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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 "clang/AST/ASTContext.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/Parse/DeclSpec.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
/// \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) {
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) {
// 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 (const TemplateSpecializationType *SpecType
= dyn_cast_or_null<TemplateSpecializationType>(NNS->getAsType())) {
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;
std::string NNSString;
llvm::raw_string_ostream OS(NNSString);
NNS->print(OS, Context.PrintingPolicy);
// FIXME: Allow us to pass a nested-name-specifier to Diag?
<< NNSString << SS.getRange();
return 0;
switch (NNS->getKind()) {
case NestedNameSpecifier::Identifier:
assert(false && "Dependent nested-name-specifier has no DeclContext");
case NestedNameSpecifier::Namespace:
return NNS->getAsNamespace();
case NestedNameSpecifier::TypeSpec:
case NestedNameSpecifier::TypeSpecWithTemplate: {
const TagType *Tag = NNS->getAsType()->getAs<TagType>();
assert(Tag && "Non-tag type in nested-name-specifier");
return Tag->getDecl();
} break;
case NestedNameSpecifier::Global:
return Context.getTranslationUnitDecl();
// Required to silence a GCC warning.
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);
// If the nested name specifier does not refer to a type, then it
// does not refer to the current instantiation.
if (T.isNull())
return 0;
T = Context.getCanonicalType(T);
for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getParent()) {
// 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)
// 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 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 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(),
return false;
/// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
/// global scope ('::').
Sema::CXXScopeTy *Sema::ActOnCXXGlobalScopeSpecifier(Scope *S,
SourceLocation CCLoc) {
return NestedNameSpecifier::GlobalSpecifier(Context);
/// 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) {
NestedNameSpecifier *Prefix
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
// If the prefix already refers to an unknown specialization, there
// is no name lookup to perform. Just build the resulting
// nested-name-specifier.
if (Prefix && isUnknownSpecialization(SS))
return NestedNameSpecifier::Create(Context, Prefix, &II);
NamedDecl *SD = LookupParsedName(S, &SS, &II, LookupNestedNameSpecifierName);
if (SD) {
if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD))
return NestedNameSpecifier::Create(Context, Prefix, Namespace);
if (TypeDecl *Type = dyn_cast<TypeDecl>(SD)) {
// 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(Type);
bool AcceptableType = false;
if (T->isDependentType())
AcceptableType = true;
else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(SD)) {
if (TD->getUnderlyingType()->isRecordType() ||
(getLangOptions().CPlusPlus0x &&
AcceptableType = true;
} else if (isa<RecordDecl>(Type) ||
(getLangOptions().CPlusPlus0x && isa<EnumDecl>(Type)))
AcceptableType = true;
if (AcceptableType)
return NestedNameSpecifier::Create(Context, Prefix, false,
if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD))
return NestedNameSpecifier::Create(Context, Prefix,
// Fall through to produce an error: we found something that isn't
// a class or a namespace.
// If we didn't find anything during our lookup, try again with
// ordinary name lookup, which can help us produce better error
// messages.
if (!SD)
SD = LookupParsedName(S, &SS, &II, LookupOrdinaryName);
unsigned DiagID;
if (SD)
DiagID = diag::err_expected_class_or_namespace;
else if (SS.isSet())
DiagID = diag::err_typecheck_no_member;
DiagID = diag::err_undeclared_var_use;
if (SS.isSet())
Diag(IdLoc, DiagID) << &II << SS.getRange();
Diag(IdLoc, DiagID) << &II;
return 0;
Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
const CXXScopeSpec &SS,
TypeTy *Ty,
SourceRange TypeRange,
SourceLocation CCLoc) {
NestedNameSpecifier *Prefix
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
QualType T = GetTypeFromParser(Ty);
return NestedNameSpecifier::Create(Context, Prefix, /*FIXME:*/false,
Sema::ActOnCXXEnterMemberScope(Scope *S, CXXScopeSpec &SS, ExprArg Base,
tok::TokenKind OpKind) {
// Since this might be a postfix expression, get rid of ParenListExprs.
Base = MaybeConvertParenListExprToParenExpr(S, move(Base));
Expr *BaseExpr = (Expr*)Base.get();
assert(BaseExpr && "no record expansion");
QualType BaseType = BaseExpr->getType();
// FIXME: handle dependent types
if (BaseType->isDependentType())
return move(Base);
// C++ [over.match.oper]p8:
// [...] When operator->returns, the operator-> is applied to the value
// returned, with the original second operand.
if (OpKind == tok::arrow) {
while (BaseType->isRecordType()) {
Base = BuildOverloadedArrowExpr(S, move(Base), BaseExpr->getExprLoc());
BaseExpr = (Expr*)Base.get();
if (BaseExpr == NULL)
return ExprError();
BaseType = BaseExpr->getType();
if (BaseType->isPointerType())
BaseType = BaseType->getPointeeType();
// We could end up with various non-record types here, such as extended
// vector types or Objective-C interfaces. Just return early and let
// ActOnMemberReferenceExpr do the work.
if (!BaseType->isRecordType())
return move(Base);
NestedNameSpecifier::Create(Context, 0, false, BaseType.getTypePtr())
if (S)
return move(Base);
void Sema::ActOnCXXExitMemberScope(Scope *S, const CXXScopeSpec &SS) {
if (S && SS.isSet())
/// 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.
void Sema::ActOnCXXEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
if (DeclContext *DC = computeDeclContext(SS, true))
EnterDeclaratorContext(S, DC);
/// 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.");
assert((SS.isInvalid() || S->getEntity() == computeDeclContext(SS, true)) &&
"Context imbalance!");
if (!SS.isInvalid())