lib/Evaluate/variable.cpp - llvm-project/flang - Git at Google

 //===-- lib/Evaluate/variable.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/variable.h"
 #include "flang/Common/idioms.h"
 #include "flang/Evaluate/check-expression.h"
 #include "flang/Evaluate/fold.h"
 #include "flang/Evaluate/tools.h"
 #include "flang/Parser/char-block.h"
 #include "flang/Parser/characters.h"
 #include "flang/Parser/message.h"
 #include "flang/Semantics/scope.h"
 #include "flang/Semantics/symbol.h"
 #include <type_traits>

 using namespace Fortran::parser::literals;

 namespace Fortran::evaluate {

 // Constructors, accessors, mutators

 Triplet::Triplet() : stride_{Expr<SubscriptInteger>{1}} {}

 Triplet::Triplet(std::optional<Expr<SubscriptInteger>> &&l,
     std::optional<Expr<SubscriptInteger>> &&u,
     std::optional<Expr<SubscriptInteger>> &&s)
     : stride_{s ? std::move(*s) : Expr<SubscriptInteger>{1}} {
   if (l) {
     lower_.emplace(std::move(*l));
   }
   if (u) {
     upper_.emplace(std::move(*u));
   }
 }

 std::optional<Expr<SubscriptInteger>> Triplet::lower() const {
   if (lower_) {
     return {lower_.value().value()};
   }
   return std::nullopt;
 }

 Triplet &Triplet::set_lower(Expr<SubscriptInteger> &&expr) {
   lower_.emplace(std::move(expr));
   return *this;
 }

 std::optional<Expr<SubscriptInteger>> Triplet::upper() const {
   if (upper_) {
     return {upper_.value().value()};
   }
   return std::nullopt;
 }

 Triplet &Triplet::set_upper(Expr<SubscriptInteger> &&expr) {
   upper_.emplace(std::move(expr));
   return *this;
 }

 Expr<SubscriptInteger> Triplet::stride() const { return stride_.value(); }

 Triplet &Triplet::set_stride(Expr<SubscriptInteger> &&expr) {
   stride_.value() = std::move(expr);
   return *this;
 }

 bool Triplet::IsStrideOne() const {
   if (auto stride{ToInt64(stride_.value())}) {
     return stride == 1;
   } else {
     return false;
   }
 }

 CoarrayRef::CoarrayRef(SymbolVector &&base, std::vector<Subscript> &&ss,
     std::vector<Expr<SubscriptInteger>> &&css)
     : base_{std::move(base)}, subscript_(std::move(ss)),
       cosubscript_(std::move(css)) {
   CHECK(!base_.empty());
   CHECK(!cosubscript_.empty());
 }

 std::optional<Expr<SomeInteger>> CoarrayRef::stat() const {
   if (stat_) {
     return stat_.value().value();
   } else {
     return std::nullopt;
   }
 }

 std::optional<Expr<SomeInteger>> CoarrayRef::team() const {
   if (team_) {
     return team_.value().value();
   } else {
     return std::nullopt;
   }
 }

 CoarrayRef &CoarrayRef::set_stat(Expr<SomeInteger> &&v) {
   CHECK(IsVariable(v));
   stat_.emplace(std::move(v));
   return *this;
 }

 CoarrayRef &CoarrayRef::set_team(Expr<SomeInteger> &&v, bool isTeamNumber) {
   CHECK(IsVariable(v));
   team_.emplace(std::move(v));
   teamIsTeamNumber_ = isTeamNumber;
   return *this;
 }

 const Symbol &CoarrayRef::GetFirstSymbol() const { return base_.front(); }

 const Symbol &CoarrayRef::GetLastSymbol() const { return base_.back(); }

 void Substring::SetBounds(std::optional<Expr<SubscriptInteger>> &lower,
     std::optional<Expr<SubscriptInteger>> &upper) {
   if (lower) {
     set_lower(std::move(lower.value()));
   }
   if (upper) {
     set_upper(std::move(upper.value()));
   }
 }

 Expr<SubscriptInteger> Substring::lower() const {
   if (lower_) {
     return lower_.value().value();
   } else {
     return AsExpr(Constant<SubscriptInteger>{1});
   }
 }

 Substring &Substring::set_lower(Expr<SubscriptInteger> &&expr) {
   lower_.emplace(std::move(expr));
   return *this;
 }

 std::optional<Expr<SubscriptInteger>> Substring::upper() const {
   if (upper_) {
     return upper_.value().value();
   } else {
     return std::visit(
         common::visitors{
             [](const DataRef &dataRef) { return dataRef.LEN(); },
             [](const StaticDataObject::Pointer &object)
                 -> std::optional<Expr<SubscriptInteger>> {
               return AsExpr(Constant<SubscriptInteger>{object->data().size()});
             },
         },
         parent_);
   }
 }

