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[Modules TS] Module ownership semantics for redeclarations. 

When declaring an entity in the "purview" of a module, it's never a
redeclaration of an entity in the purview of a default module or in no module
("in the global module"). Don't consider those other declarations as possible
redeclaration targets if they're not visible, and reject any cases where we
pick a prior visible declaration that violates this rule.

llvm-svn: 315251
This commit is contained in:
Richard Smith 2017-10-09 23:42:09 +00:00
parent 8b53f7ca6d
commit b87720b77a
20 changed files with 353 additions and 79 deletions
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10
clang/include/clang/AST/Decl.h
View File

@ -339,6 +339,12 @@ public:
return clang::isExternallyVisible(getLinkageInternal());
}
/// Determine whether this declaration can be redeclared in a
/// different translation unit.
bool isExternallyDeclarable() const {
return isExternallyVisible() && !getOwningModuleForLinkage();
}
/// \brief Determines the visibility of this entity.
Visibility getVisibility() const {
return getLinkageAndVisibility().getVisibility();
@ -379,10 +385,6 @@ public:
return hasCachedLinkage();
}
/// Get the module that owns this declaration for linkage purposes.
/// There only ever is such a module under the C++ Modules TS.
Module *getOwningModuleForLinkage() const;
/// \brief Looks through UsingDecls and ObjCCompatibleAliasDecls for
/// the underlying named decl.
NamedDecl *getUnderlyingDecl() {

4
clang/include/clang/AST/DeclBase.h
View File

@ -738,6 +738,10 @@ public:
return isFromASTFile() ? getImportedOwningModule() : getLocalOwningModule();
}
/// Get the module that owns this declaration for linkage purposes.
/// There only ever is such a module under the C++ Modules TS.
Module *getOwningModuleForLinkage() const;
/// \brief Determine whether this declaration might be hidden from name
/// lookup. Note that the declaration might be visible even if this returns
/// \c false, if the owning module is visible within the query context.

3
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -4801,6 +4801,9 @@ def err_thread_non_thread : Error<
def err_thread_thread_different_kind : Error<
"thread-local declaration of %0 with %select{static|dynamic}1 initialization "
"follows declaration with %select{dynamic|static}1 initialization">;
def err_mismatched_owning_module : Error<
"declaration of %0 in %select{the global module|module %2}1 follows "
"declaration in %select{the global module|module %4}3">;
def err_redefinition_different_type : Error<
"redefinition of %0 with a different type%diff{: $ vs $|}1,2">;
def err_redefinition_different_kind : Error<

25
clang/include/clang/Sema/Lookup.h
View File

@ -139,6 +139,7 @@ public:
LookupKind(LookupKind),
IDNS(0),
Redecl(Redecl != Sema::NotForRedeclaration),
ExternalRedecl(Redecl == Sema::ForExternalRedeclaration),
HideTags(true),
Diagnose(Redecl == Sema::NotForRedeclaration),
AllowHidden(false),
@ -161,6 +162,7 @@ public:
LookupKind(LookupKind),
IDNS(0),
Redecl(Redecl != Sema::NotForRedeclaration),
ExternalRedecl(Redecl == Sema::ForExternalRedeclaration),
HideTags(true),
Diagnose(Redecl == Sema::NotForRedeclaration),
AllowHidden(false),
@ -181,6 +183,7 @@ public:
LookupKind(Other.LookupKind),
IDNS(Other.IDNS),
Redecl(Other.Redecl),
ExternalRedecl(Other.ExternalRedecl),
HideTags(Other.HideTags),
Diagnose(false),
AllowHidden(Other.AllowHidden),
@ -201,7 +204,9 @@ public:
SemaPtr(std::move(Other.SemaPtr)), NameInfo(std::move(Other.NameInfo)),
NameContextRange(std::move(Other.NameContextRange)),
LookupKind(std::move(Other.LookupKind)), IDNS(std::move(Other.IDNS)),
Redecl(std::move(Other.Redecl)), HideTags(std::move(Other.HideTags)),
Redecl(std::move(Other.Redecl)),
ExternalRedecl(std::move(Other.ExternalRedecl)),
HideTags(std::move(Other.HideTags)),
Diagnose(std::move(Other.Diagnose)),
AllowHidden(std::move(Other.AllowHidden)),
Shadowed(std::move(Other.Shadowed)) {
@ -221,6 +226,7 @@ public:
LookupKind = std::move(Other.LookupKind);
IDNS = std::move(Other.IDNS);
Redecl = std::move(Other.Redecl);
ExternalRedecl = std::move(Other.ExternalRedecl);
HideTags = std::move(Other.HideTags);
Diagnose = std::move(Other.Diagnose);
AllowHidden = std::move(Other.AllowHidden);
@ -265,6 +271,17 @@ public:
return Redecl;
}
/// True if this lookup is just looking for an existing declaration to link
/// against a declaration with external linkage.
bool isForExternalRedeclaration() const {
return ExternalRedecl;
}
Sema::RedeclarationKind redeclarationKind() const {
return ExternalRedecl ? Sema::ForExternalRedeclaration :
Redecl ? Sema::ForVisibleRedeclaration : Sema::NotForRedeclaration;
}
/// \brief Specify whether hidden declarations are visible, e.g.,
/// for recovery reasons.
void setAllowHidden(bool AH) {
@ -275,7 +292,7 @@ public:
/// declarations, such as those in modules that have not yet been imported.
bool isHiddenDeclarationVisible(NamedDecl *ND) const {
return AllowHidden ||
(isForRedeclaration() && ND->hasExternalFormalLinkage());
(isForExternalRedeclaration() && ND->isExternallyDeclarable());
}
/// Sets whether tag declarations should be hidden by non-tag
@ -556,7 +573,8 @@ public:
/// \brief Change this lookup's redeclaration kind.
void setRedeclarationKind(Sema::RedeclarationKind RK) {
Redecl = RK;
Redecl = (RK != Sema::NotForRedeclaration);
ExternalRedecl = (RK == Sema::ForExternalRedeclaration);
configure();
}
@ -719,6 +737,7 @@ private:
unsigned IDNS; // set by configure()
bool Redecl;
bool ExternalRedecl;
/// \brief True if tag declarations should be hidden if non-tags
/// are present

