope from anything but a file context.
return CurContext->getLookupContext()->isFileContext();
case NestedNameSpecifier::Identifier:
case NestedNameSpecifier::TypeSpec:
case NestedNameSpecifier::TypeSpecWithTemplate:
// These are never namespace scopes.
return true;
}
// Silence bogus warning.
return false;
}
/// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
/// scope or nested-name-specifier) is parsed, part of a declarator-id.
/// After this method is called, according to [C++ 3.4.3p3], names should be
/// looked up in the declarator-id's scope, until the declarator is parsed and
/// ActOnCXXExitDeclaratorScope is called.
/// The 'SS' should be a non-empty valid CXXScopeSpec.
bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
if (SS.isInvalid()) return true;
DeclContext *DC = computeDeclContext(SS, true);
if (!DC) return true;
// Before we enter a declarator's context, we need to make sure that
// it is a complete declaration context.
if (!DC->isDependentContext() && RequireCompleteDeclContext(SS))
return true;
EnterDeclaratorContext(S, DC);
return false;
}
/// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
/// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
/// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
/// Used to indicate that names should revert to being looked up in the
/// defining scope.
void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
if (SS.isInvalid())
return;
assert(!SS.isInvalid() && computeDeclContext(SS, true) &&
"exiting declarator scope we never really entered");
ExitDeclaratorContext(S);
}