blob: 14abac5ff9ba801425822c38739508e348d06fab [file] [log] [blame]
//===-- lib/Evaluate/check-expression.cpp ---------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "flang/Evaluate/check-expression.h"
#include "flang/Evaluate/characteristics.h"
#include "flang/Evaluate/intrinsics.h"
#include "flang/Evaluate/tools.h"
#include "flang/Evaluate/traverse.h"
#include "flang/Evaluate/type.h"
#include "flang/Semantics/semantics.h"
#include "flang/Semantics/symbol.h"
#include "flang/Semantics/tools.h"
#include <set>
#include <string>
namespace Fortran::evaluate {
// Constant expression predicates IsConstantExpr() & IsScopeInvariantExpr().
// This code determines whether an expression is a "constant expression"
// in the sense of section 10.1.12. This is not the same thing as being
// able to fold it (yet) into a known constant value; specifically,
// the expression may reference derived type kind parameters whose values
// are not yet known.
//
// The variant form (IsScopeInvariantExpr()) also accepts symbols that are
// INTENT(IN) dummy arguments without the VALUE attribute.
template <bool INVARIANT>
class IsConstantExprHelper
: public AllTraverse<IsConstantExprHelper<INVARIANT>, true> {
public:
using Base = AllTraverse<IsConstantExprHelper, true>;
IsConstantExprHelper() : Base{*this} {}
using Base::operator();
// A missing expression is not considered to be constant.
template <typename A> bool operator()(const std::optional<A> &x) const {
return x && (*this)(*x);
}
bool operator()(const TypeParamInquiry &inq) const {
return INVARIANT || semantics::IsKindTypeParameter(inq.parameter());
}
bool operator()(const semantics::Symbol &symbol) const {
const auto &ultimate{GetAssociationRoot(symbol)};
return IsNamedConstant(ultimate) || IsImpliedDoIndex(ultimate) ||
IsInitialProcedureTarget(ultimate) ||
ultimate.has<semantics::TypeParamDetails>() ||
(INVARIANT && IsIntentIn(symbol) && !IsOptional(symbol) &&
!symbol.attrs().test(semantics::Attr::VALUE));
}
bool operator()(const CoarrayRef &) const { return false; }
bool operator()(const semantics::ParamValue &param) const {
return param.isExplicit() && (*this)(param.GetExplicit());
}
bool operator()(const ProcedureRef &) const;
bool operator()(const StructureConstructor &constructor) const {
for (const auto &[symRef, expr] : constructor) {
if (!IsConstantStructureConstructorComponent(*symRef, expr.value())) {
return false;
}
}
return true;
}
bool operator()(const Component &component) const {
return (*this)(component.base());
}
// Forbid integer division by zero in constants.
template <int KIND>
bool operator()(
const Divide<Type<TypeCategory::Integer, KIND>> &division) const {
using T = Type<TypeCategory::Integer, KIND>;
if (const auto divisor{GetScalarConstantValue<T>(division.right())}) {
return !divisor->IsZero() && (*this)(division.left());
} else {
return false;
}
}
bool operator()(const Constant<SomeDerived> &) const { return true; }
bool operator()(const DescriptorInquiry &x) const {
const Symbol &sym{x.base().GetLastSymbol()};
return INVARIANT && !IsAllocatable(sym) &&
(!IsDummy(sym) ||
(IsIntentIn(sym) && !IsOptional(sym) &&
!sym.attrs().test(semantics::Attr::VALUE)));
}
private:
bool IsConstantStructureConstructorComponent(
const Symbol &, const Expr<SomeType> &) const;
bool IsConstantExprShape(const Shape &) const;
};
template <bool INVARIANT>
bool IsConstantExprHelper<INVARIANT>::IsConstantStructureConstructorComponent(
const Symbol &component, const Expr<SomeType> &expr) const {
if (IsAllocatable(component)) {
return IsNullObjectPointer(expr);
} else if (IsPointer(component)) {
return IsNullPointer(expr) || IsInitialDataTarget(expr) ||
IsInitialProcedureTarget(expr);
} else {
return (*this)(expr);
}
}
template <bool INVARIANT>
bool IsConstantExprHelper<INVARIANT>::operator()(
const ProcedureRef &call) const {
// LBOUND, UBOUND, and SIZE with truly constant DIM= arguments will have
// been rewritten into DescriptorInquiry operations.
