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merged 4 commits into from
Apr 2, 2025
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[clang] Track final substitution for Subst* AST nodes #132748

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b50ea7d
[clang] Track final substitution for SubstTemplateTemplateParm nodes
mizvekov Mar 22, 2025
6745c23
[clang] Track final substitution for SubstNonTypeTemplateParmExpr nodes
mizvekov Mar 22, 2025
789dfa2
[clang] Track final substitution for SubstTemplateTypeParmType nodes
mizvekov Mar 23, 2025
5a7e109
Revert "[clang] Add frontend flag to enable support for broken extern…
mizvekov Mar 23, 2025
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17 changes: 9 additions & 8 deletions clang/include/clang/AST/ASTContext.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1795,10 +1795,10 @@ class ASTContext : public RefCountedBase<ASTContext> {
QualType Wrapped, QualType Contained,
const HLSLAttributedResourceType::Attributes &Attrs);

QualType
getSubstTemplateTypeParmType(QualType Replacement, Decl *AssociatedDecl,
unsigned Index,
std::optional<unsigned> PackIndex) const;
QualType getSubstTemplateTypeParmType(QualType Replacement,
Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex,
bool Final) const;
QualType getSubstTemplateTypeParmPackType(Decl *AssociatedDecl,
unsigned Index, bool Final,
const TemplateArgument &ArgPack);
Expand Down Expand Up @@ -2393,10 +2393,11 @@ class ASTContext : public RefCountedBase<ASTContext> {
TemplateName
getDependentTemplateName(const DependentTemplateStorage &Name) const;

TemplateName
getSubstTemplateTemplateParm(TemplateName replacement, Decl *AssociatedDecl,
unsigned Index,
std::optional<unsigned> PackIndex) const;
TemplateName getSubstTemplateTemplateParm(TemplateName replacement,
Decl *AssociatedDecl,
unsigned Index,
std::optional<unsigned> PackIndex,
bool Final) const;
TemplateName getSubstTemplateTemplateParmPack(const TemplateArgument &ArgPack,
Decl *AssociatedDecl,
unsigned Index,
Expand Down
25 changes: 20 additions & 5 deletions clang/include/clang/AST/ExprCXX.h
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Expand Up @@ -4514,7 +4514,9 @@ class SubstNonTypeTemplateParmExpr : public Expr {
llvm::PointerIntPair<Decl *, 1, bool> AssociatedDeclAndRef;

unsigned Index : 15;
unsigned PackIndex : 16;
unsigned PackIndex : 15;
LLVM_PREFERRED_TYPE(bool)
unsigned Final : 1;

explicit SubstNonTypeTemplateParmExpr(EmptyShell Empty)
: Expr(SubstNonTypeTemplateParmExprClass, Empty) {}
Expand All @@ -4523,11 +4525,12 @@ class SubstNonTypeTemplateParmExpr : public Expr {
SubstNonTypeTemplateParmExpr(QualType Ty, ExprValueKind ValueKind,
SourceLocation Loc, Expr *Replacement,
Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex, bool RefParam)
std::optional<unsigned> PackIndex, bool RefParam,
bool Final)
: Expr(SubstNonTypeTemplateParmExprClass, Ty, ValueKind, OK_Ordinary),
Replacement(Replacement),
AssociatedDeclAndRef(AssociatedDecl, RefParam), Index(Index),
PackIndex(PackIndex ? *PackIndex + 1 : 0) {
PackIndex(PackIndex ? *PackIndex + 1 : 0), Final(Final) {
assert(AssociatedDecl != nullptr);
SubstNonTypeTemplateParmExprBits.NameLoc = Loc;
setDependence(computeDependence(this));
Expand Down Expand Up @@ -4555,6 +4558,10 @@ class SubstNonTypeTemplateParmExpr : public Expr {
return PackIndex - 1;
}

// This substitution is Final, which means the substitution is fully
// sugared: it doesn't need to be resugared later.
bool getFinal() const { return Final; }

