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llvm-project/clang/lib/Sema/SemaConcept.cpp
Younan Zhang 2984a8db80
[Clang] Fix an iterator invalidation bug in concept normalization cache (#165352) 
The NormalizationCache may be inserted recursively when normalizing
template arguments with non-dependent default arguments. Since the ADT
doesn't preserve iterator validity, this caused undefined behavior.

This is a regression on trunk so there is no release note.

Fixes https://github.com/llvm/llvm-project/issues/165238
2025-10-28 15:15:35 +08:00

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//===-- SemaConcept.cpp - Semantic Analysis for Constraints and Concepts --===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ constraints and concepts.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/SemaConcept.h"
#include "TreeTransform.h"
#include "clang/AST/ASTConcept.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/ExprConcepts.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Basic/OperatorPrecedence.h"
#include "clang/Sema/EnterExpressionEvaluationContext.h"
#include "clang/Sema/Initialization.h"
#include "clang/Sema/Overload.h"
#include "clang/Sema/ScopeInfo.h"
#include "clang/Sema/Sema.h"
#include "clang/Sema/SemaInternal.h"
#include "clang/Sema/Template.h"
#include "clang/Sema/TemplateDeduction.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/PointerUnion.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/SaveAndRestore.h"
using namespace clang;
using namespace sema;
namespace {
class LogicalBinOp {
SourceLocation Loc;
OverloadedOperatorKind Op = OO_None;
const Expr *LHS = nullptr;
const Expr *RHS = nullptr;
public:
LogicalBinOp(const Expr *E) {
if (auto *BO = dyn_cast<BinaryOperator>(E)) {
Op = BinaryOperator::getOverloadedOperator(BO->getOpcode());
LHS = BO->getLHS();
RHS = BO->getRHS();
Loc = BO->getExprLoc();
} else if (auto *OO = dyn_cast<CXXOperatorCallExpr>(E)) {
// If OO is not || or && it might not have exactly 2 arguments.
if (OO->getNumArgs() == 2) {
Op = OO->getOperator();
LHS = OO->getArg(0);
RHS = OO->getArg(1);
Loc = OO->getOperatorLoc();
}
}
}
bool isAnd() const { return Op == OO_AmpAmp; }
bool isOr() const { return Op == OO_PipePipe; }
explicit operator bool() const { return isAnd() || isOr(); }
const Expr *getLHS() const { return LHS; }
const Expr *getRHS() const { return RHS; }
OverloadedOperatorKind getOp() const { return Op; }
ExprResult recreateBinOp(Sema &SemaRef, ExprResult LHS) const {
return recreateBinOp(SemaRef, LHS, const_cast<Expr *>(getRHS()));
}
ExprResult recreateBinOp(Sema &SemaRef, ExprResult LHS,
ExprResult RHS) const {
assert((isAnd() || isOr()) && "Not the right kind of op?");
assert((!LHS.isInvalid() && !RHS.isInvalid()) && "not good expressions?");
if (!LHS.isUsable() || !RHS.isUsable())
return ExprEmpty();
// We should just be able to 'normalize' these to the builtin Binary
// Operator, since that is how they are evaluated in constriant checks.
return BinaryOperator::Create(SemaRef.Context, LHS.get(), RHS.get(),
BinaryOperator::getOverloadedOpcode(Op),
SemaRef.Context.BoolTy, VK_PRValue,
OK_Ordinary, Loc, FPOptionsOverride{});
}
};
} // namespace
bool Sema::CheckConstraintExpression(const Expr *ConstraintExpression,
Token NextToken, bool *PossibleNonPrimary,
bool IsTrailingRequiresClause) {
// C++2a [temp.constr.atomic]p1
// ..E shall be a constant expression of type bool.
ConstraintExpression = ConstraintExpression->IgnoreParenImpCasts();
if (LogicalBinOp BO = ConstraintExpression) {
return CheckConstraintExpression(BO.getLHS(), NextToken,
PossibleNonPrimary) &&
CheckConstraintExpression(BO.getRHS(), NextToken,
PossibleNonPrimary);
} else if (auto *C = dyn_cast<ExprWithCleanups>(ConstraintExpression))
return CheckConstraintExpression(C->getSubExpr(), NextToken,
PossibleNonPrimary);
QualType Type = ConstraintExpression->getType();
auto CheckForNonPrimary = [&] {
if (!PossibleNonPrimary)
return;
*PossibleNonPrimary =
// We have the following case:
// template<typename> requires func(0) struct S { };
// The user probably isn't aware of the parentheses required around
// the function call, and we're only going to parse 'func' as the
// primary-expression, and complain that it is of non-bool type.
//
// However, if we're in a lambda, this might also be:
// []<typename> requires var () {};
// Which also looks like a function call due to the lambda parentheses,
// but unlike the first case, isn't an error, so this check is skipped.
(NextToken.is(tok::l_paren) &&
(IsTrailingRequiresClause ||
(Type->isDependentType() &&
isa<UnresolvedLookupExpr>(ConstraintExpression) &&
!dyn_cast_if_present<LambdaScopeInfo>(getCurFunction())) ||
Type->isFunctionType() ||
Type->isSpecificBuiltinType(BuiltinType::Overload))) ||
// We have the following case:
// template<typename T> requires size_<T> == 0 struct S { };
// The user probably isn't aware of the parentheses required around
// the binary operator, and we're only going to parse 'func' as the
// first operand, and complain that it is of non-bool type.
getBinOpPrecedence(NextToken.getKind(),
/*GreaterThanIsOperator=*/true,
getLangOpts().CPlusPlus11) > prec::LogicalAnd;
};
// An atomic constraint!
if (ConstraintExpression->isTypeDependent()) {
CheckForNonPrimary();
return true;
}
if (!Context.hasSameUnqualifiedType(Type, Context.BoolTy)) {
Diag(ConstraintExpression->getExprLoc(),
diag::err_non_bool_atomic_constraint)
<< Type << ConstraintExpression->getSourceRange();
CheckForNonPrimary();
return false;
}
if (PossibleNonPrimary)
*PossibleNonPrimary = false;
return true;
}
namespace {
struct SatisfactionStackRAII {
Sema &SemaRef;
bool Inserted = false;
SatisfactionStackRAII(Sema &SemaRef, const NamedDecl *ND,
const llvm::FoldingSetNodeID &FSNID)
: SemaRef(SemaRef) {
if (ND) {
SemaRef.PushSatisfactionStackEntry(ND, FSNID);
Inserted = true;
}
}
~SatisfactionStackRAII() {
if (Inserted)
SemaRef.PopSatisfactionStackEntry();
}
};
} // namespace
static bool DiagRecursiveConstraintEval(
Sema &S, llvm::FoldingSetNodeID &ID, const NamedDecl *Templ, const Expr *E,
const MultiLevelTemplateArgumentList *MLTAL = nullptr) {
E->Profile(ID, S.Context, /*Canonical=*/true);
if (MLTAL) {
for (const auto &List : *MLTAL)
for (const auto &TemplateArg : List.Args)
S.Context.getCanonicalTemplateArgument(TemplateArg)
.Profile(ID, S.Context);
}
if (S.SatisfactionStackContains(Templ, ID)) {
S.Diag(E->getExprLoc(), diag::err_constraint_depends_on_self)
<< E << E->getSourceRange();
return true;
}
return false;
}
// Figure out the to-translation-unit depth for this function declaration for
// the purpose of seeing if they differ by constraints. This isn't the same as
// getTemplateDepth, because it includes already instantiated parents.
static unsigned
CalculateTemplateDepthForConstraints(Sema &S, const NamedDecl *ND,
bool SkipForSpecialization = false) {
MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
ND, ND->getLexicalDeclContext(), /*Final=*/false,
/*Innermost=*/std::nullopt,
/*RelativeToPrimary=*/true,
/*Pattern=*/nullptr,
/*ForConstraintInstantiation=*/true, SkipForSpecialization);
return MLTAL.getNumLevels();
}
namespace {
class AdjustConstraintDepth : public TreeTransform<AdjustConstraintDepth> {
unsigned TemplateDepth = 0;
public:
using inherited = TreeTransform<AdjustConstraintDepth>;
AdjustConstraintDepth(Sema &SemaRef, unsigned TemplateDepth)
: inherited(SemaRef), TemplateDepth(TemplateDepth) {}
using inherited::TransformTemplateTypeParmType;
QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
TemplateTypeParmTypeLoc TL, bool) {
const TemplateTypeParmType *T = TL.getTypePtr();
TemplateTypeParmDecl *NewTTPDecl = nullptr;
if (TemplateTypeParmDecl *OldTTPDecl = T->getDecl())
NewTTPDecl = cast_or_null<TemplateTypeParmDecl>(
TransformDecl(TL.getNameLoc(), OldTTPDecl));
QualType Result = getSema().Context.getTemplateTypeParmType(
T->getDepth() + TemplateDepth, T->getIndex(), T->isParameterPack(),
NewTTPDecl);
TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
NewTL.setNameLoc(TL.getNameLoc());
return Result;
}
bool AlreadyTransformed(QualType T) {
if (T.isNull())
return true;
if (T->isInstantiationDependentType() || T->isVariablyModifiedType() ||
T->containsUnexpandedParameterPack())
return false;
return true;
}
};
} // namespace
namespace {
// FIXME: Convert it to DynamicRecursiveASTVisitor
class HashParameterMapping : public RecursiveASTVisitor<HashParameterMapping> {
using inherited = RecursiveASTVisitor<HashParameterMapping>;
friend inherited;
Sema &SemaRef;
const MultiLevelTemplateArgumentList &TemplateArgs;
llvm::FoldingSetNodeID &ID;
llvm::SmallVector<TemplateArgument, 10> UsedTemplateArgs;
UnsignedOrNone OuterPackSubstIndex;
bool shouldVisitTemplateInstantiations() const { return true; }
public:
HashParameterMapping(Sema &SemaRef,
const MultiLevelTemplateArgumentList &TemplateArgs,
llvm::FoldingSetNodeID &ID,
UnsignedOrNone OuterPackSubstIndex)
: SemaRef(SemaRef), TemplateArgs(TemplateArgs), ID(ID),
OuterPackSubstIndex(OuterPackSubstIndex) {}
bool VisitTemplateTypeParmType(TemplateTypeParmType *T) {
// A lambda expression can introduce template parameters that don't have
// corresponding template arguments yet.
if (T->getDepth() >= TemplateArgs.getNumLevels())
return true;
// There might not be a corresponding template argument before substituting
// into the parameter mapping, e.g. a sizeof... expression.
if (!TemplateArgs.hasTemplateArgument(T->getDepth(), T->getIndex()))
return true;
TemplateArgument Arg = TemplateArgs(T->getDepth(), T->getIndex());
if (T->isParameterPack() && SemaRef.ArgPackSubstIndex) {
assert(Arg.getKind() == TemplateArgument::Pack &&
"Missing argument pack");
Arg = SemaRef.getPackSubstitutedTemplateArgument(Arg);
}
UsedTemplateArgs.push_back(
SemaRef.Context.getCanonicalTemplateArgument(Arg));
return true;
}
bool VisitDeclRefExpr(DeclRefExpr *E) {
NamedDecl *D = E->getDecl();
NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(D);
if (!NTTP)
return TraverseDecl(D);
if (NTTP->getDepth() >= TemplateArgs.getNumLevels())
return true;
if (!TemplateArgs.hasTemplateArgument(NTTP->getDepth(), NTTP->getIndex()))
return true;
TemplateArgument Arg = TemplateArgs(NTTP->getDepth(), NTTP->getPosition());
if (NTTP->isParameterPack() && SemaRef.ArgPackSubstIndex) {
assert(Arg.getKind() == TemplateArgument::Pack &&
"Missing argument pack");
Arg = SemaRef.getPackSubstitutedTemplateArgument(Arg);
}
UsedTemplateArgs.push_back(
SemaRef.Context.getCanonicalTemplateArgument(Arg));
return true;
}
bool VisitTypedefType(TypedefType *TT) {
return inherited::TraverseType(TT->desugar());
}
bool TraverseDecl(Decl *D) {
if (auto *VD = dyn_cast<ValueDecl>(D)) {
if (auto *Var = dyn_cast<VarDecl>(VD))
TraverseStmt(Var->getInit());
return TraverseType(VD->getType());
}
return inherited::TraverseDecl(D);
}
bool TraverseCallExpr(CallExpr *CE) {
inherited::TraverseStmt(CE->getCallee());
for (Expr *Arg : CE->arguments())
inherited::TraverseStmt(Arg);
return true;
}
bool TraverseTypeLoc(TypeLoc TL, bool TraverseQualifier = true) {
// We don't care about TypeLocs. So traverse Types instead.
return TraverseType(TL.getType().getCanonicalType(), TraverseQualifier);
}
bool TraverseTagType(const TagType *T, bool TraverseQualifier) {
// T's parent can be dependent while T doesn't have any template arguments.
// We should have already traversed its qualifier.
// FIXME: Add an assert to catch cases where we failed to profile the
// concept.
return true;
}
bool TraverseInjectedClassNameType(InjectedClassNameType *T,
bool TraverseQualifier) {
return TraverseTemplateArguments(T->getTemplateArgs(SemaRef.Context));
}
bool TraverseTemplateArgument(const TemplateArgument &Arg) {
if (!Arg.containsUnexpandedParameterPack() || Arg.isPackExpansion()) {
// Act as if we are fully expanding this pack, if it is a PackExpansion.