if (const auto *intrinsic{std::get_if<SpecificIntrinsic>(&call.proc().u)}) {
const characteristics::Procedure &proc{intrinsic->characteristics.value()};
if (intrinsic->name == "kind" ||
intrinsic->name == IntrinsicProcTable::InvalidName ||
call.arguments().empty() || !call.arguments()[0]) {
// kind is always a constant, and we avoid cascading errors by considering
// invalid calls to intrinsics to be constant
return true;
} else if (intrinsic->name == "lbound") {
auto base{ExtractNamedEntity(call.arguments()[0]->UnwrapExpr())};
return base && IsConstantExprShape(GetLBOUNDs(*base));
} else if (intrinsic->name == "ubound") {
auto base{ExtractNamedEntity(call.arguments()[0]->UnwrapExpr())};
return base && IsConstantExprShape(GetUBOUNDs(*base));
} else if (intrinsic->name == "shape" || intrinsic->name == "size") {
auto shape{GetShape(call.arguments()[0]->UnwrapExpr())};
return shape && IsConstantExprShape(*shape);
} else if (proc.IsPure()) {
for (const auto &arg : call.arguments()) {
if (!arg) {
return false;
} else if (const auto *expr{arg->UnwrapExpr()};
!expr || !(*this)(*expr)) {
return false;
}
}
return true;
}
// TODO: STORAGE_SIZE
}
return false;
}
template <bool INVARIANT>
bool IsConstantExprHelper<INVARIANT>::IsConstantExprShape(
const Shape &shape) const {
for (const auto &extent : shape) {
if (!(*this)(extent)) {
return false;
}
}
return true;
}
template <typename A> bool IsConstantExpr(const A &x) {
return IsConstantExprHelper<false>{}(x);
}
template bool IsConstantExpr(const Expr<SomeType> &);
template bool IsConstantExpr(const Expr<SomeInteger> &);
template bool IsConstantExpr(const Expr<SubscriptInteger> &);
template bool IsConstantExpr(const StructureConstructor &);
// IsScopeInvariantExpr()
template <typename A> bool IsScopeInvariantExpr(const A &x) {
return IsConstantExprHelper<true>{}(x);
}
template bool IsScopeInvariantExpr(const Expr<SomeType> &);
template bool IsScopeInvariantExpr(const Expr<SomeInteger> &);
template bool IsScopeInvariantExpr(const Expr<SubscriptInteger> &);
// IsActuallyConstant()
struct IsActuallyConstantHelper {
template <typename A> bool operator()(const A &) { return false; }
template <typename T> bool operator()(const Constant<T> &) { return true; }
template <typename T> bool operator()(const Parentheses<T> &x) {
return (*this)(x.left());
}
template <typename T> bool operator()(const Expr<T> &x) {
return common::visit([=](const auto &y) { return (*this)(y); }, x.u);
}
bool operator()(const Expr<SomeType> &x) {
return common::visit([this](const auto &y) { return (*this)(y); }, x.u);
}
bool operator()(const StructureConstructor &x) {
for (const auto &pair : x) {
const Expr<SomeType> &y{pair.second.value()};
const auto sym{pair.first};
const bool compIsConstant{(*this)(y)};
// If an allocatable component is initialized by a constant,
// the structure constructor is not a constant.
if ((!compIsConstant && !IsNullPointer(y)) ||
(compIsConstant && IsAllocatable(sym))) {
return false;
}
}
return true;
}
template <typename A> bool operator()(const A *x) { return x && (*this)(*x); }
template <typename A> bool operator()(const std::optional<A> &x) {
return x && (*this)(*x);
}
};
template <typename A> bool IsActuallyConstant(const A &x) {
return IsActuallyConstantHelper{}(x);
}
template bool IsActuallyConstant(const Expr<SomeType> &);
template bool IsActuallyConstant(const Expr<SomeInteger> &);
template bool IsActuallyConstant(const Expr<SubscriptInteger> &);
template bool IsActuallyConstant(const std::optional<Expr<SubscriptInteger>> &);
// Object pointer initialization checking predicate IsInitialDataTarget().
// This code determines whether an expression is allowable as the static
// data address used to initialize a pointer with "=> x". See C765.
class IsInitialDataTargetHelper
: public AllTraverse<IsInitialDataTargetHelper, true> {
public:
using Base = AllTraverse<IsInitialDataTargetHelper, true>;
using Base::operator();
explicit IsInitialDataTargetHelper(parser::ContextualMessages *m)
: Base{*this}, messages_{m} {}
bool emittedMessage() const { return emittedMessage_; }
bool operator()(const BOZLiteralConstant &) const { return false; }
bool operator()(const NullPointer &) const { return true; }
template <typename T> bool operator()(const Constant<T> &) const {
return false;
}
bool operator()(const semantics::Symbol &symbol) {
// This function checks only base symbols, not components.