NonTypeTemplateParmDecl *getParameter() const;

bool isReferenceParameter() const { return AssociatedDeclAndRef.getInt(); }
Expand Down Expand Up @@ -4598,7 +4605,10 @@ class SubstNonTypeTemplateParmPackExpr : public Expr {
const TemplateArgument *Arguments;

/// The number of template arguments in \c Arguments.
unsigned NumArguments : 16;
unsigned NumArguments : 15;

LLVM_PREFERRED_TYPE(bool)
unsigned Final : 1;

unsigned Index : 16;

Expand All @@ -4612,7 +4622,8 @@ class SubstNonTypeTemplateParmPackExpr : public Expr {
SubstNonTypeTemplateParmPackExpr(QualType T, ExprValueKind ValueKind,
SourceLocation NameLoc,
const TemplateArgument &ArgPack,
Decl *AssociatedDecl, unsigned Index);
Decl *AssociatedDecl, unsigned Index,
bool Final);

/// A template-like entity which owns the whole pattern being substituted.
/// This will own a set of template parameters.
Expand All @@ -4622,6 +4633,10 @@ class SubstNonTypeTemplateParmPackExpr : public Expr {
/// This should match the result of `getParameterPack()->getIndex()`.
unsigned getIndex() const { return Index; }

// This substitution will be Final, which means the substitution will be fully
// sugared: it doesn't need to be resugared later.
bool getFinal() const { return Final; }

/// Retrieve the non-type template parameter pack being substituted.
NonTypeTemplateParmDecl *getParameterPack() const;

Expand Down
3 changes: 2 additions & 1 deletion clang/include/clang/AST/PropertiesBase.td
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Expand Up @@ -730,8 +730,9 @@ let Class = PropertyTypeCase<TemplateName, "SubstTemplateTemplateParm"> in {
def : Property<"packIndex", Optional<UInt32>> {
let Read = [{ parm->getPackIndex() }];
}
def : Property<"final", Bool> { let Read = [{ parm->getFinal() }]; }
def : Creator<[{
return ctx.getSubstTemplateTemplateParm(replacement, associatedDecl, index, packIndex);
return ctx.getSubstTemplateTemplateParm(replacement, associatedDecl, index, packIndex, final);
}]>;
}
let Class = PropertyTypeCase<TemplateName, "SubstTemplateTemplateParmPack"> in {
Expand Down
17 changes: 12 additions & 5 deletions clang/include/clang/AST/TemplateName.h
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Expand Up @@ -414,9 +414,11 @@ class SubstTemplateTemplateParmStorage

SubstTemplateTemplateParmStorage(TemplateName Replacement,
Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex)
std::optional<unsigned> PackIndex,
bool Final)
: UncommonTemplateNameStorage(SubstTemplateTemplateParm, Index,
PackIndex ? *PackIndex + 1 : 0),
((PackIndex ? *PackIndex + 1 : 0) << 1) |
Final),
Replacement(Replacement), AssociatedDecl(AssociatedDecl) {
assert(AssociatedDecl != nullptr);
}
Expand All @@ -430,10 +432,15 @@ class SubstTemplateTemplateParmStorage
/// This should match the result of `getParameter()->getIndex()`.
unsigned getIndex() const { return Bits.Index; }

// This substitution is Final, which means the substitution is fully
// sugared: it doesn't need to be resugared later.
bool getFinal() const { return Bits.Data & 1; }

std::optional<unsigned> getPackIndex() const {
if (Bits.Data == 0)
auto Data = Bits.Data >> 1;
if (Data == 0)
return std::nullopt;
return Bits.Data - 1;
return Data - 1;
}

TemplateTemplateParmDecl *getParameter() const;
Expand All @@ -443,7 +450,7 @@ class SubstTemplateTemplateParmStorage

static void Profile(llvm::FoldingSetNodeID &ID, TemplateName Replacement,
Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex);
std::optional<unsigned> PackIndex, bool Final);
};

class DeducedTemplateStorage : public UncommonTemplateNameStorage,
Expand Down
24 changes: 14 additions & 10 deletions clang/include/clang/AST/Type.h
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Expand Up @@ -2158,12 +2158,15 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
// The index of the template parameter this substitution represents.
unsigned Index : 15;