Sema::ArgPackSubstIndexRAII _1(SemaRef, std::nullopt);
llvm::SaveAndRestore<UnsignedOrNone> _2(OuterPackSubstIndex,
std::nullopt);
return inherited::TraverseTemplateArgument(Arg);
}
Sema::ArgPackSubstIndexRAII _1(SemaRef, OuterPackSubstIndex);
return inherited::TraverseTemplateArgument(Arg);
}
bool TraverseSizeOfPackExpr(SizeOfPackExpr *SOPE) {
return TraverseDecl(SOPE->getPack());
}
bool VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
return inherited::TraverseStmt(E->getReplacement());
}
bool TraverseTemplateName(TemplateName Template) {
if (auto *TTP = dyn_cast_if_present<TemplateTemplateParmDecl>(
Template.getAsTemplateDecl());
TTP && TTP->getDepth() < TemplateArgs.getNumLevels()) {
if (!TemplateArgs.hasTemplateArgument(TTP->getDepth(),
TTP->getPosition()))
return true;
TemplateArgument Arg = TemplateArgs(TTP->getDepth(), TTP->getPosition());
if (TTP->isParameterPack() && SemaRef.ArgPackSubstIndex) {
assert(Arg.getKind() == TemplateArgument::Pack &&
"Missing argument pack");
Arg = SemaRef.getPackSubstitutedTemplateArgument(Arg);
}
assert(!Arg.getAsTemplate().isNull() &&
"Null template template argument");
UsedTemplateArgs.push_back(
SemaRef.Context.getCanonicalTemplateArgument(Arg));
}
return inherited::TraverseTemplateName(Template);
}
void VisitConstraint(const NormalizedConstraintWithParamMapping &Constraint) {
if (!Constraint.hasParameterMapping()) {
for (const auto &List : TemplateArgs)
for (const TemplateArgument &Arg : List.Args)
SemaRef.Context.getCanonicalTemplateArgument(Arg).Profile(
ID, SemaRef.Context);
return;
}
llvm::ArrayRef<TemplateArgumentLoc> Mapping =
Constraint.getParameterMapping();
for (auto &ArgLoc : Mapping) {
TemplateArgument Canonical =
SemaRef.Context.getCanonicalTemplateArgument(ArgLoc.getArgument());
// We don't want sugars to impede the profile of cache.
UsedTemplateArgs.push_back(Canonical);
TraverseTemplateArgument(Canonical);
}
for (auto &Used : UsedTemplateArgs) {
llvm::FoldingSetNodeID R;
Used.Profile(R, SemaRef.Context);
ID.AddNodeID(R);
}
}
};
class ConstraintSatisfactionChecker {
Sema &S;
const NamedDecl *Template;
SourceLocation TemplateNameLoc;
UnsignedOrNone PackSubstitutionIndex;
ConstraintSatisfaction &Satisfaction;
bool BuildExpression;
private:
ExprResult
EvaluateAtomicConstraint(const Expr *AtomicExpr,
const MultiLevelTemplateArgumentList &MLTAL);
UnsignedOrNone EvaluateFoldExpandedConstraintSize(
const FoldExpandedConstraint &FE,
const MultiLevelTemplateArgumentList &MLTAL);
// XXX: It is SLOW! Use it very carefully.
std::optional<MultiLevelTemplateArgumentList> SubstitutionInTemplateArguments(
const NormalizedConstraintWithParamMapping &Constraint,
const MultiLevelTemplateArgumentList &MLTAL,
llvm::SmallVector<TemplateArgument> &SubstitutedOuterMost);
ExprResult EvaluateSlow(const AtomicConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
ExprResult Evaluate(const AtomicConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
ExprResult EvaluateSlow(const FoldExpandedConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
ExprResult Evaluate(const FoldExpandedConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
ExprResult EvaluateSlow(const ConceptIdConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL,
unsigned int Size);
ExprResult Evaluate(const ConceptIdConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
ExprResult Evaluate(const CompoundConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
public:
ConstraintSatisfactionChecker(Sema &SemaRef, const NamedDecl *Template,
SourceLocation TemplateNameLoc,
UnsignedOrNone PackSubstitutionIndex,
ConstraintSatisfaction &Satisfaction,
bool BuildExpression)
: S(SemaRef), Template(Template), TemplateNameLoc(TemplateNameLoc),
PackSubstitutionIndex(PackSubstitutionIndex),
Satisfaction(Satisfaction), BuildExpression(BuildExpression) {}
ExprResult Evaluate(const NormalizedConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL);
};
StringRef allocateStringFromConceptDiagnostic(const Sema &S,
const PartialDiagnostic Diag) {
SmallString<128> DiagString;
DiagString = ": ";
Diag.EmitToString(S.getDiagnostics(), DiagString);
return S.getASTContext().backupStr(DiagString);
}
} // namespace
ExprResult ConstraintSatisfactionChecker::EvaluateAtomicConstraint(
const Expr *AtomicExpr, const MultiLevelTemplateArgumentList &MLTAL) {
EnterExpressionEvaluationContext ConstantEvaluated(
S, Sema::ExpressionEvaluationContext::ConstantEvaluated,
Sema::ReuseLambdaContextDecl);
llvm::FoldingSetNodeID ID;
if (Template &&
DiagRecursiveConstraintEval(S, ID, Template, AtomicExpr, &MLTAL)) {
Satisfaction.IsSatisfied = false;
Satisfaction.ContainsErrors = true;
return ExprEmpty();
}
SatisfactionStackRAII StackRAII(S, Template, ID);
// Atomic constraint - substitute arguments and check satisfaction.
ExprResult SubstitutedExpression = const_cast<Expr *>(AtomicExpr);
{
TemplateDeductionInfo Info(TemplateNameLoc);
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())
return ExprError();
// We do not want error diagnostics escaping here.
Sema::SFINAETrap Trap(S);
SubstitutedExpression =
S.SubstConstraintExpr(const_cast<Expr *>(AtomicExpr), MLTAL);
if (SubstitutedExpression.isInvalid() || Trap.hasErrorOccurred()) {
// C++2a [temp.constr.atomic]p1
// ...If substitution results in an invalid type or expression, the
// constraint is not satisfied.
if (!Trap.hasErrorOccurred())
// A non-SFINAE error has occurred as a result of this
// substitution.
return ExprError();
PartialDiagnosticAt SubstDiag{SourceLocation(),
PartialDiagnostic::NullDiagnostic()};
Info.takeSFINAEDiagnostic(SubstDiag);
// FIXME: This is an unfortunate consequence of there
// being no serialization code for PartialDiagnostics and the fact
// that serializing them would likely take a lot more storage than
// just storing them as strings. We would still like, in the
// future, to serialize the proper PartialDiagnostic as serializing
// it as a string defeats the purpose of the diagnostic mechanism.
Satisfaction.Details.emplace_back(
new (S.Context) ConstraintSubstitutionDiagnostic{
SubstDiag.first,
allocateStringFromConceptDiagnostic(S, SubstDiag.second)});
Satisfaction.IsSatisfied = false;
return ExprEmpty();
}
}
if (!S.CheckConstraintExpression(SubstitutedExpression.get()))
return ExprError();
// [temp.constr.atomic]p3: To determine if an atomic constraint is
// satisfied, the parameter mapping and template arguments are first
// substituted into its expression. If substitution results in an
// invalid type or expression, the constraint is not satisfied.
// Otherwise, the lvalue-to-rvalue conversion is performed if necessary,
// and E shall be a constant expression of type bool.
//
// Perform the L to R Value conversion if necessary. We do so for all
// non-PRValue categories, else we fail to extend the lifetime of
// temporaries, and that fails the constant expression check.
if (!SubstitutedExpression.get()->isPRValue())
SubstitutedExpression = ImplicitCastExpr::Create(
S.Context, SubstitutedExpression.get()->getType(), CK_LValueToRValue,
SubstitutedExpression.get(),
/*BasePath=*/nullptr, VK_PRValue, FPOptionsOverride());
return SubstitutedExpression;
}
std::optional<MultiLevelTemplateArgumentList>
ConstraintSatisfactionChecker::SubstitutionInTemplateArguments(
const NormalizedConstraintWithParamMapping &Constraint,
const MultiLevelTemplateArgumentList &MLTAL,
llvm::SmallVector<TemplateArgument> &SubstitutedOutermost) {
if (!Constraint.hasParameterMapping())
return std::move(MLTAL);
// The mapping is empty, meaning no template arguments are needed for
// evaluation.
if (Constraint.getParameterMapping().empty())
return MultiLevelTemplateArgumentList();
TemplateDeductionInfo Info(Constraint.getBeginLoc());
Sema::InstantiatingTemplate Inst(
S, Constraint.getBeginLoc(),
Sema::InstantiatingTemplate::ConstraintSubstitution{},
// FIXME: improve const-correctness of InstantiatingTemplate
const_cast<NamedDecl *>(Template), Info, Constraint.getSourceRange());
if (Inst.isInvalid())
return std::nullopt;
Sema::SFINAETrap Trap(S);
TemplateArgumentListInfo SubstArgs;
Sema::ArgPackSubstIndexRAII SubstIndex(
S, Constraint.getPackSubstitutionIndex()
? Constraint.getPackSubstitutionIndex()
: PackSubstitutionIndex);
if (S.SubstTemplateArgumentsInParameterMapping(
Constraint.getParameterMapping(), Constraint.getBeginLoc(), MLTAL,
SubstArgs, /*BuildPackExpansionTypes=*/true)) {
Satisfaction.IsSatisfied = false;
return std::nullopt;
}
Sema::CheckTemplateArgumentInfo CTAI;
auto *TD = const_cast<TemplateDecl *>(
cast<TemplateDecl>(Constraint.getConstraintDecl()));
if (S.CheckTemplateArgumentList(TD, Constraint.getUsedTemplateParamList(),
TD->getLocation(), SubstArgs,
/*DefaultArguments=*/{},
/*PartialTemplateArgs=*/false, CTAI))
return std::nullopt;
const NormalizedConstraint::OccurenceList &Used =
Constraint.mappingOccurenceList();
// The empty MLTAL situation should only occur when evaluating non-dependent
// constraints.
if (MLTAL.getNumSubstitutedLevels())
SubstitutedOutermost =
llvm::to_vector_of<TemplateArgument>(MLTAL.getOutermost());
unsigned Offset = 0;
for (unsigned I = 0, MappedIndex = 0; I < Used.size(); I++) {
TemplateArgument Arg;
if (Used[I])
Arg = S.Context.getCanonicalTemplateArgument(
CTAI.SugaredConverted[MappedIndex++]);
if (I < SubstitutedOutermost.size()) {
SubstitutedOutermost[I] = Arg;
Offset = I + 1;
} else {
SubstitutedOutermost.push_back(Arg);
Offset = SubstitutedOutermost.size();
}
}
if (Offset < SubstitutedOutermost.size())
SubstitutedOutermost.erase(SubstitutedOutermost.begin() + Offset);
MultiLevelTemplateArgumentList SubstitutedTemplateArgs;
SubstitutedTemplateArgs.addOuterTemplateArguments(TD, SubstitutedOutermost,
/*Final=*/false);
return std::move(SubstitutedTemplateArgs);
}
ExprResult ConstraintSatisfactionChecker::EvaluateSlow(
const AtomicConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
llvm::SmallVector<TemplateArgument> SubstitutedOutermost;
std::optional<MultiLevelTemplateArgumentList> SubstitutedArgs =
SubstitutionInTemplateArguments(Constraint, MLTAL, SubstitutedOutermost);
if (!SubstitutedArgs) {
Satisfaction.IsSatisfied = false;
return ExprEmpty();
}
Sema::ArgPackSubstIndexRAII SubstIndex(S, PackSubstitutionIndex);
ExprResult SubstitutedAtomicExpr = EvaluateAtomicConstraint(
Constraint.getConstraintExpr(), *SubstitutedArgs);
if (SubstitutedAtomicExpr.isInvalid())
return ExprError();
if (SubstitutedAtomicExpr.isUnset())
// Evaluator has decided satisfaction without yielding an expression.
return ExprEmpty();
// We don't have the ability to evaluate this, since it contains a
// RecoveryExpr, so we want to fail overload resolution. Otherwise,
// we'd potentially pick up a different overload, and cause confusing
// diagnostics. SO, add a failure detail that will cause us to make this
// overload set not viable.
if (SubstitutedAtomicExpr.get()->containsErrors()) {
Satisfaction.IsSatisfied = false;
Satisfaction.ContainsErrors = true;
PartialDiagnostic Msg = S.PDiag(diag::note_constraint_references_error);
Satisfaction.Details.emplace_back(
new (S.Context) ConstraintSubstitutionDiagnostic{
SubstitutedAtomicExpr.get()->getBeginLoc(),
allocateStringFromConceptDiagnostic(S, Msg)});
return SubstitutedAtomicExpr;
}
if (SubstitutedAtomicExpr.get()->isValueDependent()) {
Satisfaction.IsSatisfied = true;
Satisfaction.ContainsErrors = false;
return SubstitutedAtomicExpr;
}
EnterExpressionEvaluationContext ConstantEvaluated(
S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
SmallVector<PartialDiagnosticAt, 2> EvaluationDiags;
Expr::EvalResult EvalResult;
EvalResult.Diag = &EvaluationDiags;
if (!SubstitutedAtomicExpr.get()->EvaluateAsConstantExpr(EvalResult,
S.Context) ||
!EvaluationDiags.empty()) {
// C++2a [temp.constr.atomic]p1
// ...E shall be a constant expression of type bool.