const Symbol &ultimate{symbol.GetUltimate()};
if (const auto *assoc{
ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
if (const auto &expr{assoc->expr()}) {
if (IsVariable(*expr)) {
return (*this)(*expr);
} else if (messages_) {
messages_->Say(
"An initial data target may not be an associated expression ('%s')"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
}
return false;
} else if (!ultimate.attrs().test(semantics::Attr::TARGET)) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to an object '%s' that lacks the TARGET attribute"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
} else if (!IsSaved(ultimate)) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to an object '%s' that lacks the SAVE attribute"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
} else {
return CheckVarOrComponent(ultimate);
}
}
bool operator()(const StaticDataObject &) const { return false; }
bool operator()(const TypeParamInquiry &) const { return false; }
bool operator()(const Triplet &x) const {
return IsConstantExpr(x.lower()) && IsConstantExpr(x.upper()) &&
IsConstantExpr(x.stride());
}
bool operator()(const Subscript &x) const {
return common::visit(common::visitors{
[&](const Triplet &t) { return (*this)(t); },
[&](const auto &y) {
return y.value().Rank() == 0 &&
IsConstantExpr(y.value());
},
},
x.u);
}
bool operator()(const CoarrayRef &) const { return false; }
bool operator()(const Component &x) {
return CheckVarOrComponent(x.GetLastSymbol()) && (*this)(x.base());
}
bool operator()(const Substring &x) const {
return IsConstantExpr(x.lower()) && IsConstantExpr(x.upper()) &&
(*this)(x.parent());
}
bool operator()(const DescriptorInquiry &) const { return false; }
template <typename T> bool operator()(const ArrayConstructor<T> &) const {
return false;
}
bool operator()(const StructureConstructor &) const { return false; }
template <typename D, typename R, typename... O>
bool operator()(const Operation<D, R, O...> &) const {
return false;
}
template <typename T> bool operator()(const Parentheses<T> &x) const {
return (*this)(x.left());
}
bool operator()(const ProcedureRef &x) const {
if (const SpecificIntrinsic * intrinsic{x.proc().GetSpecificIntrinsic()}) {
return intrinsic->characteristics.value().attrs.test(
characteristics::Procedure::Attr::NullPointer);
}
return false;
}
bool operator()(const Relational<SomeType> &) const { return false; }
private:
bool CheckVarOrComponent(const semantics::Symbol &symbol) {
const Symbol &ultimate{symbol.GetUltimate()};
if (IsAllocatable(ultimate)) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to an ALLOCATABLE '%s'"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
} else if (ultimate.Corank() > 0) {
if (messages_) {
messages_->Say(
"An initial data target may not be a reference to a coarray '%s'"_err_en_US,
ultimate.name());
emittedMessage_ = true;
}
return false;
}
return true;
}
parser::ContextualMessages *messages_;
bool emittedMessage_{false};
};
bool IsInitialDataTarget(
const Expr<SomeType> &x, parser::ContextualMessages *messages) {
IsInitialDataTargetHelper helper{messages};
bool result{helper(x)};
if (!result && messages && !helper.emittedMessage()) {
messages->Say(
"An initial data target must be a designator with constant subscripts"_err_en_US);
}
return result;
}
bool IsInitialProcedureTarget(const semantics::Symbol &symbol) {
const auto &ultimate{symbol.GetUltimate()};
return common::visit(
common::visitors{
[](const semantics::SubprogramDetails &subp) {
return !subp.isDummy();
},
[](const semantics::SubprogramNameDetails &) { return true; },
[&](const semantics::ProcEntityDetails &proc) {
return !semantics::IsPointer(ultimate) && !proc.isDummy();
},
[](const auto &) { return false; },
},
ultimate.details());
}
bool IsInitialProcedureTarget(const ProcedureDesignator &proc) {
if (const auto *intrin{proc.GetSpecificIntrinsic()}) {
return !intrin->isRestrictedSpecific;
} else if (proc.GetComponent()) {
return false;
} else {
return IsInitialProcedureTarget(DEREF(proc.GetSymbol()));
}
}
bool IsInitialProcedureTarget(const Expr<SomeType> &expr) {
if (const auto *proc{std::get_if<ProcedureDesignator>(&expr.u)}) {
return IsInitialProcedureTarget(*proc);
} else {
return IsNullProcedurePointer(expr);
}
}
// Converts, folds, and then checks type, rank, and shape of an
// initialization expression for a named constant, a non-pointer
// variable static initialization, a component default initializer,
// a type parameter default value, or instantiated type parameter value.
std::optional<Expr<SomeType>> NonPointerInitializationExpr(const Symbol &symbol,
Expr<SomeType> &&x, FoldingContext &context,
const semantics::Scope *instantiation) {
CHECK(!IsPointer(symbol));
if (auto symTS{
characteristics::TypeAndShape::Characterize(symbol, context)}) {
auto xType{x.GetType()};
auto converted{ConvertToType(symTS->type(), Expr<SomeType>{x})};
if (!converted &&
symbol.owner().context().IsEnabled(
common::LanguageFeature::LogicalIntegerAssignment)) {
converted = DataConstantConversionExtension(context, symTS->type(), x);
if (converted &&
symbol.owner().context().ShouldWarn(
common::LanguageFeature::LogicalIntegerAssignment)) {
context.messages().Say(
"nonstandard usage: initialization of %s with %s"_port_en_US,
symTS->type().AsFortran(), x.GetType().value().AsFortran());
}
}
if (converted) {
auto folded{Fold(context, std::move(*converted))};
if (IsActuallyConstant(folded)) {
int symRank{GetRank(symTS->shape())};
if (IsImpliedShape(symbol)) {
if (folded.Rank() == symRank) {
return ArrayConstantBoundChanger{
std::move(*AsConstantExtents(
context, GetRawLowerBounds(context, NamedEntity{symbol})))}
.ChangeLbounds(std::move(folded));
} else {
context.messages().Say(
"Implied-shape parameter '%s' has rank %d but its initializer has rank %d"_err_en_US,