38
clang/include/clang/Sema/Sema.h
View File

@ -285,15 +285,21 @@ class Sema {
bool isVisibleSlow(const NamedDecl *D);
/// Determine whether two declarations should be linked together, given that
/// the old declaration might not be visible and the new declaration might
/// not have external linkage.
bool shouldLinkPossiblyHiddenDecl(const NamedDecl *Old,
const NamedDecl *New) {
// We are about to link these. It is now safe to compute the linkage of
// the new decl. If the new decl has external linkage, we will
// link it with the hidden decl (which also has external linkage) and
// it will keep having external linkage. If it has internal linkage, we
// will not link it. Since it has no previous decls, it will remain
// with internal linkage.
return isVisible(Old) || New->isExternallyVisible();
if (isVisible(Old))
return true;
// See comment in below overload for why it's safe to compute the linkage
// of the new declaration here.
if (New->isExternallyDeclarable()) {
assert(Old->isExternallyDeclarable() &&
"should not have found a non-externally-declarable previous decl");
return true;
}
return false;
}
bool shouldLinkPossiblyHiddenDecl(LookupResult &Old, const NamedDecl *New);
@ -3035,10 +3041,22 @@ public:
/// purpose of redeclaring the name.
NotForRedeclaration = 0,
/// \brief The lookup results will be used for redeclaration of a name,
/// if an entity by that name already exists.
ForRedeclaration
/// if an entity by that name already exists and is visible.
ForVisibleRedeclaration,
/// \brief The lookup results will be used for redeclaration of a name
/// with external linkage; non-visible lookup results with external linkage
/// may also be found.
ForExternalRedeclaration
};
RedeclarationKind forRedeclarationInCurContext() {
// A declaration with an owning module for linkage can never link against
// anything that is not visible.
if (cast<Decl>(CurContext)->getOwningModuleForLinkage())
return ForVisibleRedeclaration;
return ForExternalRedeclaration;
}
/// \brief The possible outcomes of name lookup for a literal operator.
enum LiteralOperatorLookupResult {
/// \brief The lookup resulted in an error.
@ -3266,6 +3284,8 @@ public:
void FilterLookupForScope(LookupResult &R, DeclContext *Ctx, Scope *S,
bool ConsiderLinkage, bool AllowInlineNamespace);
bool CheckRedeclarationModuleOwnership(NamedDecl *New, NamedDecl *Old);
void DiagnoseAmbiguousLookup(LookupResult &Result);
//@}

16
clang/lib/AST/Decl.cpp
View File

@ -515,6 +515,7 @@ static bool isSingleLineLanguageLinkage(const Decl &D) {
}
static bool isExportedFromModuleIntefaceUnit(const NamedDecl *D) {
// FIXME: Handle isModulePrivate.
switch (D->getModuleOwnershipKind()) {
case Decl::ModuleOwnershipKind::Unowned:
case Decl::ModuleOwnershipKind::ModulePrivate:
@ -546,7 +547,8 @@ static LinkageInfo getExternalLinkageFor(const NamedDecl *D) {
// declaration has module linkage.
if (auto *M = D->getOwningModule())
if (M->Kind == Module::ModuleInterfaceUnit)
if (!isExportedFromModuleIntefaceUnit(D))
if (!isExportedFromModuleIntefaceUnit(
cast<NamedDecl>(D->getCanonicalDecl())))
return LinkageInfo(ModuleLinkage, DefaultVisibility, false);
return LinkageInfo::external();
@ -1393,7 +1395,7 @@ LinkageInfo LinkageComputer::getDeclLinkageAndVisibility(const NamedDecl *D) {
: NamedDecl::VisibilityForValue));
}
Module *NamedDecl::getOwningModuleForLinkage() const {
Module *Decl::getOwningModuleForLinkage() const {
Module *M = getOwningModule();
if (!M)
return nullptr;
@ -1411,7 +1413,15 @@ Module *NamedDecl::getOwningModuleForLinkage() const {
// for linkage purposes. But internal linkage declarations in the global
// module fragment of a particular module are owned by that module for
// linkage purposes.
return hasExternalFormalLinkage() ? nullptr : M->Parent;
bool InternalLinkage;
if (auto *ND = dyn_cast<NamedDecl>(this))
InternalLinkage = !ND->hasExternalFormalLinkage();
else {
auto *NSD = dyn_cast<NamespaceDecl>(this);
InternalLinkage = (NSD && NSD->isAnonymousNamespace()) ||
isInAnonymousNamespace();
}
return InternalLinkage ? M->Parent : nullptr;
}
llvm_unreachable("unknown module kind");

5
clang/lib/AST/DeclBase.cpp
View File

@ -315,12 +315,11 @@ bool Decl::isLexicallyWithinFunctionOrMethod() const {
}
bool Decl::isInAnonymousNamespace() const {
const DeclContext *DC = getDeclContext();
do {
for (const DeclContext *DC = getDeclContext(); DC; DC = DC->getParent()) {
if (const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(DC))
if (ND->isAnonymousNamespace())
return true;
} while ((DC = DC->getParent()));
}
return false;
}

2
clang/lib/AST/DeclCXX.cpp
View File

@ -100,7 +100,7 @@ CXXRecordDecl::CXXRecordDecl(Kind K, TagKind TK, const ASTContext &C,
CXXRecordDecl *CXXRecordDecl::Create(const ASTContext &C, TagKind TK,
DeclContext *DC, SourceLocation StartLoc,
SourceLocation IdLoc, IdentifierInfo *Id,
CXXRecordDecl* PrevDecl,
CXXRecordDecl *PrevDecl,
bool DelayTypeCreation) {
CXXRecordDecl *R = new (C, DC) CXXRecordDecl(CXXRecord, TK, C, DC, StartLoc,
IdLoc, Id, PrevDecl);

