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//===-- SemaConcept.cpp - Semantic Analysis for Constraints and Concepts --===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements semantic analysis for C++ constraints and concepts.
//
//===----------------------------------------------------------------------===//
#include "clang/Sema/Sema.h"
#include "clang/Sema/SemaDiagnostic.h"
#include "clang/Sema/TemplateDeduction.h"
#include "clang/Sema/Template.h"
#include "clang/AST/ExprCXX.h"
using namespace clang;
using namespace sema;
bool Sema::CheckConstraintExpression(Expr *ConstraintExpression) {
// C++2a [temp.constr.atomic]p1
// ..E shall be a constant expression of type bool.
ConstraintExpression = ConstraintExpression->IgnoreParenImpCasts();
if (auto *BinOp = dyn_cast<BinaryOperator>(ConstraintExpression)) {
if (BinOp->getOpcode() == BO_LAnd || BinOp->getOpcode() == BO_LOr)
return CheckConstraintExpression(BinOp->getLHS()) &&
CheckConstraintExpression(BinOp->getRHS());
} else if (auto *C = dyn_cast<ExprWithCleanups>(ConstraintExpression))
return CheckConstraintExpression(C->getSubExpr());
// An atomic constraint!
if (ConstraintExpression->isTypeDependent())
return true;
QualType Type = ConstraintExpression->getType();
if (!Context.hasSameUnqualifiedType(Type, Context.BoolTy)) {
Diag(ConstraintExpression->getExprLoc(),
diag::err_non_bool_atomic_constraint) << Type
<< ConstraintExpression->getSourceRange();
return false;
}
return true;
}
bool
Sema::CalculateConstraintSatisfaction(ConceptDecl *NamedConcept,
MultiLevelTemplateArgumentList &MLTAL,
Expr *ConstraintExpr,
bool &IsSatisfied) {
ConstraintExpr = ConstraintExpr->IgnoreParenImpCasts();
if (auto *BO = dyn_cast<BinaryOperator>(ConstraintExpr)) {
if (BO->getOpcode() == BO_LAnd) {
if (CalculateConstraintSatisfaction(NamedConcept, MLTAL, BO->getLHS(),
IsSatisfied))
return true;
if (!IsSatisfied)
return false;
return CalculateConstraintSatisfaction(NamedConcept, MLTAL, BO->getRHS(),
IsSatisfied);
} else if (BO->getOpcode() == BO_LOr) {
if (CalculateConstraintSatisfaction(NamedConcept, MLTAL, BO->getLHS(),
IsSatisfied))
return true;
if (IsSatisfied)
return false;
return CalculateConstraintSatisfaction(NamedConcept, MLTAL, BO->getRHS(),
IsSatisfied);
}
}
else if (auto *C = dyn_cast<ExprWithCleanups>(ConstraintExpr))
return CalculateConstraintSatisfaction(NamedConcept, MLTAL, C->getSubExpr(),
IsSatisfied);
EnterExpressionEvaluationContext ConstantEvaluated(
*this, Sema::ExpressionEvaluationContext::ConstantEvaluated);
// Atomic constraint - substitute arguments and check satisfaction.
ExprResult E;
{
TemplateDeductionInfo Info(ConstraintExpr->getBeginLoc());
InstantiatingTemplate Inst(*this, ConstraintExpr->getBeginLoc(),
InstantiatingTemplate::ConstraintSubstitution{},
NamedConcept, Info,
ConstraintExpr->getSourceRange());
if (Inst.isInvalid())
return true;
// We do not want error diagnostics escaping here.
Sema::SFINAETrap Trap(*this);
E = SubstExpr(ConstraintExpr, MLTAL);
if (E.isInvalid() || Trap.hasErrorOccurred()) {
// C++2a [temp.constr.atomic]p1
// ...If substitution results in an invalid type or expression, the
// constraint is not satisfied.
IsSatisfied = false;
return false;
}
}
if (!CheckConstraintExpression(E.get()))
return true;
SmallVector<PartialDiagnosticAt, 2> EvaluationDiags;
Expr::EvalResult EvalResult;
EvalResult.Diag = &EvaluationDiags;
if (!E.get()->EvaluateAsRValue(EvalResult, Context)) {
// C++2a [temp.constr.atomic]p1
// ...E shall be a constant expression of type bool.
Diag(E.get()->getBeginLoc(),
diag::err_non_constant_constraint_expression)
<< E.get()->getSourceRange();
for (const PartialDiagnosticAt &PDiag : EvaluationDiags)
Diag(PDiag.first, PDiag.second);
return true;
}
IsSatisfied = EvalResult.Val.getInt().getBoolValue();
return false;
}
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