Skip to content

[clang] Fix non-deterministic infinite recursion... #118288

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Dec 10, 2024
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 5 additions & 1 deletion clang/include/clang/AST/ASTContext.h
Original file line number Diff line number Diff line change
@@ -245,7 +245,11 @@ class ASTContext : public RefCountedBase<ASTContext> {
mutable llvm::FoldingSet<ObjCObjectPointerType> ObjCObjectPointerTypes;
mutable llvm::FoldingSet<DependentUnaryTransformType>
DependentUnaryTransformTypes;
mutable llvm::ContextualFoldingSet<AutoType, ASTContext&> AutoTypes;
// An AutoType can have a dependency on another AutoType via its template
// arguments. Since both dependent and dependency are on the same set,
// we can end up in an infinite recursion when looking for a node if we used
// a `FoldingSet`, since both could end up in the same bucket.
mutable llvm::DenseMap<llvm::FoldingSetNodeID, AutoType *> AutoTypes;
mutable llvm::FoldingSet<DeducedTemplateSpecializationType>
DeducedTemplateSpecializationTypes;
mutable llvm::FoldingSet<AtomicType> AtomicTypes;
2 changes: 1 addition & 1 deletion clang/include/clang/AST/Type.h
Original file line number Diff line number Diff line change
@@ -6551,7 +6551,7 @@ class DeducedType : public Type {

/// Represents a C++11 auto or C++14 decltype(auto) type, possibly constrained
/// by a type-constraint.
class AutoType : public DeducedType, public llvm::FoldingSetNode {
class AutoType : public DeducedType {
friend class ASTContext; // ASTContext creates these

ConceptDecl *TypeConstraintConcept;
46 changes: 35 additions & 11 deletions clang/lib/AST/ASTContext.cpp
Original file line number Diff line number Diff line change
@@ -112,6 +112,27 @@ enum FloatingRank {
Ibm128Rank
};

template <> struct llvm::DenseMapInfo<llvm::FoldingSetNodeID> {
static FoldingSetNodeID getEmptyKey() { return FoldingSetNodeID{}; }

static FoldingSetNodeID getTombstoneKey() {
FoldingSetNodeID id;
for (size_t i = 0; i < sizeof(id) / sizeof(unsigned); ++i) {
id.AddInteger(std::numeric_limits<unsigned>::max());
}
return id;
}

static unsigned getHashValue(const FoldingSetNodeID &Val) {
return Val.ComputeHash();
}

static bool isEqual(const FoldingSetNodeID &LHS,
const FoldingSetNodeID &RHS) {
return LHS == RHS;
}
};

/// \returns The locations that are relevant when searching for Doc comments
/// related to \p D.
static SmallVector<SourceLocation, 2>
@@ -899,7 +920,7 @@ ASTContext::ASTContext(LangOptions &LOpts, SourceManager &SM,
FunctionProtoTypes(this_(), FunctionProtoTypesLog2InitSize),
DependentTypeOfExprTypes(this_()), DependentDecltypeTypes(this_()),
TemplateSpecializationTypes(this_()),
DependentTemplateSpecializationTypes(this_()), AutoTypes(this_()),
DependentTemplateSpecializationTypes(this_()),
DependentBitIntTypes(this_()), SubstTemplateTemplateParmPacks(this_()),
DeducedTemplates(this_()), ArrayParameterTypes(this_()),
CanonTemplateTemplateParms(this_()), SourceMgr(SM), LangOpts(LOpts),
@@ -6294,12 +6315,14 @@ QualType ASTContext::getAutoTypeInternal(
return getAutoDeductType();

// Look in the folding set for an existing type.
void *InsertPos = nullptr;
llvm::FoldingSetNodeID ID;
AutoType::Profile(ID, *this, DeducedType, Keyword, IsDependent,
TypeConstraintConcept, TypeConstraintArgs);
if (AutoType *AT = AutoTypes.FindNodeOrInsertPos(ID, InsertPos))
return QualType(AT, 0);
bool IsDeducedDependent =
!DeducedType.isNull() && DeducedType->isDependentType();
AutoType::Profile(ID, *this, DeducedType, Keyword,
IsDependent || IsDeducedDependent, TypeConstraintConcept,
TypeConstraintArgs);
if (auto const AT_iter = AutoTypes.find(ID); AT_iter != AutoTypes.end())
return QualType(AT_iter->getSecond(), 0);

QualType Canon;
if (!IsCanon) {
@@ -6314,10 +6337,6 @@ QualType ASTContext::getAutoTypeInternal(
Canon =
getAutoTypeInternal(QualType(), Keyword, IsDependent, IsPack,
CanonicalConcept, CanonicalConceptArgs, true);
// Find the insert position again.
[[maybe_unused]] auto *Nothing =
AutoTypes.FindNodeOrInsertPos(ID, InsertPos);
assert(!Nothing && "canonical type broken");
}
}
}
@@ -6331,8 +6350,13 @@ QualType ASTContext::getAutoTypeInternal(
: TypeDependence::None) |
(IsPack ? TypeDependence::UnexpandedPack : TypeDependence::None),
Canon, TypeConstraintConcept, TypeConstraintArgs);
#ifndef NDEBUG
llvm::FoldingSetNodeID InsertedID;
AT->Profile(InsertedID, *this);
assert(InsertedID == ID && "ID does not match");
#endif
Types.push_back(AT);
AutoTypes.InsertNode(AT, InsertPos);
AutoTypes.try_emplace(ID, AT);
return QualType(AT, 0);
}

12 changes: 12 additions & 0 deletions clang/test/Parser/gh110231.cpp
Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
// RUN: seq 100 | xargs -Ifoo %clang_cc1 -std=c++20 -fsyntax-only -verify %s
// expected-no-diagnostics
// This is a regression test for a non-deterministic stack-overflow.

template < typename >
concept C1 = true;

template < typename , auto >
concept C2 = true;

template < C1 auto V, C2< V > auto>
struct S;