85
clang/lib/Sema/SemaDecl.cpp
View File

@ -1448,6 +1448,46 @@ void Sema::FilterLookupForScope(LookupResult &R, DeclContext *Ctx, Scope *S,
F.done();
}
/// We've determined that \p New is a redeclaration of \p Old. Check that they
/// have compatible owning modules.
bool Sema::CheckRedeclarationModuleOwnership(NamedDecl *New, NamedDecl *Old) {
// FIXME: The Modules TS is not clear about how friend declarations are
// to be treated. It's not meaningful to have different owning modules for
// linkage in redeclarations of the same entity, so for now allow the
// redeclaration and change the owning modules to match.
if (New->getFriendObjectKind() &&
Old->getOwningModuleForLinkage() != New->getOwningModuleForLinkage()) {
New->setLocalOwningModule(Old->getOwningModule());
makeMergedDefinitionVisible(New);
return false;
}
Module *NewM = New->getOwningModule();
Module *OldM = Old->getOwningModule();
if (NewM == OldM)
return false;
// FIXME: Check proclaimed-ownership-declarations here too.
bool NewIsModuleInterface = NewM && NewM->Kind == Module::ModuleInterfaceUnit;
bool OldIsModuleInterface = OldM && OldM->Kind == Module::ModuleInterfaceUnit;
if (NewIsModuleInterface || OldIsModuleInterface) {
// C++ Modules TS [basic.def.odr] 6.2/6.7 [sic]:
// if a declaration of D [...] appears in the purview of a module, all
// other such declarations shall appear in the purview of the same module
Diag(New->getLocation(), diag::err_mismatched_owning_module)
<< New
<< NewIsModuleInterface
<< (NewIsModuleInterface ? NewM->getFullModuleName() : "")
<< OldIsModuleInterface
<< (OldIsModuleInterface ? OldM->getFullModuleName() : "");
Diag(Old->getLocation(), diag::note_previous_declaration);
New->setInvalidDecl();
return true;
}
return false;
}
static bool isUsingDecl(NamedDecl *D) {
return isa<UsingShadowDecl>(D) ||
isa<UnresolvedUsingTypenameDecl>(D) ||
@ -2962,6 +3002,9 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD,
New->dropAttr<InternalLinkageAttr>();
}
if (CheckRedeclarationModuleOwnership(New, Old))
return true;
if (!getLangOpts().CPlusPlus) {
bool OldOvl = Old->hasAttr<OverloadableAttr>();
if (OldOvl != New->hasAttr<OverloadableAttr>() && !Old->isImplicit()) {
@ -3831,6 +3874,9 @@ void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
return New->setInvalidDecl();
}
if (CheckRedeclarationModuleOwnership(New, Old))
return;
// Variables with external linkage are analyzed in FinalizeDeclaratorGroup.
// FIXME: The test for external storage here seems wrong? We still
@ -4382,7 +4428,7 @@ static bool CheckAnonMemberRedeclaration(Sema &SemaRef,
SourceLocation NameLoc,
bool IsUnion) {
LookupResult R(SemaRef, Name, NameLoc, Sema::LookupMemberName,
Sema::ForRedeclaration);
Sema::ForVisibleRedeclaration);
if (!SemaRef.LookupName(R, S)) return false;
// Pick a representative declaration.
@ -5321,7 +5367,7 @@ NamedDecl *Sema::HandleDeclarator(Scope *S, Declarator &D,
D.setInvalidType();
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForRedeclaration);
forRedeclarationInCurContext());
// See if this is a redefinition of a variable in the same scope.
if (!D.getCXXScopeSpec().isSet()) {
@ -5347,8 +5393,10 @@ NamedDecl *Sema::HandleDeclarator(Scope *S, Declarator &D,
D.getDeclSpec().getStorageClassSpec() != DeclSpec::SCS_static)
CreateBuiltins = true;
if (IsLinkageLookup)
if (IsLinkageLookup) {
Previous.clear(LookupRedeclarationWithLinkage);
Previous.setRedeclarationKind(ForExternalRedeclaration);
}
LookupName(Previous, S, CreateBuiltins);
} else { // Something like "int foo::x;"
@ -7096,7 +7144,7 @@ void Sema::CheckShadow(Scope *S, VarDecl *D) {
return;
LookupResult R(*this, D->getDeclName(), D->getLocation(),
Sema::LookupOrdinaryName, Sema::ForRedeclaration);
Sema::LookupOrdinaryName, Sema::ForVisibleRedeclaration);
LookupName(R, S);
if (NamedDecl *ShadowedDecl = getShadowedDeclaration(D, R))
CheckShadow(D, ShadowedDecl, R);
@ -7672,7 +7720,7 @@ static NamedDecl *DiagnoseInvalidRedeclaration(
LookupResult Prev(SemaRef, Name, NewFD->getLocation(),
IsLocalFriend ? Sema::LookupLocalFriendName
: Sema::LookupOrdinaryName,
Sema::ForRedeclaration);
Sema::ForVisibleRedeclaration);
NewFD->setInvalidDecl();
if (IsLocalFriend)