 Substring &Substring::set_upper(Expr<SubscriptInteger> &&expr) {
   upper_.emplace(std::move(expr));
   return *this;
 }

 std::optional<Expr<SomeCharacter>> Substring::Fold(FoldingContext &context) {
   if (!lower_) {
     lower_ = AsExpr(Constant<SubscriptInteger>{1});
   }
   lower_.value() = evaluate::Fold(context, std::move(lower_.value().value()));
   std::optional<ConstantSubscript> lbi{ToInt64(lower_.value().value())};
   if (lbi && *lbi < 1) {
     context.messages().Say(
         "Lower bound (%jd) on substring is less than one"_en_US, *lbi);
     *lbi = 1;
     lower_ = AsExpr(Constant<SubscriptInteger>{1});
   }
   if (!upper_) {
     upper_ = upper();
     if (!upper_) {
       return std::nullopt;
     }
   }
   upper_.value() = evaluate::Fold(context, std::move(upper_.value().value()));
   if (std::optional<ConstantSubscript> ubi{ToInt64(upper_.value().value())}) {
     auto *literal{std::get_if<StaticDataObject::Pointer>(&parent_)};
     std::optional<ConstantSubscript> length;
     if (literal) {
       length = (*literal)->data().size();
     } else if (const Symbol * symbol{GetLastSymbol()}) {
       if (const semantics::DeclTypeSpec * type{symbol->GetType()}) {
         if (type->category() == semantics::DeclTypeSpec::Character) {
           length = ToInt64(type->characterTypeSpec().length().GetExplicit());
         }
       }
     }
     if (*ubi < 1 || (lbi && *ubi < *lbi)) {
       // Zero-length string: canonicalize
       *lbi = 1, *ubi = 0;
       lower_ = AsExpr(Constant<SubscriptInteger>{*lbi});
       upper_ = AsExpr(Constant<SubscriptInteger>{*ubi});
     } else if (length && *ubi > *length) {
       context.messages().Say("Upper bound (%jd) on substring is greater "
                              "than character length (%jd)"_en_US,
           *ubi, *length);
       *ubi = *length;
     }
     if (lbi && literal) {
       auto newStaticData{StaticDataObject::Create()};
       auto items{0}; // If the lower bound is greater, the length is 0
       if (*ubi >= *lbi) {
         items = *ubi - *lbi + 1;
       }
       auto width{(*literal)->itemBytes()};
       auto bytes{items * width};
       auto startByte{(*lbi - 1) * width};
       const auto *from{&(*literal)->data()[0] + startByte};
       for (auto j{0}; j < bytes; ++j) {
         newStaticData->data().push_back(from[j]);
       }
       parent_ = newStaticData;
       lower_ = AsExpr(Constant<SubscriptInteger>{1});
       ConstantSubscript length = newStaticData->data().size();
       upper_ = AsExpr(Constant<SubscriptInteger>{length});
       switch (width) {
       case 1:
         return {
             AsCategoryExpr(AsExpr(Constant<Type<TypeCategory::Character, 1>>{
                 *newStaticData->AsString()}))};
       case 2:
         return {AsCategoryExpr(Constant<Type<TypeCategory::Character, 2>>{
             *newStaticData->AsU16String()})};
       case 4:
         return {AsCategoryExpr(Constant<Type<TypeCategory::Character, 4>>{
             *newStaticData->AsU32String()})};
       default:
         CRASH_NO_CASE;
       }
     }
   }
   return std::nullopt;
 }

 DescriptorInquiry::DescriptorInquiry(
     const NamedEntity &base, Field field, int dim)
     : base_{base}, field_{field}, dimension_{dim} {
   const Symbol &last{base_.GetLastSymbol()};
   CHECK(IsDescriptor(last));
   CHECK((field == Field::Len && dim == 0) ||
       (field != Field::Len && dim >= 0 && dim < last.Rank()));
 }

 DescriptorInquiry::DescriptorInquiry(NamedEntity &&base, Field field, int dim)
     : base_{std::move(base)}, field_{field}, dimension_{dim} {
   const Symbol &last{base_.GetLastSymbol()};
   CHECK(IsDescriptor(last));
   CHECK((field == Field::Len && dim == 0) ||
       (field != Field::Len && dim >= 0 && dim < last.Rank()));
 }

 // LEN()
 static std::optional<Expr<SubscriptInteger>> SymbolLEN(const Symbol &symbol) {
   const Symbol &ultimate{symbol.GetUltimate()};
   if (const auto *assoc{ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
     if (const auto *chExpr{UnwrapExpr<Expr<SomeCharacter>>(assoc->expr())}) {
       return chExpr->LEN();
     }
   } else if (auto dyType{DynamicType::From(ultimate)}) {
     if (auto len{dyType->GetCharLength()}) {
       return len;
     } else if (IsDescriptor(ultimate) && !ultimate.owner().IsDerivedType()) {
       return Expr<SubscriptInteger>{DescriptorInquiry{
           NamedEntity{symbol}, DescriptorInquiry::Field::Len}};
     }
   }
   return std::nullopt;
 }

 std::optional<Expr<SubscriptInteger>> BaseObject::LEN() const {
   return std::visit(
       common::visitors{
           [](const Symbol &symbol) { return SymbolLEN(symbol); },
           [](const StaticDataObject::Pointer &object)
               -> std::optional<Expr<SubscriptInteger>> {
             return AsExpr(Constant<SubscriptInteger>{object->data().size()});
           },
       },
       u);
 }