S.Diag(SubstitutedAtomicExpr.get()->getBeginLoc(),
diag::err_non_constant_constraint_expression)
<< SubstitutedAtomicExpr.get()->getSourceRange();
for (const PartialDiagnosticAt &PDiag : EvaluationDiags)
S.Diag(PDiag.first, PDiag.second);
return ExprError();
}
assert(EvalResult.Val.isInt() &&
"evaluating bool expression didn't produce int");
Satisfaction.IsSatisfied = EvalResult.Val.getInt().getBoolValue();
if (!Satisfaction.IsSatisfied)
Satisfaction.Details.emplace_back(SubstitutedAtomicExpr.get());
return SubstitutedAtomicExpr;
}
ExprResult ConstraintSatisfactionChecker::Evaluate(
const AtomicConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
unsigned Size = Satisfaction.Details.size();
llvm::FoldingSetNodeID ID;
UnsignedOrNone OuterPackSubstIndex =
Constraint.getPackSubstitutionIndex()
? Constraint.getPackSubstitutionIndex()
: PackSubstitutionIndex;
ID.AddPointer(Constraint.getConstraintExpr());
ID.AddInteger(OuterPackSubstIndex.toInternalRepresentation());
HashParameterMapping(S, MLTAL, ID, OuterPackSubstIndex)
.VisitConstraint(Constraint);
if (auto Iter = S.UnsubstitutedConstraintSatisfactionCache.find(ID);
Iter != S.UnsubstitutedConstraintSatisfactionCache.end()) {
auto &Cached = Iter->second.Satisfaction;
Satisfaction.ContainsErrors = Cached.ContainsErrors;
Satisfaction.IsSatisfied = Cached.IsSatisfied;
Satisfaction.Details.insert(Satisfaction.Details.begin() + Size,
Cached.Details.begin(), Cached.Details.end());
return Iter->second.SubstExpr;
}
ExprResult E = EvaluateSlow(Constraint, MLTAL);
UnsubstitutedConstraintSatisfactionCacheResult Cache;
Cache.Satisfaction.ContainsErrors = Satisfaction.ContainsErrors;
Cache.Satisfaction.IsSatisfied = Satisfaction.IsSatisfied;
Cache.Satisfaction.Details.insert(Cache.Satisfaction.Details.end(),
Satisfaction.Details.begin() + Size,
Satisfaction.Details.end());
Cache.SubstExpr = E;
S.UnsubstitutedConstraintSatisfactionCache.insert({ID, std::move(Cache)});
return E;
}
UnsignedOrNone
ConstraintSatisfactionChecker::EvaluateFoldExpandedConstraintSize(
const FoldExpandedConstraint &FE,
const MultiLevelTemplateArgumentList &MLTAL) {
// We should ignore errors in the presence of packs of different size.
Sema::SFINAETrap Trap(S);
Expr *Pattern = const_cast<Expr *>(FE.getPattern());
SmallVector<UnexpandedParameterPack, 2> Unexpanded;
S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
assert(!Unexpanded.empty() && "Pack expansion without parameter packs?");
bool Expand = true;
bool RetainExpansion = false;
UnsignedOrNone NumExpansions(std::nullopt);
if (S.CheckParameterPacksForExpansion(
Pattern->getExprLoc(), Pattern->getSourceRange(), Unexpanded, MLTAL,
/*FailOnPackProducingTemplates=*/false, Expand, RetainExpansion,
NumExpansions) ||
!Expand || RetainExpansion)
return std::nullopt;
if (NumExpansions && S.getLangOpts().BracketDepth < *NumExpansions) {
S.Diag(Pattern->getExprLoc(),
clang::diag::err_fold_expression_limit_exceeded)
<< *NumExpansions << S.getLangOpts().BracketDepth
<< Pattern->getSourceRange();
S.Diag(Pattern->getExprLoc(), diag::note_bracket_depth);
return std::nullopt;
}
return NumExpansions;
}
ExprResult ConstraintSatisfactionChecker::EvaluateSlow(
const FoldExpandedConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
bool Conjunction = Constraint.getFoldOperator() ==
FoldExpandedConstraint::FoldOperatorKind::And;
unsigned EffectiveDetailEndIndex = Satisfaction.Details.size();
llvm::SmallVector<TemplateArgument> SubstitutedOutermost;
// FIXME: Is PackSubstitutionIndex correct?
llvm::SaveAndRestore _(PackSubstitutionIndex, S.ArgPackSubstIndex);
std::optional<MultiLevelTemplateArgumentList> SubstitutedArgs =
SubstitutionInTemplateArguments(
static_cast<const NormalizedConstraintWithParamMapping &>(Constraint),
MLTAL, SubstitutedOutermost);
if (!SubstitutedArgs) {
Satisfaction.IsSatisfied = false;
return ExprError();
}
ExprResult Out;
UnsignedOrNone NumExpansions =
EvaluateFoldExpandedConstraintSize(Constraint, *SubstitutedArgs);
if (!NumExpansions)
return ExprEmpty();
if (*NumExpansions == 0) {
Satisfaction.IsSatisfied = Conjunction;
return ExprEmpty();
}
for (unsigned I = 0; I < *NumExpansions; I++) {
Sema::ArgPackSubstIndexRAII SubstIndex(S, I);
Satisfaction.IsSatisfied = false;
Satisfaction.ContainsErrors = false;
ExprResult Expr =
ConstraintSatisfactionChecker(S, Template, TemplateNameLoc,
UnsignedOrNone(I), Satisfaction,
/*BuildExpression=*/false)
.Evaluate(Constraint.getNormalizedPattern(), *SubstitutedArgs);
if (BuildExpression && Expr.isUsable()) {
if (Out.isUnset())
Out = Expr;
else
Out = BinaryOperator::Create(S.Context, Out.get(), Expr.get(),
Conjunction ? BinaryOperatorKind::BO_LAnd
: BinaryOperatorKind::BO_LOr,
S.Context.BoolTy, VK_PRValue, OK_Ordinary,
Constraint.getBeginLoc(),
FPOptionsOverride{});
} else {
assert(!BuildExpression || !Satisfaction.IsSatisfied);
}
if (!Conjunction && Satisfaction.IsSatisfied) {
Satisfaction.Details.erase(Satisfaction.Details.begin() +
EffectiveDetailEndIndex,
Satisfaction.Details.end());
break;
}
if (Satisfaction.IsSatisfied != Conjunction)
return Out;
}
return Out;
}
ExprResult ConstraintSatisfactionChecker::Evaluate(
const FoldExpandedConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
llvm::FoldingSetNodeID ID;
ID.AddPointer(Constraint.getPattern());
HashParameterMapping(S, MLTAL, ID, std::nullopt).VisitConstraint(Constraint);
if (auto Iter = S.UnsubstitutedConstraintSatisfactionCache.find(ID);
Iter != S.UnsubstitutedConstraintSatisfactionCache.end()) {
auto &Cached = Iter->second.Satisfaction;
Satisfaction.ContainsErrors = Cached.ContainsErrors;
Satisfaction.IsSatisfied = Cached.IsSatisfied;
Satisfaction.Details.insert(Satisfaction.Details.end(),
Cached.Details.begin(), Cached.Details.end());
return Iter->second.SubstExpr;
}
unsigned Size = Satisfaction.Details.size();
ExprResult E = EvaluateSlow(Constraint, MLTAL);
UnsubstitutedConstraintSatisfactionCacheResult Cache;
Cache.Satisfaction.ContainsErrors = Satisfaction.ContainsErrors;
Cache.Satisfaction.IsSatisfied = Satisfaction.IsSatisfied;
Cache.Satisfaction.Details.insert(Cache.Satisfaction.Details.end(),
Satisfaction.Details.begin() + Size,
Satisfaction.Details.end());
Cache.SubstExpr = E;
S.UnsubstitutedConstraintSatisfactionCache.insert({ID, std::move(Cache)});
return E;
}
ExprResult ConstraintSatisfactionChecker::EvaluateSlow(
const ConceptIdConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL, unsigned Size) {
const ConceptReference *ConceptId = Constraint.getConceptId();
llvm::SmallVector<TemplateArgument> SubstitutedOutermost;
std::optional<MultiLevelTemplateArgumentList> SubstitutedArgs =
SubstitutionInTemplateArguments(Constraint, MLTAL, SubstitutedOutermost);
if (!SubstitutedArgs) {
Satisfaction.IsSatisfied = false;
// FIXME: diagnostics?
return ExprError();
}
Sema::SFINAETrap Trap(S);
Sema::ArgPackSubstIndexRAII SubstIndex(
S, Constraint.getPackSubstitutionIndex()
? Constraint.getPackSubstitutionIndex()
: PackSubstitutionIndex);
const ASTTemplateArgumentListInfo *Ori =
ConceptId->getTemplateArgsAsWritten();
TemplateDeductionInfo Info(TemplateNameLoc);
Sema::InstantiatingTemplate _(
S, TemplateNameLoc, Sema::InstantiatingTemplate::ConstraintSubstitution{},
const_cast<NamedDecl *>(Template), Info, Constraint.getSourceRange());
TemplateArgumentListInfo OutArgs(Ori->LAngleLoc, Ori->RAngleLoc);
if (S.SubstTemplateArguments(Ori->arguments(), *SubstitutedArgs, OutArgs) ||
Trap.hasErrorOccurred()) {
Satisfaction.IsSatisfied = false;
if (!Trap.hasErrorOccurred())
return ExprError();
PartialDiagnosticAt SubstDiag{SourceLocation(),
PartialDiagnostic::NullDiagnostic()};
Info.takeSFINAEDiagnostic(SubstDiag);
// FIXME: This is an unfortunate consequence of there
// being no serialization code for PartialDiagnostics and the fact
// that serializing them would likely take a lot more storage than
// just storing them as strings. We would still like, in the
// future, to serialize the proper PartialDiagnostic as serializing
// it as a string defeats the purpose of the diagnostic mechanism.
Satisfaction.Details.insert(
Satisfaction.Details.begin() + Size,
new (S.Context) ConstraintSubstitutionDiagnostic{
SubstDiag.first,
allocateStringFromConceptDiagnostic(S, SubstDiag.second)});
return ExprError();
}
CXXScopeSpec SS;
SS.Adopt(ConceptId->getNestedNameSpecifierLoc());
ExprResult SubstitutedConceptId = S.CheckConceptTemplateId(
SS, ConceptId->getTemplateKWLoc(), ConceptId->getConceptNameInfo(),
ConceptId->getFoundDecl(), ConceptId->getNamedConcept(), &OutArgs,
/*DoCheckConstraintSatisfaction=*/false);
if (SubstitutedConceptId.isInvalid() || Trap.hasErrorOccurred())
return ExprError();
if (Size != Satisfaction.Details.size()) {
Satisfaction.Details.insert(
Satisfaction.Details.begin() + Size,
UnsatisfiedConstraintRecord(
SubstitutedConceptId.getAs<ConceptSpecializationExpr>()
->getConceptReference()));
}
return SubstitutedConceptId;
}
ExprResult ConstraintSatisfactionChecker::Evaluate(
const ConceptIdConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
const ConceptReference *ConceptId = Constraint.getConceptId();
UnsignedOrNone OuterPackSubstIndex =
Constraint.getPackSubstitutionIndex()
? Constraint.getPackSubstitutionIndex()
: PackSubstitutionIndex;
Sema::InstantiatingTemplate InstTemplate(
S, ConceptId->getBeginLoc(),
Sema::InstantiatingTemplate::ConstraintsCheck{},
ConceptId->getNamedConcept(),
// We may have empty template arguments when checking non-dependent
// nested constraint expressions.
// In such cases, non-SFINAE errors would have already been diagnosed
// during parameter mapping substitution, so the instantiating template
// arguments are less useful here.
MLTAL.getNumSubstitutedLevels() ? MLTAL.getInnermost()
: ArrayRef<TemplateArgument>{},
Constraint.getSourceRange());
if (InstTemplate.isInvalid())
return ExprError();
unsigned Size = Satisfaction.Details.size();
ExprResult E = Evaluate(Constraint.getNormalizedConstraint(), MLTAL);
if (E.isInvalid()) {
Satisfaction.Details.insert(Satisfaction.Details.begin() + Size, ConceptId);
return E;
}
// ConceptIdConstraint is only relevant for diagnostics,
// so if the normalized constraint is satisfied, we should not
// substitute into the constraint.
if (Satisfaction.IsSatisfied)
return E;
llvm::FoldingSetNodeID ID;
ID.AddPointer(Constraint.getConceptId());
ID.AddInteger(OuterPackSubstIndex.toInternalRepresentation());
HashParameterMapping(S, MLTAL, ID, OuterPackSubstIndex)
.VisitConstraint(Constraint);
if (auto Iter = S.UnsubstitutedConstraintSatisfactionCache.find(ID);
Iter != S.UnsubstitutedConstraintSatisfactionCache.end()) {
auto &Cached = Iter->second.Satisfaction;
Satisfaction.ContainsErrors = Cached.ContainsErrors;
Satisfaction.IsSatisfied = Cached.IsSatisfied;
Satisfaction.Details.insert(Satisfaction.Details.begin() + Size,
Cached.Details.begin(), Cached.Details.end());
return Iter->second.SubstExpr;
}
ExprResult CE = EvaluateSlow(Constraint, MLTAL, Size);
if (CE.isInvalid())
return E;
UnsubstitutedConstraintSatisfactionCacheResult Cache;
Cache.Satisfaction.ContainsErrors = Satisfaction.ContainsErrors;
Cache.Satisfaction.IsSatisfied = Satisfaction.IsSatisfied;
Cache.Satisfaction.Details.insert(Cache.Satisfaction.Details.end(),
Satisfaction.Details.begin() + Size,
Satisfaction.Details.end());
Cache.SubstExpr = CE;
S.UnsubstitutedConstraintSatisfactionCache.insert({ID, std::move(Cache)});
return CE;
}
ExprResult ConstraintSatisfactionChecker::Evaluate(
const CompoundConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
unsigned EffectiveDetailEndIndex = Satisfaction.Details.size();
bool Conjunction =
Constraint.getCompoundKind() == NormalizedConstraint::CCK_Conjunction;
ExprResult LHS = Evaluate(Constraint.getLHS(), MLTAL);
if (Conjunction && (!Satisfaction.IsSatisfied || Satisfaction.ContainsErrors))
return LHS;
if (!Conjunction && !LHS.isInvalid() && Satisfaction.IsSatisfied &&
!Satisfaction.ContainsErrors)
return LHS;
Satisfaction.ContainsErrors = false;
Satisfaction.IsSatisfied = false;
ExprResult RHS = Evaluate(Constraint.getRHS(), MLTAL);
if (!Conjunction && !RHS.isInvalid() && Satisfaction.IsSatisfied &&
!Satisfaction.ContainsErrors)
Satisfaction.Details.erase(Satisfaction.Details.begin() +
EffectiveDetailEndIndex,
Satisfaction.Details.end());
if (!BuildExpression)
return Satisfaction.ContainsErrors ? ExprError() : ExprEmpty();
if (!LHS.isUsable())
return RHS;
if (!RHS.isUsable())
return LHS;
return BinaryOperator::Create(S.Context, LHS.get(), RHS.get(),
Conjunction ? BinaryOperatorKind::BO_LAnd
: BinaryOperatorKind::BO_LOr,
S.Context.BoolTy, VK_PRValue, OK_Ordinary,
Constraint.getBeginLoc(), FPOptionsOverride{});
}
ExprResult ConstraintSatisfactionChecker::Evaluate(
const NormalizedConstraint &Constraint,
const MultiLevelTemplateArgumentList &MLTAL) {
switch (Constraint.getKind()) {
case NormalizedConstraint::ConstraintKind::Atomic:
return Evaluate(static_cast<const AtomicConstraint &>(Constraint), MLTAL);
case NormalizedConstraint::ConstraintKind::FoldExpanded:
return Evaluate(static_cast<const FoldExpandedConstraint &>(Constraint),
MLTAL);
case NormalizedConstraint::ConstraintKind::ConceptId:
return Evaluate(static_cast<const ConceptIdConstraint &>(Constraint),
MLTAL);
case NormalizedConstraint::ConstraintKind::Compound:
return Evaluate(static_cast<const CompoundConstraint &>(Constraint), MLTAL);
}
llvm_unreachable("Unknown ConstraintKind enum");
}
static bool CheckConstraintSatisfaction(
Sema &S, const NamedDecl *Template,
ArrayRef<AssociatedConstraint> AssociatedConstraints,
const MultiLevelTemplateArgumentList &TemplateArgsLists,
SourceRange TemplateIDRange, ConstraintSatisfaction &Satisfaction,
Expr **ConvertedExpr, const ConceptReference *TopLevelConceptId = nullptr) {
if (ConvertedExpr)
*ConvertedExpr = nullptr;
if (AssociatedConstraints.empty()) {
Satisfaction.IsSatisfied = true;
return false;
}
if (TemplateArgsLists.isAnyArgInstantiationDependent()) {
// No need to check satisfaction for dependent constraint expressions.