@ -11708,7 +11756,7 @@ Decl *Sema::ActOnParamDeclarator(Scope *S, Declarator &D) {
// Check for redeclaration of parameters, e.g. int foo(int x, int x);
if (II) {
LookupResult R(*this, II, D.getIdentifierLoc(), LookupOrdinaryName,
ForRedeclaration);
ForVisibleRedeclaration);
LookupName(R, S);
if (R.isSingleResult()) {
NamedDecl *PrevDecl = R.getFoundDecl();
@ -13268,7 +13316,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
bool isStdBadAlloc = false;
bool isStdAlignValT = false;
RedeclarationKind Redecl = ForRedeclaration;
RedeclarationKind Redecl = forRedeclarationInCurContext();
if (TUK == TUK_Friend || TUK == TUK_Reference)
Redecl = NotForRedeclaration;
@ -13546,10 +13594,10 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
// type declared by an elaborated-type-specifier. In C that is not correct
// and we should instead merge compatible types found by lookup.
if (getLangOpts().CPlusPlus) {
Previous.setRedeclarationKind(ForRedeclaration);
Previous.setRedeclarationKind(forRedeclarationInCurContext());
LookupQualifiedName(Previous, SearchDC);
} else {
Previous.setRedeclarationKind(ForRedeclaration);
Previous.setRedeclarationKind(forRedeclarationInCurContext());
LookupName(Previous, S);
}
}
@ -14047,6 +14095,9 @@ CreateNewDecl:
if (!Invalid && SearchDC->isRecord())
SetMemberAccessSpecifier(New, PrevDecl, AS);
if (PrevDecl)
CheckRedeclarationModuleOwnership(New, PrevDecl);
if (TUK == TUK_Definition)
New->startDefinition();
@ -14400,7 +14451,8 @@ FieldDecl *Sema::HandleField(Scope *S, RecordDecl *Record,
// Check to see if this name was declared as a member previously
NamedDecl *PrevDecl = nullptr;
LookupResult Previous(*this, II, Loc, LookupMemberName, ForRedeclaration);
LookupResult Previous(*this, II, Loc, LookupMemberName,
ForVisibleRedeclaration);
LookupName(Previous, S);
switch (Previous.getResultKind()) {
case LookupResult::Found:
@ -14788,7 +14840,7 @@ Decl *Sema::ActOnIvar(Scope *S,
if (II) {
NamedDecl *PrevDecl = LookupSingleName(S, II, Loc, LookupMemberName,
ForRedeclaration);
ForVisibleRedeclaration);
if (PrevDecl && isDeclInScope(PrevDecl, EnclosingContext, S)
&& !isa<TagDecl>(PrevDecl)) {
Diag(Loc, diag::err_duplicate_member) << II;
@ -15509,7 +15561,7 @@ Sema::SkipBodyInfo Sema::shouldSkipAnonEnumBody(Scope *S, IdentifierInfo *II,
// determine if we should merge the definition with an existing one and
// skip the body.
NamedDecl *PrevDecl = LookupSingleName(S, II, IILoc, LookupOrdinaryName,
ForRedeclaration);
forRedeclarationInCurContext());
auto *PrevECD = dyn_cast_or_null<EnumConstantDecl>(PrevDecl);
if (!PrevECD)
return SkipBodyInfo();
@ -15540,7 +15592,7 @@ Decl *Sema::ActOnEnumConstant(Scope *S, Decl *theEnumDecl, Decl *lastEnumConst,
// Verify that there isn't already something declared with this name in this
// scope.
NamedDecl *PrevDecl = LookupSingleName(S, Id, IdLoc, LookupOrdinaryName,
ForRedeclaration);
ForVisibleRedeclaration);
if (PrevDecl && PrevDecl->isTemplateParameter()) {
// Maybe we will complain about the shadowed template parameter.
DiagnoseTemplateParameterShadow(IdLoc, PrevDecl);
@ -15567,8 +15619,7 @@ Decl *Sema::ActOnEnumConstant(Scope *S, Decl *theEnumDecl, Decl *lastEnumConst,
// enum constant will 'hide' the tag.
assert((getLangOpts().CPlusPlus || !isa<TagDecl>(PrevDecl)) &&
"Received TagDecl when not in C++!");
if (!isa<TagDecl>(PrevDecl) && isDeclInScope(PrevDecl, CurContext, S) &&
shouldLinkPossiblyHiddenDecl(PrevDecl, New)) {
if (!isa<TagDecl>(PrevDecl) && isDeclInScope(PrevDecl, CurContext, S)) {
if (isa<EnumConstantDecl>(PrevDecl))
Diag(IdLoc, diag::err_redefinition_of_enumerator) << Id;
else
@ -16150,7 +16201,8 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
else if (const auto *FE = M->getASTFile())
Diag(M->DefinitionLoc, diag::note_prev_module_definition_from_ast_file)
<< FE->getName();
return nullptr;
Mod = M;
break;
}
// Create a Module for the module that we're defining.
@ -16169,6 +16221,7 @@ Sema::DeclGroupPtrTy Sema::ActOnModuleDecl(SourceLocation StartLoc,
PP.getIdentifierInfo(ModuleName), Path[0].second);
Mod = getModuleLoader().loadModule(ModuleLoc, Path, Module::AllVisible,
/*IsIncludeDirective=*/false);
// FIXME: Produce an error in this case.
if (!Mod)
return nullptr;
break;

