blob: 856ddf6eaa610efc4e3e776a875abae5240963f9 [file] [log] [blame]
//===--- SemaDecl.cpp - Semantic Analysis for Declarations ----------------===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// This file implements semantic analysis for declarations.
#include "TypeLocBuilder.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/CommentDiagnostic.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/PartialDiagnostic.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Lex/HeaderSearch.h" // TODO: Sema shouldn't depend on Lex
#include "clang/Lex/Lexer.h" // TODO: Extract static functions to fix layering.
#include "clang/Lex/ModuleLoader.h" // TODO: Sema shouldn't depend on Lex
#include "clang/Lex/Preprocessor.h" // Included for isCodeCompletionEnabled()
#include "clang/Sema/CXXFieldCollector.h"
#include "clang/Sema/DeclSpec.h"
#include "clang/Sema/DelayedDiagnostic.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Lookup.h"
#include "clang/Sema/ParsedTemplate.h"
#include "clang/Sema/Scope.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Triple.h"
#include <algorithm>
#include <cstring>
#include <functional>
using namespace clang;
using namespace sema;
Sema::DeclGroupPtrTy Sema::ConvertDeclToDeclGroup(Decl *Ptr, Decl *OwnedType) {
if (OwnedType) {
Decl *Group[2] = { OwnedType, Ptr };
return DeclGroupPtrTy::make(DeclGroupRef::Create(Context, Group, 2));
return DeclGroupPtrTy::make(DeclGroupRef(Ptr));
namespace {
class TypeNameValidatorCCC : public CorrectionCandidateCallback {
TypeNameValidatorCCC(bool AllowInvalid, bool WantClass = false,
bool AllowTemplates = false,
bool AllowNonTemplates = true)
: AllowInvalidDecl(AllowInvalid), WantClassName(WantClass),
AllowTemplates(AllowTemplates), AllowNonTemplates(AllowNonTemplates) {
WantExpressionKeywords = false;
WantCXXNamedCasts = false;
WantRemainingKeywords = false;
bool ValidateCandidate(const TypoCorrection &candidate) override {
if (NamedDecl *ND = candidate.getCorrectionDecl()) {
if (!AllowInvalidDecl && ND->isInvalidDecl())
return false;
if (getAsTypeTemplateDecl(ND))
return AllowTemplates;
bool IsType = isa<TypeDecl>(ND) || isa<ObjCInterfaceDecl>(ND);
if (!IsType)
return false;
if (AllowNonTemplates)
return true;
// An injected-class-name of a class template (specialization) is valid
// as a template or as a non-template.
if (AllowTemplates) {
auto *RD = dyn_cast<CXXRecordDecl>(ND);
if (!RD || !RD->isInjectedClassName())
return false;
RD = cast<CXXRecordDecl>(RD->getDeclContext());
return RD->getDescribedClassTemplate() ||
return false;
return !WantClassName && candidate.isKeyword();
bool AllowInvalidDecl;
bool WantClassName;
bool AllowTemplates;
bool AllowNonTemplates;
} // end anonymous namespace
/// \brief Determine whether the token kind starts a simple-type-specifier.
bool Sema::isSimpleTypeSpecifier(tok::TokenKind Kind) const {
switch (Kind) {
// FIXME: Take into account the current language when deciding whether a
// token kind is a valid type specifier
case tok::kw_short:
case tok::kw_long:
case tok::kw___int64:
case tok::kw___int128:
case tok::kw_signed:
case tok::kw_unsigned:
case tok::kw_void:
case tok::kw_char:
case tok::kw_int:
case tok::kw_half:
case tok::kw_float:
case tok::kw_double:
case tok::kw___float128:
case tok::kw_wchar_t:
case tok::kw_bool:
case tok::kw___underlying_type:
case tok::kw___auto_type:
return true;
case tok::annot_typename:
case tok::kw_char16_t:
case tok::kw_char32_t:
case tok::kw_typeof:
case tok::annot_decltype:
case tok::kw_decltype:
return getLangOpts().CPlusPlus;
return false;
namespace {
enum class UnqualifiedTypeNameLookupResult {
} // end anonymous namespace
/// \brief Tries to perform unqualified lookup of the type decls in bases for
/// dependent class.
/// \return \a NotFound if no any decls is found, \a FoundNotType if found not a
/// type decl, \a FoundType if only type decls are found.
static UnqualifiedTypeNameLookupResult
lookupUnqualifiedTypeNameInBase(Sema &S, const IdentifierInfo &II,
SourceLocation NameLoc,
const CXXRecordDecl *RD) {
if (!RD->hasDefinition())
return UnqualifiedTypeNameLookupResult::NotFound;
// Look for type decls in base classes.
UnqualifiedTypeNameLookupResult FoundTypeDecl =
for (const auto &Base : RD->bases()) {
const CXXRecordDecl *BaseRD = nullptr;
if (auto *BaseTT = Base.getType()->getAs<TagType>())
BaseRD = BaseTT->getAsCXXRecordDecl();
else if (auto *TST = Base.getType()->getAs<TemplateSpecializationType>()) {
// Look for type decls in dependent base classes that have known primary
// templates.
if (!TST || !TST->isDependentType())
auto *TD = TST->getTemplateName().getAsTemplateDecl();
if (!TD)
if (auto *BasePrimaryTemplate =
dyn_cast_or_null<CXXRecordDecl>(TD->getTemplatedDecl())) {
if (BasePrimaryTemplate->getCanonicalDecl() != RD->getCanonicalDecl())
BaseRD = BasePrimaryTemplate;
else if (auto *CTD = dyn_cast<ClassTemplateDecl>(TD)) {
if (const ClassTemplatePartialSpecializationDecl *PS =
if (PS->getCanonicalDecl() != RD->getCanonicalDecl())
BaseRD = PS;
if (BaseRD) {
for (NamedDecl *ND : BaseRD->lookup(&II)) {
if (!isa<TypeDecl>(ND))
return UnqualifiedTypeNameLookupResult::FoundNonType;
FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
if (FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound) {
switch (lookupUnqualifiedTypeNameInBase(S, II, NameLoc, BaseRD)) {
case UnqualifiedTypeNameLookupResult::FoundNonType:
return UnqualifiedTypeNameLookupResult::FoundNonType;
case UnqualifiedTypeNameLookupResult::FoundType:
FoundTypeDecl = UnqualifiedTypeNameLookupResult::FoundType;
case UnqualifiedTypeNameLookupResult::NotFound:
return FoundTypeDecl;
static ParsedType recoverFromTypeInKnownDependentBase(Sema &S,
const IdentifierInfo &II,
SourceLocation NameLoc) {
// Lookup in the parent class template context, if any.
const CXXRecordDecl *RD = nullptr;
UnqualifiedTypeNameLookupResult FoundTypeDecl =
for (DeclContext *DC = S.CurContext;
DC && FoundTypeDecl == UnqualifiedTypeNameLookupResult::NotFound;
DC = DC->getParent()) {
// Look for type decls in dependent base classes that have known primary
// templates.
RD = dyn_cast<CXXRecordDecl>(DC);
if (RD && RD->getDescribedClassTemplate())
FoundTypeDecl = lookupUnqualifiedTypeNameInBase(S, II, NameLoc, RD);
if (FoundTypeDecl != UnqualifiedTypeNameLookupResult::FoundType)
return nullptr;
// We found some types in dependent base classes. Recover as if the user
// wrote 'typename MyClass::II' instead of 'II'. We'll fully resolve the
// lookup during template instantiation.
S.Diag(NameLoc, diag::ext_found_via_dependent_bases_lookup) << &II;
ASTContext &Context = S.Context;
auto *NNS = NestedNameSpecifier::Create(Context, nullptr, false,
QualType T = Context.getDependentNameType(ETK_Typename, NNS, &II);
CXXScopeSpec SS;
SS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
TypeLocBuilder Builder;
DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
/// \brief If the identifier refers to a type name within this scope,
/// return the declaration of that type.
/// This routine performs ordinary name lookup of the identifier II
/// within the given scope, with optional C++ scope specifier SS, to
/// determine whether the name refers to a type. If so, returns an
/// opaque pointer (actually a QualType) corresponding to that
/// type. Otherwise, returns NULL.
ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
Scope *S, CXXScopeSpec *SS,
bool isClassName, bool HasTrailingDot,
ParsedType ObjectTypePtr,
bool IsCtorOrDtorName,
bool WantNontrivialTypeSourceInfo,
bool IsClassTemplateDeductionContext,
IdentifierInfo **CorrectedII) {
// FIXME: Consider allowing this outside C++1z mode as an extension.
bool AllowDeducedTemplate = IsClassTemplateDeductionContext &&
getLangOpts().CPlusPlus1z && !IsCtorOrDtorName &&
!isClassName && !HasTrailingDot;
// Determine where we will perform name lookup.
DeclContext *LookupCtx = nullptr;
if (ObjectTypePtr) {
QualType ObjectType = ObjectTypePtr.get();
if (ObjectType->isRecordType())
LookupCtx = computeDeclContext(ObjectType);
} else if (SS && SS->isNotEmpty()) {
LookupCtx = computeDeclContext(*SS, false);
if (!LookupCtx) {
if (isDependentScopeSpecifier(*SS)) {
// C++ [temp.res]p3:
// A qualified-id that refers to a type and in which the
// nested-name-specifier depends on a template-parameter (14.6.2)
// shall be prefixed by the keyword typename to indicate that the
// qualified-id denotes a type, forming an
// elaborated-type-specifier (
// We therefore do not perform any name lookup if the result would
// refer to a member of an unknown specialization.
if (!isClassName && !IsCtorOrDtorName)
return nullptr;
// We know from the grammar that this name refers to a type,
// so build a dependent node to describe the type.
if (WantNontrivialTypeSourceInfo)
return ActOnTypenameType(S, SourceLocation(), *SS, II, NameLoc).get();
NestedNameSpecifierLoc QualifierLoc = SS->getWithLocInContext(Context);
QualType T = CheckTypenameType(ETK_None, SourceLocation(), QualifierLoc,
II, NameLoc);
return ParsedType::make(T);
return nullptr;
if (!LookupCtx->isDependentContext() &&
RequireCompleteDeclContext(*SS, LookupCtx))
return nullptr;
// FIXME: LookupNestedNameSpecifierName isn't the right kind of
// lookup for class-names.
LookupNameKind Kind = isClassName ? LookupNestedNameSpecifierName :
LookupResult Result(*this, &II, NameLoc, Kind);
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.
LookupQualifiedName(Result, LookupCtx);
if (ObjectTypePtr && Result.empty()) {
// C++ [basic.lookup.classref]p3:
// If the unqualified-id is ~type-name, the type-name is looked up
// in the context of the entire postfix-expression. If the type T of
// the object expression is of a class type C, the type-name is also
// looked up in the scope of class C. At least one of the lookups shall
// find a name that refers to (possibly cv-qualified) T.
LookupName(Result, S);
} else {
// Perform unqualified name lookup.