Satisfaction.IsSatisfied = true;
return false;
}
llvm::ArrayRef<TemplateArgument> Args;
if (TemplateArgsLists.getNumLevels() != 0)
Args = TemplateArgsLists.getInnermost();
std::optional<Sema::InstantiatingTemplate> SynthesisContext;
if (!TopLevelConceptId) {
SynthesisContext.emplace(S, TemplateIDRange.getBegin(),
Sema::InstantiatingTemplate::ConstraintsCheck{},
const_cast<NamedDecl *>(Template), Args,
TemplateIDRange);
}
const NormalizedConstraint *C =
S.getNormalizedAssociatedConstraints(Template, AssociatedConstraints);
if (!C) {
Satisfaction.IsSatisfied = false;
return true;
}
if (TopLevelConceptId)
C = ConceptIdConstraint::Create(S.getASTContext(), TopLevelConceptId,
const_cast<NormalizedConstraint *>(C),
Template, /*CSE=*/nullptr,
S.ArgPackSubstIndex);
ExprResult Res = ConstraintSatisfactionChecker(
S, Template, TemplateIDRange.getBegin(),
S.ArgPackSubstIndex, Satisfaction,
/*BuildExpression=*/ConvertedExpr != nullptr)
.Evaluate(*C, TemplateArgsLists);
if (Res.isInvalid())
return true;
if (Res.isUsable() && ConvertedExpr)
*ConvertedExpr = Res.get();
return false;
}
bool Sema::CheckConstraintSatisfaction(
ConstrainedDeclOrNestedRequirement Entity,
ArrayRef<AssociatedConstraint> AssociatedConstraints,
const MultiLevelTemplateArgumentList &TemplateArgsLists,
SourceRange TemplateIDRange, ConstraintSatisfaction &OutSatisfaction,
const ConceptReference *TopLevelConceptId, Expr **ConvertedExpr) {
if (AssociatedConstraints.empty()) {
OutSatisfaction.IsSatisfied = true;
return false;
}
const auto *Template = Entity.dyn_cast<const NamedDecl *>();
if (!Template) {
return ::CheckConstraintSatisfaction(
*this, nullptr, AssociatedConstraints, TemplateArgsLists,
TemplateIDRange, OutSatisfaction, ConvertedExpr, TopLevelConceptId);
}
// Invalid templates could make their way here. Substituting them could result
// in dependent expressions.
if (Template->isInvalidDecl()) {
OutSatisfaction.IsSatisfied = false;
return true;
}
// A list of the template argument list flattened in a predictible manner for
// the purposes of caching. The ConstraintSatisfaction type is in AST so it
// has no access to the MultiLevelTemplateArgumentList, so this has to happen
// here.
llvm::SmallVector<TemplateArgument, 4> FlattenedArgs;
for (auto List : TemplateArgsLists)
for (const TemplateArgument &Arg : List.Args)
FlattenedArgs.emplace_back(Context.getCanonicalTemplateArgument(Arg));
const NamedDecl *Owner = Template;
if (TopLevelConceptId)
Owner = TopLevelConceptId->getNamedConcept();
llvm::FoldingSetNodeID ID;
ConstraintSatisfaction::Profile(ID, Context, Owner, FlattenedArgs);
void *InsertPos;
if (auto *Cached = SatisfactionCache.FindNodeOrInsertPos(ID, InsertPos)) {
OutSatisfaction = *Cached;
return false;
}
auto Satisfaction =
std::make_unique<ConstraintSatisfaction>(Owner, FlattenedArgs);
if (::CheckConstraintSatisfaction(
*this, Template, AssociatedConstraints, TemplateArgsLists,
TemplateIDRange, *Satisfaction, ConvertedExpr, TopLevelConceptId)) {
OutSatisfaction = std::move(*Satisfaction);
return true;
}
if (auto *Cached = SatisfactionCache.FindNodeOrInsertPos(ID, InsertPos)) {
// The evaluation of this constraint resulted in us trying to re-evaluate it
// recursively. This isn't really possible, except we try to form a
// RecoveryExpr as a part of the evaluation. If this is the case, just
// return the 'cached' version (which will have the same result), and save
// ourselves the extra-insert. If it ever becomes possible to legitimately
// recursively check a constraint, we should skip checking the 'inner' one
// above, and replace the cached version with this one, as it would be more
// specific.
OutSatisfaction = *Cached;
return false;
}
// Else we can simply add this satisfaction to the list.
OutSatisfaction = *Satisfaction;
// We cannot use InsertPos here because CheckConstraintSatisfaction might have
// invalidated it.
// Note that entries of SatisfactionCache are deleted in Sema's destructor.
SatisfactionCache.InsertNode(Satisfaction.release());
return false;
}
static ExprResult
SubstituteConceptsInConstraintExpression(Sema &S, const NamedDecl *D,
const ConceptSpecializationExpr *CSE,
UnsignedOrNone SubstIndex) {
// [C++2c] [temp.constr.normal]
// Otherwise, to form CE, any non-dependent concept template argument Ai
// is substituted into the constraint-expression of C.
// If any such substitution results in an invalid concept-id,
// the program is ill-formed; no diagnostic is required.
ConceptDecl *Concept = CSE->getNamedConcept()->getCanonicalDecl();
Sema::ArgPackSubstIndexRAII _(S, SubstIndex);
const ASTTemplateArgumentListInfo *ArgsAsWritten =
CSE->getTemplateArgsAsWritten();
if (llvm::none_of(
ArgsAsWritten->arguments(), [&](const TemplateArgumentLoc &ArgLoc) {
return !ArgLoc.getArgument().isDependent() &&
ArgLoc.getArgument().isConceptOrConceptTemplateParameter();
})) {
return Concept->getConstraintExpr();
}
MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
Concept, Concept->getLexicalDeclContext(),
/*Final=*/false, CSE->getTemplateArguments(),
/*RelativeToPrimary=*/true,
/*Pattern=*/nullptr,
/*ForConstraintInstantiation=*/true);
return S.SubstConceptTemplateArguments(CSE, Concept->getConstraintExpr(),
MLTAL);
}
bool Sema::CheckConstraintSatisfaction(
const ConceptSpecializationExpr *ConstraintExpr,
ConstraintSatisfaction &Satisfaction) {
ExprResult Res = SubstituteConceptsInConstraintExpression(
*this, nullptr, ConstraintExpr, ArgPackSubstIndex);
if (!Res.isUsable())
return true;
llvm::SmallVector<AssociatedConstraint, 1> Constraints;
Constraints.emplace_back(Res.get());
MultiLevelTemplateArgumentList MLTAL(ConstraintExpr->getNamedConcept(),
ConstraintExpr->getTemplateArguments(),
true);
return CheckConstraintSatisfaction(
ConstraintExpr->getNamedConcept(), Constraints, MLTAL,
ConstraintExpr->getSourceRange(), Satisfaction,
ConstraintExpr->getConceptReference());
}
bool Sema::SetupConstraintScope(
FunctionDecl *FD, std::optional<ArrayRef<TemplateArgument>> TemplateArgs,
const MultiLevelTemplateArgumentList &MLTAL,
LocalInstantiationScope &Scope) {
assert(!isLambdaCallOperator(FD) &&
"Use LambdaScopeForCallOperatorInstantiationRAII to handle lambda "
"instantiations");
if (FD->isTemplateInstantiation() && FD->getPrimaryTemplate()) {
FunctionTemplateDecl *PrimaryTemplate = FD->getPrimaryTemplate();
InstantiatingTemplate Inst(
*this, FD->getPointOfInstantiation(),
Sema::InstantiatingTemplate::ConstraintsCheck{}, PrimaryTemplate,
TemplateArgs ? *TemplateArgs : ArrayRef<TemplateArgument>{},
SourceRange());
if (Inst.isInvalid())
return true;
// addInstantiatedParametersToScope creates a map of 'uninstantiated' to
// 'instantiated' parameters and adds it to the context. For the case where
// this function is a template being instantiated NOW, we also need to add
// the list of current template arguments to the list so that they also can
// be picked out of the map.
if (auto *SpecArgs = FD->getTemplateSpecializationArgs()) {
MultiLevelTemplateArgumentList JustTemplArgs(FD, SpecArgs->asArray(),
/*Final=*/false);
if (addInstantiatedParametersToScope(
FD, PrimaryTemplate->getTemplatedDecl(), Scope, JustTemplArgs))
return true;
}
// If this is a member function, make sure we get the parameters that
// reference the original primary template.
if (FunctionTemplateDecl *FromMemTempl =
PrimaryTemplate->getInstantiatedFromMemberTemplate()) {
if (addInstantiatedParametersToScope(FD, FromMemTempl->getTemplatedDecl(),
Scope, MLTAL))
return true;
}
return false;
}
if (FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization ||
FD->getTemplatedKind() == FunctionDecl::TK_DependentNonTemplate) {
FunctionDecl *InstantiatedFrom =
FD->getTemplatedKind() == FunctionDecl::TK_MemberSpecialization
? FD->getInstantiatedFromMemberFunction()
: FD->getInstantiatedFromDecl();
InstantiatingTemplate Inst(
*this, FD->getPointOfInstantiation(),
Sema::InstantiatingTemplate::ConstraintsCheck{}, InstantiatedFrom,
TemplateArgs ? *TemplateArgs : ArrayRef<TemplateArgument>{},
SourceRange());
if (Inst.isInvalid())
return true;
// Case where this was not a template, but instantiated as a
// child-function.
if (addInstantiatedParametersToScope(FD, InstantiatedFrom, Scope, MLTAL))
return true;
}
return false;
}
// This function collects all of the template arguments for the purposes of
// constraint-instantiation and checking.
std::optional<MultiLevelTemplateArgumentList>
Sema::SetupConstraintCheckingTemplateArgumentsAndScope(
FunctionDecl *FD, std::optional<ArrayRef<TemplateArgument>> TemplateArgs,
LocalInstantiationScope &Scope) {
MultiLevelTemplateArgumentList MLTAL;
// Collect the list of template arguments relative to the 'primary' template.
// We need the entire list, since the constraint is completely uninstantiated
// at this point.
MLTAL =
getTemplateInstantiationArgs(FD, FD->getLexicalDeclContext(),
/*Final=*/false, /*Innermost=*/std::nullopt,
/*RelativeToPrimary=*/true,
/*Pattern=*/nullptr,
/*ForConstraintInstantiation=*/true);
// Lambdas are handled by LambdaScopeForCallOperatorInstantiationRAII.
if (isLambdaCallOperator(FD))
return MLTAL;
if (SetupConstraintScope(FD, TemplateArgs, MLTAL, Scope))
return std::nullopt;
return MLTAL;
}
bool Sema::CheckFunctionConstraints(const FunctionDecl *FD,
ConstraintSatisfaction &Satisfaction,
SourceLocation UsageLoc,
bool ForOverloadResolution) {
// Don't check constraints if the function is dependent. Also don't check if
// this is a function template specialization, as the call to
// CheckFunctionTemplateConstraints after this will check it
// better.
if (FD->isDependentContext() ||
FD->getTemplatedKind() ==
FunctionDecl::TK_FunctionTemplateSpecialization) {
Satisfaction.IsSatisfied = true;
return false;
}
// A lambda conversion operator has the same constraints as the call operator
// and constraints checking relies on whether we are in a lambda call operator
// (and may refer to its parameters), so check the call operator instead.