31
clang/lib/Sema/SemaDeclCXX.cpp
View File

@ -790,7 +790,7 @@ Sema::ActOnDecompositionDeclarator(Scope *S, Declarator &D,
// Check for name conflicts.
DeclarationNameInfo NameInfo(B.Name, B.NameLoc);
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForRedeclaration);
ForVisibleRedeclaration);
LookupName(Previous, S,
/*CreateBuiltins*/DC->getRedeclContext()->isTranslationUnit());
@ -822,7 +822,8 @@ Sema::ActOnDecompositionDeclarator(Scope *S, Declarator &D,
// is unnamed.
DeclarationNameInfo NameInfo((IdentifierInfo *)nullptr,
Decomp.getLSquareLoc());
LookupResult Previous(*this, NameInfo, LookupOrdinaryName, ForRedeclaration);
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForVisibleRedeclaration);
// Build the variable that holds the non-decomposed object.
bool AddToScope = true;
@ -8465,7 +8466,8 @@ Decl *Sema::ActOnStartNamespaceDef(Scope *NamespcScope,
// Since namespace names are unique in their scope, and we don't
// look through using directives, just look for any ordinary names
// as if by qualified name lookup.
LookupResult R(*this, II, IdentLoc, LookupOrdinaryName, ForRedeclaration);
LookupResult R(*this, II, IdentLoc, LookupOrdinaryName,
ForExternalRedeclaration);
LookupQualifiedName(R, CurContext->getRedeclContext());
NamedDecl *PrevDecl =
R.isSingleResult() ? R.getRepresentativeDecl() : nullptr;
@ -9402,7 +9404,7 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
// Do the redeclaration lookup in the current scope.
LookupResult Previous(*this, UsingName, LookupUsingDeclName,
ForRedeclaration);
ForVisibleRedeclaration);
Previous.setHideTags(false);
if (S) {
LookupName(Previous, S);
@ -9982,7 +9984,10 @@ Decl *Sema::ActOnAliasDeclaration(Scope *S,
TInfo->getTypeLoc().getBeginLoc());
}
LookupResult Previous(*this, NameInfo, LookupOrdinaryName, ForRedeclaration);
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
TemplateParamLists.size()
? forRedeclarationInCurContext()
: ForVisibleRedeclaration);
LookupName(Previous, S);
// Warn about shadowing the name of a template parameter.
@ -10085,8 +10090,10 @@ Decl *Sema::ActOnAliasDeclaration(Scope *S,
if (Invalid)
NewDecl->setInvalidDecl();
else if (OldDecl)
else if (OldDecl) {
NewDecl->setPreviousDecl(OldDecl);
CheckRedeclarationModuleOwnership(NewDecl, OldDecl);
}
NewND = NewDecl;
} else {
@ -10127,7 +10134,7 @@ Decl *Sema::ActOnNamespaceAliasDef(Scope *S, SourceLocation NamespaceLoc,
// Check if we have a previous declaration with the same name.
LookupResult PrevR(*this, Alias, AliasLoc, LookupOrdinaryName,
ForRedeclaration);
ForVisibleRedeclaration);
LookupName(PrevR, S);
// Check we're not shadowing a template parameter.
@ -10340,7 +10347,8 @@ void Sema::CheckImplicitSpecialMemberDeclaration(Scope *S, FunctionDecl *FD) {
// implicit special members with this name.
DeclarationName Name = FD->getDeclName();
LookupResult R(*this, Name, SourceLocation(), LookupOrdinaryName,
ForRedeclaration);
FD->isExternallyDeclarable() ? ForExternalRedeclaration
: ForVisibleRedeclaration);
for (auto *D : FD->getParent()->lookup(Name))
if (auto *Acceptable = R.getAcceptableDecl(D))
R.addDecl(Acceptable);
@ -13224,7 +13232,7 @@ Decl *Sema::ActOnExceptionDeclarator(Scope *S, Declarator &D) {
IdentifierInfo *II = D.getIdentifier();
if (NamedDecl *PrevDecl = LookupSingleName(S, II, D.getIdentifierLoc(),
LookupOrdinaryName,
ForRedeclaration)) {
ForVisibleRedeclaration)) {
// The scope should be freshly made just for us. There is just no way
// it contains any previous declaration, except for function parameters in
// a function-try-block's catch statement.
@ -13673,7 +13681,7 @@ NamedDecl *Sema::ActOnFriendFunctionDecl(Scope *S, Declarator &D,
DeclContext *DC;
Scope *DCScope = S;
LookupResult Previous(*this, NameInfo, LookupOrdinaryName,
ForRedeclaration);
ForExternalRedeclaration);
// There are five cases here.
// - There's no scope specifier and we're in a local class. Only look
@ -14947,7 +14955,8 @@ MSPropertyDecl *Sema::HandleMSProperty(Scope *S, RecordDecl *Record,
// Check to see if this name was declared as a member previously
NamedDecl *PrevDecl = nullptr;
LookupResult Previous(*this, II, Loc, LookupMemberName, ForRedeclaration);
LookupResult Previous(*this, II, Loc, LookupMemberName,
ForVisibleRedeclaration);
LookupName(Previous, S);
switch (Previous.getResultKind()) {
case LookupResult::Found:

28
clang/lib/Sema/SemaDeclObjC.cpp
View File

@ -943,8 +943,9 @@ ActOnStartClassInterface(Scope *S, SourceLocation AtInterfaceLoc,
assert(ClassName && "Missing class identifier");
// Check for another declaration kind with the same name.
NamedDecl *PrevDecl = LookupSingleName(TUScope, ClassName, ClassLoc,
LookupOrdinaryName, ForRedeclaration);
NamedDecl *PrevDecl =
LookupSingleName(TUScope, ClassName, ClassLoc, LookupOrdinaryName,
forRedeclarationInCurContext());
if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
Diag(ClassLoc, diag::err_redefinition_different_kind) << ClassName;
@ -1095,16 +1096,18 @@ Decl *Sema::ActOnCompatibilityAlias(SourceLocation AtLoc,
IdentifierInfo *ClassName,
SourceLocation ClassLocation) {
// Look for previous declaration of alias name
NamedDecl *ADecl = LookupSingleName(TUScope, AliasName, AliasLocation,
LookupOrdinaryName, ForRedeclaration);
NamedDecl *ADecl =
LookupSingleName(TUScope, AliasName, AliasLocation, LookupOrdinaryName,
forRedeclarationInCurContext());
if (ADecl) {
Diag(AliasLocation, diag::err_conflicting_aliasing_type) << AliasName;
Diag(ADecl->getLocation(), diag::note_previous_declaration);
return nullptr;
}
// Check for class declaration
NamedDecl *CDeclU = LookupSingleName(TUScope, ClassName, ClassLocation,
LookupOrdinaryName, ForRedeclaration);
NamedDecl *CDeclU =
LookupSingleName(TUScope, ClassName, ClassLocation, LookupOrdinaryName,
forRedeclarationInCurContext());
if (const TypedefNameDecl *TDecl =
dyn_cast_or_null<TypedefNameDecl>(CDeclU)) {
QualType T = TDecl->getUnderlyingType();
@ -1112,7 +1115,8 @@ Decl *Sema::ActOnCompatibilityAlias(SourceLocation AtLoc,
if (NamedDecl *IDecl = T->getAs<ObjCObjectType>()->getInterface()) {
ClassName = IDecl->getIdentifier();
CDeclU = LookupSingleName(TUScope, ClassName, ClassLocation,
LookupOrdinaryName, ForRedeclaration);
LookupOrdinaryName,
forRedeclarationInCurContext());
}
}
}
@ -1174,7 +1178,7 @@ Sema::ActOnStartProtocolInterface(SourceLocation AtProtoInterfaceLoc,
// FIXME: Deal with AttrList.
assert(ProtocolName && "Missing protocol identifier");
ObjCProtocolDecl *PrevDecl = LookupProtocol(ProtocolName, ProtocolLoc,
ForRedeclaration);
forRedeclarationInCurContext());
ObjCProtocolDecl *PDecl = nullptr;
if (ObjCProtocolDecl *Def = PrevDecl? PrevDecl->getDefinition() : nullptr) {
// If we already have a definition, complain.
@ -1730,7 +1734,7 @@ Sema::ActOnForwardProtocolDeclaration(SourceLocation AtProtocolLoc,
for (const IdentifierLocPair &IdentPair : IdentList) {
IdentifierInfo *Ident = IdentPair.first;
ObjCProtocolDecl *PrevDecl = LookupProtocol(Ident, IdentPair.second,
ForRedeclaration);
forRedeclarationInCurContext());
ObjCProtocolDecl *PDecl
= ObjCProtocolDecl::Create(Context, CurContext, Ident,
IdentPair.second, AtProtocolLoc,
@ -1921,7 +1925,7 @@ Decl *Sema::ActOnStartClassImplementation(
// Check for another declaration kind with the same name.
NamedDecl *PrevDecl
= LookupSingleName(TUScope, ClassName, ClassLoc, LookupOrdinaryName,
ForRedeclaration);
forRedeclarationInCurContext());
if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
Diag(ClassLoc, diag::err_redefinition_different_kind) << ClassName;
Diag(PrevDecl->getLocation(), diag::note_previous_definition);
@ -2997,7 +3001,7 @@ Sema::ActOnForwardClassDeclaration(SourceLocation AtClassLoc,
// Check for another declaration kind with the same name.
NamedDecl *PrevDecl
= LookupSingleName(TUScope, IdentList[i], IdentLocs[i],
LookupOrdinaryName, ForRedeclaration);
LookupOrdinaryName, forRedeclarationInCurContext());
if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
// GCC apparently allows the following idiom:
//
@ -4443,7 +4447,7 @@ Decl *Sema::ActOnMethodDeclaration(
}
LookupResult R(*this, ArgInfo[i].Name, ArgInfo[i].NameLoc,
LookupOrdinaryName, ForRedeclaration);
LookupOrdinaryName, forRedeclarationInCurContext());
LookupName(R, S);
if (R.isSingleResult()) {
NamedDecl *PrevDecl = R.getFoundDecl();

3
clang/lib/Sema/SemaExprMember.cpp
View File

@ -693,8 +693,7 @@ static bool LookupMemberExprInRecord(Sema &SemaRef, LookupResult &R,
Sema::RedeclarationKind Redecl;
};
QueryState Q = {R.getSema(), R.getLookupNameInfo(), R.getLookupKind(),
R.isForRedeclaration() ? Sema::ForRedeclaration
: Sema::NotForRedeclaration};
R.redeclarationKind()};
TE = SemaRef.CorrectTypoDelayed(
R.getLookupNameInfo(), R.getLookupKind(), nullptr, &SS,
llvm::make_unique<RecordMemberExprValidatorCCC>(RTy),

30
clang/lib/Sema/SemaLookup.cpp
View File

@ -1609,11 +1609,39 @@ bool Sema::isVisibleSlow(const NamedDecl *D) {
}
bool Sema::shouldLinkPossiblyHiddenDecl(LookupResult &R, const NamedDecl *New) {
// FIXME: If there are both visible and hidden declarations, we need to take
// into account whether redeclaration is possible. Example:
//
// Non-imported module:
// int f(T); // #1
// Some TU:
// static int f(U); // #2, not a redeclaration of #1
// int f(T); // #3, finds both, should link with #1 if T != U, but
// // with #2 if T == U; neither should be ambiguous.
for (auto *D : R) {
if (isVisible(D))
return true;
assert(D->isExternallyDeclarable() &&
"should not have hidden, non-externally-declarable result here");
}
return New->isExternallyVisible();
// This function is called once "New" is essentially complete, but before a
// previous declaration is attached. We can't query the linkage of "New" in
// general, because attaching the previous declaration can change the
// linkage of New to match the previous declaration.
//
// However, because we've just determined that there is no *visible* prior
// declaration, we can compute the linkage here. There are two possibilities:
//
// * This is not a redeclaration; it's safe to compute the linkage now.
//
// * This is a redeclaration of a prior declaration that is externally
// redeclarable. In that case, the linkage of the declaration is not
// changed by attaching the prior declaration, because both are externally
// declarable (and thus ExternalLinkage or VisibleNoLinkage).
//
// FIXME: This is subtle and fragile.
return New->isExternallyDeclarable();
}
/// \brief Retrieve the visible declaration corresponding to D, if any.

