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 "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 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 0;
}
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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: {
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)
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 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(),
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 isAcceptableNestedNameSpecifier(ASTContext &Context, NamedDecl *SD) {
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;
// 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;
}
/// 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,
TypeTy *ObjectTypePtr,
bool EnteringContext) {
NestedNameSpecifier *Prefix
= static_cast<NestedNameSpecifier *>(SS.getScopeRep());
// Determine where to perform name lookup
DeclContext *LookupCtx = 0;
bool isDependent = false;
if (ObjectTypePtr) {
// 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");
QualType ObjectType = QualType::getFromOpaquePtr(ObjectTypePtr);
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);
}
LookupResult Found;
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;
Found = LookupQualifiedName(LookupCtx, &II, LookupNestedNameSpecifierName,
false);
if (ObjectTypePtr && Found.getKind() == LookupResult::NotFound && S) {
// 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.
// FIXME: When we're instantiating a template, do we actually have to
// look in the scope of the template? Both EDG and GCC do it; GCC
// requires the lookup to be successful, EDG doesn't.
Found = LookupName(S, &II, LookupNestedNameSpecifierName);
ObjectTypeSearchedInScope = true;
}
} else if (isDependent) {
// 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.
Found = LookupName(S, &II, LookupNestedNameSpecifierName);
}
// FIXME: Deal with ambiguities cleanly.
NamedDecl *SD = Found;
if (isAcceptableNestedNameSpecifier(Context, SD)) {
if (ObjectTypePtr && !ObjectTypeSearchedInScope && S) {
// 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.
LookupResult FoundOuter
= LookupName(S, &II, LookupNestedNameSpecifierName);
// FIXME: Handle ambiguities in FoundOuter!
NamedDecl *OuterDecl = FoundOuter;
if (isAcceptableNestedNameSpecifier(Context, OuterDecl) &&
OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
(!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
!Context.hasSameType(
Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
Diag(IdLoc, diag::err_nested_name_member_ref_lookup_ambiguous)
<< &II;
Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
<< QualType::getFromOpaquePtr(ObjectTypePtr);
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());
}
// 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 = LookupName(S, &II, LookupOrdinaryName);
unsigned DiagID;
if (SD)
DiagID = diag::err_expected_class_or_namespace;
else if (SS.isSet()) {
DiagnoseMissingMember(IdLoc, DeclarationName(&II),
(NestedNameSpecifier *)SS.getScopeRep(),
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;
}
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,
T.getTypePtr());
}
/// 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.");
if (SS.isInvalid())
return;
if (computeDeclContext(SS, true))
ExitDeclaratorContext(S);
}