symbol.name(), symRank, folded.Rank());
}
} else if (auto extents{AsConstantExtents(context, symTS->shape())}) {
if (folded.Rank() == 0 && symRank == 0) {
// symbol and constant are both scalars
return {std::move(folded)};
} else if (folded.Rank() == 0 && symRank > 0) {
// expand the scalar constant to an array
return ScalarConstantExpander{std::move(*extents),
AsConstantExtents(
context, GetRawLowerBounds(context, NamedEntity{symbol}))}
.Expand(std::move(folded));
} else if (auto resultShape{GetShape(context, folded)}) {
if (CheckConformance(context.messages(), symTS->shape(),
*resultShape, CheckConformanceFlags::None,
"initialized object", "initialization expression")
.value_or(false /*fail if not known now to conform*/)) {
// make a constant array with adjusted lower bounds
return ArrayConstantBoundChanger{
std::move(*AsConstantExtents(context,
GetRawLowerBounds(context, NamedEntity{symbol})))}
.ChangeLbounds(std::move(folded));
}
}
} else if (IsNamedConstant(symbol)) {
if (IsExplicitShape(symbol)) {
context.messages().Say(
"Named constant '%s' array must have constant shape"_err_en_US,
symbol.name());
} else {
// Declaration checking handles other cases
}
} else {
context.messages().Say(
"Shape of initialized object '%s' must be constant"_err_en_US,
symbol.name());
}
} else if (IsErrorExpr(folded)) {
} else if (IsLenTypeParameter(symbol)) {
return {std::move(folded)};
} else if (IsKindTypeParameter(symbol)) {
if (instantiation) {
context.messages().Say(
"Value of kind type parameter '%s' (%s) must be a scalar INTEGER constant"_err_en_US,
symbol.name(), folded.AsFortran());
} else {
return {std::move(folded)};
}
} else if (IsNamedConstant(symbol)) {
context.messages().Say(
"Value of named constant '%s' (%s) cannot be computed as a constant value"_err_en_US,
symbol.name(), folded.AsFortran());
} else {
context.messages().Say(
"Initialization expression for '%s' (%s) cannot be computed as a constant value"_err_en_US,
symbol.name(), folded.AsFortran());
}
} else if (xType) {
context.messages().Say(
"Initialization expression cannot be converted to declared type of '%s' from %s"_err_en_US,
symbol.name(), xType->AsFortran());
} else {
context.messages().Say(
"Initialization expression cannot be converted to declared type of '%s'"_err_en_US,
symbol.name());
}
}
return std::nullopt;
}
static bool IsNonLocal(const semantics::Symbol &symbol) {
return semantics::IsDummy(symbol) || symbol.has<semantics::UseDetails>() ||
symbol.owner().kind() == semantics::Scope::Kind::Module ||
semantics::FindCommonBlockContaining(symbol) ||
symbol.has<semantics::HostAssocDetails>();
}
static bool IsPermissibleInquiry(const semantics::Symbol &firstSymbol,
const semantics::Symbol &lastSymbol, DescriptorInquiry::Field field,
const semantics::Scope &localScope) {
if (IsNonLocal(firstSymbol)) {
return true;
}
if (&localScope != &firstSymbol.owner()) {
return true;
}
// Inquiries on local objects may not access a deferred bound or length.
// (This code used to be a switch, but it proved impossible to write it
// thus without running afoul of bogus warnings from different C++
// compilers.)
if (field == DescriptorInquiry::Field::Rank) {
return true; // always known
}
const auto *object{lastSymbol.detailsIf<semantics::ObjectEntityDetails>()};
if (field == DescriptorInquiry::Field::LowerBound ||
field == DescriptorInquiry::Field::Extent ||
field == DescriptorInquiry::Field::Stride) {
return object && !object->shape().CanBeDeferredShape();
}
if (field == DescriptorInquiry::Field::Len) {
return object && object->type() &&
object->type()->category() == semantics::DeclTypeSpec::Character &&
!object->type()->characterTypeSpec().length().isDeferred();
}
return false;
}
// Specification expression validation (10.1.11(2), C1010)
class CheckSpecificationExprHelper
: public AnyTraverse<CheckSpecificationExprHelper,
std::optional<std::string>> {
public:
using Result = std::optional<std::string>;
using Base = AnyTraverse<CheckSpecificationExprHelper, Result>;
explicit CheckSpecificationExprHelper(
const semantics::Scope &s, FoldingContext &context)
: Base{*this}, scope_{s}, context_{context} {}
using Base::operator();
Result operator()(const CoarrayRef &) const { return "coindexed reference"; }
Result operator()(const semantics::Symbol &symbol) const {
const auto &ultimate{symbol.GetUltimate()};
if (const auto *assoc{
ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
return (*this)(assoc->expr());
} else if (semantics::IsNamedConstant(ultimate) ||
ultimate.owner().IsModule() || ultimate.owner().IsSubmodule()) {
return std::nullopt;
} else if (scope_.IsDerivedType() &&
IsVariableName(ultimate)) { // C750, C754
return "derived type component or type parameter value not allowed to "
"reference variable '"s +
ultimate.name().ToString() + "'";
} else if (IsDummy(ultimate)) {
if (ultimate.attrs().test(semantics::Attr::OPTIONAL)) {
return "reference to OPTIONAL dummy argument '"s +
ultimate.name().ToString() + "'";
} else if (!inInquiry_ &&
ultimate.attrs().test(semantics::Attr::INTENT_OUT)) {
return "reference to INTENT(OUT) dummy argument '"s +
ultimate.name().ToString() + "'";
} else if (ultimate.has<semantics::ObjectEntityDetails>()) {
return std::nullopt;
} else {
return "dummy procedure argument";
}
} else if (&symbol.owner() != &scope_ || &ultimate.owner() != &scope_) {
return std::nullopt; // host association is in play
} else if (const auto *object{
ultimate.detailsIf<semantics::ObjectEntityDetails>()}) {
if (object->commonBlock()) {
return std::nullopt;
}
}
if (inInquiry_) {
return std::nullopt;
} else {
return "reference to local entity '"s + ultimate.name().ToString() + "'";
}
}
Result operator()(const Component &x) const {
// Don't look at the component symbol.