LookupName(Result, S);
// For unqualified lookup in a class template in MSVC mode, look into
// dependent base classes where the primary class template is known.
if (Result.empty() && getLangOpts().MSVCCompat && (!SS || SS->isEmpty())) {
if (ParsedType TypeInBase =
recoverFromTypeInKnownDependentBase(*this, II, NameLoc))
return TypeInBase;
NamedDecl *IIDecl = nullptr;
switch (Result.getResultKind()) {
case LookupResult::NotFound:
case LookupResult::NotFoundInCurrentInstantiation:
if (CorrectedII) {
TypoCorrection Correction =
CorrectTypo(Result.getLookupNameInfo(), Kind, S, SS,
true, isClassName, AllowDeducedTemplate),
IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
TemplateTy Template;
bool MemberOfUnknownSpecialization;
UnqualifiedId TemplateName;
TemplateName.setIdentifier(NewII, NameLoc);
NestedNameSpecifier *NNS = Correction.getCorrectionSpecifier();
CXXScopeSpec NewSS, *NewSSPtr = SS;
if (SS && NNS) {
NewSS.MakeTrivial(Context, NNS, SourceRange(NameLoc));
NewSSPtr = &NewSS;
if (Correction && (NNS || NewII != &II) &&
// Ignore a correction to a template type as the to-be-corrected
// identifier is not a template (typo correction for template names
// is handled elsewhere).
!(getLangOpts().CPlusPlus && NewSSPtr &&
isTemplateName(S, *NewSSPtr, false, TemplateName, nullptr, false,
Template, MemberOfUnknownSpecialization))) {
ParsedType Ty = getTypeName(*NewII, NameLoc, S, NewSSPtr,
isClassName, HasTrailingDot, ObjectTypePtr,
if (Ty) {
<< Result.getLookupName() << isClassName);
if (SS && NNS)
SS->MakeTrivial(Context, NNS, SourceRange(NameLoc));
*CorrectedII = NewII;
return Ty;
// If typo correction failed or was not performed, fall through
case LookupResult::FoundOverloaded:
case LookupResult::FoundUnresolvedValue:
return nullptr;
case LookupResult::Ambiguous:
// Recover from type-hiding ambiguities by hiding the type. We'll
// do the lookup again when looking for an object, and we can
// diagnose the error then. If we don't do this, then the error
// about hiding the type will be immediately followed by an error
// that only makes sense if the identifier was treated like a type.
if (Result.getAmbiguityKind() == LookupResult::AmbiguousTagHiding) {
return nullptr;
// Look to see if we have a type anywhere in the list of results.
for (LookupResult::iterator Res = Result.begin(), ResEnd = Result.end();
Res != ResEnd; ++Res) {
if (isa<TypeDecl>(*Res) || isa<ObjCInterfaceDecl>(*Res) ||
(AllowDeducedTemplate && getAsTypeTemplateDecl(*Res))) {
if (!IIDecl ||
(*Res)->getLocation().getRawEncoding() <
IIDecl = *Res;
if (!IIDecl) {
// None of the entities we found is a type, so there is no way
// to even assume that the result is a type. In this case, don't
// complain about the ambiguity. The parser will either try to
// perform this lookup again (e.g., as an object name), which
// will produce the ambiguity, or will complain that it expected
// a type name.
return nullptr;
// We found a type within the ambiguous lookup; diagnose the
// ambiguity and then return that type. This might be the right
// answer, or it might not be, but it suppresses any attempt to
// perform the name lookup again.
case LookupResult::Found:
IIDecl = Result.getFoundDecl();
assert(IIDecl && "Didn't find decl");
QualType T;
if (TypeDecl *TD = dyn_cast<TypeDecl>(IIDecl)) {
// C++ [class.qual]p2: A lookup that would find the injected-class-name
// instead names the constructors of the class, except when naming a class.
// This is ill-formed when we're not actually forming a ctor or dtor name.
auto *LookupRD = dyn_cast_or_null<CXXRecordDecl>(LookupCtx);
auto *FoundRD = dyn_cast<CXXRecordDecl>(TD);
if (!isClassName && !IsCtorOrDtorName && LookupRD && FoundRD &&
FoundRD->isInjectedClassName() &&
declaresSameEntity(LookupRD, cast<Decl>(FoundRD->getParent())))
Diag(NameLoc, diag::err_out_of_line_qualified_id_type_names_constructor)
<< &II << /*Type*/1;
DiagnoseUseOfDecl(IIDecl, NameLoc);
T = Context.getTypeDeclType(TD);
MarkAnyDeclReferenced(TD->getLocation(), TD, /*OdrUse=*/false);
} else if (ObjCInterfaceDecl *IDecl = dyn_cast<ObjCInterfaceDecl>(IIDecl)) {
(void)DiagnoseUseOfDecl(IDecl, NameLoc);
if (!HasTrailingDot)
T = Context.getObjCInterfaceType(IDecl);
} else if (AllowDeducedTemplate) {
if (auto *TD = getAsTypeTemplateDecl(IIDecl))
T = Context.getDeducedTemplateSpecializationType(TemplateName(TD),
QualType(), false);
if (T.isNull()) {
// If it's not plausibly a type, suppress diagnostics.
return nullptr;
// NOTE: avoid constructing an ElaboratedType(Loc) if this is a
// constructor or destructor name (in such a case, the scope specifier
// will be attached to the enclosing Expr or Decl node).
if (SS && SS->isNotEmpty() && !IsCtorOrDtorName &&
!isa<ObjCInterfaceDecl>(IIDecl)) {
if (WantNontrivialTypeSourceInfo) {
// Construct a type with type-source information.
TypeLocBuilder Builder;
T = getElaboratedType(ETK_None, *SS, T);
ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
} else {
T = getElaboratedType(ETK_None, *SS, T);
return ParsedType::make(T);
// Builds a fake NNS for the given decl context.
static NestedNameSpecifier *
synthesizeCurrentNestedNameSpecifier(ASTContext &Context, DeclContext *DC) {
for (;; DC = DC->getLookupParent()) {
DC = DC->getPrimaryContext();
auto *ND = dyn_cast<NamespaceDecl>(DC);
if (ND && !ND->isInline() && !ND->isAnonymousNamespace())
return NestedNameSpecifier::Create(Context, nullptr, ND);
else if (auto *RD = dyn_cast<CXXRecordDecl>(DC))
return NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
else if (isa<TranslationUnitDecl>(DC))
return NestedNameSpecifier::GlobalSpecifier(Context);
llvm_unreachable("something isn't in TU scope?");
/// Find the parent class with dependent bases of the innermost enclosing method
/// context. Do not look for enclosing CXXRecordDecls directly, or we will end
/// up allowing unqualified dependent type names at class-level, which MSVC
/// correctly rejects.
static const CXXRecordDecl *
findRecordWithDependentBasesOfEnclosingMethod(const DeclContext *DC) {
for (; DC && DC->isDependentContext(); DC = DC->getLookupParent()) {
DC = DC->getPrimaryContext();
if (const auto *MD = dyn_cast<CXXMethodDecl>(DC))
if (MD->getParent()->hasAnyDependentBases())
return MD->getParent();
return nullptr;
ParsedType Sema::ActOnMSVCUnknownTypeName(const IdentifierInfo &II,
SourceLocation NameLoc,
bool IsTemplateTypeArg) {
assert(getLangOpts().MSVCCompat && "shouldn't be called in non-MSVC mode");
NestedNameSpecifier *NNS = nullptr;
if (IsTemplateTypeArg && getCurScope()->isTemplateParamScope()) {
// If we weren't able to parse a default template argument, delay lookup
// until instantiation time by making a non-dependent DependentTypeName. We
// pretend we saw a NestedNameSpecifier referring to the current scope, and
// lookup is retried.
// FIXME: This hurts our diagnostic quality, since we get errors like "no
// type named 'Foo' in 'current_namespace'" when the user didn't write any
// name specifiers.
NNS = synthesizeCurrentNestedNameSpecifier(Context, CurContext);
Diag(NameLoc, diag::ext_ms_delayed_template_argument) << &II;
} else if (const CXXRecordDecl *RD =
findRecordWithDependentBasesOfEnclosingMethod(CurContext)) {
// Build a DependentNameType that will perform lookup into RD at
// instantiation time.
NNS = NestedNameSpecifier::Create(Context, nullptr, RD->isTemplateDecl(),
// Diagnose that this identifier was undeclared, and retry the lookup during
// template instantiation.
Diag(NameLoc, diag::ext_undeclared_unqual_id_with_dependent_base) << &II
<< RD;
} else {
// This is not a situation that we should recover from.
return ParsedType();
QualType T = Context.getDependentNameType(ETK_None, NNS, &II);
// Build type location information. We synthesized the qualifier, so we have
// to build a fake NestedNameSpecifierLoc.
NestedNameSpecifierLocBuilder NNSLocBuilder;
NNSLocBuilder.MakeTrivial(Context, NNS, SourceRange(NameLoc));
NestedNameSpecifierLoc QualifierLoc = NNSLocBuilder.getWithLocInContext(Context);
TypeLocBuilder Builder;
DependentNameTypeLoc DepTL = Builder.push<DependentNameTypeLoc>(T);
return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
/// isTagName() - This method is called *for error recovery purposes only*
/// to determine if the specified name is a valid tag name ("struct foo"). If
/// so, this returns the TST for the tag corresponding to it (TST_enum,
/// TST_union, TST_struct, TST_interface, TST_class). This is used to diagnose
/// cases in C where the user forgot to specify the tag.
DeclSpec::TST Sema::isTagName(IdentifierInfo &II, Scope *S) {
// Do a tag name lookup in this scope.
LookupResult R(*this, &II, SourceLocation(), LookupTagName);
LookupName(R, S, false);
if (R.getResultKind() == LookupResult::Found)
if (const TagDecl *TD = R.getAsSingle<TagDecl>()) {
switch (TD->getTagKind()) {
case TTK_Struct: return DeclSpec::TST_struct;
case TTK_Interface: return DeclSpec::TST_interface;
case TTK_Union: return DeclSpec::TST_union;
case TTK_Class: return DeclSpec::TST_class;
case TTK_Enum: return DeclSpec::TST_enum;
return DeclSpec::TST_unspecified;
/// isMicrosoftMissingTypename - In Microsoft mode, within class scope,
/// if a CXXScopeSpec's type is equal to the type of one of the base classes
/// then downgrade the missing typename error to a warning.
/// This is needed for MSVC compatibility; Example:
/// @code
/// template<class T> class A {
/// public:
/// typedef int TYPE;
/// };
/// template<class T> class B : public A<T> {
/// public:
/// A<T>::TYPE a; // no typename required because A<T> is a base class.
/// };
/// @endcode
bool Sema::isMicrosoftMissingTypename(const CXXScopeSpec *SS, Scope *S) {
if (CurContext->isRecord()) {
if (SS->getScopeRep()->getKind() == NestedNameSpecifier::Super)
return true;
const Type *Ty = SS->getScopeRep()->getAsType();
CXXRecordDecl *RD = cast<CXXRecordDecl>(CurContext);
for (const auto &Base : RD->bases())
if (Ty && Context.hasSameUnqualifiedType(QualType(Ty, 1), Base.getType()))
return true;
return S->isFunctionPrototypeScope();
return CurContext->isFunctionOrMethod() || S->isFunctionPrototypeScope();
void Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
SourceLocation IILoc,
Scope *S,
CXXScopeSpec *SS,
ParsedType &SuggestedType,
bool IsTemplateName) {
// Don't report typename errors for editor placeholders.
if (II->isEditorPlaceholder())
// We don't have anything to suggest (yet).