 std::optional<Expr<SubscriptInteger>> Component::LEN() const {
   return SymbolLEN(GetLastSymbol());
 }

 std::optional<Expr<SubscriptInteger>> NamedEntity::LEN() const {
   return SymbolLEN(GetLastSymbol());
 }

 std::optional<Expr<SubscriptInteger>> ArrayRef::LEN() const {
   return base_.LEN();
 }

 std::optional<Expr<SubscriptInteger>> CoarrayRef::LEN() const {
   return SymbolLEN(GetLastSymbol());
 }

 std::optional<Expr<SubscriptInteger>> DataRef::LEN() const {
   return std::visit(common::visitors{
                         [](SymbolRef symbol) { return SymbolLEN(symbol); },
                         [](const auto &x) { return x.LEN(); },
                     },
       u);
 }

 std::optional<Expr<SubscriptInteger>> Substring::LEN() const {
   if (auto top{upper()}) {
     return AsExpr(Extremum<SubscriptInteger>{Ordering::Greater,
         AsExpr(Constant<SubscriptInteger>{0}),
         *std::move(top) - lower() + AsExpr(Constant<SubscriptInteger>{1})});
   } else {
     return std::nullopt;
   }
 }

 template <typename T>
 std::optional<Expr<SubscriptInteger>> Designator<T>::LEN() const {
   if constexpr (T::category == TypeCategory::Character) {
     return std::visit(common::visitors{
                           [](SymbolRef symbol) { return SymbolLEN(symbol); },
                           [](const auto &x) { return x.LEN(); },
                       },
         u);
   } else {
     common::die("Designator<non-char>::LEN() called");
     return std::nullopt;
   }
 }

 std::optional<Expr<SubscriptInteger>> ProcedureDesignator::LEN() const {
   using T = std::optional<Expr<SubscriptInteger>>;
   return std::visit(
       common::visitors{
           [](SymbolRef symbol) -> T { return SymbolLEN(symbol); },
           [](const common::CopyableIndirection<Component> &c) -> T {
             return c.value().LEN();
           },
           [](const SpecificIntrinsic &i) -> T {
             // Some cases whose results' lengths can be determined
             // from the lengths of their arguments are handled in
             // ProcedureRef::LEN() before coming here.
             if (const auto &result{i.characteristics.value().functionResult}) {
               if (const auto *type{result->GetTypeAndShape()}) {
                 if (auto length{type->type().GetCharLength()}) {
                   return std::move(*length);
                 }
               }
             }
             return std::nullopt;
           },
       },
       u);
 }

 // Rank()
 int BaseObject::Rank() const {
   return std::visit(common::visitors{
                         [](SymbolRef symbol) { return symbol->Rank(); },
                         [](const StaticDataObject::Pointer &) { return 0; },
                     },
       u);
 }

 int Component::Rank() const {
   if (int rank{symbol_->Rank()}; rank > 0) {
     return rank;
   }
   return base().Rank();
 }

 int NamedEntity::Rank() const {
   return std::visit(common::visitors{
                         [](const SymbolRef s) { return s->Rank(); },
                         [](const Component &c) { return c.Rank(); },
                     },
       u_);
 }

 int Subscript::Rank() const {
   return std::visit(common::visitors{
                         [](const IndirectSubscriptIntegerExpr &x) {
                           return x.value().Rank();
                         },
                         [](const Triplet &) { return 1; },
                     },
       u);
 }

 int ArrayRef::Rank() const {
   int rank{0};
   for (const auto &expr : subscript_) {
     rank += expr.Rank();
   }
   if (rank > 0) {
     return rank;
   } else if (const Component * component{base_.UnwrapComponent()}) {
     return component->base().Rank();
   } else {
     return 0;
   }
 }

 int CoarrayRef::Rank() const {
   if (!subscript_.empty()) {
     int rank{0};
     for (const auto &expr : subscript_) {
       rank += expr.Rank();
     }
     return rank;
   } else {
     return base_.back()->Rank();
   }
 }

 int DataRef::Rank() const {
   return std::visit(common::visitors{
                         [](SymbolRef symbol) { return symbol->Rank(); },
                         [](const auto &x) { return x.Rank(); },
                     },
       u);
 }

 int Substring::Rank() const {
   return std::visit(common::visitors{
                         [](const DataRef &dataRef) { return dataRef.Rank(); },
                         [](const StaticDataObject::Pointer &) { return 0; },
                     },
       parent_);
 }

 int ComplexPart::Rank() const { return complex_.Rank(); }

 template <typename T> int Designator<T>::Rank() const {
   return std::visit(common::visitors{
                         [](SymbolRef symbol) { return symbol->Rank(); },
                         [](const auto &x) { return x.Rank(); },
                     },
       u);
 }

