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[Clang][NFC] Improve const correctess of constraint normalization #133633

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Mar 30, 2025
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[Clang][NFC] Improve const correctess of constraint normalization #133633

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17 changes: 10 additions & 7 deletions clang/include/clang/Sema/Sema.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14660,7 +14660,8 @@ class Sema final : public SemaBase {
bool First = true);

const NormalizedConstraint *getNormalizedAssociatedConstraints(
NamedDecl *ConstrainedDecl, ArrayRef<const Expr *> AssociatedConstraints);
const NamedDecl *ConstrainedDecl,
ArrayRef<const Expr *> AssociatedConstraints);

/// \brief Check whether the given declaration's associated constraints are
/// at least as constrained than another declaration's according to the
Expand All @@ -14670,28 +14671,30 @@ class Sema final : public SemaBase {
/// at least constrained than D2, and false otherwise.
///
/// \returns true if an error occurred, false otherwise.
bool IsAtLeastAsConstrained(NamedDecl *D1, MutableArrayRef<const Expr *> AC1,
NamedDecl *D2, MutableArrayRef<const Expr *> AC2,
bool &Result);
bool IsAtLeastAsConstrained(const NamedDecl *D1,
MutableArrayRef<const Expr *> AC1,
const NamedDecl *D2,
MutableArrayRef<const Expr *> AC2, bool &Result);

/// If D1 was not at least as constrained as D2, but would've been if a pair
/// of atomic constraints involved had been declared in a concept and not
/// repeated in two separate places in code.
/// \returns true if such a diagnostic was emitted, false otherwise.
bool MaybeEmitAmbiguousAtomicConstraintsDiagnostic(
NamedDecl *D1, ArrayRef<const Expr *> AC1, NamedDecl *D2,
const NamedDecl *D1, ArrayRef<const Expr *> AC1, const NamedDecl *D2,
ArrayRef<const Expr *> AC2);

private:
/// Caches pairs of template-like decls whose associated constraints were
/// checked for subsumption and whether or not the first's constraints did in
/// fact subsume the second's.
llvm::DenseMap<std::pair<NamedDecl *, NamedDecl *>, bool> SubsumptionCache;
llvm::DenseMap<std::pair<const NamedDecl *, const NamedDecl *>, bool>
SubsumptionCache;
/// Caches the normalized associated constraints of declarations (concepts or
/// constrained declarations). If an error occurred while normalizing the
/// associated constraints of the template or concept, nullptr will be cached
/// here.
llvm::DenseMap<NamedDecl *, NormalizedConstraint *> NormalizationCache;
llvm::DenseMap<const NamedDecl *, NormalizedConstraint *> NormalizationCache;

llvm::ContextualFoldingSet<ConstraintSatisfaction, const ASTContext &>
SatisfactionCache;
Expand Down
14 changes: 7 additions & 7 deletions clang/include/clang/Sema/SemaConcept.h
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Expand Up @@ -31,10 +31,10 @@ enum { ConstraintAlignment = 8 };

struct alignas(ConstraintAlignment) AtomicConstraint {
const Expr *ConstraintExpr;
NamedDecl *ConstraintDecl;
const NamedDecl *ConstraintDecl;
std::optional<ArrayRef<TemplateArgumentLoc>> ParameterMapping;

AtomicConstraint(const Expr *ConstraintExpr, NamedDecl *ConstraintDecl)
AtomicConstraint(const Expr *ConstraintExpr, const NamedDecl *ConstraintDecl)
: ConstraintExpr(ConstraintExpr), ConstraintDecl(ConstraintDecl) {};

bool hasMatchingParameterMapping(ASTContext &C,
Expand Down Expand Up @@ -114,9 +114,9 @@ struct NormalizedConstraint {

private:
static std::optional<NormalizedConstraint>
fromConstraintExprs(Sema &S, NamedDecl *D, ArrayRef<const Expr *> E);
fromConstraintExprs(Sema &S, const NamedDecl *D, ArrayRef<const Expr *> E);
static std::optional<NormalizedConstraint>
fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E);
fromConstraintExpr(Sema &S, const NamedDecl *D, const Expr *E);
};