SuggestedType = nullptr;
// There may have been a typo in the name of the type. Look up typo
// results, in case we have something that we can suggest.
if (TypoCorrection Corrected =
CorrectTypo(DeclarationNameInfo(II, IILoc), LookupOrdinaryName, S, SS,
false, false, IsTemplateName, !IsTemplateName),
CTK_ErrorRecovery)) {
// FIXME: Support error recovery for the template-name case.
bool CanRecover = !IsTemplateName;
if (Corrected.isKeyword()) {
// We corrected to a keyword.
PDiag(IsTemplateName ? diag::err_no_template_suggest
: diag::err_unknown_typename_suggest)
<< II);
II = Corrected.getCorrectionAsIdentifierInfo();
} else {
// We found a similarly-named type or interface; suggest that.
if (!SS || !SS->isSet()) {
PDiag(IsTemplateName ? diag::err_no_template_suggest
: diag::err_unknown_typename_suggest)
<< II, CanRecover);
} else if (DeclContext *DC = computeDeclContext(*SS, false)) {
std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
? diag::err_no_member_template_suggest
: diag::err_unknown_nested_typename_suggest)
<< II << DC << DroppedSpecifier << SS->getRange(),
} else {
llvm_unreachable("could not have corrected a typo here");
if (!CanRecover)
CXXScopeSpec tmpSS;
if (Corrected.getCorrectionSpecifier())
tmpSS.MakeTrivial(Context, Corrected.getCorrectionSpecifier(),
// FIXME: Support class template argument deduction here.
SuggestedType =
getTypeName(*Corrected.getCorrectionAsIdentifierInfo(), IILoc, S,
tmpSS.isSet() ? &tmpSS : SS, false, false, nullptr,
if (getLangOpts().CPlusPlus && !IsTemplateName) {
// See if II is a class template that the user forgot to pass arguments to.
UnqualifiedId Name;
Name.setIdentifier(II, IILoc);
CXXScopeSpec EmptySS;
TemplateTy TemplateResult;
bool MemberOfUnknownSpecialization;
if (isTemplateName(S, SS ? *SS : EmptySS, /*hasTemplateKeyword=*/false,
Name, nullptr, true, TemplateResult,
MemberOfUnknownSpecialization) == TNK_Type_template) {
TemplateName TplName = TemplateResult.get();
Diag(IILoc, diag::err_template_missing_args)
<< (int)getTemplateNameKindForDiagnostics(TplName) << TplName;
if (TemplateDecl *TplDecl = TplName.getAsTemplateDecl()) {
Diag(TplDecl->getLocation(), diag::note_template_decl_here)
<< TplDecl->getTemplateParameters()->getSourceRange();
// FIXME: Should we move the logic that tries to recover from a missing tag
// (struct, union, enum) from Parser::ParseImplicitInt here, instead?
if (!SS || (!SS->isSet() && !SS->isInvalid()))
Diag(IILoc, IsTemplateName ? diag::err_no_template
: diag::err_unknown_typename)
<< II;
else if (DeclContext *DC = computeDeclContext(*SS, false))
Diag(IILoc, IsTemplateName ? diag::err_no_member_template
: diag::err_typename_nested_not_found)
<< II << DC << SS->getRange();
else if (isDependentScopeSpecifier(*SS)) {
unsigned DiagID = diag::err_typename_missing;
if (getLangOpts().MSVCCompat && isMicrosoftMissingTypename(SS, S))
DiagID = diag::ext_typename_missing;
Diag(SS->getRange().getBegin(), DiagID)
<< SS->getScopeRep() << II->getName()
<< SourceRange(SS->getRange().getBegin(), IILoc)
<< FixItHint::CreateInsertion(SS->getRange().getBegin(), "typename ");
SuggestedType = ActOnTypenameType(S, SourceLocation(),
*SS, *II, IILoc).get();
} else {
assert(SS && SS->isInvalid() &&
"Invalid scope specifier has already been diagnosed");
/// \brief Determine whether the given result set contains either a type name
/// or
static bool isResultTypeOrTemplate(LookupResult &R, const Token &NextToken) {
bool CheckTemplate = R.getSema().getLangOpts().CPlusPlus &&;
for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I) {
if (isa<TypeDecl>(*I) || isa<ObjCInterfaceDecl>(*I))
return true;
if (CheckTemplate && isa<TemplateDecl>(*I))
return true;
return false;
static bool isTagTypeWithMissingTag(Sema &SemaRef, LookupResult &Result,
Scope *S, CXXScopeSpec &SS,
IdentifierInfo *&Name,
SourceLocation NameLoc) {
LookupResult R(SemaRef, Name, NameLoc, Sema::LookupTagName);
SemaRef.LookupParsedName(R, S, &SS);
if (TagDecl *Tag = R.getAsSingle<TagDecl>()) {
StringRef FixItTagName;
switch (Tag->getTagKind()) {
case TTK_Class:
FixItTagName = "class ";
case TTK_Enum:
FixItTagName = "enum ";
case TTK_Struct:
FixItTagName = "struct ";
case TTK_Interface:
FixItTagName = "__interface ";
case TTK_Union:
FixItTagName = "union ";
StringRef TagName = FixItTagName.drop_back();
SemaRef.Diag(NameLoc, diag::err_use_of_tag_name_without_tag)
<< Name << TagName << SemaRef.getLangOpts().CPlusPlus
<< FixItHint::CreateInsertion(NameLoc, FixItTagName);
for (LookupResult::iterator I = Result.begin(), IEnd = Result.end();
I != IEnd; ++I)
SemaRef.Diag((*I)->getLocation(), diag::note_decl_hiding_tag_type)
<< Name << TagName;
// Replace lookup results with just the tag decl.
SemaRef.LookupParsedName(Result, S, &SS);
return true;
return false;
/// Build a ParsedType for a simple-type-specifier with a nested-name-specifier.
static ParsedType buildNestedType(Sema &S, CXXScopeSpec &SS,
QualType T, SourceLocation NameLoc) {
ASTContext &Context = S.Context;
TypeLocBuilder Builder;
T = S.getElaboratedType(ETK_None, SS, T);
ElaboratedTypeLoc ElabTL = Builder.push<ElaboratedTypeLoc>(T);
return S.CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
Sema::ClassifyName(Scope *S, CXXScopeSpec &SS, IdentifierInfo *&Name,
SourceLocation NameLoc, const Token &NextToken,
bool IsAddressOfOperand,
std::unique_ptr<CorrectionCandidateCallback> CCC) {
DeclarationNameInfo NameInfo(Name, NameLoc);
ObjCMethodDecl *CurMethod = getCurMethodDecl();
if ( {
NestedNameSpecInfo IdInfo(Name, NameLoc, NextToken.getLocation());
BuildCXXNestedNameSpecifier(S, IdInfo, false, SS, nullptr, false);
} else if (getLangOpts().CPlusPlus && SS.isSet() &&
isCurrentClassName(*Name, S, &SS)) {
// Per [class.qual]p2, this names the constructors of SS, not the
// injected-class-name. We don't have a classification for that.
// There's not much point caching this result, since the parser
// will reject it later.
return NameClassification::Unknown();
LookupResult Result(*this, Name, NameLoc, LookupOrdinaryName);
LookupParsedName(Result, S, &SS, !CurMethod);
// For unqualified lookup in a class template in MSVC mode, look into
// dependent base classes where the primary class template is known.
if (Result.empty() && SS.isEmpty() && getLangOpts().MSVCCompat) {
if (ParsedType TypeInBase =
recoverFromTypeInKnownDependentBase(*this, *Name, NameLoc))
return TypeInBase;
// Perform lookup for Objective-C instance variables (including automatically
// synthesized instance variables), if we're in an Objective-C method.
// FIXME: This lookup really, really needs to be folded in to the normal
// unqualified lookup mechanism.
if (!SS.isSet() && CurMethod && !isResultTypeOrTemplate(Result, NextToken)) {
ExprResult E = LookupInObjCMethod(Result, S, Name, true);
if (E.get() || E.isInvalid())
return E;
bool SecondTry = false;
bool IsFilteredTemplateName = false;
switch (Result.getResultKind()) {
case LookupResult::NotFound:
// If an unqualified-id is followed by a '(', then we have a function
// call.
if (!SS.isSet() && {
// In C++, this is an ADL-only call.
// FIXME: Reference?
if (getLangOpts().CPlusPlus)
return BuildDeclarationNameExpr(SS, Result, /*ADL=*/true);
// C90
// If the expression that precedes the parenthesized argument list in a
// function call consists solely of an identifier, and if no
// declaration is visible for this identifier, the identifier is
// implicitly declared exactly as if, in the innermost block containing
// the function call, the declaration
// extern int identifier ();
// appeared.
// We also allow this in C99 as an extension.
if (NamedDecl *D = ImplicitlyDefineFunction(NameLoc, *Name, S)) {
return BuildDeclarationNameExpr(SS, Result, /*ADL=*/false);
// In C, we first see whether there is a tag type by the same name, in
// which case it's likely that the user just forgot to write "enum",
// "struct", or "union".
if (!getLangOpts().CPlusPlus && !SecondTry &&
isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
// Perform typo correction to determine if there is another name that is
// close to this name.
if (!SecondTry && CCC) {
SecondTry = true;
if (TypoCorrection Corrected = CorrectTypo(Result.getLookupNameInfo(),
Result.getLookupKind(), S,
&SS, std::move(CCC),
CTK_ErrorRecovery)) {
unsigned UnqualifiedDiag = diag::err_undeclared_var_use_suggest;
unsigned QualifiedDiag = diag::err_no_member_suggest;
NamedDecl *FirstDecl = Corrected.getFoundDecl();
NamedDecl *UnderlyingFirstDecl = Corrected.getCorrectionDecl();
if (getLangOpts().CPlusPlus && &&
UnderlyingFirstDecl && isa<TemplateDecl>(UnderlyingFirstDecl)) {
UnqualifiedDiag = diag::err_no_template_suggest;
QualifiedDiag = diag::err_no_member_template_suggest;
} else if (UnderlyingFirstDecl &&
(isa<TypeDecl>(UnderlyingFirstDecl) ||
isa<ObjCInterfaceDecl>(UnderlyingFirstDecl) ||
isa<ObjCCompatibleAliasDecl>(UnderlyingFirstDecl))) {
UnqualifiedDiag = diag::err_unknown_typename_suggest;
QualifiedDiag = diag::err_unknown_nested_typename_suggest;
if (SS.isEmpty()) {
diagnoseTypo(Corrected, PDiag(UnqualifiedDiag) << Name);
} else {// FIXME: is this even reachable? Test it.
std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
diagnoseTypo(Corrected, PDiag(QualifiedDiag)
<< Name << computeDeclContext(SS, false)
<< DroppedSpecifier << SS.getRange());
// Update the name, so that the caller has the new name.
Name = Corrected.getCorrectionAsIdentifierInfo();
// Typo correction corrected to a keyword.
if (Corrected.isKeyword())
return Name;
// Also update the LookupResult...
// FIXME: This should probably go away at some point
if (FirstDecl)
// If we found an Objective-C instance variable, let
// LookupInObjCMethod build the appropriate expression to
// reference the ivar.
// FIXME: This is a gross hack.
if (ObjCIvarDecl *Ivar = Result.getAsSingle<ObjCIvarDecl>()) {
ExprResult E(LookupInObjCMethod(Result, S, Ivar->getIdentifier()));
return E;
goto Corrected;
// We failed to correct; just fall through and let the parser deal with it.
return NameClassification::Unknown();
case LookupResult::NotFoundInCurrentInstantiation: {
// We performed name lookup into the current instantiation, and there were
// dependent bases, so we treat this result the same way as any other
// dependent nested-name-specifier.