// Note that the declarations outside of the lambda should also be
// considered. Turning on the 'ForOverloadResolution' flag results in the
// LocalInstantiationScope not looking into its parents, but we can still
// access Decls from the parents while building a lambda RAII scope later.
if (const auto *MD = dyn_cast<CXXConversionDecl>(FD);
MD && isLambdaConversionOperator(const_cast<CXXConversionDecl *>(MD)))
return CheckFunctionConstraints(MD->getParent()->getLambdaCallOperator(),
Satisfaction, UsageLoc,
/*ShouldAddDeclsFromParentScope=*/true);
DeclContext *CtxToSave = const_cast<FunctionDecl *>(FD);
while (isLambdaCallOperator(CtxToSave) || FD->isTransparentContext()) {
if (isLambdaCallOperator(CtxToSave))
CtxToSave = CtxToSave->getParent()->getParent();
else
CtxToSave = CtxToSave->getNonTransparentContext();
}
ContextRAII SavedContext{*this, CtxToSave};
LocalInstantiationScope Scope(*this, !ForOverloadResolution);
std::optional<MultiLevelTemplateArgumentList> MLTAL =
SetupConstraintCheckingTemplateArgumentsAndScope(
const_cast<FunctionDecl *>(FD), {}, Scope);
if (!MLTAL)
return true;
Qualifiers ThisQuals;
CXXRecordDecl *Record = nullptr;
if (auto *Method = dyn_cast<CXXMethodDecl>(FD)) {
ThisQuals = Method->getMethodQualifiers();
Record = const_cast<CXXRecordDecl *>(Method->getParent());
}
CXXThisScopeRAII ThisScope(*this, Record, ThisQuals, Record != nullptr);
LambdaScopeForCallOperatorInstantiationRAII LambdaScope(
*this, const_cast<FunctionDecl *>(FD), *MLTAL, Scope,
ForOverloadResolution);
return CheckConstraintSatisfaction(
FD, FD->getTrailingRequiresClause(), *MLTAL,
SourceRange(UsageLoc.isValid() ? UsageLoc : FD->getLocation()),
Satisfaction);
}
static const Expr *SubstituteConstraintExpressionWithoutSatisfaction(
Sema &S, const Sema::TemplateCompareNewDeclInfo &DeclInfo,
const Expr *ConstrExpr) {
MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
DeclInfo.getDecl(), DeclInfo.getDeclContext(), /*Final=*/false,
/*Innermost=*/std::nullopt,
/*RelativeToPrimary=*/true,
/*Pattern=*/nullptr, /*ForConstraintInstantiation=*/true,
/*SkipForSpecialization*/ false);
if (MLTAL.getNumSubstitutedLevels() == 0)
return ConstrExpr;
Sema::SFINAETrap SFINAE(S);
Sema::InstantiatingTemplate Inst(
S, DeclInfo.getLocation(),
Sema::InstantiatingTemplate::ConstraintNormalization{},
const_cast<NamedDecl *>(DeclInfo.getDecl()), SourceRange{});
if (Inst.isInvalid())
return nullptr;
// Set up a dummy 'instantiation' scope in the case of reference to function
// parameters that the surrounding function hasn't been instantiated yet. Note
// this may happen while we're comparing two templates' constraint
// equivalence.
std::optional<LocalInstantiationScope> ScopeForParameters;
if (const NamedDecl *ND = DeclInfo.getDecl();
ND && ND->isFunctionOrFunctionTemplate()) {
ScopeForParameters.emplace(S, /*CombineWithOuterScope=*/true);
const FunctionDecl *FD = ND->getAsFunction();
if (FunctionTemplateDecl *Template = FD->getDescribedFunctionTemplate();
Template && Template->getInstantiatedFromMemberTemplate())
FD = Template->getInstantiatedFromMemberTemplate()->getTemplatedDecl();
for (auto *PVD : FD->parameters()) {
if (ScopeForParameters->getInstantiationOfIfExists(PVD))
continue;
if (!PVD->isParameterPack()) {
ScopeForParameters->InstantiatedLocal(PVD, PVD);
continue;
}
// This is hacky: we're mapping the parameter pack to a size-of-1 argument
// to avoid building SubstTemplateTypeParmPackTypes for
// PackExpansionTypes. The SubstTemplateTypeParmPackType node would
// otherwise reference the AssociatedDecl of the template arguments, which
// is, in this case, the template declaration.
//
// However, as we are in the process of comparing potential
// re-declarations, the canonical declaration is the declaration itself at
// this point. So if we didn't expand these packs, we would end up with an
// incorrect profile difference because we will be profiling the
// canonical types!
//
// FIXME: Improve the "no-transform" machinery in FindInstantiatedDecl so
// that we can eliminate the Scope in the cases where the declarations are
// not necessarily instantiated. It would also benefit the noexcept
// specifier comparison.
ScopeForParameters->MakeInstantiatedLocalArgPack(PVD);
ScopeForParameters->InstantiatedLocalPackArg(PVD, PVD);
}
}
std::optional<Sema::CXXThisScopeRAII> ThisScope;
// See TreeTransform::RebuildTemplateSpecializationType. A context scope is
// essential for having an injected class as the canonical type for a template
// specialization type at the rebuilding stage. This guarantees that, for
// out-of-line definitions, injected class name types and their equivalent
// template specializations can be profiled to the same value, which makes it
// possible that e.g. constraints involving C<Class<T>> and C<Class> are
// perceived identical.
std::optional<Sema::ContextRAII> ContextScope;
const DeclContext *DC = [&] {
if (!DeclInfo.getDecl())
return DeclInfo.getDeclContext();
return DeclInfo.getDecl()->getFriendObjectKind()
? DeclInfo.getLexicalDeclContext()
: DeclInfo.getDeclContext();
}();
if (auto *RD = dyn_cast<CXXRecordDecl>(DC)) {
ThisScope.emplace(S, const_cast<CXXRecordDecl *>(RD), Qualifiers());
ContextScope.emplace(S, const_cast<DeclContext *>(cast<DeclContext>(RD)),
/*NewThisContext=*/false);
}
EnterExpressionEvaluationContext UnevaluatedContext(
S, Sema::ExpressionEvaluationContext::Unevaluated,
Sema::ReuseLambdaContextDecl);
ExprResult SubstConstr = S.SubstConstraintExprWithoutSatisfaction(
const_cast<clang::Expr *>(ConstrExpr), MLTAL);
if (SFINAE.hasErrorOccurred() || !SubstConstr.isUsable())
return nullptr;
return SubstConstr.get();
}
bool Sema::AreConstraintExpressionsEqual(const NamedDecl *Old,
const Expr *OldConstr,
const TemplateCompareNewDeclInfo &New,
const Expr *NewConstr) {
if (OldConstr == NewConstr)
return true;
// C++ [temp.constr.decl]p4
if (Old && !New.isInvalid() && !New.ContainsDecl(Old) &&
Old->getLexicalDeclContext() != New.getLexicalDeclContext()) {
if (const Expr *SubstConstr =
SubstituteConstraintExpressionWithoutSatisfaction(*this, Old,
OldConstr))
OldConstr = SubstConstr;
else
return false;
if (const Expr *SubstConstr =
SubstituteConstraintExpressionWithoutSatisfaction(*this, New,
NewConstr))
NewConstr = SubstConstr;
else
return false;
}
llvm::FoldingSetNodeID ID1, ID2;
OldConstr->Profile(ID1, Context, /*Canonical=*/true);
NewConstr->Profile(ID2, Context, /*Canonical=*/true);
return ID1 == ID2;
}
bool Sema::FriendConstraintsDependOnEnclosingTemplate(const FunctionDecl *FD) {
assert(FD->getFriendObjectKind() && "Must be a friend!");
// The logic for non-templates is handled in ASTContext::isSameEntity, so we
// don't have to bother checking 'DependsOnEnclosingTemplate' for a
// non-function-template.
assert(FD->getDescribedFunctionTemplate() &&
"Non-function templates don't need to be checked");
SmallVector<AssociatedConstraint, 3> ACs;
FD->getDescribedFunctionTemplate()->getAssociatedConstraints(ACs);
unsigned OldTemplateDepth = CalculateTemplateDepthForConstraints(*this, FD);
for (const AssociatedConstraint &AC : ACs)
if (ConstraintExpressionDependsOnEnclosingTemplate(FD, OldTemplateDepth,
AC.ConstraintExpr))
return true;
return false;
}
bool Sema::EnsureTemplateArgumentListConstraints(
TemplateDecl *TD, const MultiLevelTemplateArgumentList &TemplateArgsLists,
SourceRange TemplateIDRange) {
ConstraintSatisfaction Satisfaction;
llvm::SmallVector<AssociatedConstraint, 3> AssociatedConstraints;
TD->getAssociatedConstraints(AssociatedConstraints);
if (CheckConstraintSatisfaction(TD, AssociatedConstraints, TemplateArgsLists,
TemplateIDRange, Satisfaction))
return true;
if (!Satisfaction.IsSatisfied) {
SmallString<128> TemplateArgString;
TemplateArgString = " ";
TemplateArgString += getTemplateArgumentBindingsText(
TD->getTemplateParameters(), TemplateArgsLists.getInnermost().data(),
TemplateArgsLists.getInnermost().size());
Diag(TemplateIDRange.getBegin(),
diag::err_template_arg_list_constraints_not_satisfied)
<< (int)getTemplateNameKindForDiagnostics(TemplateName(TD)) << TD
<< TemplateArgString << TemplateIDRange;
DiagnoseUnsatisfiedConstraint(Satisfaction);
return true;
}
return false;
}
static bool CheckFunctionConstraintsWithoutInstantiation(
Sema &SemaRef, SourceLocation PointOfInstantiation,
FunctionTemplateDecl *Template, ArrayRef<TemplateArgument> TemplateArgs,
ConstraintSatisfaction &Satisfaction) {
SmallVector<AssociatedConstraint, 3> TemplateAC;
Template->getAssociatedConstraints(TemplateAC);
if (TemplateAC.empty()) {
Satisfaction.IsSatisfied = true;
return false;
}
LocalInstantiationScope Scope(SemaRef);
FunctionDecl *FD = Template->getTemplatedDecl();
// Collect the list of template arguments relative to the 'primary'
// template. We need the entire list, since the constraint is completely
// uninstantiated at this point.
MultiLevelTemplateArgumentList MLTAL;
{
// getTemplateInstantiationArgs uses this instantiation context to find out
// template arguments for uninstantiated functions.
// We don't want this RAII object to persist, because there would be
// otherwise duplicate diagnostic notes.
Sema::InstantiatingTemplate Inst(
SemaRef, PointOfInstantiation,
Sema::InstantiatingTemplate::ConstraintsCheck{}, Template, TemplateArgs,
PointOfInstantiation);
if (Inst.isInvalid())
return true;
MLTAL = SemaRef.getTemplateInstantiationArgs(
/*D=*/FD, FD,
/*Final=*/false, /*Innermost=*/{}, /*RelativeToPrimary=*/true,
/*Pattern=*/nullptr, /*ForConstraintInstantiation=*/true);
}
Sema::ContextRAII SavedContext(SemaRef, FD);
return SemaRef.CheckConstraintSatisfaction(
Template, TemplateAC, MLTAL, PointOfInstantiation, Satisfaction);
}
bool Sema::CheckFunctionTemplateConstraints(
SourceLocation PointOfInstantiation, FunctionDecl *Decl,
ArrayRef<TemplateArgument> TemplateArgs,
ConstraintSatisfaction &Satisfaction) {
// In most cases we're not going to have constraints, so check for that first.
FunctionTemplateDecl *Template = Decl->getPrimaryTemplate();
if (!Template)
return ::CheckFunctionConstraintsWithoutInstantiation(
*this, PointOfInstantiation, Decl->getDescribedFunctionTemplate(),
TemplateArgs, Satisfaction);
// Note - code synthesis context for the constraints check is created
// inside CheckConstraintsSatisfaction.
SmallVector<AssociatedConstraint, 3> TemplateAC;
Template->getAssociatedConstraints(TemplateAC);
if (TemplateAC.empty()) {
Satisfaction.IsSatisfied = true;
return false;
}
// Enter the scope of this instantiation. We don't use
// PushDeclContext because we don't have a scope.