LLVM_PREFERRED_TYPE(bool)
unsigned Final : 1;

/// Represents the index within a pack if this represents a substitution
/// from a pack expansion. This index starts at the end of the pack and
/// increments towards the beginning.
/// Positive non-zero number represents the index + 1.
/// Zero means this is not substituted from an expansion.
unsigned PackIndex : 16;
unsigned PackIndex : 15;
};

class SubstTemplateTypeParmPackTypeBitfields {
Expand Down Expand Up @@ -6397,7 +6400,8 @@ class SubstTemplateTypeParmType final
Decl *AssociatedDecl;

SubstTemplateTypeParmType(QualType Replacement, Decl *AssociatedDecl,
unsigned Index, std::optional<unsigned> PackIndex);
unsigned Index, std::optional<unsigned> PackIndex,
bool Final);

public:
/// Gets the type that was substituted for the template
Expand All @@ -6420,6 +6424,10 @@ class SubstTemplateTypeParmType final
/// This should match the result of `getReplacedParameter()->getIndex()`.
unsigned getIndex() const { return SubstTemplateTypeParmTypeBits.Index; }

// This substitution is Final, which means the substitution is fully
// sugared: it doesn't need to be resugared later.
unsigned getFinal() const { return SubstTemplateTypeParmTypeBits.Final; }

std::optional<unsigned> getPackIndex() const {
if (SubstTemplateTypeParmTypeBits.PackIndex == 0)
return std::nullopt;
Expand All @@ -6431,17 +6439,12 @@ class SubstTemplateTypeParmType final

void Profile(llvm::FoldingSetNodeID &ID) {
Profile(ID, getReplacementType(), getAssociatedDecl(), getIndex(),
getPackIndex());
getPackIndex(), getFinal());
}

static void Profile(llvm::FoldingSetNodeID &ID, QualType Replacement,
const Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex) {
Replacement.Profile(ID);
ID.AddPointer(AssociatedDecl);
ID.AddInteger(Index);
ID.AddInteger(PackIndex ? *PackIndex - 1 : 0);
}
std::optional<unsigned> PackIndex, bool Final);

static bool classof(const Type *T) {
return T->getTypeClass() == SubstTemplateTypeParm;
Expand Down Expand Up @@ -6488,7 +6491,8 @@ class SubstTemplateTypeParmPackType : public Type, public llvm::FoldingSetNode {
/// This should match the result of `getReplacedParameter()->getIndex()`.
unsigned getIndex() const { return SubstTemplateTypeParmPackTypeBits.Index; }

// When true the substitution will be 'Final' (subst node won't be placed).
// This substitution will be Final, which means the substitution will be fully
// sugared: it doesn't need to be resugared later.
bool getFinal() const;

unsigned getNumArgs() const {
Expand Down
4 changes: 2 additions & 2 deletions clang/include/clang/AST/TypeProperties.td
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Expand Up @@ -842,11 +842,11 @@ let Class = SubstTemplateTypeParmType in {
def : Property<"PackIndex", Optional<UInt32>> {
let Read = [{ node->getPackIndex() }];
}
def : Property<"Final", Bool> { let Read = [{ node->getFinal() }]; }

// The call to getCanonicalType here existed in ASTReader.cpp, too.
def : Creator<[{
return ctx.getSubstTemplateTypeParmType(
replacementType, associatedDecl, Index, PackIndex);
replacementType, associatedDecl, Index, PackIndex, Final);
}]>;
}