2
clang/lib/Sema/SemaOpenMP.cpp
View File

@ -11539,7 +11539,7 @@ Sema::DeclGroupPtrTy Sema::ActOnOpenMPDeclareReductionDirectiveStart(
Decls.reserve(ReductionTypes.size());
LookupResult Lookup(*this, Name, SourceLocation(), LookupOMPReductionName,
ForRedeclaration);
forRedeclarationInCurContext());
// [OpenMP 4.0], 2.15 declare reduction Directive, Restrictions
// A reduction-identifier may not be re-declared in the current scope for the
// same type or for a type that is compatible according to the base language

13
clang/lib/Sema/SemaTemplate.cpp
View File

@ -778,7 +778,7 @@ static void maybeDiagnoseTemplateParameterShadow(Sema &SemaRef, Scope *S,
SourceLocation Loc,
IdentifierInfo *Name) {
NamedDecl *PrevDecl = SemaRef.LookupSingleName(
S, Name, Loc, Sema::LookupOrdinaryName, Sema::ForRedeclaration);
S, Name, Loc, Sema::LookupOrdinaryName, Sema::ForVisibleRedeclaration);
if (PrevDecl && PrevDecl->isTemplateParameter())
SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
}
@ -1133,7 +1133,7 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
LookupResult Previous(*this, Name, NameLoc,
(SS.isEmpty() && TUK == TUK_Friend)
? LookupTagName : LookupOrdinaryName,
ForRedeclaration);
forRedeclarationInCurContext());
if (SS.isNotEmpty() && !SS.isInvalid()) {
SemanticContext = computeDeclContext(SS, true);
if (!SemanticContext) {
@ -1192,8 +1192,8 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
// If there is a previous declaration with the same name, check
// whether this is a valid redeclaration.
ClassTemplateDecl *PrevClassTemplate
= dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
ClassTemplateDecl *PrevClassTemplate =
dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
// We may have found the injected-class-name of a class template,
// class template partial specialization, or class template specialization.
@ -1484,6 +1484,9 @@ Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
CurContext->addDecl(Friend);
}
if (PrevClassTemplate)
CheckRedeclarationModuleOwnership(NewTemplate, PrevClassTemplate);
if (Invalid) {
NewTemplate->setInvalidDecl();
NewClass->setInvalidDecl();
@ -3677,7 +3680,7 @@ DeclResult Sema::ActOnVarTemplateSpecialization(
// Check that this isn't a redefinition of this specialization,
// merging with previous declarations.
LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
ForRedeclaration);
forRedeclarationInCurContext());
PrevSpec.addDecl(PrevDecl);
D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
} else if (Specialization->isStaticDataMember() &&

17
clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
View File

@ -1195,7 +1195,8 @@ Decl *TemplateDeclInstantiator::VisitClassTemplateDecl(ClassTemplateDecl *D) {
// Look for a previous declaration of the template in the owning
// context.
LookupResult R(SemaRef, Pattern->getDeclName(), Pattern->getLocation(),
Sema::LookupOrdinaryName, Sema::ForRedeclaration);
Sema::LookupOrdinaryName,
SemaRef.forRedeclarationInCurContext());
SemaRef.LookupQualifiedName(R, DC);
if (R.isSingleResult()) {
@ -1735,7 +1736,8 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(FunctionDecl *D,
SemaRef, Function->getDeclName(), SourceLocation(),
D->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
: Sema::LookupOrdinaryName,
Sema::ForRedeclaration);
D->isLocalExternDecl() ? Sema::ForExternalRedeclaration
: SemaRef.forRedeclarationInCurContext());
if (DependentFunctionTemplateSpecializationInfo *Info
= D->getDependentSpecializationInfo()) {
@ -2053,7 +2055,7 @@ TemplateDeclInstantiator::VisitCXXMethodDecl(CXXMethodDecl *D,
Method->setInvalidDecl();
LookupResult Previous(SemaRef, NameInfo, Sema::LookupOrdinaryName,
Sema::ForRedeclaration);
Sema::ForExternalRedeclaration);
if (!FunctionTemplate || TemplateParams || isFriend) {
SemaRef.LookupQualifiedName(Previous, Record);
@ -2492,7 +2494,7 @@ Decl *TemplateDeclInstantiator::VisitUsingDecl(UsingDecl *D) {
bool CheckRedeclaration = Owner->isRecord();
LookupResult Prev(SemaRef, NameInfo, Sema::LookupUsingDeclName,
Sema::ForRedeclaration);
Sema::ForVisibleRedeclaration);
UsingDecl *NewUD = UsingDecl::Create(SemaRef.Context, Owner,
D->getUsingLoc(),
@ -2711,7 +2713,7 @@ Decl *TemplateDeclInstantiator::VisitClassScopeFunctionSpecializationDecl(
return nullptr;
LookupResult Previous(SemaRef, NewFD->getNameInfo(), Sema::LookupOrdinaryName,
Sema::ForRedeclaration);
Sema::ForExternalRedeclaration);
TemplateArgumentListInfo TemplateArgs;
TemplateArgumentListInfo *TemplateArgsPtr = nullptr;
@ -4074,7 +4076,8 @@ void Sema::BuildVariableInstantiation(
*this, NewVar->getDeclName(), NewVar->getLocation(),
NewVar->isLocalExternDecl() ? Sema::LookupRedeclarationWithLinkage
: Sema::LookupOrdinaryName,
Sema::ForRedeclaration);
NewVar->isLocalExternDecl() ? Sema::ForExternalRedeclaration
: forRedeclarationInCurContext());
if (NewVar->isLocalExternDecl() && OldVar->getPreviousDecl() &&
(!OldVar->getPreviousDecl()->getDeclContext()->isDependentContext() ||
@ -4432,7 +4435,7 @@ void Sema::InstantiateVariableDefinition(SourceLocation PointOfInstantiation,
// Merge the definition with the declaration.
LookupResult R(*this, Var->getDeclName(), Var->getLocation(),
LookupOrdinaryName, ForRedeclaration);
LookupOrdinaryName, forRedeclarationInCurContext());
R.addDecl(OldVar);
MergeVarDecl(Var, R);

55
clang/test/CXX/modules-ts/basic/basic.def.odr/p6/global-vs-module.cpp Normal file
View File