return (*this)(x.base());
}
Result operator()(const ArrayRef &x) const {
if (auto result{(*this)(x.base())}) {
return result;
}
// The subscripts don't get special protection for being in a
// specification inquiry context;
auto restorer{common::ScopedSet(inInquiry_, false)};
return (*this)(x.subscript());
}
Result operator()(const Substring &x) const {
if (auto result{(*this)(x.parent())}) {
return result;
}
// The bounds don't get special protection for being in a
// specification inquiry context;
auto restorer{common::ScopedSet(inInquiry_, false)};
if (auto result{(*this)(x.lower())}) {
return result;
}
return (*this)(x.upper());
}
Result operator()(const DescriptorInquiry &x) const {
// Many uses of SIZE(), LBOUND(), &c. that are valid in specification
// expressions will have been converted to expressions over descriptor
// inquiries by Fold().
// Catch REAL, ALLOCATABLE :: X(:); REAL :: Y(SIZE(X))
if (IsPermissibleInquiry(x.base().GetFirstSymbol(),
x.base().GetLastSymbol(), x.field(), scope_)) {
auto restorer{common::ScopedSet(inInquiry_, true)};
return (*this)(x.base());
} else if (IsConstantExpr(x)) {
return std::nullopt;
} else {
return "non-constant descriptor inquiry not allowed for local object";
}
}
Result operator()(const TypeParamInquiry &inq) const {
if (scope_.IsDerivedType() && !IsConstantExpr(inq) &&
inq.base() /* X%T, not local T */) { // C750, C754
return "non-constant reference to a type parameter inquiry not "
"allowed for derived type components or type parameter values";
}
return std::nullopt;
}
Result operator()(const ProcedureRef &x) const {
bool inInquiry{false};
if (const auto *symbol{x.proc().GetSymbol()}) {
const Symbol &ultimate{symbol->GetUltimate()};
if (!semantics::IsPureProcedure(ultimate)) {
return "reference to impure function '"s + ultimate.name().ToString() +
"'";
}
if (semantics::IsStmtFunction(ultimate)) {
return "reference to statement function '"s +
ultimate.name().ToString() + "'";
}
if (scope_.IsDerivedType()) { // C750, C754
return "reference to function '"s + ultimate.name().ToString() +
"' not allowed for derived type components or type parameter"
" values";
}
if (auto procChars{
characteristics::Procedure::Characterize(x.proc(), context_)}) {
const auto iter{std::find_if(procChars->dummyArguments.begin(),
procChars->dummyArguments.end(),
[](const characteristics::DummyArgument &dummy) {
return std::holds_alternative<characteristics::DummyProcedure>(
dummy.u);
})};
if (iter != procChars->dummyArguments.end()) {
return "reference to function '"s + ultimate.name().ToString() +
"' with dummy procedure argument '" + iter->name + '\'';
}
}
// References to internal functions are caught in expression semantics.
// TODO: other checks for standard module procedures
} else { // intrinsic
const SpecificIntrinsic &intrin{DEREF(x.proc().GetSpecificIntrinsic())};
inInquiry = context_.intrinsics().GetIntrinsicClass(intrin.name) ==
IntrinsicClass::inquiryFunction;
if (scope_.IsDerivedType()) { // C750, C754
if ((context_.intrinsics().IsIntrinsic(intrin.name) &&
badIntrinsicsForComponents_.find(intrin.name) !=
badIntrinsicsForComponents_.end())) {
return "reference to intrinsic '"s + intrin.name +
"' not allowed for derived type components or type parameter"
" values";
}
if (inInquiry && !IsConstantExpr(x)) {
return "non-constant reference to inquiry intrinsic '"s +
intrin.name +
"' not allowed for derived type components or type"
" parameter values";
}
}
// Type-determined inquiries (DIGITS, HUGE, &c.) will have already been
// folded and won't arrive here. Inquiries that are represented with
// DescriptorInquiry operations (LBOUND) are checked elsewhere. If a
// call that makes it to here satisfies the requirements of a constant
// expression (as Fortran defines it), it's fine.