struct alignas(ConstraintAlignment) NormalizedConstraintPair {
Expand All @@ -137,7 +137,7 @@ struct alignas(ConstraintAlignment) FoldExpandedConstraint {
};

const NormalizedConstraint *getNormalizedAssociatedConstraints(
Sema &S, NamedDecl *ConstrainedDecl,
Sema &S, const NamedDecl *ConstrainedDecl,
ArrayRef<const Expr *> AssociatedConstraints);

/// \brief SubsumptionChecker establishes subsumption
Expand All @@ -149,8 +149,8 @@ class SubsumptionChecker {

SubsumptionChecker(Sema &SemaRef, SubsumptionCallable Callable = {});

std::optional<bool> Subsumes(NamedDecl *DP, ArrayRef<const Expr *> P,
NamedDecl *DQ, ArrayRef<const Expr *> Q);
std::optional<bool> Subsumes(const NamedDecl *DP, ArrayRef<const Expr *> P,
const NamedDecl *DQ, ArrayRef<const Expr *> Q);

bool Subsumes(const NormalizedConstraint *P, const NormalizedConstraint *Q);

Expand Down
36 changes: 20 additions & 16 deletions clang/lib/Sema/SemaConcept.cpp
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Expand Up @@ -453,6 +453,7 @@ static ExprResult calculateConstraintSatisfaction(
Sema::InstantiatingTemplate Inst(
S, AtomicExpr->getBeginLoc(),
Sema::InstantiatingTemplate::ConstraintSubstitution{},
// FIXME: improve const-correctness of InstantiatingTemplate
const_cast<NamedDecl *>(Template), Info,
AtomicExpr->getSourceRange());
if (Inst.isInvalid())
Expand Down Expand Up @@ -1435,9 +1436,9 @@ void Sema::DiagnoseUnsatisfiedConstraint(
}
}

const NormalizedConstraint *
Sema::getNormalizedAssociatedConstraints(
NamedDecl *ConstrainedDecl, ArrayRef<const Expr *> AssociatedConstraints) {
const NormalizedConstraint *Sema::getNormalizedAssociatedConstraints(
const NamedDecl *ConstrainedDecl,
ArrayRef<const Expr *> AssociatedConstraints) {
// In case the ConstrainedDecl comes from modules, it is necessary to use
// the canonical decl to avoid different atomic constraints with the 'same'
// declarations.
Expand All @@ -1461,7 +1462,7 @@ Sema::getNormalizedAssociatedConstraints(
}

const NormalizedConstraint *clang::getNormalizedAssociatedConstraints(
Sema &S, NamedDecl *ConstrainedDecl,
Sema &S, const NamedDecl *ConstrainedDecl,
ArrayRef<const Expr *> AssociatedConstraints) {
return S.getNormalizedAssociatedConstraints(ConstrainedDecl,
AssociatedConstraints);
Expand Down Expand Up @@ -1527,7 +1528,8 @@ substituteParameterMappings(Sema &S, NormalizedConstraint &N,
Sema::InstantiatingTemplate Inst(
S, InstLocBegin,
Sema::InstantiatingTemplate::ParameterMappingSubstitution{},
Atomic.ConstraintDecl, {InstLocBegin, InstLocEnd});
const_cast<NamedDecl *>(Atomic.ConstraintDecl),
{InstLocBegin, InstLocEnd});
if (Inst.isInvalid())
return true;
if (S.SubstTemplateArguments(*Atomic.ParameterMapping, MLTAL, SubstArgs))
Expand Down Expand Up @@ -1591,7 +1593,7 @@ NormalizedConstraint &NormalizedConstraint::getRHS() const {
}

std::optional<NormalizedConstraint>
NormalizedConstraint::fromConstraintExprs(Sema &S, NamedDecl *D,
NormalizedConstraint::fromConstraintExprs(Sema &S, const NamedDecl *D,
ArrayRef<const Expr *> E) {
assert(E.size() != 0);
auto Conjunction = fromConstraintExpr(S, D, E[0]);
Expand All @@ -1608,7 +1610,8 @@ NormalizedConstraint::fromConstraintExprs(Sema &S, NamedDecl *D,
}

std::optional<NormalizedConstraint>
NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
NormalizedConstraint::fromConstraintExpr(Sema &S, const NamedDecl *D,
const Expr *E) {
assert(E != nullptr);