@ -0,0 +1,55 @@
// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s
// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s -DEXPORT
// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s -DUSING
#ifndef NO_GLOBAL
extern int var; // expected-note {{previous declaration is here}}
int func(); // expected-note {{previous declaration is here}}
struct str; // expected-note {{previous declaration is here}}
using type = int;
template<typename> extern int var_tpl; // expected-note {{previous declaration is here}}
template<typename> int func_tpl(); // expected-note-re {{{{previous declaration is here|target of using declaration}}}}
template<typename> struct str_tpl; // expected-note {{previous declaration is here}}
template<typename> using type_tpl = int; // expected-note {{previous declaration is here}}
typedef int type;
namespace ns { using ::func; }
namespace ns_alias = ns;
#endif
export module M;
#ifdef USING
using ::var;
using ::func;
using ::str;
using ::type;
using ::var_tpl;
using ::func_tpl; // expected-note {{using declaration}}
using ::str_tpl;
using ::type_tpl;
#endif
#ifdef EXPORT
export {
#endif
extern int var; // expected-error {{declaration of 'var' in module M follows declaration in the global module}}
int func(); // expected-error {{declaration of 'func' in module M follows declaration in the global module}}
struct str; // expected-error {{declaration of 'str' in module M follows declaration in the global module}}
using type = int;
template<typename> extern int var_tpl; // expected-error {{declaration of 'var_tpl' in module M follows declaration in the global module}}
// FIXME: Is this the right diagnostic in the -DUSING case?
template<typename> int func_tpl(); // expected-error-re {{{{declaration of 'func_tpl' in module M follows declaration in the global module|conflicts with target of using declaration}}}}
template<typename> struct str_tpl; // expected-error {{declaration of 'str_tpl' in module M follows declaration in the global module}}
template<typename> using type_tpl = int; // expected-error {{declaration of 'type_tpl' in module M follows declaration in the global module}}
typedef int type;
namespace ns { using ::func; }
namespace ns_alias = ns;
#ifdef EXPORT
}
#endif

19
clang/test/CXX/modules-ts/basic/basic.def.odr/p6/module-vs-global.cpp Normal file
View File

@ -0,0 +1,19 @@
// RUN: rm -rf %t
// RUN: %clang_cc1 -fmodules-ts -emit-module-interface -std=c++17 %S/global-vs-module.cpp -o %t -DNO_GLOBAL -DEXPORT
// RUN: %clang_cc1 -fmodules-ts -verify -std=c++17 %s -fmodule-file=%t
import M;
extern int var; // expected-error {{declaration of 'var' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:38 {{previous}}
int func(); // expected-error {{declaration of 'func' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:39 {{previous}}
struct str; // expected-error {{declaration of 'str' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:40 {{previous}}
using type = int;
template<typename> extern int var_tpl; // expected-error {{declaration of 'var_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:43 {{previous}}
template<typename> int func_tpl(); // expected-error {{declaration of 'func_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:45 {{previous}}
template<typename> struct str_tpl; // expected-error {{declaration of 'str_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:46 {{previous}}
template<typename> using type_tpl = int; // expected-error {{declaration of 'type_tpl' in the global module follows declaration in module M}} expected-note@global-vs-module.cpp:47 {{previous}}
typedef int type;
namespace ns { using ::func; }
namespace ns_alias = ns;

44
clang/test/CXX/modules-ts/basic/basic.def.odr/p6/module-vs-module.cpp Normal file
View File

@ -0,0 +1,44 @@
// RUN: rm -rf %t
// RUN: mkdir %t
//
// Some of the following tests intentionally have no -verify in their RUN
// lines; we are testing that those cases do not produce errors.
//
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %S/global-vs-module.cpp -emit-module-interface -o %t/M.pcm -DNO_GLOBAL -DEXPORT
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/M.pcm -DMODULE_INTERFACE -verify
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/M.pcm -DMODULE_INTERFACE -DNO_IMPORT
//
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/M.pcm -emit-module-interface -o %t/N.pcm -DMODULE_INTERFACE -DNO_ERRORS
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/N.pcm -verify
// FIXME: Once we start importing "import" declarations properly, this should
// be rejected (-verify should be added to the following line).
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/N.pcm -DNO_IMPORT
//
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/M.pcm -emit-module-interface -o %t/N-no-M.pcm -DMODULE_INTERFACE -DNO_ERRORS -DNO_IMPORT
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/N-no-M.pcm -verify
// RUN: %clang_cc1 -fmodules-ts -std=c++17 %s -fmodule-file=%t/N-no-M.pcm -DNO_IMPORT
#ifdef MODULE_INTERFACE
export
#endif
module N;
#ifndef NO_IMPORT
import M;
#endif
#ifndef NO_ERRORS
extern int var; // expected-error {{declaration of 'var' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:38 {{previous}}
int func(); // expected-error {{declaration of 'func' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:39 {{previous}}
struct str; // expected-error {{declaration of 'str' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:40 {{previous}}
using type = int;
template<typename> extern int var_tpl; // expected-error {{declaration of 'var_tpl' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:43 {{previous}}
template<typename> int func_tpl(); // expected-error {{declaration of 'func_tpl' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:45 {{previous}}
template<typename> struct str_tpl; // expected-error {{declaration of 'str_tpl' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:46 {{previous}}
template<typename> using type_tpl = int; // expected-error {{declaration of 'type_tpl' in module N follows declaration in module M}} expected-note@global-vs-module.cpp:47 {{previous}}
typedef int type;
namespace ns { using ::func; }
namespace ns_alias = ns;
#endif

2
clang/test/SemaCXX/modules-ts.cppm
View File

@ -14,7 +14,7 @@ export module foo;
#endif
static int m;
#if TEST == 2 // FIXME: 'm' has internal linkage, so there should be no error here
#if TEST == 2
// expected-error@-2 {{redefinition of '}}
// expected-note@-3 {{unguarded header; consider using #ifdef guards or #pragma once}}
// FIXME: We should drop the "header from" in this diagnostic.