// C++ [temp.res]p2:
// A name used in a template declaration or definition and that is
// dependent on a template-parameter is assumed not to name a type
// unless the applicable name lookup finds a type name or the name is
// qualified by the keyword typename.
// FIXME: If the next token is '<', we might want to ask the parser to
// perform some heroics to see if we actually have a
// template-argument-list, which would indicate a missing 'template'
// keyword here.
return ActOnDependentIdExpression(SS, /*TemplateKWLoc=*/SourceLocation(),
NameInfo, IsAddressOfOperand,
case LookupResult::Found:
case LookupResult::FoundOverloaded:
case LookupResult::FoundUnresolvedValue:
case LookupResult::Ambiguous:
if (getLangOpts().CPlusPlus && &&
hasAnyAcceptableTemplateNames(Result)) {
// C++ [temp.local]p3:
// A lookup that finds an injected-class-name (10.2) can result in an
// ambiguity in certain cases (for example, if it is found in more than
// one base class). If all of the injected-class-names that are found
// refer to specializations of the same class template, and if the name
// is followed by a template-argument-list, the reference refers to the
// class template itself and not a specialization thereof, and is not
// ambiguous.
// This filtering can make an ambiguous result into an unambiguous one,
// so try again after filtering out template names.
if (!Result.isAmbiguous()) {
IsFilteredTemplateName = true;
// Diagnose the ambiguity and return an error.
return NameClassification::Error();
if (getLangOpts().CPlusPlus && &&
(IsFilteredTemplateName || hasAnyAcceptableTemplateNames(Result))) {
// C++ [temp.names]p3:
// After name lookup (3.4) finds that a name is a template-name or that
// an operator-function-id or a literal- operator-id refers to a set of
// overloaded functions any member of which is a function template if
// this is followed by a <, the < is always taken as the delimiter of a
// template-argument-list and never as the less-than operator.
if (!IsFilteredTemplateName)
if (!Result.empty()) {
bool IsFunctionTemplate;
bool IsVarTemplate;
TemplateName Template;
if (Result.end() - Result.begin() > 1) {
IsFunctionTemplate = true;
Template = Context.getOverloadedTemplateName(Result.begin(),
} else {
TemplateDecl *TD
= cast<TemplateDecl>((*Result.begin())->getUnderlyingDecl());
IsFunctionTemplate = isa<FunctionTemplateDecl>(TD);
IsVarTemplate = isa<VarTemplateDecl>(TD);
if (SS.isSet() && !SS.isInvalid())
Template = Context.getQualifiedTemplateName(SS.getScopeRep(),
Template = TemplateName(TD);
if (IsFunctionTemplate) {
// Function templates always go through overload resolution, at which
// point we'll perform the various checks (e.g., accessibility) we need
// to based on which function we selected.
return NameClassification::FunctionTemplate(Template);
return IsVarTemplate ? NameClassification::VarTemplate(Template)
: NameClassification::TypeTemplate(Template);
NamedDecl *FirstDecl = (*Result.begin())->getUnderlyingDecl();
if (TypeDecl *Type = dyn_cast<TypeDecl>(FirstDecl)) {
DiagnoseUseOfDecl(Type, NameLoc);
MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
QualType T = Context.getTypeDeclType(Type);
if (SS.isNotEmpty())
return buildNestedType(*this, SS, T, NameLoc);
return ParsedType::make(T);
ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(FirstDecl);
if (!Class) {
// FIXME: It's unfortunate that we don't have a Type node for handling this.
if (ObjCCompatibleAliasDecl *Alias =
Class = Alias->getClassInterface();
if (Class) {
DiagnoseUseOfDecl(Class, NameLoc);
if ( {
// Interface. <something> is parsed as a property reference expression.
// Just return "unknown" as a fall-through for now.
return NameClassification::Unknown();
QualType T = Context.getObjCInterfaceType(Class);
return ParsedType::make(T);
// We can have a type template here if we're classifying a template argument.
if (isa<TemplateDecl>(FirstDecl) && !isa<FunctionTemplateDecl>(FirstDecl) &&
return NameClassification::TypeTemplate(
// Check for a tag type hidden by a non-type decl in a few cases where it
// seems likely a type is wanted instead of the non-type that was found.
bool NextIsOp = NextToken.isOneOf(tok::amp, tok::star);
if (( ||
(NextIsOp &&
FirstDecl->getUnderlyingDecl()->isFunctionOrFunctionTemplate())) &&
isTagTypeWithMissingTag(*this, Result, S, SS, Name, NameLoc)) {
TypeDecl *Type = Result.getAsSingle<TypeDecl>();
DiagnoseUseOfDecl(Type, NameLoc);
QualType T = Context.getTypeDeclType(Type);
if (SS.isNotEmpty())
return buildNestedType(*this, SS, T, NameLoc);
return ParsedType::make(T);
if (FirstDecl->isCXXClassMember())
return BuildPossibleImplicitMemberExpr(SS, SourceLocation(), Result,
nullptr, S);
bool ADL = UseArgumentDependentLookup(SS, Result,;
return BuildDeclarationNameExpr(SS, Result, ADL);
Sema::getTemplateNameKindForDiagnostics(TemplateName Name) {
auto *TD = Name.getAsTemplateDecl();
if (!TD)
return TemplateNameKindForDiagnostics::DependentTemplate;
if (isa<ClassTemplateDecl>(TD))
return TemplateNameKindForDiagnostics::ClassTemplate;
if (isa<FunctionTemplateDecl>(TD))
return TemplateNameKindForDiagnostics::FunctionTemplate;
if (isa<VarTemplateDecl>(TD))
return TemplateNameKindForDiagnostics::VarTemplate;
if (isa<TypeAliasTemplateDecl>(TD))
return TemplateNameKindForDiagnostics::AliasTemplate;
if (isa<TemplateTemplateParmDecl>(TD))
return TemplateNameKindForDiagnostics::TemplateTemplateParam;
return TemplateNameKindForDiagnostics::DependentTemplate;
// Determines the context to return to after temporarily entering a
// context. This depends in an unnecessarily complicated way on the
// exact ordering of callbacks from the parser.
DeclContext *Sema::getContainingDC(DeclContext *DC) {
// Functions defined inline within classes aren't parsed until we've
// finished parsing the top-level class, so the top-level class is
// the context we'll need to return to.
// A Lambda call operator whose parent is a class must not be treated
// as an inline member function. A Lambda can be used legally
// either as an in-class member initializer or a default argument. These
// are parsed once the class has been marked complete and so the containing
// context would be the nested class (when the lambda is defined in one);
// If the class is not complete, then the lambda is being used in an
// ill-formed fashion (such as to specify the width of a bit-field, or
// in an array-bound) - in which case we still want to return the
// lexically containing DC (which could be a nested class).
if (isa<FunctionDecl>(DC) && !isLambdaCallOperator(DC)) {
DC = DC->getLexicalParent();
// A function not defined within a class will always return to its
// lexical context.
if (!isa<CXXRecordDecl>(DC))
return DC;
// A C++ inline method/friend is parsed *after* the topmost class
// it was declared in is fully parsed ("complete"); the topmost
// class is the context we need to return to.
while (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(DC->getLexicalParent()))
DC = RD;
// Return the declaration context of the topmost class the inline method is
// declared in.
return DC;
return DC->getLexicalParent();
void Sema::PushDeclContext(Scope *S, DeclContext *DC) {
assert(getContainingDC(DC) == CurContext &&
"The next DeclContext should be lexically contained in the current one.");
CurContext = DC;
void Sema::PopDeclContext() {
assert(CurContext && "DeclContext imbalance!");
CurContext = getContainingDC(CurContext);
assert(CurContext && "Popped translation unit!");
Sema::SkippedDefinitionContext Sema::ActOnTagStartSkippedDefinition(Scope *S,
Decl *D) {
// Unlike PushDeclContext, the context to which we return is not necessarily
// the containing DC of TD, because the new context will be some pre-existing
// TagDecl definition instead of a fresh one.
auto Result = static_cast<SkippedDefinitionContext>(CurContext);
CurContext = cast<TagDecl>(D)->getDefinition();
assert(CurContext && "skipping definition of undefined tag");
// Start lookups from the parent of the current context; we don't want to look
// into the pre-existing complete definition.
return Result;
void Sema::ActOnTagFinishSkippedDefinition(SkippedDefinitionContext Context) {
CurContext = static_cast<decltype(CurContext)>(Context);
/// EnterDeclaratorContext - Used when we must lookup names in the context
/// of a declarator's nested name specifier.
void Sema::EnterDeclaratorContext(Scope *S, DeclContext *DC) {
// C++0x [basic.lookup.unqual]p13:
// A name used in the definition of a static data member of class
// X (after the qualified-id of the static member) is looked up as
// if the name was used in a member function of X.
// C++0x [basic.lookup.unqual]p14:
// If a variable member of a namespace is defined outside of the
// scope of its namespace then any name used in the definition of
// the variable member (after the declarator-id) is looked up as
// if the definition of the variable member occurred in its
// namespace.
// Both of these imply that we should push a scope whose context
// is the semantic context of the declaration. We can't use
// PushDeclContext here because that context is not necessarily
// lexically contained in the current context. Fortunately,
// the containing scope should have the appropriate information.
assert(!S->getEntity() && "scope already has entity");
#ifndef NDEBUG
Scope *Ancestor = S->getParent();
while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
assert(Ancestor->getEntity() == CurContext && "ancestor context mismatch");
CurContext = DC;
void Sema::ExitDeclaratorContext(Scope *S) {
assert(S->getEntity() == CurContext && "Context imbalance!");
// Switch back to the lexical context. The safety of this is
// enforced by an assert in EnterDeclaratorContext.
Scope *Ancestor = S->getParent();
while (!Ancestor->getEntity()) Ancestor = Ancestor->getParent();
CurContext = Ancestor->getEntity();
// We don't need to do anything with the scope, which is going to
// disappear.
void Sema::ActOnReenterFunctionContext(Scope* S, Decl *D) {
// We assume that the caller has already called
// ActOnReenterTemplateScope so getTemplatedDecl() works.
FunctionDecl *FD = D->getAsFunction();
if (!FD)
// Same implementation as PushDeclContext, but enters the context
// from the lexical parent, rather than the top-level class.
assert(CurContext == FD->getLexicalParent() &&
"The next DeclContext should be lexically contained in the current one.");
CurContext = FD;
for (unsigned P = 0, NumParams = FD->getNumParams(); P < NumParams; ++P) {
ParmVarDecl *Param = FD->getParamDecl(P);
// If the parameter has an identifier, then add it to the scope
if (Param->getIdentifier()) {
void Sema::ActOnExitFunctionContext() {
// Same implementation as PopDeclContext, but returns to the lexical parent,
// rather than the top-level class.
assert(CurContext && "DeclContext imbalance!");
CurContext = CurContext->getLexicalParent();
assert(CurContext && "Popped translation unit!");
/// \brief Determine whether we allow overloading of the function
/// PrevDecl with another declaration.