// C++ [temp.constr.normal]p1.1
Expand Down Expand Up @@ -1637,8 +1640,9 @@ NormalizedConstraint::fromConstraintExpr(Sema &S, NamedDecl *D, const Expr *E) {
{
Sema::InstantiatingTemplate Inst(
S, CSE->getExprLoc(),
Sema::InstantiatingTemplate::ConstraintNormalization{}, D,
CSE->getSourceRange());
Sema::InstantiatingTemplate::ConstraintNormalization{},
// FIXME: improve const-correctness of InstantiatingTemplate
const_cast<NamedDecl *>(D), CSE->getSourceRange());
if (Inst.isInvalid())
return std::nullopt;
// C++ [temp.constr.normal]p1.1
Expand Down Expand Up @@ -1726,9 +1730,9 @@ bool FoldExpandedConstraint::AreCompatibleForSubsumption(
return false;
}

bool Sema::IsAtLeastAsConstrained(NamedDecl *D1,
bool Sema::IsAtLeastAsConstrained(const NamedDecl *D1,
MutableArrayRef<const Expr *> AC1,
NamedDecl *D2,
const NamedDecl *D2,
MutableArrayRef<const Expr *> AC2,
bool &Result) {
#ifndef NDEBUG
Expand All @@ -1755,7 +1759,7 @@ bool Sema::IsAtLeastAsConstrained(NamedDecl *D1,
return false;
}

std::pair<NamedDecl *, NamedDecl *> Key{D1, D2};
std::pair<const NamedDecl *, const NamedDecl *> Key{D1, D2};
auto CacheEntry = SubsumptionCache.find(Key);
if (CacheEntry != SubsumptionCache.end()) {
Result = CacheEntry->second;
Expand Down Expand Up @@ -1789,7 +1793,7 @@ bool Sema::IsAtLeastAsConstrained(NamedDecl *D1,
}

bool Sema::MaybeEmitAmbiguousAtomicConstraintsDiagnostic(
NamedDecl *D1, ArrayRef<const Expr *> AC1, NamedDecl *D2,
const NamedDecl *D1, ArrayRef<const Expr *> AC1, const NamedDecl *D2,
ArrayRef<const Expr *> AC2) {

if (isSFINAEContext())
Expand Down Expand Up @@ -2055,7 +2059,7 @@ FormulaType SubsumptionChecker::Normalize(const NormalizedConstraint &NC) {
FormulaType Res;

auto Add = [&, this](Clause C) {
// Sort each clause and remove duplicates for faster comparisons
// Sort each clause and remove duplicates for faster comparisons.
llvm::sort(C);
C.erase(llvm::unique(C), C.end());
AddUniqueClauseToFormula(Res, std::move(C));
Expand Down Expand Up @@ -2102,9 +2106,9 @@ void SubsumptionChecker::AddUniqueClauseToFormula(Formula &F, Clause C) {
F.push_back(C);
}

std::optional<bool> SubsumptionChecker::Subsumes(NamedDecl *DP,
std::optional<bool> SubsumptionChecker::Subsumes(const NamedDecl *DP,
ArrayRef<const Expr *> P,
NamedDecl *DQ,
const NamedDecl *DQ,
ArrayRef<const Expr *> Q) {
const NormalizedConstraint *PNormalized =
getNormalizedAssociatedConstraints(SemaRef, DP, P);
Expand Down
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