if (IsConstantExpr(x)) {
return std::nullopt;
}
if (intrin.name == "present") {
return std::nullopt; // always ok
}
// Catch CHARACTER(:), ALLOCATABLE :: X; CHARACTER(LEN(X)) :: Y
if (inInquiry && x.arguments().size() >= 1) {
if (const auto &arg{x.arguments().at(0)}) {
if (auto dataRef{ExtractDataRef(*arg, true, true)}) {
if (intrin.name == "allocated" || intrin.name == "associated" ||
intrin.name == "is_contiguous") { // ok
} else if (intrin.name == "len" &&
IsPermissibleInquiry(dataRef->GetFirstSymbol(),
dataRef->GetLastSymbol(), DescriptorInquiry::Field::Len,
scope_)) { // ok
} else if (intrin.name == "lbound" &&
IsPermissibleInquiry(dataRef->GetFirstSymbol(),
dataRef->GetLastSymbol(),
DescriptorInquiry::Field::LowerBound, scope_)) { // ok
} else if ((intrin.name == "shape" || intrin.name == "size" ||
intrin.name == "sizeof" ||
intrin.name == "storage_size" ||
intrin.name == "ubound") &&
IsPermissibleInquiry(dataRef->GetFirstSymbol(),
dataRef->GetLastSymbol(), DescriptorInquiry::Field::Extent,
scope_)) { // ok
} else {
return "non-constant inquiry function '"s + intrin.name +
"' not allowed for local object";
}
}
}
}
}
auto restorer{common::ScopedSet(inInquiry_, inInquiry)};
return (*this)(x.arguments());
}
private:
const semantics::Scope &scope_;
FoldingContext &context_;
// Contextual information: this flag is true when in an argument to
// an inquiry intrinsic like SIZE().
mutable bool inInquiry_{false};
const std::set<std::string> badIntrinsicsForComponents_{
"allocated", "associated", "extends_type_of", "present", "same_type_as"};
};
template <typename A>
void CheckSpecificationExpr(
const A &x, const semantics::Scope &scope, FoldingContext &context) {
if (auto why{CheckSpecificationExprHelper{scope, context}(x)}) {
context.messages().Say(
"Invalid specification expression: %s"_err_en_US, *why);
}
}
template void CheckSpecificationExpr(
const Expr<SomeType> &, const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(
const Expr<SomeInteger> &, const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(
const Expr<SubscriptInteger> &, const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(const std::optional<Expr<SomeType>> &,
const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(const std::optional<Expr<SomeInteger>> &,
const semantics::Scope &, FoldingContext &);
template void CheckSpecificationExpr(
const std::optional<Expr<SubscriptInteger>> &, const semantics::Scope &,
FoldingContext &);
// IsContiguous() -- 9.5.4
class IsContiguousHelper
: public AnyTraverse<IsContiguousHelper, std::optional<bool>> {
public:
using Result = std::optional<bool>; // tri-state
using Base = AnyTraverse<IsContiguousHelper, Result>;
explicit IsContiguousHelper(FoldingContext &c) : Base{*this}, context_{c} {}
using Base::operator();
template <typename T> Result operator()(const Constant<T> &) const {
return true;
}
Result operator()(const StaticDataObject &) const { return true; }
Result operator()(const semantics::Symbol &symbol) const {
const auto &ultimate{symbol.GetUltimate()};
if (ultimate.attrs().test(semantics::Attr::CONTIGUOUS)) {
return true;
} else if (!IsVariable(symbol)) {
return true;
} else if (ultimate.Rank() == 0) {
// Extension: accept scalars as a degenerate case of
// simple contiguity to allow their use in contexts like
// data targets in pointer assignments with remapping.
return true;
} else if (ultimate.has<semantics::AssocEntityDetails>()) {
return Base::operator()(ultimate); // use expr
} else if (semantics::IsPointer(ultimate) ||
semantics::IsAssumedShape(ultimate) || IsAssumedRank(ultimate)) {
return std::nullopt;
} else if (ultimate.has<semantics::ObjectEntityDetails>()) {
return true;
} else {
return Base::operator()(ultimate);
}
}
Result operator()(const ArrayRef &x) const {
if (x.Rank() == 0) {
return true; // scalars considered contiguous
}
int subscriptRank{0};
auto baseLbounds{GetLBOUNDs(context_, x.base())};
auto baseUbounds{GetUBOUNDs(context_, x.base())};
auto subscripts{CheckSubscripts(
x.subscript(), subscriptRank, &baseLbounds, &baseUbounds)};
if (!subscripts.value_or(false)) {
return subscripts; // subscripts not known to be contiguous
} else if (subscriptRank > 0) {
// a(1)%b(:,:) is contiguous if and only if a(1)%b is contiguous.
return (*this)(x.base());
} else {
// a(:)%b(1,1) is (probably) not contiguous.
return std::nullopt;
}
}
Result operator()(const CoarrayRef &x) const {
int rank{0};
return CheckSubscripts(x.subscript(), rank).has_value();
}
Result operator()(const Component &x) const {
if (x.base().Rank() == 0) {
return (*this)(x.GetLastSymbol());
} else {
if (Result baseIsContiguous{(*this)(x.base())}) {
if (!*baseIsContiguous) {
return false;
}
// TODO could be true if base contiguous and this is only component, or
// if base has only one element?