 // GetBaseObject(), GetFirstSymbol(), GetLastSymbol(), &c.
 const Symbol &Component::GetFirstSymbol() const {
   return base_.value().GetFirstSymbol();
 }

 const Symbol &NamedEntity::GetFirstSymbol() const {
   return std::visit(common::visitors{
                         [](SymbolRef s) -> const Symbol & { return s; },
                         [](const Component &c) -> const Symbol & {
                           return c.GetFirstSymbol();
                         },
                     },
       u_);
 }

 const Symbol &NamedEntity::GetLastSymbol() const {
   return std::visit(common::visitors{
                         [](SymbolRef s) -> const Symbol & { return s; },
                         [](const Component &c) -> const Symbol & {
                           return c.GetLastSymbol();
                         },
                     },
       u_);
 }

 const Component *NamedEntity::UnwrapComponent() const {
   return std::visit(common::visitors{
                         [](SymbolRef) -> const Component * { return nullptr; },
                         [](const Component &c) { return &c; },
                     },
       u_);
 }

 Component *NamedEntity::UnwrapComponent() {
   return std::visit(common::visitors{
                         [](SymbolRef &) -> Component * { return nullptr; },
                         [](Component &c) { return &c; },
                     },
       u_);
 }

 const Symbol &ArrayRef::GetFirstSymbol() const {
   return base_.GetFirstSymbol();
 }

 const Symbol &ArrayRef::GetLastSymbol() const { return base_.GetLastSymbol(); }

 const Symbol &DataRef::GetFirstSymbol() const {
   return *std::visit(common::visitors{
                          [](SymbolRef symbol) { return &*symbol; },
                          [](const auto &x) { return &x.GetFirstSymbol(); },
                      },
       u);
 }

 const Symbol &DataRef::GetLastSymbol() const {
   return *std::visit(common::visitors{
                          [](SymbolRef symbol) { return &*symbol; },
                          [](const auto &x) { return &x.GetLastSymbol(); },
                      },
       u);
 }

 BaseObject Substring::GetBaseObject() const {
   return std::visit(common::visitors{
                         [](const DataRef &dataRef) {
                           return BaseObject{dataRef.GetFirstSymbol()};
                         },
                         [](StaticDataObject::Pointer pointer) {
                           return BaseObject{std::move(pointer)};
                         },
                     },
       parent_);
 }

 const Symbol *Substring::GetLastSymbol() const {
   return std::visit(
       common::visitors{
           [](const DataRef &dataRef) { return &dataRef.GetLastSymbol(); },
           [](const auto &) -> const Symbol * { return nullptr; },
       },
       parent_);
 }

 template <typename T> BaseObject Designator<T>::GetBaseObject() const {
   return std::visit(
       common::visitors{
           [](SymbolRef symbol) { return BaseObject{symbol}; },
           [](const Substring &sstring) { return sstring.GetBaseObject(); },
           [](const auto &x) {
 #if !__clang__ && __GNUC__ == 7 && __GNUC_MINOR__ == 2
             if constexpr (std::is_same_v<std::decay_t<decltype(x)>,
                               Substring>) {
               return x.GetBaseObject();
             } else
 #endif
               return BaseObject{x.GetFirstSymbol()};
           },
       },
       u);
 }

 template <typename T> const Symbol *Designator<T>::GetLastSymbol() const {
   return std::visit(
       common::visitors{
           [](SymbolRef symbol) { return &*symbol; },
           [](const Substring &sstring) { return sstring.GetLastSymbol(); },
           [](const auto &x) {
 #if !__clang__ && __GNUC__ == 7 && __GNUC_MINOR__ == 2
             if constexpr (std::is_same_v<std::decay_t<decltype(x)>,
                               Substring>) {
               return x.GetLastSymbol();
             } else
 #endif
               return &x.GetLastSymbol();
           },
       },
       u);
 }

 template <typename T>
 std::optional<DynamicType> Designator<T>::GetType() const {
   if constexpr (IsLengthlessIntrinsicType<Result>) {
     return Result::GetType();
   } else if (const Symbol * symbol{GetLastSymbol()}) {
     return DynamicType::From(*symbol);
   } else if constexpr (Result::category == TypeCategory::Character) {
     if (const Substring * substring{std::get_if<Substring>(&u)}) {
       const auto *parent{substring->GetParentIf<StaticDataObject::Pointer>()};
       CHECK(parent);
       return DynamicType{TypeCategory::Character, (*parent)->itemBytes()};
     }
   }
   return std::nullopt;
 }

 static NamedEntity AsNamedEntity(const SymbolVector &x) {
   CHECK(!x.empty());
   NamedEntity result{x.front()};
   int j{0};
   for (const Symbol &symbol : x) {
     if (j++ != 0) {
       DataRef base{result.IsSymbol() ? DataRef{result.GetLastSymbol()}
                                      : DataRef{result.GetComponent()}};
       result = NamedEntity{Component{std::move(base), symbol}};
     }
   }
   return result;
 }