/// This routine determines whether overloading is possible, not
/// whether some new function is actually an overload. It will return
/// true in C++ (where we can always provide overloads) or, as an
/// extension, in C when the previous function is already an
/// overloaded function declaration or has the "overloadable"
/// attribute.
static bool AllowOverloadingOfFunction(LookupResult &Previous,
ASTContext &Context,
const FunctionDecl *New) {
if (Context.getLangOpts().CPlusPlus)
return true;
if (Previous.getResultKind() == LookupResult::FoundOverloaded)
return true;
return Previous.getResultKind() == LookupResult::Found &&
(Previous.getFoundDecl()->hasAttr<OverloadableAttr>() ||
/// Add this decl to the scope shadowed decl chains.
void Sema::PushOnScopeChains(NamedDecl *D, Scope *S, bool AddToContext) {
// Move up the scope chain until we find the nearest enclosing
// non-transparent context. The declaration will be introduced into this
// scope.
while (S->getEntity() && S->getEntity()->isTransparentContext())
S = S->getParent();
// Add scoped declarations into their context, so that they can be
// found later. Declarations without a context won't be inserted
// into any context.
if (AddToContext)
// Out-of-line definitions shouldn't be pushed into scope in C++, unless they
// are function-local declarations.
if (getLangOpts().CPlusPlus && D->isOutOfLine() &&
D->getLexicalDeclContext()->getRedeclContext()) &&
// Template instantiations should also not be pushed into scope.
if (isa<FunctionDecl>(D) &&
// If this replaces anything in the current scope,
IdentifierResolver::iterator I = IdResolver.begin(D->getDeclName()),
IEnd = IdResolver.end();
for (; I != IEnd; ++I) {
if (S->isDeclScope(*I) && D->declarationReplaces(*I)) {
// Should only need to replace one decl.
if (isa<LabelDecl>(D) && !cast<LabelDecl>(D)->isGnuLocal()) {
// Implicitly-generated labels may end up getting generated in an order that
// isn't strictly lexical, which breaks name lookup. Be careful to insert
// the label at the appropriate place in the identifier chain.
for (I = IdResolver.begin(D->getDeclName()); I != IEnd; ++I) {
DeclContext *IDC = (*I)->getLexicalDeclContext()->getRedeclContext();
if (IDC == CurContext) {
if (!S->isDeclScope(*I))
} else if (IDC->Encloses(CurContext))
IdResolver.InsertDeclAfter(I, D);
} else {
void Sema::pushExternalDeclIntoScope(NamedDecl *D, DeclarationName Name) {
if (IdResolver.tryAddTopLevelDecl(D, Name) && TUScope)
bool Sema::isDeclInScope(NamedDecl *D, DeclContext *Ctx, Scope *S,
bool AllowInlineNamespace) {
return IdResolver.isDeclInScope(D, Ctx, S, AllowInlineNamespace);
Scope *Sema::getScopeForDeclContext(Scope *S, DeclContext *DC) {
DeclContext *TargetDC = DC->getPrimaryContext();
do {
if (DeclContext *ScopeDC = S->getEntity())
if (ScopeDC->getPrimaryContext() == TargetDC)
return S;
} while ((S = S->getParent()));
return nullptr;
static bool isOutOfScopePreviousDeclaration(NamedDecl *,
/// Filters out lookup results that don't fall within the given scope
/// as determined by isDeclInScope.
void Sema::FilterLookupForScope(LookupResult &R, DeclContext *Ctx, Scope *S,
bool ConsiderLinkage,
bool AllowInlineNamespace) {
LookupResult::Filter F = R.makeFilter();
while (F.hasNext()) {
NamedDecl *D =;
if (isDeclInScope(D, Ctx, S, AllowInlineNamespace))
if (ConsiderLinkage && isOutOfScopePreviousDeclaration(D, Ctx, Context))
static bool isUsingDecl(NamedDecl *D) {
return isa<UsingShadowDecl>(D) ||
isa<UnresolvedUsingTypenameDecl>(D) ||
/// Removes using shadow declarations from the lookup results.
static void RemoveUsingDecls(LookupResult &R) {
LookupResult::Filter F = R.makeFilter();
while (F.hasNext())
if (isUsingDecl(
/// \brief Check for this common pattern:
/// @code
/// class S {
/// S(const S&); // DO NOT IMPLEMENT
/// void operator=(const S&); // DO NOT IMPLEMENT
/// };
/// @endcode
static bool IsDisallowedCopyOrAssign(const CXXMethodDecl *D) {
// FIXME: Should check for private access too but access is set after we get
// the decl here.
if (D->doesThisDeclarationHaveABody())
return false;
if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(D))
return CD->isCopyConstructor();
if (const CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D))
return Method->isCopyAssignmentOperator();
return false;
// We need this to handle
// typedef struct {
// void *foo() { return 0; }
// } A;
// When we see foo we don't know if after the typedef we will get 'A' or '*A'
// for example. If 'A', foo will have external linkage. If we have '*A',
// foo will have no linkage. Since we can't know until we get to the end
// of the typedef, this function finds out if D might have non-external linkage.
// Callers should verify at the end of the TU if it D has external linkage or
// not.
bool Sema::mightHaveNonExternalLinkage(const DeclaratorDecl *D) {
const DeclContext *DC = D->getDeclContext();
while (!DC->isTranslationUnit()) {
if (const RecordDecl *RD = dyn_cast<RecordDecl>(DC)){
if (!RD->hasNameForLinkage())
return true;
DC = DC->getParent();
return !D->isExternallyVisible();
// FIXME: This needs to be refactored; some other isInMainFile users want
// these semantics.
static bool isMainFileLoc(const Sema &S, SourceLocation Loc) {
if (S.TUKind != TU_Complete)
return false;
return S.SourceMgr.isInMainFile(Loc);
bool Sema::ShouldWarnIfUnusedFileScopedDecl(const DeclaratorDecl *D) const {
if (D->isInvalidDecl() || D->isUsed() || D->hasAttr<UnusedAttr>())
return false;
// Ignore all entities declared within templates, and out-of-line definitions
// of members of class templates.
if (D->getDeclContext()->isDependentContext() ||
return false;
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
if (FD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
return false;
// A non-out-of-line declaration of a member specialization was implicitly
// instantiated; it's the out-of-line declaration that we're interested in.
if (FD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
FD->getMemberSpecializationInfo() && !FD->isOutOfLine())
return false;
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD)) {
if (MD->isVirtual() || IsDisallowedCopyOrAssign(MD))
return false;
} else {
// 'static inline' functions are defined in headers; don't warn.
if (FD->isInlined() && !isMainFileLoc(*this, FD->getLocation()))
return false;
if (FD->doesThisDeclarationHaveABody() &&
return false;
} else if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
// Constants and utility variables are defined in headers with internal
// linkage; don't warn. (Unlike functions, there isn't a convenient marker
// like "inline".)
if (!isMainFileLoc(*this, VD->getLocation()))
return false;
if (Context.DeclMustBeEmitted(VD))
return false;
if (VD->isStaticDataMember() &&
VD->getTemplateSpecializationKind() == TSK_ImplicitInstantiation)
return false;
if (VD->isStaticDataMember() &&
VD->getTemplateSpecializationKind() == TSK_ExplicitSpecialization &&
VD->getMemberSpecializationInfo() && !VD->isOutOfLine())
return false;
if (VD->isInline() && !isMainFileLoc(*this, VD->getLocation()))
return false;
} else {
return false;
// Only warn for unused decls internal to the translation unit.
// FIXME: This seems like a bogus check; it suppresses -Wunused-function
// for inline functions defined in the main source file, for instance.
return mightHaveNonExternalLinkage(D);
void Sema::MarkUnusedFileScopedDecl(const DeclaratorDecl *D) {
if (!D)
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
const FunctionDecl *First = FD->getFirstDecl();
if (FD != First && ShouldWarnIfUnusedFileScopedDecl(First))
return; // First should already be in the vector.
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
const VarDecl *First = VD->getFirstDecl();
if (VD != First && ShouldWarnIfUnusedFileScopedDecl(First))
return; // First should already be in the vector.
if (ShouldWarnIfUnusedFileScopedDecl(D))
static bool ShouldDiagnoseUnusedDecl(const NamedDecl *D) {
if (D->isInvalidDecl())
return false;
if (D->isReferenced() || D->isUsed() || D->hasAttr<UnusedAttr>() ||
return false;
if (isa<LabelDecl>(D))
return true;
// Except for labels, we only care about unused decls that are local to
// functions.
bool WithinFunction = D->getDeclContext()->isFunctionOrMethod();
if (const auto *R = dyn_cast<CXXRecordDecl>(D->getDeclContext()))
// For dependent types, the diagnostic is deferred.
WithinFunction =
WithinFunction || (R->isLocalClass() && !R->isDependentType());
if (!WithinFunction)
return false;
if (isa<TypedefNameDecl>(D))
return true;
// White-list anything that isn't a local variable.
if (!isa<VarDecl>(D) || isa<ParmVarDecl>(D) || isa<ImplicitParamDecl>(D))
return false;
// Types of valid local variables should be complete, so this should succeed.
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
// White-list anything with an __attribute__((unused)) type.
const auto *Ty = VD->getType().getTypePtr();
// Only look at the outermost level of typedef.
if (const TypedefType *TT = Ty->getAs<TypedefType>()) {
if (TT->getDecl()->hasAttr<UnusedAttr>())
return false;
// If we failed to complete the type for some reason, or if the type is
// dependent, don't diagnose the variable.
if (Ty->isIncompleteType() || Ty->isDependentType())
return false;
// Look at the element type to ensure that the warning behaviour is
// consistent for both scalars and arrays.
Ty = Ty->getBaseElementTypeUnsafe();
if (const TagType *TT = Ty->getAs<TagType>()) {
const TagDecl *Tag = TT->getDecl();
if (Tag->hasAttr<UnusedAttr>())
return false;
if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Tag)) {
if (!RD->hasTrivialDestructor() && !RD->hasAttr<WarnUnusedAttr>())
return false;
if (const Expr *Init = VD->getInit()) {
if (const ExprWithCleanups *Cleanups =
Init = Cleanups->getSubExpr();
const CXXConstructExpr *Construct =
if (Construct && !Construct->isElidable()) {
CXXConstructorDecl *CD = Construct->getConstructor();
if (!CD->isTrivial() && !RD->hasAttr<WarnUnusedAttr>())
return false;
// TODO: __attribute__((unused)) templates?
return true;
static void GenerateFixForUnusedDecl(const NamedDecl *D, ASTContext &Ctx,
FixItHint &Hint) {
if (isa<LabelDecl>(D)) {
SourceLocation AfterColon = Lexer::findLocationAfterToken(D->getLocEnd(),
tok::colon, Ctx.getSourceManager(), Ctx.getLangOpts(), true);
if (AfterColon.isInvalid())
Hint = FixItHint::CreateRemoval(CharSourceRange::
getCharRange(D->getLocStart(), AfterColon));
void Sema::DiagnoseUnusedNestedTypedefs(const RecordDecl *D) {
if (D->getTypeForDecl()->isDependentType())
for (auto *TmpD : D->decls()) {
if (const auto *T = dyn_cast<TypedefNameDecl>(TmpD))
else if(const auto *R = dyn_cast<RecordDecl>(TmpD))
/// DiagnoseUnusedDecl - Emit warnings about declarations that are not used
/// unless they are marked attr(unused).
void Sema::DiagnoseUnusedDecl(const NamedDecl *D) {
if (!ShouldDiagnoseUnusedDecl(D))
if (auto *TD = dyn_cast<TypedefNameDecl>(D)) {
// typedefs can be referenced later on, so the diagnostics are emitted
// at end-of-translation-unit.