}
return std::nullopt;
}
}
Result operator()(const ComplexPart &x) const {
return x.complex().Rank() == 0;
}
Result operator()(const Substring &) const { return std::nullopt; }
Result operator()(const ProcedureRef &x) const {
if (auto chars{
characteristics::Procedure::Characterize(x.proc(), context_)}) {
if (chars->functionResult) {
const auto &result{*chars->functionResult};
if (!result.IsProcedurePointer()) {
if (result.attrs.test(
characteristics::FunctionResult::Attr::Contiguous)) {
return true;
}
if (!result.attrs.test(
characteristics::FunctionResult::Attr::Pointer)) {
return true;
}
if (const auto *type{result.GetTypeAndShape()};
type && type->Rank() == 0) {
return true; // pointer to scalar
}
// Must be non-CONTIGUOUS pointer to array
}
}
}
return std::nullopt;
}
Result operator()(const NullPointer &) const { return true; }
private:
// Returns "true" for a provably empty or simply contiguous array section;
// return "false" for a provably nonempty discontiguous section or for use
// of a vector subscript.
std::optional<bool> CheckSubscripts(const std::vector<Subscript> &subscript,
int &rank, const Shape *baseLbounds = nullptr,
const Shape *baseUbounds = nullptr) const {
bool anyTriplet{false};
rank = 0;
// Detect any provably empty dimension in this array section, which would
// render the whole section empty and therefore vacuously contiguous.
std::optional<bool> result;
bool mayBeEmpty{false};
auto dims{subscript.size()};
std::vector<bool> knownPartialSlice(dims, false);
for (auto j{dims}; j-- > 0;) {
std::optional<ConstantSubscript> dimLbound;
std::optional<ConstantSubscript> dimUbound;
std::optional<ConstantSubscript> dimExtent;
if (baseLbounds && j < baseLbounds->size()) {
if (const auto &lb{baseLbounds->at(j)}) {
dimLbound = ToInt64(Fold(context_, Expr<SubscriptInteger>{*lb}));
}
}
if (baseUbounds && j < baseUbounds->size()) {
if (const auto &ub{baseUbounds->at(j)}) {
dimUbound = ToInt64(Fold(context_, Expr<SubscriptInteger>{*ub}));
}
}
if (dimLbound && dimUbound) {
if (*dimLbound <= *dimUbound) {
dimExtent = *dimUbound - *dimLbound + 1;
} else {
// This is an empty dimension.
result = true;
dimExtent = 0;
}
}
if (const auto *triplet{std::get_if<Triplet>(&subscript[j].u)}) {
++rank;
if (auto stride{ToInt64(triplet->stride())}) {
const Expr<SubscriptInteger> *lowerBound{triplet->GetLower()};
const Expr<SubscriptInteger> *upperBound{triplet->GetUpper()};
std::optional<ConstantSubscript> lowerVal{lowerBound
? ToInt64(Fold(context_, Expr<SubscriptInteger>{*lowerBound}))
: dimLbound};
std::optional<ConstantSubscript> upperVal{upperBound
? ToInt64(Fold(context_, Expr<SubscriptInteger>{*upperBound}))
: dimUbound};
if (lowerVal && upperVal) {
if (*lowerVal < *upperVal) {
if (*stride < 0) {
result = true; // empty dimension
} else if (!result && *stride > 1 &&
*lowerVal + *stride <= *upperVal) {
result = false; // discontiguous if not empty
}
} else if (*lowerVal > *upperVal) {
if (*stride > 0) {
result = true; // empty dimension
} else if (!result && *stride < 0 &&
*lowerVal + *stride >= *upperVal) {
result = false; // discontiguous if not empty
}
} else {
mayBeEmpty = true;
}
} else {
mayBeEmpty = true;
}
} else {
mayBeEmpty = true;
}
} else if (subscript[j].Rank() > 0) {
++rank;
if (!result) {
result = false; // vector subscript
}
mayBeEmpty = true;
} else {
// Scalar subscript.
if (dimExtent && *dimExtent > 1) {
knownPartialSlice[j] = true;
}
}
}
if (rank == 0) {
result = true; // scalar
}
if (result) {
return result;
}
// Not provably discontiguous at this point.
// Return "true" if simply contiguous, otherwise nullopt.
for (auto j{subscript.size()}; j-- > 0;) {
if (const auto *triplet{std::get_if<Triplet>(&subscript[j].u)}) {
auto stride{ToInt64(triplet->stride())};
if (!stride || stride != 1) {
return std::nullopt;
} else if (anyTriplet) {
if (triplet->GetLower() || triplet->GetUpper()) {
// all triplets before the last one must be just ":" for
// simple contiguity
return std::nullopt;
}
} else {
anyTriplet = true;
}
++rank;
} else if (anyTriplet) {
// If the section cannot be empty, and this dimension's
// scalar subscript is known not to cover the whole
// dimension, then the array section is provably
// discontiguous.