 NamedEntity CoarrayRef::GetBase() const { return AsNamedEntity(base_); }

 // Equality testing

 // For the purposes of comparing type parameter expressions while
 // testing the compatibility of procedure characteristics, two
 // object dummy arguments with the same name are considered equal.
 static bool AreSameSymbol(const Symbol &x, const Symbol &y) {
   if (&x == &y) {
     return true;
   }
   if (x.name() == y.name()) {
     if (const auto *xObject{x.detailsIf<semantics::ObjectEntityDetails>()}) {
       if (const auto *yObject{y.detailsIf<semantics::ObjectEntityDetails>()}) {
         return xObject->isDummy() && yObject->isDummy();
       }
     }
   }
   return false;
 }

 // Implements operator==() for a union type, using special case handling
 // for Symbol references.
 template <typename A> static bool TestVariableEquality(const A &x, const A &y) {
   const SymbolRef *xSymbol{std::get_if<SymbolRef>(&x.u)};
   if (const SymbolRef * ySymbol{std::get_if<SymbolRef>(&y.u)}) {
     return xSymbol && AreSameSymbol(*xSymbol, *ySymbol);
   } else {
     return x.u == y.u;
   }
 }

 bool BaseObject::operator==(const BaseObject &that) const {
   return TestVariableEquality(*this, that);
 }
 bool Component::operator==(const Component &that) const {
   return base_ == that.base_ && &*symbol_ == &*that.symbol_;
 }
 bool NamedEntity::operator==(const NamedEntity &that) const {
   if (IsSymbol()) {
     return that.IsSymbol() &&
         AreSameSymbol(GetFirstSymbol(), that.GetFirstSymbol());
   } else {
     return !that.IsSymbol() && GetComponent() == that.GetComponent();
   }
 }
 bool TypeParamInquiry::operator==(const TypeParamInquiry &that) const {
   return &*parameter_ == &*that.parameter_ && base_ == that.base_;
 }
 bool Triplet::operator==(const Triplet &that) const {
   return lower_ == that.lower_ && upper_ == that.upper_ &&
       stride_ == that.stride_;
 }
 bool Subscript::operator==(const Subscript &that) const { return u == that.u; }
 bool ArrayRef::operator==(const ArrayRef &that) const {
   return base_ == that.base_ && subscript_ == that.subscript_;
 }
 bool CoarrayRef::operator==(const CoarrayRef &that) const {
   return base_ == that.base_ && subscript_ == that.subscript_ &&
       cosubscript_ == that.cosubscript_ && stat_ == that.stat_ &&
       team_ == that.team_ && teamIsTeamNumber_ == that.teamIsTeamNumber_;
 }
 bool DataRef::operator==(const DataRef &that) const {
   return TestVariableEquality(*this, that);
 }
 bool Substring::operator==(const Substring &that) const {
   return parent_ == that.parent_ && lower_ == that.lower_ &&
       upper_ == that.upper_;
 }
 bool ComplexPart::operator==(const ComplexPart &that) const {
   return part_ == that.part_ && complex_ == that.complex_;
 }
 bool ProcedureRef::operator==(const ProcedureRef &that) const {
   return proc_ == that.proc_ && arguments_ == that.arguments_;
 }
 template <typename T>
 bool Designator<T>::operator==(const Designator<T> &that) const {
   return TestVariableEquality(*this, that);
 }
 bool DescriptorInquiry::operator==(const DescriptorInquiry &that) const {
   return field_ == that.field_ && base_ == that.base_ &&
       dimension_ == that.dimension_;
 }

 INSTANTIATE_VARIABLE_TEMPLATES
 } // namespace Fortran::evaluate

 template class Fortran::common::Indirection<Fortran::evaluate::Component, true>;
	//===-- lib/Evaluate/variable.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/variable.h"
	#include "flang/Common/idioms.h"
	#include "flang/Evaluate/check-expression.h"
	#include "flang/Evaluate/fold.h"
	#include "flang/Evaluate/tools.h"
	#include "flang/Parser/char-block.h"
	#include "flang/Parser/characters.h"
	#include "flang/Parser/message.h"
	#include "flang/Semantics/scope.h"
	#include "flang/Semantics/symbol.h"
	#include <type_traits>

	using namespace Fortran::parser::literals;

	namespace Fortran::evaluate {

	// Constructors, accessors, mutators

	Triplet::Triplet() : stride_{Expr<SubscriptInteger>{1}} {}

	Triplet::Triplet(std::optional<Expr<SubscriptInteger>> &&l,
	std::optional<Expr<SubscriptInteger>> &&u,
	std::optional<Expr<SubscriptInteger>> &&s)
	: stride_{s ? std::move(*s) : Expr<SubscriptInteger>{1}} {
	if (l) {
	lower_.emplace(std::move(*l));
	}
	if (u) {
	upper_.emplace(std::move(*u));
	}
	}

	std::optional<Expr<SubscriptInteger>> Triplet::lower() const {
	if (lower_) {
	return {lower_.value().value()};
	}
	return std::nullopt;
	}

	Triplet &Triplet::set_lower(Expr<SubscriptInteger> &&expr) {
	lower_.emplace(std::move(expr));
	return *this;
	}

	std::optional<Expr<SubscriptInteger>> Triplet::upper() const {
	if (upper_) {
	return {upper_.value().value()};
	}
	return std::nullopt;
	}