Sema::ContextRAII savedContext(*this, Decl);
LocalInstantiationScope Scope(*this);
std::optional<MultiLevelTemplateArgumentList> MLTAL =
SetupConstraintCheckingTemplateArgumentsAndScope(Decl, TemplateArgs,
Scope);
if (!MLTAL)
return true;
Qualifiers ThisQuals;
CXXRecordDecl *Record = nullptr;
if (auto *Method = dyn_cast<CXXMethodDecl>(Decl)) {
ThisQuals = Method->getMethodQualifiers();
Record = Method->getParent();
}
CXXThisScopeRAII ThisScope(*this, Record, ThisQuals, Record != nullptr);
LambdaScopeForCallOperatorInstantiationRAII LambdaScope(*this, Decl, *MLTAL,
Scope);
return CheckConstraintSatisfaction(Template, TemplateAC, *MLTAL,
PointOfInstantiation, Satisfaction);
}
static void diagnoseUnsatisfiedRequirement(Sema &S,
concepts::ExprRequirement *Req,
bool First) {
assert(!Req->isSatisfied() &&
"Diagnose() can only be used on an unsatisfied requirement");
switch (Req->getSatisfactionStatus()) {
case concepts::ExprRequirement::SS_Dependent:
llvm_unreachable("Diagnosing a dependent requirement");
break;
case concepts::ExprRequirement::SS_ExprSubstitutionFailure: {
auto *SubstDiag = Req->getExprSubstitutionDiagnostic();
if (!SubstDiag->DiagMessage.empty())
S.Diag(SubstDiag->DiagLoc,
diag::note_expr_requirement_expr_substitution_error)
<< (int)First << SubstDiag->SubstitutedEntity
<< SubstDiag->DiagMessage;
else
S.Diag(SubstDiag->DiagLoc,
diag::note_expr_requirement_expr_unknown_substitution_error)
<< (int)First << SubstDiag->SubstitutedEntity;
break;
}
case concepts::ExprRequirement::SS_NoexceptNotMet:
S.Diag(Req->getNoexceptLoc(), diag::note_expr_requirement_noexcept_not_met)
<< (int)First << Req->getExpr();
break;
case concepts::ExprRequirement::SS_TypeRequirementSubstitutionFailure: {
auto *SubstDiag =
Req->getReturnTypeRequirement().getSubstitutionDiagnostic();
if (!SubstDiag->DiagMessage.empty())
S.Diag(SubstDiag->DiagLoc,
diag::note_expr_requirement_type_requirement_substitution_error)
<< (int)First << SubstDiag->SubstitutedEntity
<< SubstDiag->DiagMessage;
else
S.Diag(
SubstDiag->DiagLoc,
diag::
note_expr_requirement_type_requirement_unknown_substitution_error)
<< (int)First << SubstDiag->SubstitutedEntity;
break;
}
case concepts::ExprRequirement::SS_ConstraintsNotSatisfied: {
ConceptSpecializationExpr *ConstraintExpr =
Req->getReturnTypeRequirementSubstitutedConstraintExpr();
S.DiagnoseUnsatisfiedConstraint(ConstraintExpr);
break;
}
case concepts::ExprRequirement::SS_Satisfied:
llvm_unreachable("We checked this above");
}
}
static void diagnoseUnsatisfiedRequirement(Sema &S,
concepts::TypeRequirement *Req,
bool First) {
assert(!Req->isSatisfied() &&
"Diagnose() can only be used on an unsatisfied requirement");
switch (Req->getSatisfactionStatus()) {
case concepts::TypeRequirement::SS_Dependent:
llvm_unreachable("Diagnosing a dependent requirement");
return;
case concepts::TypeRequirement::SS_SubstitutionFailure: {
auto *SubstDiag = Req->getSubstitutionDiagnostic();
if (!SubstDiag->DiagMessage.empty())
S.Diag(SubstDiag->DiagLoc, diag::note_type_requirement_substitution_error)
<< (int)First << SubstDiag->SubstitutedEntity
<< SubstDiag->DiagMessage;
else
S.Diag(SubstDiag->DiagLoc,
diag::note_type_requirement_unknown_substitution_error)
<< (int)First << SubstDiag->SubstitutedEntity;
return;
}
default:
llvm_unreachable("Unknown satisfaction status");
return;
}
}
static void diagnoseUnsatisfiedConceptIdExpr(Sema &S,
const ConceptReference *Concept,
SourceLocation Loc, bool First) {
if (Concept->getTemplateArgsAsWritten()->NumTemplateArgs == 1) {
S.Diag(
Loc,
diag::
note_single_arg_concept_specialization_constraint_evaluated_to_false)
<< (int)First
<< Concept->getTemplateArgsAsWritten()->arguments()[0].getArgument()
<< Concept->getNamedConcept();
} else {
S.Diag(Loc, diag::note_concept_specialization_constraint_evaluated_to_false)
<< (int)First << Concept;
}
}
static void diagnoseUnsatisfiedConstraintExpr(
Sema &S, const UnsatisfiedConstraintRecord &Record, SourceLocation Loc,
bool First, concepts::NestedRequirement *Req = nullptr);
static void DiagnoseUnsatisfiedConstraint(
Sema &S, ArrayRef<UnsatisfiedConstraintRecord> Records, SourceLocation Loc,
bool First = true, concepts::NestedRequirement *Req = nullptr) {
for (auto &Record : Records) {
diagnoseUnsatisfiedConstraintExpr(S, Record, Loc, First, Req);
Loc = {};
First = isa<const ConceptReference *>(Record);
}
}
static void diagnoseUnsatisfiedRequirement(Sema &S,
concepts::NestedRequirement *Req,
bool First) {
DiagnoseUnsatisfiedConstraint(S, Req->getConstraintSatisfaction().records(),
Req->hasInvalidConstraint()
? SourceLocation()
: Req->getConstraintExpr()->getExprLoc(),
First, Req);
}
static void diagnoseWellFormedUnsatisfiedConstraintExpr(Sema &S,
const Expr *SubstExpr,
bool First) {
SubstExpr = SubstExpr->IgnoreParenImpCasts();
if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(SubstExpr)) {
switch (BO->getOpcode()) {
// These two cases will in practice only be reached when using fold
// expressions with || and &&, since otherwise the || and && will have been
// broken down into atomic constraints during satisfaction checking.
case BO_LOr:
// Or evaluated to false - meaning both RHS and LHS evaluated to false.
diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getLHS(), First);
diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getRHS(),
/*First=*/false);
return;
case BO_LAnd: {
bool LHSSatisfied =
BO->getLHS()->EvaluateKnownConstInt(S.Context).getBoolValue();
if (LHSSatisfied) {
// LHS is true, so RHS must be false.
diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getRHS(), First);
return;
}
// LHS is false
diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getLHS(), First);
// RHS might also be false
bool RHSSatisfied =
BO->getRHS()->EvaluateKnownConstInt(S.Context).getBoolValue();
if (!RHSSatisfied)
diagnoseWellFormedUnsatisfiedConstraintExpr(S, BO->getRHS(),
/*First=*/false);
return;
}
case BO_GE:
case BO_LE:
case BO_GT:
case BO_LT:
case BO_EQ:
case BO_NE:
if (BO->getLHS()->getType()->isIntegerType() &&
BO->getRHS()->getType()->isIntegerType()) {
Expr::EvalResult SimplifiedLHS;
Expr::EvalResult SimplifiedRHS;
BO->getLHS()->EvaluateAsInt(SimplifiedLHS, S.Context,
Expr::SE_NoSideEffects,
/*InConstantContext=*/true);
BO->getRHS()->EvaluateAsInt(SimplifiedRHS, S.Context,
Expr::SE_NoSideEffects,
/*InConstantContext=*/true);
if (!SimplifiedLHS.Diag && !SimplifiedRHS.Diag) {
S.Diag(SubstExpr->getBeginLoc(),
diag::note_atomic_constraint_evaluated_to_false_elaborated)
<< (int)First << SubstExpr
<< toString(SimplifiedLHS.Val.getInt(), 10)
<< BinaryOperator::getOpcodeStr(BO->getOpcode())
<< toString(SimplifiedRHS.Val.getInt(), 10);
return;
}
}
break;
default:
break;
}
} else if (auto *RE = dyn_cast<RequiresExpr>(SubstExpr)) {
// FIXME: RequiresExpr should store dependent diagnostics.
for (concepts::Requirement *Req : RE->getRequirements())
if (!Req->isDependent() && !Req->isSatisfied()) {
if (auto *E = dyn_cast<concepts::ExprRequirement>(Req))
diagnoseUnsatisfiedRequirement(S, E, First);
else if (auto *T = dyn_cast<concepts::TypeRequirement>(Req))
diagnoseUnsatisfiedRequirement(S, T, First);
else
diagnoseUnsatisfiedRequirement(
S, cast<concepts::NestedRequirement>(Req), First);
break;
}
return;
} else if (auto *CSE = dyn_cast<ConceptSpecializationExpr>(SubstExpr)) {
// Drill down concept ids treated as atomic constraints
S.DiagnoseUnsatisfiedConstraint(CSE, First);
return;
} else if (auto *TTE = dyn_cast<TypeTraitExpr>(SubstExpr);
TTE && TTE->getTrait() == clang::TypeTrait::BTT_IsDeducible) {
assert(TTE->getNumArgs() == 2);
S.Diag(SubstExpr->getSourceRange().getBegin(),
diag::note_is_deducible_constraint_evaluated_to_false)
<< TTE->getArg(0)->getType() << TTE->getArg(1)->getType();
return;
}
S.Diag(SubstExpr->getSourceRange().getBegin(),
diag::note_atomic_constraint_evaluated_to_false)
<< (int)First << SubstExpr;
S.DiagnoseTypeTraitDetails(SubstExpr);
}
static void diagnoseUnsatisfiedConstraintExpr(
Sema &S, const UnsatisfiedConstraintRecord &Record, SourceLocation Loc,
bool First, concepts::NestedRequirement *Req) {
if (auto *Diag =
Record
.template dyn_cast<const ConstraintSubstitutionDiagnostic *>()) {
if (Req)
S.Diag(Diag->first, diag::note_nested_requirement_substitution_error)
<< (int)First << Req->getInvalidConstraintEntity() << Diag->second;
else
S.Diag(Diag->first, diag::note_substituted_constraint_expr_is_ill_formed)
<< Diag->second;
return;
}
if (const auto *Concept = dyn_cast<const ConceptReference *>(Record)) {
if (Loc.isInvalid())
Loc = Concept->getBeginLoc();
diagnoseUnsatisfiedConceptIdExpr(S, Concept, Loc, First);
return;
}
diagnoseWellFormedUnsatisfiedConstraintExpr(
S, cast<const class Expr *>(Record), First);
}
void Sema::DiagnoseUnsatisfiedConstraint(
const ConstraintSatisfaction &Satisfaction, SourceLocation Loc,
bool First) {
assert(!Satisfaction.IsSatisfied &&
"Attempted to diagnose a satisfied constraint");
::DiagnoseUnsatisfiedConstraint(*this, Satisfaction.Details, Loc, First);
}
void Sema::DiagnoseUnsatisfiedConstraint(
const ConceptSpecializationExpr *ConstraintExpr, bool First) {
const ASTConstraintSatisfaction &Satisfaction =
ConstraintExpr->getSatisfaction();
assert(!Satisfaction.IsSatisfied &&
"Attempted to diagnose a satisfied constraint");
::DiagnoseUnsatisfiedConstraint(*this, Satisfaction.records(),
ConstraintExpr->getBeginLoc(), First);
}
namespace {
class SubstituteParameterMappings {
Sema &SemaRef;
const MultiLevelTemplateArgumentList *MLTAL;
const ASTTemplateArgumentListInfo *ArgsAsWritten;
bool InFoldExpr;
SubstituteParameterMappings(Sema &SemaRef,
const MultiLevelTemplateArgumentList *MLTAL,
const ASTTemplateArgumentListInfo *ArgsAsWritten,
bool InFoldExpr)
: SemaRef(SemaRef), MLTAL(MLTAL), ArgsAsWritten(ArgsAsWritten),
InFoldExpr(InFoldExpr) {}
void buildParameterMapping(NormalizedConstraintWithParamMapping &N);
bool substitute(NormalizedConstraintWithParamMapping &N);
bool substitute(ConceptIdConstraint &CC);
public:
SubstituteParameterMappings(Sema &SemaRef, bool InFoldExpr = false)
: SemaRef(SemaRef), MLTAL(nullptr), ArgsAsWritten(nullptr),
InFoldExpr(InFoldExpr) {}
bool substitute(NormalizedConstraint &N);
};
void SubstituteParameterMappings::buildParameterMapping(
NormalizedConstraintWithParamMapping &N) {
TemplateParameterList *TemplateParams =
cast<TemplateDecl>(N.getConstraintDecl())->getTemplateParameters();
llvm::SmallBitVector OccurringIndices(TemplateParams->size());
llvm::SmallBitVector OccurringIndicesForSubsumption(TemplateParams->size());
if (N.getKind() == NormalizedConstraint::ConstraintKind::Atomic) {
SemaRef.MarkUsedTemplateParameters(
static_cast<AtomicConstraint &>(N).getConstraintExpr(),
/*OnlyDeduced=*/false,
/*Depth=*/0, OccurringIndices);
SemaRef.MarkUsedTemplateParametersForSubsumptionParameterMapping(
static_cast<AtomicConstraint &>(N).getConstraintExpr(),
/*Depth=*/0, OccurringIndicesForSubsumption);
} else if (N.getKind() ==
NormalizedConstraint::ConstraintKind::FoldExpanded) {
SemaRef.MarkUsedTemplateParameters(
static_cast<FoldExpandedConstraint &>(N).getPattern(),
/*OnlyDeduced=*/false,
/*Depth=*/0, OccurringIndices);
} else if (N.getKind() == NormalizedConstraint::ConstraintKind::ConceptId) {
auto *Args = static_cast<ConceptIdConstraint &>(N)
.getConceptId()
->getTemplateArgsAsWritten();
if (Args)
SemaRef.MarkUsedTemplateParameters(Args->arguments(),
/*Depth=*/0, OccurringIndices);
}
unsigned Size = OccurringIndices.count();
// When the constraint is independent of any template parameters,
// we build an empty mapping so that we can distinguish these cases
// from cases where no mapping exists at all, e.g. when there are only atomic
// constraints.
TemplateArgumentLoc *TempArgs =
new (SemaRef.Context) TemplateArgumentLoc[Size];
llvm::SmallVector<NamedDecl *> UsedParams;
for (unsigned I = 0, J = 0, C = TemplateParams->size(); I != C; ++I) {
SourceLocation Loc = ArgsAsWritten->NumTemplateArgs > I
? ArgsAsWritten->arguments()[I].getLocation()
: SourceLocation();
// FIXME: Investigate why we couldn't always preserve the SourceLoc. We
// can't assert Loc.isValid() now.
if (OccurringIndices[I]) {
NamedDecl *Param = TemplateParams->begin()[I];
new (&(TempArgs)[J]) TemplateArgumentLoc(
SemaRef.getIdentityTemplateArgumentLoc(Param, Loc));
UsedParams.push_back(Param);
J++;
}
}
auto *UsedList = TemplateParameterList::Create(
SemaRef.Context, TemplateParams->getTemplateLoc(),
TemplateParams->getLAngleLoc(), UsedParams,
/*RAngleLoc=*/SourceLocation(),
/*RequiresClause=*/nullptr);
N.updateParameterMapping(
std::move(OccurringIndices), std::move(OccurringIndicesForSubsumption),
MutableArrayRef<TemplateArgumentLoc>{TempArgs, Size}, UsedList);
}
bool SubstituteParameterMappings::substitute(
NormalizedConstraintWithParamMapping &N) {
if (!N.hasParameterMapping())
buildParameterMapping(N);
// If the parameter mapping is empty, there is nothing to substitute.
if (N.getParameterMapping().empty())
return false;
SourceLocation InstLocBegin, InstLocEnd;
llvm::ArrayRef Arguments = ArgsAsWritten->arguments();
if (Arguments.empty()) {
InstLocBegin = ArgsAsWritten->getLAngleLoc();
InstLocEnd = ArgsAsWritten->getRAngleLoc();
} else {
auto SR = Arguments[0].getSourceRange();
InstLocBegin = SR.getBegin();
InstLocEnd = SR.getEnd();
}
Sema::InstantiatingTemplate Inst(
SemaRef, InstLocBegin,
Sema::InstantiatingTemplate::ParameterMappingSubstitution{},
const_cast<NamedDecl *>(N.getConstraintDecl()),
{InstLocBegin, InstLocEnd});
if (Inst.isInvalid())
return true;
// TransformTemplateArguments is unable to preserve the source location of a
// pack. The SourceLocation is necessary for the instantiation location.