Expand Down
15 changes: 8 additions & 7 deletions clang/lib/AST/ASTContext.cpp
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Expand Up @@ -5447,10 +5447,10 @@ QualType ASTContext::getHLSLAttributedResourceType(
/// Retrieve a substitution-result type.
QualType ASTContext::getSubstTemplateTypeParmType(
QualType Replacement, Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex) const {
std::optional<unsigned> PackIndex, bool Final) const {
llvm::FoldingSetNodeID ID;
SubstTemplateTypeParmType::Profile(ID, Replacement, AssociatedDecl, Index,
PackIndex);
PackIndex, Final);
void *InsertPos = nullptr;
SubstTemplateTypeParmType *SubstParm =
SubstTemplateTypeParmTypes.FindNodeOrInsertPos(ID, InsertPos);
Expand All @@ -5460,7 +5460,7 @@ QualType ASTContext::getSubstTemplateTypeParmType(
!Replacement.isCanonical()),
alignof(SubstTemplateTypeParmType));
SubstParm = new (Mem) SubstTemplateTypeParmType(Replacement, AssociatedDecl,
Index, PackIndex);
Index, PackIndex, Final);
Types.push_back(SubstParm);
SubstTemplateTypeParmTypes.InsertNode(SubstParm, InsertPos);
}
Expand Down Expand Up @@ -10090,18 +10090,18 @@ ASTContext::getDependentTemplateName(const DependentTemplateStorage &S) const {

TemplateName ASTContext::getSubstTemplateTemplateParm(
TemplateName Replacement, Decl *AssociatedDecl, unsigned Index,
std::optional<unsigned> PackIndex) const {
std::optional<unsigned> PackIndex, bool Final) const {
llvm::FoldingSetNodeID ID;
SubstTemplateTemplateParmStorage::Profile(ID, Replacement, AssociatedDecl,
Index, PackIndex);
Index, PackIndex, Final);

void *insertPos = nullptr;
SubstTemplateTemplateParmStorage *subst
= SubstTemplateTemplateParms.FindNodeOrInsertPos(ID, insertPos);

if (!subst) {
subst = new (*this) SubstTemplateTemplateParmStorage(
Replacement, AssociatedDecl, Index, PackIndex);
Replacement, AssociatedDecl, Index, PackIndex, Final);
SubstTemplateTemplateParms.InsertNode(subst, insertPos);
}

Expand Down Expand Up @@ -14202,7 +14202,8 @@ static QualType getCommonSugarTypeNode(ASTContext &Ctx, const Type *X,
if (PackIndex != SY->getPackIndex())
return QualType();
return Ctx.getSubstTemplateTypeParmType(Ctx.getQualifiedType(Underlying),
CD, Index, PackIndex);
CD, Index, PackIndex,
SX->getFinal() && SY->getFinal());
}
case Type::ObjCTypeParam:
// FIXME: Try to merge these.
Expand Down
9 changes: 5 additions & 4 deletions clang/lib/AST/ASTImporter.cpp
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Expand Up @@ -1631,8 +1631,8 @@ ExpectedType ASTNodeImporter::VisitSubstTemplateTypeParmType(
return ToReplacementTypeOrErr.takeError();

return Importer.getToContext().getSubstTemplateTypeParmType(
*ToReplacementTypeOrErr, *ReplacedOrErr, T->getIndex(),
T->getPackIndex());
*ToReplacementTypeOrErr, *ReplacedOrErr, T->getIndex(), T->getPackIndex(),
T->getFinal());
}

ExpectedType ASTNodeImporter::VisitSubstTemplateTypeParmPackType(
Expand Down Expand Up @@ -8937,7 +8937,8 @@ ExpectedStmt ASTNodeImporter::VisitSubstNonTypeTemplateParmExpr(

return new (Importer.getToContext()) SubstNonTypeTemplateParmExpr(
ToType, E->getValueKind(), ToExprLoc, ToReplacement, ToAssociatedDecl,
E->getIndex(), E->getPackIndex(), E->isReferenceParameter());
E->getIndex(), E->getPackIndex(), E->isReferenceParameter(),
E->getFinal());
}

ExpectedStmt ASTNodeImporter::VisitTypeTraitExpr(TypeTraitExpr *E) {
Expand Down Expand Up @@ -9932,7 +9933,7 @@ Expected<TemplateName> ASTImporter::Import(TemplateName From) {

return ToContext.getSubstTemplateTemplateParm(
*ReplacementOrErr, *AssociatedDeclOrErr, Subst->getIndex(),
Subst->getPackIndex());
Subst->getPackIndex(), Subst->getFinal());
}

case TemplateName::SubstTemplateTemplateParmPack: {
Expand Down
6 changes: 4 additions & 2 deletions clang/lib/AST/ExprCXX.cpp
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Expand Up @@ -1760,10 +1760,12 @@ QualType SubstNonTypeTemplateParmExpr::getParameterType(