	Triplet &Triplet::set_upper(Expr<SubscriptInteger> &&expr) {
	upper_.emplace(std::move(expr));
	return *this;
	}

	Expr<SubscriptInteger> Triplet::stride() const { return stride_.value(); }

	Triplet &Triplet::set_stride(Expr<SubscriptInteger> &&expr) {
	stride_.value() = std::move(expr);
	return *this;
	}

	bool Triplet::IsStrideOne() const {
	if (auto stride{ToInt64(stride_.value())}) {
	return stride == 1;
	} else {
	return false;
	}
	}

	CoarrayRef::CoarrayRef(SymbolVector &&base, std::vector<Subscript> &&ss,
	std::vector<Expr<SubscriptInteger>> &&css)
	: base_{std::move(base)}, subscript_(std::move(ss)),
	cosubscript_(std::move(css)) {
	CHECK(!base_.empty());
	CHECK(!cosubscript_.empty());
	}

	std::optional<Expr<SomeInteger>> CoarrayRef::stat() const {
	if (stat_) {
	return stat_.value().value();
	} else {
	return std::nullopt;
	}
	}

	std::optional<Expr<SomeInteger>> CoarrayRef::team() const {
	if (team_) {
	return team_.value().value();
	} else {
	return std::nullopt;
	}
	}

	CoarrayRef &CoarrayRef::set_stat(Expr<SomeInteger> &&v) {
	CHECK(IsVariable(v));
	stat_.emplace(std::move(v));
	return *this;
	}

	CoarrayRef &CoarrayRef::set_team(Expr<SomeInteger> &&v, bool isTeamNumber) {
	CHECK(IsVariable(v));
	team_.emplace(std::move(v));
	teamIsTeamNumber_ = isTeamNumber;
	return *this;
	}

	const Symbol &CoarrayRef::GetFirstSymbol() const { return base_.front(); }

	const Symbol &CoarrayRef::GetLastSymbol() const { return base_.back(); }

	void Substring::SetBounds(std::optional<Expr<SubscriptInteger>> &lower,
	std::optional<Expr<SubscriptInteger>> &upper) {
	if (lower) {
	set_lower(std::move(lower.value()));
	}
	if (upper) {
	set_upper(std::move(upper.value()));
	}
	}

	Expr<SubscriptInteger> Substring::lower() const {
	if (lower_) {
	return lower_.value().value();
	} else {
	return AsExpr(Constant<SubscriptInteger>{1});
	}
	}

	Substring &Substring::set_lower(Expr<SubscriptInteger> &&expr) {
	lower_.emplace(std::move(expr));
	return *this;
	}

	std::optional<Expr<SubscriptInteger>> Substring::upper() const {
	if (upper_) {
	return upper_.value().value();
	} else {
	return std::visit(
	common::visitors{
	[](const DataRef &dataRef) { return dataRef.LEN(); },
	[](const StaticDataObject::Pointer &object)
	-> std::optional<Expr<SubscriptInteger>> {
	return AsExpr(Constant<SubscriptInteger>{object->data().size()});
	},
	},
	parent_);
	}
	}

	Substring &Substring::set_upper(Expr<SubscriptInteger> &&expr) {
	upper_.emplace(std::move(expr));
	return *this;
	}

	std::optional<Expr<SomeCharacter>> Substring::Fold(FoldingContext &context) {
	if (!lower_) {
	lower_ = AsExpr(Constant<SubscriptInteger>{1});
	}
	lower_.value() = evaluate::Fold(context, std::move(lower_.value().value()));
	std::optional<ConstantSubscript> lbi{ToInt64(lower_.value().value())};
	if (lbi && *lbi < 1) {
	context.messages().Say(
	"Lower bound (%jd) on substring is less than one"_en_US, *lbi);
	*lbi = 1;
	lower_ = AsExpr(Constant<SubscriptInteger>{1});
	}
	if (!upper_) {
	upper_ = upper();
	if (!upper_) {
	return std::nullopt;
	}
	}
	upper_.value() = evaluate::Fold(context, std::move(upper_.value().value()));
	if (std::optional<ConstantSubscript> ubi{ToInt64(upper_.value().value())}) {
	auto *literal{std::get_if<StaticDataObject::Pointer>(&parent_)};
	std::optional<ConstantSubscript> length;
	if (literal) {
	length = (*literal)->data().size();
	} else if (const Symbol * symbol{GetLastSymbol()}) {
	if (const semantics::DeclTypeSpec * type{symbol->GetType()}) {
	if (type->category() == semantics::DeclTypeSpec::Character) {
	length = ToInt64(type->characterTypeSpec().length().GetExplicit());
	}
	}
	}
	if (ubi < 1 \|\| (lbi && ubi < *lbi)) {
	// Zero-length string: canonicalize
	lbi = 1, ubi = 0;
	lower_ = AsExpr(Constant<SubscriptInteger>{*lbi});
	upper_ = AsExpr(Constant<SubscriptInteger>{*ubi});
	} else if (length && ubi > length) {
	context.messages().Say("Upper bound (%jd) on substring is greater "
	"than character length (%jd)"_en_US,
	ubi, length);
	ubi = length;
	}
	if (lbi && literal) {
	auto newStaticData{StaticDataObject::Create()};
	auto items{0}; // If the lower bound is greater, the length is 0
	if (ubi >= lbi) {
	items = ubi - lbi + 1;
	}
	auto width{(*literal)->itemBytes()};
	auto bytes{items * width};
	auto startByte{(lbi - 1) width};
	const auto from{&(literal)->data()[0] + startByte};
	for (auto j{0}; j < bytes; ++j) {
	newStaticData->data().push_back(from[j]);
	}
	parent_ = newStaticData;
	lower_ = AsExpr(Constant<SubscriptInteger>{1});
	ConstantSubscript length = newStaticData->data().size();
	upper_ = AsExpr(Constant<SubscriptInteger>{length});
	switch (width) {
	case 1:
	return {
	AsCategoryExpr(AsExpr(Constant<Type<TypeCategory::Character, 1>>{
	*newStaticData->AsString()}))};
	case 2:
	return {AsCategoryExpr(Constant<Type<TypeCategory::Character, 2>>{
	*newStaticData->AsU16String()})};
	case 4:
	return {AsCategoryExpr(Constant<Type<TypeCategory::Character, 4>>{
	*newStaticData->AsU32String()})};
	default:
	CRASH_NO_CASE;
	}
	}
	}
	return std::nullopt;
	}