return (mayBeEmpty || !knownPartialSlice[j])
? std::nullopt
: std::make_optional(false);
}
}
return true; // simply contiguous
}
FoldingContext &context_;
};
template <typename A>
std::optional<bool> IsContiguous(const A &x, FoldingContext &context) {
return IsContiguousHelper{context}(x);
}
template std::optional<bool> IsContiguous(
const Expr<SomeType> &, FoldingContext &);
template std::optional<bool> IsContiguous(const ArrayRef &, FoldingContext &);
template std::optional<bool> IsContiguous(const Substring &, FoldingContext &);
template std::optional<bool> IsContiguous(const Component &, FoldingContext &);
template std::optional<bool> IsContiguous(
const ComplexPart &, FoldingContext &);
template std::optional<bool> IsContiguous(const CoarrayRef &, FoldingContext &);
template std::optional<bool> IsContiguous(const Symbol &, FoldingContext &);
// IsErrorExpr()
struct IsErrorExprHelper : public AnyTraverse<IsErrorExprHelper, bool> {
using Result = bool;
using Base = AnyTraverse<IsErrorExprHelper, Result>;
IsErrorExprHelper() : Base{*this} {}
using Base::operator();
bool operator()(const SpecificIntrinsic &x) {
return x.name == IntrinsicProcTable::InvalidName;
}
};
template <typename A> bool IsErrorExpr(const A &x) {
return IsErrorExprHelper{}(x);
}
template bool IsErrorExpr(const Expr<SomeType> &);
// C1577
// TODO: Also check C1579 & C1582 here
class StmtFunctionChecker
: public AnyTraverse<StmtFunctionChecker, std::optional<parser::Message>> {
public:
using Result = std::optional<parser::Message>;
using Base = AnyTraverse<StmtFunctionChecker, Result>;
StmtFunctionChecker(const Symbol &sf, FoldingContext &context)
: Base{*this}, sf_{sf}, context_{context} {
if (!context_.languageFeatures().IsEnabled(
common::LanguageFeature::StatementFunctionExtensions)) {
severity_ = parser::Severity::Error;
} else if (context_.languageFeatures().ShouldWarn(
common::LanguageFeature::StatementFunctionExtensions)) {
severity_ = parser::Severity::Portability;
}
}
using Base::operator();
template <typename T> Result operator()(const ArrayConstructor<T> &) const {
if (severity_) {
auto msg{
"Statement function '%s' should not contain an array constructor"_port_en_US};
msg.set_severity(*severity_);
return parser::Message{sf_.name(), std::move(msg), sf_.name()};
} else {
return std::nullopt;
}
}
Result operator()(const StructureConstructor &) const {
if (severity_) {
auto msg{
"Statement function '%s' should not contain a structure constructor"_port_en_US};
msg.set_severity(*severity_);
return parser::Message{sf_.name(), std::move(msg), sf_.name()};
} else {
return std::nullopt;
}
}
Result operator()(const TypeParamInquiry &) const {
if (severity_) {
auto msg{
"Statement function '%s' should not contain a type parameter inquiry"_port_en_US};
msg.set_severity(*severity_);
return parser::Message{sf_.name(), std::move(msg), sf_.name()};
} else {
return std::nullopt;
}
}
Result operator()(const ProcedureDesignator &proc) const {
if (const Symbol * symbol{proc.GetSymbol()}) {
const Symbol &ultimate{symbol->GetUltimate()};
if (const auto *subp{
ultimate.detailsIf<semantics::SubprogramDetails>()}) {
if (subp->stmtFunction() && &ultimate.owner() == &sf_.owner()) {
if (ultimate.name().begin() > sf_.name().begin()) {
return parser::Message{sf_.name(),
"Statement function '%s' may not reference another statement function '%s' that is defined later"_err_en_US,
sf_.name(), ultimate.name()};
}
}
}
if (auto chars{
characteristics::Procedure::Characterize(proc, context_)}) {
if (!chars->CanBeCalledViaImplicitInterface()) {
if (severity_) {
auto msg{
"Statement function '%s' should not reference function '%s' that requires an explicit interface"_port_en_US};
msg.set_severity(*severity_);
return parser::Message{
sf_.name(), std::move(msg), sf_.name(), symbol->name()};
}
}
}
}
if (proc.Rank() > 0) {
if (severity_) {
auto msg{
"Statement function '%s' should not reference a function that returns an array"_port_en_US};
msg.set_severity(*severity_);
return parser::Message{sf_.name(), std::move(msg), sf_.name()};
}
}
return std::nullopt;
}
Result operator()(const ActualArgument &arg) const {
if (const auto *expr{arg.UnwrapExpr()}) {
if (auto result{(*this)(*expr)}) {
return result;
}
if (expr->Rank() > 0 && !UnwrapWholeSymbolOrComponentDataRef(*expr)) {
if (severity_) {
auto msg{
"Statement function '%s' should not pass an array argument that is not a whole array"_port_en_US};
msg.set_severity(*severity_);
return parser::Message{sf_.name(), std::move(msg), sf_.name()};
}
}
}
return std::nullopt;
}
private:
const Symbol &sf_;
FoldingContext &context_;
std::optional<parser::Severity> severity_;
};
std::optional<parser::Message> CheckStatementFunction(
const Symbol &sf, const Expr<SomeType> &expr, FoldingContext &context) {
return StmtFunctionChecker{sf, context}(expr);
}
} // namespace Fortran::evaluate