FixItHint Hint;
GenerateFixForUnusedDecl(D, Context, Hint);
unsigned DiagID;
if (isa<VarDecl>(D) && cast<VarDecl>(D)->isExceptionVariable())
DiagID = diag::warn_unused_exception_param;
else if (isa<LabelDecl>(D))
DiagID = diag::warn_unused_label;
DiagID = diag::warn_unused_variable;
Diag(D->getLocation(), DiagID) << D->getDeclName() << Hint;
static void CheckPoppedLabel(LabelDecl *L, Sema &S) {
// Verify that we have no forward references left. If so, there was a goto
// or address of a label taken, but no definition of it. Label fwd
// definitions are indicated with a null substmt which is also not a resolved
// MS inline assembly label name.
bool Diagnose = false;
if (L->isMSAsmLabel())
Diagnose = !L->isResolvedMSAsmLabel();
Diagnose = L->getStmt() == nullptr;
if (Diagnose)
S.Diag(L->getLocation(), diag::err_undeclared_label_use) <<L->getDeclName();
void Sema::ActOnPopScope(SourceLocation Loc, Scope *S) {
if (S->decl_empty()) return;
assert((S->getFlags() & (Scope::DeclScope | Scope::TemplateParamScope)) &&
"Scope shouldn't contain decls!");
for (auto *TmpD : S->decls()) {
assert(TmpD && "This decl didn't get pushed??");
assert(isa<NamedDecl>(TmpD) && "Decl isn't NamedDecl?");
NamedDecl *D = cast<NamedDecl>(TmpD);
if (!D->getDeclName()) continue;
// Diagnose unused variables in this scope.
if (!S->hasUnrecoverableErrorOccurred()) {
if (const auto *RD = dyn_cast<RecordDecl>(D))
// If this was a forward reference to a label, verify it was defined.
if (LabelDecl *LD = dyn_cast<LabelDecl>(D))
CheckPoppedLabel(LD, *this);
// Remove this name from our lexical scope, and warn on it if we haven't
// already.
auto ShadowI = ShadowingDecls.find(D);
if (ShadowI != ShadowingDecls.end()) {
if (const auto *FD = dyn_cast<FieldDecl>(ShadowI->second)) {
Diag(D->getLocation(), diag::warn_ctor_parm_shadows_field)
<< D << FD << FD->getParent();
Diag(FD->getLocation(), diag::note_previous_declaration);
/// \brief Look for an Objective-C class in the translation unit.
/// \param Id The name of the Objective-C class we're looking for. If
/// typo-correction fixes this name, the Id will be updated
/// to the fixed name.
/// \param IdLoc The location of the name in the translation unit.
/// \param DoTypoCorrection If true, this routine will attempt typo correction
/// if there is no class with the given name.
/// \returns The declaration of the named Objective-C class, or NULL if the
/// class could not be found.
ObjCInterfaceDecl *Sema::getObjCInterfaceDecl(IdentifierInfo *&Id,
SourceLocation IdLoc,
bool DoTypoCorrection) {
// The third "scope" argument is 0 since we aren't enabling lazy built-in
// creation from this context.
NamedDecl *IDecl = LookupSingleName(TUScope, Id, IdLoc, LookupOrdinaryName);
if (!IDecl && DoTypoCorrection) {
// Perform typo correction at the given location, but only if we
// find an Objective-C class name.
if (TypoCorrection C = CorrectTypo(
DeclarationNameInfo(Id, IdLoc), LookupOrdinaryName, TUScope, nullptr,
CTK_ErrorRecovery)) {
diagnoseTypo(C, PDiag(diag::err_undef_interface_suggest) << Id);
IDecl = C.getCorrectionDeclAs<ObjCInterfaceDecl>();
Id = IDecl->getIdentifier();
ObjCInterfaceDecl *Def = dyn_cast_or_null<ObjCInterfaceDecl>(IDecl);
// This routine must always return a class definition, if any.
if (Def && Def->getDefinition())
Def = Def->getDefinition();
return Def;
/// getNonFieldDeclScope - Retrieves the innermost scope, starting
/// from S, where a non-field would be declared. This routine copes
/// with the difference between C and C++ scoping rules in structs and
/// unions. For example, the following code is well-formed in C but
/// ill-formed in C++:
/// @code
/// struct S6 {
/// enum { BAR } e;
/// };
/// void test_S6() {
/// struct S6 a;
/// a.e = BAR;
/// }
/// @endcode
/// For the declaration of BAR, this routine will return a different
/// scope. The scope S will be the scope of the unnamed enumeration
/// within S6. In C++, this routine will return the scope associated
/// with S6, because the enumeration's scope is a transparent
/// context but structures can contain non-field names. In C, this
/// routine will return the translation unit scope, since the
/// enumeration's scope is a transparent context and structures cannot
/// contain non-field names.
Scope *Sema::getNonFieldDeclScope(Scope *S) {
while (((S->getFlags() & Scope::DeclScope) == 0) ||
(S->getEntity() && S->getEntity()->isTransparentContext()) ||
(S->isClassScope() && !getLangOpts().CPlusPlus))
S = S->getParent();
return S;
/// \brief Looks up the declaration of "struct objc_super" and
/// saves it for later use in building builtin declaration of
/// objc_msgSendSuper and objc_msgSendSuper_stret. If no such
/// pre-existing declaration exists no action takes place.
static void LookupPredefedObjCSuperType(Sema &ThisSema, Scope *S,
IdentifierInfo *II) {
if (!II->isStr("objc_msgSendSuper"))
ASTContext &Context = ThisSema.Context;
LookupResult Result(ThisSema, &Context.Idents.get("objc_super"),
SourceLocation(), Sema::LookupTagName);
ThisSema.LookupName(Result, S);
if (Result.getResultKind() == LookupResult::Found)
if (const TagDecl *TD = Result.getAsSingle<TagDecl>())
static StringRef getHeaderName(ASTContext::GetBuiltinTypeError Error) {
switch (Error) {
case ASTContext::GE_None:
return "";
case ASTContext::GE_Missing_stdio:
return "stdio.h";
case ASTContext::GE_Missing_setjmp:
return "setjmp.h";
case ASTContext::GE_Missing_ucontext:
return "ucontext.h";
llvm_unreachable("unhandled error kind");
/// LazilyCreateBuiltin - The specified Builtin-ID was first used at
/// file scope. lazily create a decl for it. ForRedeclaration is true
/// if we're creating this built-in in anticipation of redeclaring the
/// built-in.
NamedDecl *Sema::LazilyCreateBuiltin(IdentifierInfo *II, unsigned ID,
Scope *S, bool ForRedeclaration,
SourceLocation Loc) {
LookupPredefedObjCSuperType(*this, S, II);
ASTContext::GetBuiltinTypeError Error;
QualType R = Context.GetBuiltinType(ID, Error);
if (Error) {
if (ForRedeclaration)
Diag(Loc, diag::warn_implicit_decl_requires_sysheader)
<< getHeaderName(Error) << Context.BuiltinInfo.getName(ID);
return nullptr;
if (!ForRedeclaration &&
(Context.BuiltinInfo.isPredefinedLibFunction(ID) ||
Context.BuiltinInfo.isHeaderDependentFunction(ID))) {
Diag(Loc, diag::ext_implicit_lib_function_decl)
<< Context.BuiltinInfo.getName(ID) << R;
if (Context.BuiltinInfo.getHeaderName(ID) &&
!Diags.isIgnored(diag::ext_implicit_lib_function_decl, Loc))
Diag(Loc, diag::note_include_header_or_declare)
<< Context.BuiltinInfo.getHeaderName(ID)
<< Context.BuiltinInfo.getName(ID);
if (R.isNull())
return nullptr;
DeclContext *Parent = Context.getTranslationUnitDecl();
if (getLangOpts().CPlusPlus) {
LinkageSpecDecl *CLinkageDecl =
LinkageSpecDecl::Create(Context, Parent, Loc, Loc,
LinkageSpecDecl::lang_c, false);
Parent = CLinkageDecl;
FunctionDecl *New = FunctionDecl::Create(Context,
Loc, Loc, II, R, /*TInfo=*/nullptr,
// Create Decl objects for each parameter, adding them to the
// FunctionDecl.
if (const FunctionProtoType *FT = dyn_cast<FunctionProtoType>(R)) {
SmallVector<ParmVarDecl*, 16> Params;
for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
ParmVarDecl *parm =
ParmVarDecl::Create(Context, New, SourceLocation(), SourceLocation(),
nullptr, FT->getParamType(i), /*TInfo=*/nullptr,
SC_None, nullptr);
parm->setScopeInfo(0, i);
RegisterLocallyScopedExternCDecl(New, S);
// TUScope is the translation-unit scope to insert this function into.
// FIXME: This is hideous. We need to teach PushOnScopeChains to
// relate Scopes to DeclContexts, and probably eliminate CurContext
// entirely, but we're not there yet.
DeclContext *SavedContext = CurContext;
CurContext = Parent;
PushOnScopeChains(New, TUScope);
CurContext = SavedContext;
return New;
/// Typedef declarations don't have linkage, but they still denote the same
/// entity if their types are the same.
/// FIXME: This is notionally doing the same thing as ASTReaderDecl's
/// isSameEntity.
static void filterNonConflictingPreviousTypedefDecls(Sema &S,
TypedefNameDecl *Decl,
LookupResult &Previous) {
// This is only interesting when modules are enabled.
if (!S.getLangOpts().Modules && !S.getLangOpts().ModulesLocalVisibility)
// Empty sets are uninteresting.
if (Previous.empty())
LookupResult::Filter Filter = Previous.makeFilter();
while (Filter.hasNext()) {
NamedDecl *Old =;
// Non-hidden declarations are never ignored.
if (S.isVisible(Old))
// Declarations of the same entity are not ignored, even if they have
// different linkages.
if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
if (S.Context.hasSameType(OldTD->getUnderlyingType(),
// If both declarations give a tag declaration a typedef name for linkage
// purposes, then they declare the same entity.
if (OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true) &&
bool Sema::isIncompatibleTypedef(TypeDecl *Old, TypedefNameDecl *New) {
QualType OldType;
if (TypedefNameDecl *OldTypedef = dyn_cast<TypedefNameDecl>(Old))
OldType = OldTypedef->getUnderlyingType();
OldType = Context.getTypeDeclType(Old);
QualType NewType = New->getUnderlyingType();
if (NewType->isVariablyModifiedType()) {
// Must not redefine a typedef with a variably-modified type.
int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
Diag(New->getLocation(), diag::err_redefinition_variably_modified_typedef)
<< Kind << NewType;
if (Old->getLocation().isValid())
notePreviousDefinition(Old, New->getLocation());
return true;
if (OldType != NewType &&
!OldType->isDependentType() &&
!NewType->isDependentType() &&
!Context.hasSameType(OldType, NewType)) {
int Kind = isa<TypeAliasDecl>(Old) ? 1 : 0;
Diag(New->getLocation(), diag::err_redefinition_different_typedef)
<< Kind << NewType << OldType;
if (Old->getLocation().isValid())
notePreviousDefinition(Old, New->getLocation());
return true;
return false;
/// MergeTypedefNameDecl - We just parsed a typedef 'New' which has the
/// same name and scope as a previous declaration 'Old'. Figure out
/// how to resolve this situation, merging decls or emitting
/// diagnostics as appropriate. If there was an error, set New to be invalid.
void Sema::MergeTypedefNameDecl(Scope *S, TypedefNameDecl *New,
LookupResult &OldDecls) {
// If the new decl is known invalid already, don't bother doing any
// merging checks.
if (New->isInvalidDecl()) return;
// Allow multiple definitions for ObjC built-in typedefs.