	DescriptorInquiry::DescriptorInquiry(
	const NamedEntity &base, Field field, int dim)
	: base_{base}, field_{field}, dimension_{dim} {
	const Symbol &last{base_.GetLastSymbol()};
	CHECK(IsDescriptor(last));
	CHECK((field == Field::Len && dim == 0) \|\|
	(field != Field::Len && dim >= 0 && dim < last.Rank()));
	}

	DescriptorInquiry::DescriptorInquiry(NamedEntity &&base, Field field, int dim)
	: base_{std::move(base)}, field_{field}, dimension_{dim} {
	const Symbol &last{base_.GetLastSymbol()};
	CHECK(IsDescriptor(last));
	CHECK((field == Field::Len && dim == 0) \|\|
	(field != Field::Len && dim >= 0 && dim < last.Rank()));
	}

	// LEN()
	static std::optional<Expr<SubscriptInteger>> SymbolLEN(const Symbol &symbol) {
	const Symbol &ultimate{symbol.GetUltimate()};
	if (const auto *assoc{ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
	if (const auto *chExpr{UnwrapExpr<Expr<SomeCharacter>>(assoc->expr())}) {
	return chExpr->LEN();
	}
	} else if (auto dyType{DynamicType::From(ultimate)}) {
	if (auto len{dyType->GetCharLength()}) {
	return len;
	} else if (IsDescriptor(ultimate) && !ultimate.owner().IsDerivedType()) {
	return Expr<SubscriptInteger>{DescriptorInquiry{
	NamedEntity{symbol}, DescriptorInquiry::Field::Len}};
	}
	}
	return std::nullopt;
	}

	std::optional<Expr<SubscriptInteger>> BaseObject::LEN() const {
	return std::visit(
	common::visitors{
	[](const Symbol &symbol) { return SymbolLEN(symbol); },
	[](const StaticDataObject::Pointer &object)
	-> std::optional<Expr<SubscriptInteger>> {
	return AsExpr(Constant<SubscriptInteger>{object->data().size()});
	},
	},
	u);
	}

	std::optional<Expr<SubscriptInteger>> Component::LEN() const {
	return SymbolLEN(GetLastSymbol());
	}

	std::optional<Expr<SubscriptInteger>> NamedEntity::LEN() const {
	return SymbolLEN(GetLastSymbol());
	}

	std::optional<Expr<SubscriptInteger>> ArrayRef::LEN() const {
	return base_.LEN();
	}

	std::optional<Expr<SubscriptInteger>> CoarrayRef::LEN() const {
	return SymbolLEN(GetLastSymbol());
	}

	std::optional<Expr<SubscriptInteger>> DataRef::LEN() const {
	return std::visit(common::visitors{
	[](SymbolRef symbol) { return SymbolLEN(symbol); },
	[](const auto &x) { return x.LEN(); },
	},
	u);
	}

	std::optional<Expr<SubscriptInteger>> Substring::LEN() const {
	if (auto top{upper()}) {
	return AsExpr(Extremum<SubscriptInteger>{Ordering::Greater,
	AsExpr(Constant<SubscriptInteger>{0}),
	*std::move(top) - lower() + AsExpr(Constant<SubscriptInteger>{1})});
	} else {
	return std::nullopt;
	}
	}

	template <typename T>
	std::optional<Expr<SubscriptInteger>> Designator<T>::LEN() const {
	if constexpr (T::category == TypeCategory::Character) {
	return std::visit(common::visitors{
	[](SymbolRef symbol) { return SymbolLEN(symbol); },
	[](const auto &x) { return x.LEN(); },
	},
	u);
	} else {
	common::die("Designator<non-char>::LEN() called");
	return std::nullopt;
	}
	}