// FIXME: The BaseLoc will be used as the location of the pack expansion,
// which is wrong.
TemplateArgumentListInfo SubstArgs;
if (SemaRef.SubstTemplateArgumentsInParameterMapping(
N.getParameterMapping(), N.getBeginLoc(), *MLTAL, SubstArgs,
/*BuildPackExpansionTypes=*/!InFoldExpr))
return true;
Sema::CheckTemplateArgumentInfo CTAI;
auto *TD =
const_cast<TemplateDecl *>(cast<TemplateDecl>(N.getConstraintDecl()));
if (SemaRef.CheckTemplateArgumentList(TD, N.getUsedTemplateParamList(),
TD->getLocation(), SubstArgs,
/*DefaultArguments=*/{},
/*PartialTemplateArgs=*/false, CTAI))
return true;
TemplateArgumentLoc *TempArgs =
new (SemaRef.Context) TemplateArgumentLoc[CTAI.SugaredConverted.size()];
for (unsigned I = 0; I < CTAI.SugaredConverted.size(); ++I) {
SourceLocation Loc;
// If this is an empty pack, we have no corresponding SubstArgs.
if (I < SubstArgs.size())
Loc = SubstArgs.arguments()[I].getLocation();
TempArgs[I] = SemaRef.getTrivialTemplateArgumentLoc(
CTAI.SugaredConverted[I], QualType(), Loc);
}
MutableArrayRef<TemplateArgumentLoc> Mapping(TempArgs,
CTAI.SugaredConverted.size());
N.updateParameterMapping(N.mappingOccurenceList(),
N.mappingOccurenceListForSubsumption(), Mapping,
N.getUsedTemplateParamList());
return false;
}
bool SubstituteParameterMappings::substitute(ConceptIdConstraint &CC) {
assert(CC.getConstraintDecl() && MLTAL && ArgsAsWritten);
if (substitute(static_cast<NormalizedConstraintWithParamMapping &>(CC)))
return true;
auto *CSE = CC.getConceptSpecializationExpr();
assert(CSE);
assert(!CC.getBeginLoc().isInvalid());
SourceLocation InstLocBegin, InstLocEnd;
if (llvm::ArrayRef Arguments = ArgsAsWritten->arguments();
Arguments.empty()) {
InstLocBegin = ArgsAsWritten->getLAngleLoc();
InstLocEnd = ArgsAsWritten->getRAngleLoc();
} else {
auto SR = Arguments[0].getSourceRange();
InstLocBegin = SR.getBegin();
InstLocEnd = SR.getEnd();
}
// This is useful for name lookup across modules; see Sema::getLookupModules.
Sema::InstantiatingTemplate Inst(
SemaRef, InstLocBegin,
Sema::InstantiatingTemplate::ParameterMappingSubstitution{},
const_cast<NamedDecl *>(CC.getConstraintDecl()),
{InstLocBegin, InstLocEnd});
if (Inst.isInvalid())
return true;
TemplateArgumentListInfo Out;
// TransformTemplateArguments is unable to preserve the source location of a
// pack. The SourceLocation is necessary for the instantiation location.
// FIXME: The BaseLoc will be used as the location of the pack expansion,
// which is wrong.
const ASTTemplateArgumentListInfo *ArgsAsWritten =
CSE->getTemplateArgsAsWritten();
if (SemaRef.SubstTemplateArgumentsInParameterMapping(
ArgsAsWritten->arguments(), CC.getBeginLoc(), *MLTAL, Out,
/*BuildPackExpansionTypes=*/!InFoldExpr))
return true;
Sema::CheckTemplateArgumentInfo CTAI;
if (SemaRef.CheckTemplateArgumentList(CSE->getNamedConcept(),
CSE->getConceptNameInfo().getLoc(), Out,
/*DefaultArgs=*/{},
/*PartialTemplateArgs=*/false, CTAI,
/*UpdateArgsWithConversions=*/false))
return true;
auto TemplateArgs = *MLTAL;
TemplateArgs.replaceOutermostTemplateArguments(CSE->getNamedConcept(),
CTAI.SugaredConverted);
return SubstituteParameterMappings(SemaRef, &TemplateArgs, ArgsAsWritten,
InFoldExpr)
.substitute(CC.getNormalizedConstraint());
}
bool SubstituteParameterMappings::substitute(NormalizedConstraint &N) {
switch (N.getKind()) {
case NormalizedConstraint::ConstraintKind::Atomic: {
if (!MLTAL) {
assert(!ArgsAsWritten);
return false;
}
return substitute(static_cast<NormalizedConstraintWithParamMapping &>(N));
}
case NormalizedConstraint::ConstraintKind::FoldExpanded: {
auto &FE = static_cast<FoldExpandedConstraint &>(N);
if (!MLTAL) {
llvm::SaveAndRestore _1(InFoldExpr, true);
assert(!ArgsAsWritten);
return substitute(FE.getNormalizedPattern());
}
Sema::ArgPackSubstIndexRAII _(SemaRef, std::nullopt);
substitute(static_cast<NormalizedConstraintWithParamMapping &>(FE));
return SubstituteParameterMappings(SemaRef, /*InFoldExpr=*/true)
.substitute(FE.getNormalizedPattern());
}
case NormalizedConstraint::ConstraintKind::ConceptId: {
auto &CC = static_cast<ConceptIdConstraint &>(N);
if (MLTAL) {
assert(ArgsAsWritten);
return substitute(CC);
}
assert(!ArgsAsWritten);
const ConceptSpecializationExpr *CSE = CC.getConceptSpecializationExpr();
ConceptDecl *Concept = CSE->getNamedConcept();
MultiLevelTemplateArgumentList MLTAL = SemaRef.getTemplateInstantiationArgs(
Concept, Concept->getLexicalDeclContext(),
/*Final=*/true, CSE->getTemplateArguments(),
/*RelativeToPrimary=*/true,
/*Pattern=*/nullptr,
/*ForConstraintInstantiation=*/true);
return SubstituteParameterMappings(
SemaRef, &MLTAL, CSE->getTemplateArgsAsWritten(), InFoldExpr)
.substitute(CC.getNormalizedConstraint());
}
case NormalizedConstraint::ConstraintKind::Compound: {
auto &Compound = static_cast<CompoundConstraint &>(N);
if (substitute(Compound.getLHS()))
return true;
return substitute(Compound.getRHS());
}
}
llvm_unreachable("Unknown ConstraintKind enum");
}
} // namespace
NormalizedConstraint *NormalizedConstraint::fromAssociatedConstraints(
Sema &S, const NamedDecl *D, ArrayRef<AssociatedConstraint> ACs) {
assert(ACs.size() != 0);
auto *Conjunction =
fromConstraintExpr(S, D, ACs[0].ConstraintExpr, ACs[0].ArgPackSubstIndex);
if (!Conjunction)
return nullptr;
for (unsigned I = 1; I < ACs.size(); ++I) {
auto *Next = fromConstraintExpr(S, D, ACs[I].ConstraintExpr,
ACs[I].ArgPackSubstIndex);
if (!Next)
return nullptr;
Conjunction = CompoundConstraint::CreateConjunction(S.getASTContext(),
Conjunction, Next);
}
return Conjunction;
}
NormalizedConstraint *NormalizedConstraint::fromConstraintExpr(
Sema &S, const NamedDecl *D, const Expr *E, UnsignedOrNone SubstIndex) {
assert(E != nullptr);
// C++ [temp.constr.normal]p1.1
// [...]
// - The normal form of an expression (E) is the normal form of E.
// [...]
E = E->IgnoreParenImpCasts();
llvm::FoldingSetNodeID ID;
if (D && DiagRecursiveConstraintEval(S, ID, D, E)) {
return nullptr;
}
SatisfactionStackRAII StackRAII(S, D, ID);
// C++2a [temp.param]p4:
// [...] If T is not a pack, then E is E', otherwise E is (E' && ...).
// Fold expression is considered atomic constraints per current wording.
// See http://cplusplus.github.io/concepts-ts/ts-active.html#28
if (LogicalBinOp BO = E) {
auto *LHS = fromConstraintExpr(S, D, BO.getLHS(), SubstIndex);
if (!LHS)
return nullptr;
auto *RHS = fromConstraintExpr(S, D, BO.getRHS(), SubstIndex);
if (!RHS)
return nullptr;
return CompoundConstraint::Create(
S.Context, LHS, BO.isAnd() ? CCK_Conjunction : CCK_Disjunction, RHS);
} else if (auto *CSE = dyn_cast<const ConceptSpecializationExpr>(E)) {
NormalizedConstraint *SubNF;
{
Sema::InstantiatingTemplate Inst(
S, CSE->getExprLoc(),
Sema::InstantiatingTemplate::ConstraintNormalization{},
// FIXME: improve const-correctness of InstantiatingTemplate
const_cast<NamedDecl *>(D), CSE->getSourceRange());
if (Inst.isInvalid())
return nullptr;
// C++ [temp.constr.normal]p1.1
// [...]
// The normal form of an id-expression of the form C<A1, A2, ..., AN>,
// where C names a concept, is the normal form of the
// constraint-expression of C, after substituting A1, A2, ..., AN for C’s
// respective template parameters in the parameter mappings in each atomic
// constraint. If any such substitution results in an invalid type or
// expression, the program is ill-formed; no diagnostic is required.
// [...]
// Use canonical declarations to merge ConceptDecls across
// different modules.
ConceptDecl *CD = CSE->getNamedConcept()->getCanonicalDecl();
ExprResult Res =
SubstituteConceptsInConstraintExpression(S, D, CSE, SubstIndex);
if (!Res.isUsable())
return nullptr;
SubNF = NormalizedConstraint::fromAssociatedConstraints(
S, CD, AssociatedConstraint(Res.get(), SubstIndex));
if (!SubNF)
return nullptr;
}
return ConceptIdConstraint::Create(S.getASTContext(),
CSE->getConceptReference(), SubNF, D,
CSE, SubstIndex);
} else if (auto *FE = dyn_cast<const CXXFoldExpr>(E);
FE && S.getLangOpts().CPlusPlus26 &&
(FE->getOperator() == BinaryOperatorKind::BO_LAnd ||
FE->getOperator() == BinaryOperatorKind::BO_LOr)) {
// Normalize fold expressions in C++26.
FoldExpandedConstraint::FoldOperatorKind Kind =
FE->getOperator() == BinaryOperatorKind::BO_LAnd
? FoldExpandedConstraint::FoldOperatorKind::And
: FoldExpandedConstraint::FoldOperatorKind::Or;
if (FE->getInit()) {
auto *LHS = fromConstraintExpr(S, D, FE->getLHS(), SubstIndex);
auto *RHS = fromConstraintExpr(S, D, FE->getRHS(), SubstIndex);
if (!LHS || !RHS)
return nullptr;
if (FE->isRightFold())
LHS = FoldExpandedConstraint::Create(S.getASTContext(),
FE->getPattern(), D, Kind, LHS);
else
RHS = FoldExpandedConstraint::Create(S.getASTContext(),
FE->getPattern(), D, Kind, RHS);
return CompoundConstraint::Create(
S.getASTContext(), LHS,
(FE->getOperator() == BinaryOperatorKind::BO_LAnd ? CCK_Conjunction
: CCK_Disjunction),
RHS);
}
auto *Sub = fromConstraintExpr(S, D, FE->getPattern(), SubstIndex);
if (!Sub)
return nullptr;
return FoldExpandedConstraint::Create(S.getASTContext(), FE->getPattern(),
D, Kind, Sub);
}
return AtomicConstraint::Create(S.getASTContext(), E, D, SubstIndex);
}
const NormalizedConstraint *Sema::getNormalizedAssociatedConstraints(
ConstrainedDeclOrNestedRequirement ConstrainedDeclOrNestedReq,
ArrayRef<AssociatedConstraint> AssociatedConstraints) {
if (!ConstrainedDeclOrNestedReq) {
auto *Normalized = NormalizedConstraint::fromAssociatedConstraints(
*this, nullptr, AssociatedConstraints);
if (!Normalized ||
SubstituteParameterMappings(*this).substitute(*Normalized))
return nullptr;
return Normalized;
}
// FIXME: ConstrainedDeclOrNestedReq is never a NestedRequirement!
const NamedDecl *ND =
ConstrainedDeclOrNestedReq.dyn_cast<const NamedDecl *>();
auto CacheEntry = NormalizationCache.find(ConstrainedDeclOrNestedReq);
if (CacheEntry == NormalizationCache.end()) {
auto *Normalized = NormalizedConstraint::fromAssociatedConstraints(
*this, ND, AssociatedConstraints);
if (!Normalized) {
NormalizationCache.try_emplace(ConstrainedDeclOrNestedReq, nullptr);
return nullptr;
}
// substitute() can invalidate iterators of NormalizationCache.
bool Failed = SubstituteParameterMappings(*this).substitute(*Normalized);
CacheEntry =
NormalizationCache.try_emplace(ConstrainedDeclOrNestedReq, Normalized)
.first;
if (Failed)
return nullptr;
}
return CacheEntry->second;
}
bool FoldExpandedConstraint::AreCompatibleForSubsumption(
const FoldExpandedConstraint &A, const FoldExpandedConstraint &B) {
// [C++26] [temp.constr.fold]
// Two fold expanded constraints are compatible for subsumption
// if their respective constraints both contain an equivalent unexpanded pack.
llvm::SmallVector<UnexpandedParameterPack> APacks, BPacks;
Sema::collectUnexpandedParameterPacks(const_cast<Expr *>(A.getPattern()),
APacks);
Sema::collectUnexpandedParameterPacks(const_cast<Expr *>(B.getPattern()),
BPacks);
for (const UnexpandedParameterPack &APack : APacks) {
auto ADI = getDepthAndIndex(APack);
if (!ADI)
continue;
auto It = llvm::find_if(BPacks, [&](const UnexpandedParameterPack &BPack) {
return getDepthAndIndex(BPack) == ADI;
});
if (It != BPacks.end())
return true;
}
return false;
}
bool Sema::IsAtLeastAsConstrained(const NamedDecl *D1,
MutableArrayRef<AssociatedConstraint> AC1,
const NamedDecl *D2,
MutableArrayRef<AssociatedConstraint> AC2,
bool &Result) {
#ifndef NDEBUG
if (const auto *FD1 = dyn_cast<FunctionDecl>(D1)) {
auto IsExpectedEntity = [](const FunctionDecl *FD) {
FunctionDecl::TemplatedKind Kind = FD->getTemplatedKind();
return Kind == FunctionDecl::TK_NonTemplate ||
Kind == FunctionDecl::TK_FunctionTemplate;
};
const auto *FD2 = dyn_cast<FunctionDecl>(D2);
assert(IsExpectedEntity(FD1) && FD2 && IsExpectedEntity(FD2) &&
"use non-instantiated function declaration for constraints partial "
"ordering");
}
#endif
if (AC1.empty()) {
Result = AC2.empty();
return false;
}
if (AC2.empty()) {
// TD1 has associated constraints and TD2 does not.