// FIXME: Verify the underlying types are equivalent!
if (getLangOpts().ObjC1) {
const IdentifierInfo *TypeID = New->getIdentifier();
switch (TypeID->getLength()) {
default: break;
case 2:
if (!TypeID->isStr("id"))
QualType T = New->getUnderlyingType();
if (!T->isPointerType())
if (!T->isVoidPointerType()) {
QualType PT = T->getAs<PointerType>()->getPointeeType();
if (!PT->isStructureType())
// Install the built-in type for 'id', ignoring the current definition.
case 5:
if (!TypeID->isStr("Class"))
// Install the built-in type for 'Class', ignoring the current definition.
case 3:
if (!TypeID->isStr("SEL"))
// Install the built-in type for 'SEL', ignoring the current definition.
// Fall through - the typedef name was not a builtin type.
// Verify the old decl was also a type.
TypeDecl *Old = OldDecls.getAsSingle<TypeDecl>();
if (!Old) {
Diag(New->getLocation(), diag::err_redefinition_different_kind)
<< New->getDeclName();
NamedDecl *OldD = OldDecls.getRepresentativeDecl();
if (OldD->getLocation().isValid())
notePreviousDefinition(OldD, New->getLocation());
return New->setInvalidDecl();
// If the old declaration is invalid, just give up here.
if (Old->isInvalidDecl())
return New->setInvalidDecl();
if (auto *OldTD = dyn_cast<TypedefNameDecl>(Old)) {
auto *OldTag = OldTD->getAnonDeclWithTypedefName(/*AnyRedecl*/true);
auto *NewTag = New->getAnonDeclWithTypedefName();
NamedDecl *Hidden = nullptr;
if (OldTag && NewTag &&
OldTag->getCanonicalDecl() != NewTag->getCanonicalDecl() &&
!hasVisibleDefinition(OldTag, &Hidden)) {
// There is a definition of this tag, but it is not visible. Use it
// instead of our tag.
if (OldTD->isModed())
// Make the old tag definition visible.
// If this was an unscoped enumeration, yank all of its enumerators
// out of the scope.
if (isa<EnumDecl>(NewTag)) {
Scope *EnumScope = getNonFieldDeclScope(S);
for (auto *D : NewTag->decls()) {
auto *ED = cast<EnumConstantDecl>(D);
// If the typedef types are not identical, reject them in all languages and
// with any extensions enabled.
if (isIncompatibleTypedef(Old, New))
// The types match. Link up the redeclaration chain and merge attributes if
// the old declaration was a typedef.
if (TypedefNameDecl *Typedef = dyn_cast<TypedefNameDecl>(Old)) {
mergeDeclAttributes(New, Old);
if (getLangOpts().MicrosoftExt)
if (getLangOpts().CPlusPlus) {
// C++ [dcl.typedef]p2:
// In a given non-class scope, a typedef specifier can be used to
// redefine the name of any type declared in that scope to refer
// to the type to which it already refers.
if (!isa<CXXRecordDecl>(CurContext))
// C++0x [dcl.typedef]p4:
// In a given class scope, a typedef specifier can be used to redefine
// any class-name declared in that scope that is not also a typedef-name
// to refer to the type to which it already refers.
// This wording came in via DR424, which was a correction to the
// wording in DR56, which accidentally banned code like:
// struct S {
// typedef struct A { } A;
// };
// in the C++03 standard. We implement the C++0x semantics, which
// allow the above but disallow
// struct S {
// typedef int I;
// typedef int I;
// };
// since that was the intent of DR56.
if (!isa<TypedefNameDecl>(Old))
Diag(New->getLocation(), diag::err_redefinition)
<< New->getDeclName();
notePreviousDefinition(Old, New->getLocation());
return New->setInvalidDecl();
// Modules always permit redefinition of typedefs, as does C11.
if (getLangOpts().Modules || getLangOpts().C11)
// If we have a redefinition of a typedef in C, emit a warning. This warning
// is normally mapped to an error, but can be controlled with
// -Wtypedef-redefinition. If either the original or the redefinition is
// in a system header, don't emit this for compatibility with GCC.
if (getDiagnostics().getSuppressSystemWarnings() &&
// Some standard types are defined implicitly in Clang (e.g. OpenCL).
(Old->isImplicit() ||
Context.getSourceManager().isInSystemHeader(Old->getLocation()) ||
Diag(New->getLocation(), diag::ext_redefinition_of_typedef)
<< New->getDeclName();
notePreviousDefinition(Old, New->getLocation());
/// DeclhasAttr - returns true if decl Declaration already has the target
/// attribute.
static bool DeclHasAttr(const Decl *D, const Attr *A) {
const OwnershipAttr *OA = dyn_cast<OwnershipAttr>(A);
const AnnotateAttr *Ann = dyn_cast<AnnotateAttr>(A);
for (const auto *i : D->attrs())
if (i->getKind() == A->getKind()) {
if (Ann) {
if (Ann->getAnnotation() == cast<AnnotateAttr>(i)->getAnnotation())
return true;
// FIXME: Don't hardcode this check
if (OA && isa<OwnershipAttr>(i))
return OA->getOwnKind() == cast<OwnershipAttr>(i)->getOwnKind();
return true;
return false;
static bool isAttributeTargetADefinition(Decl *D) {
if (VarDecl *VD = dyn_cast<VarDecl>(D))
return VD->isThisDeclarationADefinition();
if (TagDecl *TD = dyn_cast<TagDecl>(D))
return TD->isCompleteDefinition() || TD->isBeingDefined();
return true;
/// Merge alignment attributes from \p Old to \p New, taking into account the
/// special semantics of C11's _Alignas specifier and C++11's alignas attribute.
/// \return \c true if any attributes were added to \p New.
static bool mergeAlignedAttrs(Sema &S, NamedDecl *New, Decl *Old) {
// Look for alignas attributes on Old, and pick out whichever attribute
// specifies the strictest alignment requirement.
AlignedAttr *OldAlignasAttr = nullptr;
AlignedAttr *OldStrictestAlignAttr = nullptr;
unsigned OldAlign = 0;
for (auto *I : Old->specific_attrs<AlignedAttr>()) {
// FIXME: We have no way of representing inherited dependent alignments
// in a case like:
// template<int A, int B> struct alignas(A) X;
// template<int A, int B> struct alignas(B) X {};
// For now, we just ignore any alignas attributes which are not on the
// definition in such a case.
if (I->isAlignmentDependent())
return false;
if (I->isAlignas())
OldAlignasAttr = I;
unsigned Align = I->getAlignment(S.Context);
if (Align > OldAlign) {
OldAlign = Align;
OldStrictestAlignAttr = I;
// Look for alignas attributes on New.
AlignedAttr *NewAlignasAttr = nullptr;
unsigned NewAlign = 0;
for (auto *I : New->specific_attrs<AlignedAttr>()) {
if (I->isAlignmentDependent())
return false;
if (I->isAlignas())
NewAlignasAttr = I;
unsigned Align = I->getAlignment(S.Context);
if (Align > NewAlign)
NewAlign = Align;
if (OldAlignasAttr && NewAlignasAttr && OldAlign != NewAlign) {
// Both declarations have 'alignas' attributes. We require them to match.
// C++11 [dcl.align]p6 and C11 6.7.5/7 both come close to saying this, but
// fall short. (If two declarations both have alignas, they must both match
// every definition, and so must match each other if there is a definition.)
// If either declaration only contains 'alignas(0)' specifiers, then it
// specifies the natural alignment for the type.
if (OldAlign == 0 || NewAlign == 0) {
QualType Ty;
if (ValueDecl *VD = dyn_cast<ValueDecl>(New))
Ty = VD->getType();
Ty = S.Context.getTagDeclType(cast<TagDecl>(New));
if (OldAlign == 0)
OldAlign = S.Context.getTypeAlign(Ty);
if (NewAlign == 0)
NewAlign = S.Context.getTypeAlign(Ty);
if (OldAlign != NewAlign) {
S.Diag(NewAlignasAttr->getLocation(), diag::err_alignas_mismatch)
<< (unsigned)S.Context.toCharUnitsFromBits(OldAlign).getQuantity()
<< (unsigned)S.Context.toCharUnitsFromBits(NewAlign).getQuantity();
S.Diag(OldAlignasAttr->getLocation(), diag::note_previous_declaration);
if (OldAlignasAttr && !NewAlignasAttr && isAttributeTargetADefinition(New)) {
// C++11 [dcl.align]p6:
// if any declaration of an entity has an alignment-specifier,
// every defining declaration of that entity shall specify an
// equivalent alignment.
// C11 6.7.5/7:
// If the definition of an object does not have an alignment
// specifier, any other declaration of that object shall also
// have no alignment specifier.
S.Diag(New->getLocation(), diag::err_alignas_missing_on_definition)
<< OldAlignasAttr;
S.Diag(OldAlignasAttr->getLocation(), diag::note_alignas_on_declaration)
<< OldAlignasAttr;
bool AnyAdded = false;
// Ensure we have an attribute representing the strictest alignment.
if (OldAlign > NewAlign) {
AlignedAttr *Clone = OldStrictestAlignAttr->clone(S.Context);
AnyAdded = true;
// Ensure we have an alignas attribute if the old declaration had one.
if (OldAlignasAttr && !NewAlignasAttr &&
!(AnyAdded && OldStrictestAlignAttr->isAlignas())) {
AlignedAttr *Clone = OldAlignasAttr->clone(S.Context);
AnyAdded = true;
return AnyAdded;
static bool mergeDeclAttribute(Sema &S, NamedDecl *D,
const InheritableAttr *Attr,
Sema::AvailabilityMergeKind AMK) {
// This function copies an attribute Attr from a previous declaration to the
// new declaration D if the new declaration doesn't itself have that attribute
// yet or if that attribute allows duplicates.
// If you're adding a new attribute that requires logic different from
// "use explicit attribute on decl if present, else use attribute from
// previous decl", for example if the attribute needs to be consistent
// between redeclarations, you need to call a custom merge function here.