SubstNonTypeTemplateParmPackExpr::SubstNonTypeTemplateParmPackExpr(
QualType T, ExprValueKind ValueKind, SourceLocation NameLoc,
const TemplateArgument &ArgPack, Decl *AssociatedDecl, unsigned Index)
const TemplateArgument &ArgPack, Decl *AssociatedDecl, unsigned Index,
bool Final)
: Expr(SubstNonTypeTemplateParmPackExprClass, T, ValueKind, OK_Ordinary),
AssociatedDecl(AssociatedDecl), Arguments(ArgPack.pack_begin()),
NumArguments(ArgPack.pack_size()), Index(Index), NameLoc(NameLoc) {
NumArguments(ArgPack.pack_size()), Final(Final), Index(Index),
NameLoc(NameLoc) {
assert(AssociatedDecl != nullptr);
setDependence(ExprDependence::TypeValueInstantiation |
ExprDependence::UnexpandedPack);
Expand Down
6 changes: 4 additions & 2 deletions clang/lib/AST/TemplateName.cpp
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Expand Up @@ -77,16 +77,18 @@ SubstTemplateTemplateParmStorage::getParameter() const {
}

void SubstTemplateTemplateParmStorage::Profile(llvm::FoldingSetNodeID &ID) {
Profile(ID, Replacement, getAssociatedDecl(), getIndex(), getPackIndex());
Profile(ID, Replacement, getAssociatedDecl(), getIndex(), getPackIndex(),
getFinal());
}

void SubstTemplateTemplateParmStorage::Profile(
llvm::FoldingSetNodeID &ID, TemplateName Replacement, Decl *AssociatedDecl,
unsigned Index, std::optional<unsigned> PackIndex) {
unsigned Index, std::optional<unsigned> PackIndex, bool Final) {
Replacement.Profile(ID);
ID.AddPointer(AssociatedDecl);
ID.AddInteger(Index);
ID.AddInteger(PackIndex ? *PackIndex + 1 : 0);
ID.AddBoolean(Final);
}

SubstTemplateTemplateParmPackStorage::SubstTemplateTemplateParmPackStorage(
Expand Down
4 changes: 4 additions & 0 deletions clang/lib/AST/TextNodeDumper.cpp
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Expand Up @@ -1298,6 +1298,8 @@ void TextNodeDumper::dumpBareTemplateName(TemplateName TN) {
OS << " index " << STS->getIndex();
if (std::optional<unsigned int> PackIndex = STS->getPackIndex())
OS << " pack_index " << *PackIndex;
if (STS->getFinal())
OS << " final";
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as final is a keyword in C++ I wonder if we can find a better name for this. I certainly wouldn't see this in an AST and know what it means. I wonder if we should find a better name than final throughout this patch. Something like, FullySugared or something? Though open to other/better names.

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I am open for suggestions, but I'd prefer to change this in a follow up, since the term is existing and this would make the patch much larger.

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FullySugared seems fine to me, unless you have a better idea. I would be ok with changing the name in a followup, which wouldn't really require review once we agree on a name.

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FullySugared seems fine to me, unless you have a better idea. I would be ok with changing the name in a followup, which wouldn't really require review once we agree on a name.

+1

if (const TemplateTemplateParmDecl *P = STS->getParameter())
AddChild("parameter", [=] { Visit(P); });
dumpDeclRef(STS->getAssociatedDecl(), "associated");
Expand Down Expand Up @@ -2124,6 +2126,8 @@ void TextNodeDumper::VisitSubstTemplateTypeParmType(
VisitTemplateTypeParmDecl(T->getReplacedParameter());
if (auto PackIndex = T->getPackIndex())
OS << " pack_index " << *PackIndex;
if (T->getFinal())
OS << " final";
}

void TextNodeDumper::VisitSubstTemplateTypeParmPackType(
Expand Down
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