Result = true;
return false;
}
std::pair<const NamedDecl *, const NamedDecl *> Key{D1, D2};
auto CacheEntry = SubsumptionCache.find(Key);
if (CacheEntry != SubsumptionCache.end()) {
Result = CacheEntry->second;
return false;
}
unsigned Depth1 = CalculateTemplateDepthForConstraints(*this, D1, true);
unsigned Depth2 = CalculateTemplateDepthForConstraints(*this, D2, true);
for (size_t I = 0; I != AC1.size() && I != AC2.size(); ++I) {
if (Depth2 > Depth1) {
AC1[I].ConstraintExpr =
AdjustConstraintDepth(*this, Depth2 - Depth1)
.TransformExpr(const_cast<Expr *>(AC1[I].ConstraintExpr))
.get();
} else if (Depth1 > Depth2) {
AC2[I].ConstraintExpr =
AdjustConstraintDepth(*this, Depth1 - Depth2)
.TransformExpr(const_cast<Expr *>(AC2[I].ConstraintExpr))
.get();
}
}
SubsumptionChecker SC(*this);
std::optional<bool> Subsumes = SC.Subsumes(D1, AC1, D2, AC2);
if (!Subsumes) {
// Normalization failed
return true;
}
Result = *Subsumes;
SubsumptionCache.try_emplace(Key, *Subsumes);
return false;
}
bool Sema::MaybeEmitAmbiguousAtomicConstraintsDiagnostic(
const NamedDecl *D1, ArrayRef<AssociatedConstraint> AC1,
const NamedDecl *D2, ArrayRef<AssociatedConstraint> AC2) {
if (isSFINAEContext())
// No need to work here because our notes would be discarded.
return false;
if (AC1.empty() || AC2.empty())
return false;
const Expr *AmbiguousAtomic1 = nullptr, *AmbiguousAtomic2 = nullptr;
auto IdenticalExprEvaluator = [&](const AtomicConstraint &A,
const AtomicConstraint &B) {
if (!A.hasMatchingParameterMapping(Context, B))
return false;
const Expr *EA = A.getConstraintExpr(), *EB = B.getConstraintExpr();
if (EA == EB)
return true;
// Not the same source level expression - are the expressions
// identical?
llvm::FoldingSetNodeID IDA, IDB;
EA->Profile(IDA, Context, /*Canonical=*/true);
EB->Profile(IDB, Context, /*Canonical=*/true);
if (IDA != IDB)
return false;
AmbiguousAtomic1 = EA;
AmbiguousAtomic2 = EB;
return true;
};
{
// The subsumption checks might cause diagnostics
SFINAETrap Trap(*this);
auto *Normalized1 = getNormalizedAssociatedConstraints(D1, AC1);
if (!Normalized1)
return false;
auto *Normalized2 = getNormalizedAssociatedConstraints(D2, AC2);
if (!Normalized2)
return false;
SubsumptionChecker SC(*this);
bool Is1AtLeastAs2Normally = SC.Subsumes(Normalized1, Normalized2);
bool Is2AtLeastAs1Normally = SC.Subsumes(Normalized2, Normalized1);
SubsumptionChecker SC2(*this, IdenticalExprEvaluator);
bool Is1AtLeastAs2 = SC2.Subsumes(Normalized1, Normalized2);
bool Is2AtLeastAs1 = SC2.Subsumes(Normalized2, Normalized1);
if (Is1AtLeastAs2 == Is1AtLeastAs2Normally &&
Is2AtLeastAs1 == Is2AtLeastAs1Normally)
// Same result - no ambiguity was caused by identical atomic expressions.
return false;
}
// A different result! Some ambiguous atomic constraint(s) caused a difference
assert(AmbiguousAtomic1 && AmbiguousAtomic2);
Diag(AmbiguousAtomic1->getBeginLoc(), diag::note_ambiguous_atomic_constraints)
<< AmbiguousAtomic1->getSourceRange();
Diag(AmbiguousAtomic2->getBeginLoc(),
diag::note_ambiguous_atomic_constraints_similar_expression)
<< AmbiguousAtomic2->getSourceRange();
return true;
}
//
//
// ------------------------ Subsumption -----------------------------------
//
//
SubsumptionChecker::SubsumptionChecker(Sema &SemaRef,
SubsumptionCallable Callable)
: SemaRef(SemaRef), Callable(Callable), NextID(1) {}
uint16_t SubsumptionChecker::getNewLiteralId() {
assert((unsigned(NextID) + 1 < std::numeric_limits<uint16_t>::max()) &&
"too many constraints!");
return NextID++;
}
auto SubsumptionChecker::find(const AtomicConstraint *Ori) -> Literal {
auto &Elems = AtomicMap[Ori->getConstraintExpr()];
// C++ [temp.constr.order] p2
// - an atomic constraint A subsumes another atomic constraint B
// if and only if the A and B are identical [...]
//
// C++ [temp.constr.atomic] p2
// Two atomic constraints are identical if they are formed from the
// same expression and the targets of the parameter mappings are
// equivalent according to the rules for expressions [...]
// Because subsumption of atomic constraints is an identity
// relationship that does not require further analysis
// We cache the results such that if an atomic constraint literal
// subsumes another, their literal will be the same
llvm::FoldingSetNodeID ID;
ID.AddBoolean(Ori->hasParameterMapping());
if (Ori->hasParameterMapping()) {
const auto &Mapping = Ori->getParameterMapping();
const NormalizedConstraint::OccurenceList &Indexes =
Ori->mappingOccurenceListForSubsumption();
for (auto [Idx, TAL] : llvm::enumerate(Mapping)) {
if (Indexes[Idx])
SemaRef.getASTContext()
.getCanonicalTemplateArgument(TAL.getArgument())
.Profile(ID, SemaRef.getASTContext());
}
}
auto It = Elems.find(ID);
if (It == Elems.end()) {
It = Elems
.insert({ID,
MappedAtomicConstraint{
Ori, {getNewLiteralId(), Literal::Atomic}}})
.first;
ReverseMap[It->second.ID.Value] = Ori;
}
return It->getSecond().ID;
}
auto SubsumptionChecker::find(const FoldExpandedConstraint *Ori) -> Literal {
auto &Elems = FoldMap[Ori->getPattern()];
FoldExpendedConstraintKey K;
K.Kind = Ori->getFoldOperator();
auto It = llvm::find_if(Elems, [&K](const FoldExpendedConstraintKey &Other) {
return K.Kind == Other.Kind;
});
if (It == Elems.end()) {
K.ID = {getNewLiteralId(), Literal::FoldExpanded};
It = Elems.insert(Elems.end(), std::move(K));
ReverseMap[It->ID.Value] = Ori;
}
return It->ID;
}
auto SubsumptionChecker::CNF(const NormalizedConstraint &C) -> CNFFormula {
return SubsumptionChecker::Normalize<CNFFormula>(C);
}
auto SubsumptionChecker::DNF(const NormalizedConstraint &C) -> DNFFormula {
return SubsumptionChecker::Normalize<DNFFormula>(C);
}
///
/// \brief SubsumptionChecker::Normalize
///
/// Normalize a formula to Conjunctive Normal Form or
/// Disjunctive normal form.
///
/// Each Atomic (and Fold Expanded) constraint gets represented by
/// a single id to reduce space.
///
/// To minimize risks of exponential blow up, if two atomic
/// constraints subsumes each other (same constraint and mapping),
/// they are represented by the same literal.
///
template <typename FormulaType>
FormulaType SubsumptionChecker::Normalize(const NormalizedConstraint &NC) {
FormulaType Res;
auto Add = [&, this](Clause C) {
// Sort each clause and remove duplicates for faster comparisons.
llvm::sort(C);
C.erase(llvm::unique(C), C.end());
AddUniqueClauseToFormula(Res, std::move(C));
};
switch (NC.getKind()) {
case NormalizedConstraint::ConstraintKind::Atomic:
return {{find(&static_cast<const AtomicConstraint &>(NC))}};
case NormalizedConstraint::ConstraintKind::FoldExpanded:
return {{find(&static_cast<const FoldExpandedConstraint &>(NC))}};
case NormalizedConstraint::ConstraintKind::ConceptId:
return Normalize<FormulaType>(
static_cast<const ConceptIdConstraint &>(NC).getNormalizedConstraint());
case NormalizedConstraint::ConstraintKind::Compound: {
const auto &Compound = static_cast<const CompoundConstraint &>(NC);
FormulaType Left, Right;
SemaRef.runWithSufficientStackSpace(SourceLocation(), [&] {
Left = Normalize<FormulaType>(Compound.getLHS());
Right = Normalize<FormulaType>(Compound.getRHS());
});
if (Compound.getCompoundKind() == FormulaType::Kind) {
unsigned SizeLeft = Left.size();
Res = std::move(Left);
Res.reserve(SizeLeft + Right.size());
std::for_each(std::make_move_iterator(Right.begin()),
std::make_move_iterator(Right.end()), Add);
return Res;
}
Res.reserve(Left.size() * Right.size());
for (const auto &LTransform : Left) {
for (const auto &RTransform : Right) {
Clause Combined;
Combined.reserve(LTransform.size() + RTransform.size());
llvm::copy(LTransform, std::back_inserter(Combined));
llvm::copy(RTransform, std::back_inserter(Combined));
Add(std::move(Combined));
}
}
return Res;
}
}
llvm_unreachable("Unknown ConstraintKind enum");
}
void SubsumptionChecker::AddUniqueClauseToFormula(Formula &F, Clause C) {
for (auto &Other : F) {
if (llvm::equal(C, Other))
return;
}
F.push_back(C);
}
std::optional<bool> SubsumptionChecker::Subsumes(
const NamedDecl *DP, ArrayRef<AssociatedConstraint> P, const NamedDecl *DQ,
ArrayRef<AssociatedConstraint> Q) {
const NormalizedConstraint *PNormalized =
SemaRef.getNormalizedAssociatedConstraints(DP, P);
if (!PNormalized)
return std::nullopt;
const NormalizedConstraint *QNormalized =
SemaRef.getNormalizedAssociatedConstraints(DQ, Q);
if (!QNormalized)
return std::nullopt;
return Subsumes(PNormalized, QNormalized);
}
bool SubsumptionChecker::Subsumes(const NormalizedConstraint *P,
const NormalizedConstraint *Q) {
DNFFormula DNFP = DNF(*P);
CNFFormula CNFQ = CNF(*Q);
return Subsumes(DNFP, CNFQ);
}
bool SubsumptionChecker::Subsumes(const DNFFormula &PDNF,
const CNFFormula &QCNF) {
for (const auto &Pi : PDNF) {
for (const auto &Qj : QCNF) {
// C++ [temp.constr.order] p2
// - [...] a disjunctive clause Pi subsumes a conjunctive clause Qj if
// and only if there exists an atomic constraint Pia in Pi for which
// there exists an atomic constraint, Qjb, in Qj such that Pia
// subsumes Qjb.
if (!DNFSubsumes(Pi, Qj))
return false;
}
}
return true;
}
bool SubsumptionChecker::DNFSubsumes(const Clause &P, const Clause &Q) {
return llvm::any_of(P, [&](Literal LP) {
return llvm::any_of(Q, [this, LP](Literal LQ) { return Subsumes(LP, LQ); });
});
}
bool SubsumptionChecker::Subsumes(const FoldExpandedConstraint *A,
const FoldExpandedConstraint *B) {
std::pair<const FoldExpandedConstraint *, const FoldExpandedConstraint *> Key{
A, B};
auto It = FoldSubsumptionCache.find(Key);
if (It == FoldSubsumptionCache.end()) {
// C++ [temp.constr.order]
// a fold expanded constraint A subsumes another fold expanded
// constraint B if they are compatible for subsumption, have the same
// fold-operator, and the constraint of A subsumes that of B.
bool DoesSubsume =
A->getFoldOperator() == B->getFoldOperator() &&
FoldExpandedConstraint::AreCompatibleForSubsumption(*A, *B) &&
Subsumes(&A->getNormalizedPattern(), &B->getNormalizedPattern());
It = FoldSubsumptionCache.try_emplace(std::move(Key), DoesSubsume).first;
}
return It->second;
}
bool SubsumptionChecker::Subsumes(Literal A, Literal B) {
if (A.Kind != B.Kind)
return false;
switch (A.Kind) {
case Literal::Atomic:
if (!Callable)
return A.Value == B.Value;
return Callable(
*static_cast<const AtomicConstraint *>(ReverseMap[A.Value]),
*static_cast<const AtomicConstraint *>(ReverseMap[B.Value]));
case Literal::FoldExpanded:
return Subsumes(
static_cast<const FoldExpandedConstraint *>(ReverseMap[A.Value]),
static_cast<const FoldExpandedConstraint *>(ReverseMap[B.Value]));
}
llvm_unreachable("unknown literal kind");
}
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