InheritableAttr *NewAttr = nullptr;
unsigned AttrSpellingListIndex = Attr->getSpellingListIndex();
if (const auto *AA = dyn_cast<AvailabilityAttr>(Attr))
NewAttr = S.mergeAvailabilityAttr(D, AA->getRange(), AA->getPlatform(),
AA->isImplicit(), AA->getIntroduced(),
AA->getObsoleted(), AA->getUnavailable(),
AA->getMessage(), AA->getStrict(),
AA->getReplacement(), AMK,
else if (const auto *VA = dyn_cast<VisibilityAttr>(Attr))
NewAttr = S.mergeVisibilityAttr(D, VA->getRange(), VA->getVisibility(),
else if (const auto *VA = dyn_cast<TypeVisibilityAttr>(Attr))
NewAttr = S.mergeTypeVisibilityAttr(D, VA->getRange(), VA->getVisibility(),
else if (const auto *ImportA = dyn_cast<DLLImportAttr>(Attr))
NewAttr = S.mergeDLLImportAttr(D, ImportA->getRange(),
else if (const auto *ExportA = dyn_cast<DLLExportAttr>(Attr))
NewAttr = S.mergeDLLExportAttr(D, ExportA->getRange(),
else if (const auto *FA = dyn_cast<FormatAttr>(Attr))
NewAttr = S.mergeFormatAttr(D, FA->getRange(), FA->getType(),
FA->getFormatIdx(), FA->getFirstArg(),
else if (const auto *SA = dyn_cast<SectionAttr>(Attr))
NewAttr = S.mergeSectionAttr(D, SA->getRange(), SA->getName(),
else if (const auto *IA = dyn_cast<MSInheritanceAttr>(Attr))
NewAttr = S.mergeMSInheritanceAttr(D, IA->getRange(), IA->getBestCase(),
else if (const auto *AA = dyn_cast<AlwaysInlineAttr>(Attr))
NewAttr = S.mergeAlwaysInlineAttr(D, AA->getRange(),
else if (S.getLangOpts().CUDA && isa<FunctionDecl>(D) &&
(isa<CUDAHostAttr>(Attr) || isa<CUDADeviceAttr>(Attr) ||
isa<CUDAGlobalAttr>(Attr))) {
// CUDA target attributes are part of function signature for
// overloading purposes and must not be merged.
return false;
} else if (const auto *MA = dyn_cast<MinSizeAttr>(Attr))
NewAttr = S.mergeMinSizeAttr(D, MA->getRange(), AttrSpellingListIndex);
else if (const auto *OA = dyn_cast<OptimizeNoneAttr>(Attr))
NewAttr = S.mergeOptimizeNoneAttr(D, OA->getRange(), AttrSpellingListIndex);
else if (const auto *SNA = dyn_cast<SwiftNameAttr>(Attr))
NewAttr = S.mergeSwiftNameAttr(D, SNA->getRange(), SNA->getName(),
AMK == Sema::AMK_Override,
else if (const auto *InternalLinkageA = dyn_cast<InternalLinkageAttr>(Attr))
NewAttr = S.mergeInternalLinkageAttr(
D, InternalLinkageA->getRange(),
else if (const auto *CommonA = dyn_cast<CommonAttr>(Attr))
NewAttr = S.mergeCommonAttr(D, CommonA->getRange(),
else if (isa<AlignedAttr>(Attr))
// AlignedAttrs are handled separately, because we need to handle all
// such attributes on a declaration at the same time.
NewAttr = nullptr;
else if ((isa<DeprecatedAttr>(Attr) || isa<UnavailableAttr>(Attr)) &&
(AMK == Sema::AMK_Override ||
AMK == Sema::AMK_ProtocolImplementation))
NewAttr = nullptr;
else if (isa<SwiftPrivateAttr>(Attr) && AMK == Sema::AMK_Override)
NewAttr = nullptr;
else if (const auto *UA = dyn_cast<UuidAttr>(Attr))
NewAttr = S.mergeUuidAttr(D, UA->getRange(), AttrSpellingListIndex,
else if (Attr->duplicatesAllowed() || !DeclHasAttr(D, Attr))
NewAttr = cast<InheritableAttr>(Attr->clone(S.Context));
if (NewAttr) {
if (isa<MSInheritanceAttr>(NewAttr))
return true;
return false;
static const NamedDecl *getDefinition(const Decl *D) {
if (const TagDecl *TD = dyn_cast<TagDecl>(D))
return TD->getDefinition();
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
const VarDecl *Def = VD->getDefinition();
if (Def)
return Def;
return VD->getActingDefinition();
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
return FD->getDefinition();
return nullptr;
static bool hasAttribute(const Decl *D, attr::Kind Kind) {
for (const auto *Attribute : D->attrs())
if (Attribute->getKind() == Kind)
return true;
return false;
/// checkNewAttributesAfterDef - If we already have a definition, check that
/// there are no new attributes in this declaration.
static void checkNewAttributesAfterDef(Sema &S, Decl *New, const Decl *Old) {
if (!New->hasAttrs())
const NamedDecl *Def = getDefinition(Old);
if (!Def || Def == New)
AttrVec &NewAttributes = New->getAttrs();
for (unsigned I = 0, E = NewAttributes.size(); I != E;) {
const Attr *NewAttribute = NewAttributes[I];
if (isa<AliasAttr>(NewAttribute) || isa<IFuncAttr>(NewAttribute)) {
if (FunctionDecl *FD = dyn_cast<FunctionDecl>(New)) {
Sema::SkipBodyInfo SkipBody;
S.CheckForFunctionRedefinition(FD, cast<FunctionDecl>(Def), &SkipBody);
// If we're skipping this definition, drop the "alias" attribute.
if (SkipBody.ShouldSkip) {
NewAttributes.erase(NewAttributes.begin() + I);
} else {
VarDecl *VD = cast<VarDecl>(New);
unsigned Diag = cast<VarDecl>(Def)->isThisDeclarationADefinition() ==
? diag::err_alias_after_tentative
: diag::err_redefinition;
S.Diag(VD->getLocation(), Diag) << VD->getDeclName();
if (Diag == diag::err_redefinition)
S.notePreviousDefinition(Def, VD->getLocation());
S.Diag(Def->getLocation(), diag::note_previous_definition);
if (const VarDecl *VD = dyn_cast<VarDecl>(Def)) {
// Tentative definitions are only interesting for the alias check above.
if (VD->isThisDeclarationADefinition() != VarDecl::Definition) {
if (hasAttribute(Def, NewAttribute->getKind())) {
continue; // regular attr merging will take care of validating this.
if (isa<C11NoReturnAttr>(NewAttribute)) {
// C's _Noreturn is allowed to be added to a function after it is defined.
} else if (const AlignedAttr *AA = dyn_cast<AlignedAttr>(NewAttribute)) {
if (AA->isAlignas()) {
// C++11 [dcl.align]p6:
// if any declaration of an entity has an alignment-specifier,
// every defining declaration of that entity shall specify an
// equivalent alignment.
// C11 6.7.5/7:
// If the definition of an object does not have an alignment
// specifier, any other declaration of that object shall also
// have no alignment specifier.
S.Diag(Def->getLocation(), diag::err_alignas_missing_on_definition)
<< AA;
S.Diag(NewAttribute->getLocation(), diag::note_alignas_on_declaration)
<< AA;
NewAttributes.erase(NewAttributes.begin() + I);
S.Diag(Def->getLocation(), diag::note_previous_definition);
NewAttributes.erase(NewAttributes.begin() + I);
/// mergeDeclAttributes - Copy attributes from the Old decl to the New one.
void Sema::mergeDeclAttributes(NamedDecl *New, Decl *Old,
AvailabilityMergeKind AMK) {
if (UsedAttr *OldAttr = Old->getMostRecentDecl()->getAttr<UsedAttr>()) {
UsedAttr *NewAttr = OldAttr->clone(Context);
if (!Old->hasAttrs() && !New->hasAttrs())
// Attributes declared post-definition are currently ignored.
checkNewAttributesAfterDef(*this, New, Old);
if (AsmLabelAttr *NewA = New->getAttr<AsmLabelAttr>()) {
if (AsmLabelAttr *OldA = Old->getAttr<AsmLabelAttr>()) {
if (OldA->getLabel() != NewA->getLabel()) {
// This redeclaration changes __asm__ label.
Diag(New->getLocation(), diag::err_different_asm_label);
Diag(OldA->getLocation(), diag::note_previous_declaration);
} else if (Old->isUsed()) {
// This redeclaration adds an __asm__ label to a declaration that has
// already been ODR-used.
Diag(New->getLocation(), diag::err_late_asm_label_name)
<< isa<FunctionDecl>(Old) << New->getAttr<AsmLabelAttr>()->getRange();
// Re-declaration cannot add abi_tag's.
if (const auto *NewAbiTagAttr = New->getAttr<AbiTagAttr>()) {
if (const auto *OldAbiTagAttr = Old->getAttr<AbiTagAttr>()) {
for (const auto &NewTag : NewAbiTagAttr->tags()) {
if (std::find(OldAbiTagAttr->tags_begin(), OldAbiTagAttr->tags_end(),
NewTag) == OldAbiTagAttr->tags_end()) {
<< NewTag;
Diag(OldAbiTagAttr->getLocation(), diag::note_previous_declaration);
} else {
Diag(NewAbiTagAttr->getLocation(), diag::err_abi_tag_on_redeclaration);
Diag(Old->getLocation(), diag::note_previous_declaration);
if (!Old->hasAttrs())
bool foundAny = New->hasAttrs();
// Ensure that any moving of objects within the allocated map is done before
// we process them.
if (!foundAny) New->setAttrs(AttrVec());
for (auto *I : Old->specific_attrs<InheritableAttr>()) {
// Ignore deprecated/unavailable/availability attributes if requested.
AvailabilityMergeKind LocalAMK = AMK_None;
if (isa<DeprecatedAttr>(I) ||
isa<UnavailableAttr>(I) ||
isa<AvailabilityAttr>(I)) {
switch (AMK) {
case AMK_None:
case AMK_Redeclaration:
case AMK_Override:
case AMK_ProtocolImplementation:
LocalAMK = AMK;
// Already handled.
if (isa<UsedAttr>(I))
if (mergeDeclAttribute(*this, New, I, LocalAMK))
foundAny = true;
if (mergeAlignedAttrs(*this, New, Old))
foundAny = true;
if (!foundAny) New->dropAttrs();
/// mergeParamDeclAttributes - Copy attributes from the old parameter
/// to the new one.
static void mergeParamDeclAttributes(ParmVarDecl *newDecl,
const ParmVarDecl *oldDecl,
Sema &S) {
// C++11 [dcl.attr.depend]p2:
// The first declaration of a function shall specify the
// carries_dependency attribute for its declarator-id if any declaration
// of the function specifies the carries_dependency attribute.
const CarriesDependencyAttr *CDA = newDecl->getAttr<CarriesDependencyAttr>();
if (CDA && !oldDecl->hasAttr<CarriesDependencyAttr>()) {
diag::err_carries_dependency_missing_on_first_decl) << 1/*Param*/;
// Find the first declaration of the parameter.
// FIXME: Should we build redeclaration chains for function parameters?
const FunctionDecl *FirstFD =
const ParmVarDecl *FirstVD =
diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
if (!oldDecl->hasAttrs())
bool foundAny = newDecl->hasAttrs();
// Ensure that any moving of objects within the allocated map is
// done before we process them.
if (!foundAny) newDecl->setAttrs(AttrVec());
for (const auto *I : oldDecl->specific_attrs<InheritableParamAttr>()) {
if (!DeclHasAttr(newDecl, I)) {
InheritableAttr *newAttr =
foundAny = true;
if (!foundAny) newDecl->dropAttrs();
static void mergeParamDeclTypes(ParmVarDecl *NewParam,
const ParmVarDecl *OldParam,
Sema &S) {
if (auto Oldnullability = OldParam->getType()->getNullability(S.Context)) {
if (auto Newnullability = NewParam->getType()->getNullability(S.Context)) {
if (*Oldnullability != *Newnullability) {
S.Diag(NewParam->getLocation(), diag::warn_mismatched_nullability_attr)
<< DiagNullabilityKind(
((NewParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
!= 0))
<< DiagNullabilityKind(
((OldParam->getObjCDeclQualifier() & Decl::OBJC_TQ_CSNullability)
!= 0));
S.Diag(OldParam->getLocation(), diag::note_previous_declaration);
} else {
QualType NewT = NewParam->getType();
NewT = S.Context.getAttributedType(
NewT, NewT);