	std::optional<Expr<SubscriptInteger>> ProcedureDesignator::LEN() const {
	using T = std::optional<Expr<SubscriptInteger>>;
	return std::visit(
	common::visitors{
	[](SymbolRef symbol) -> T { return SymbolLEN(symbol); },
	[](const common::CopyableIndirection<Component> &c) -> T {
	return c.value().LEN();
	},
	[](const SpecificIntrinsic &i) -> T {
	// Some cases whose results' lengths can be determined
	// from the lengths of their arguments are handled in
	// ProcedureRef::LEN() before coming here.
	if (const auto &result{i.characteristics.value().functionResult}) {
	if (const auto *type{result->GetTypeAndShape()}) {
	if (auto length{type->type().GetCharLength()}) {
	return std::move(*length);
	}
	}
	}
	return std::nullopt;
	},
	},
	u);
	}

	// Rank()
	int BaseObject::Rank() const {
	return std::visit(common::visitors{
	[](SymbolRef symbol) { return symbol->Rank(); },
	[](const StaticDataObject::Pointer &) { return 0; },
	},
	u);
	}

	int Component::Rank() const {
	if (int rank{symbol_->Rank()}; rank > 0) {
	return rank;
	}
	return base().Rank();
	}

	int NamedEntity::Rank() const {
	return std::visit(common::visitors{
	[](const SymbolRef s) { return s->Rank(); },
	[](const Component &c) { return c.Rank(); },
	},
	u_);
	}

	int Subscript::Rank() const {
	return std::visit(common::visitors{
	[](const IndirectSubscriptIntegerExpr &x) {
	return x.value().Rank();
	},
	[](const Triplet &) { return 1; },
	},
	u);
	}

	int ArrayRef::Rank() const {
	int rank{0};
	for (const auto &expr : subscript_) {
	rank += expr.Rank();
	}
	if (rank > 0) {
	return rank;
	} else if (const Component * component{base_.UnwrapComponent()}) {
	return component->base().Rank();
	} else {
	return 0;
	}
	}

	int CoarrayRef::Rank() const {
	if (!subscript_.empty()) {
	int rank{0};
	for (const auto &expr : subscript_) {
	rank += expr.Rank();
	}
	return rank;
	} else {
	return base_.back()->Rank();
	}
	}

	int DataRef::Rank() const {
	return std::visit(common::visitors{
	[](SymbolRef symbol) { return symbol->Rank(); },
	[](const auto &x) { return x.Rank(); },
	},
	u);
	}

	int Substring::Rank() const {
	return std::visit(common::visitors{
	[](const DataRef &dataRef) { return dataRef.Rank(); },
	[](const StaticDataObject::Pointer &) { return 0; },
	},
	parent_);
	}

	int ComplexPart::Rank() const { return complex_.Rank(); }

	template <typename T> int Designator<T>::Rank() const {
	return std::visit(common::visitors{
	[](SymbolRef symbol) { return symbol->Rank(); },
	[](const auto &x) { return x.Rank(); },
	},
	u);
	}

	// GetBaseObject(), GetFirstSymbol(), GetLastSymbol(), &c.
	const Symbol &Component::GetFirstSymbol() const {
	return base_.value().GetFirstSymbol();
	}

	const Symbol &NamedEntity::GetFirstSymbol() const {
	return std::visit(common::visitors{
	[](SymbolRef s) -> const Symbol & { return s; },
	[](const Component &c) -> const Symbol & {
	return c.GetFirstSymbol();
	},
	},
	u_);
	}

	const Symbol &NamedEntity::GetLastSymbol() const {
	return std::visit(common::visitors{
	[](SymbolRef s) -> const Symbol & { return s; },
	[](const Component &c) -> const Symbol & {
	return c.GetLastSymbol();
	},
	},
	u_);
	}

	const Component *NamedEntity::UnwrapComponent() const {
	return std::visit(common::visitors{
	[](SymbolRef) -> const Component * { return nullptr; },
	[](const Component &c) { return &c; },
	},
	u_);
	}

	Component *NamedEntity::UnwrapComponent() {
	return std::visit(common::visitors{
	[](SymbolRef &) -> Component * { return nullptr; },
	[](Component &c) { return &c; },
	},
	u_);
	}

	const Symbol &ArrayRef::GetFirstSymbol() const {
	return base_.GetFirstSymbol();
	}

	const Symbol &ArrayRef::GetLastSymbol() const { return base_.GetLastSymbol(); }

	const Symbol &DataRef::GetFirstSymbol() const {
	return *std::visit(common::visitors{
	[](SymbolRef symbol) { return &*symbol; },
	[](const auto &x) { return &x.GetFirstSymbol(); },
	},
	u);
	}

	const Symbol &DataRef::GetLastSymbol() const {
	return *std::visit(common::visitors{
	[](SymbolRef symbol) { return &*symbol; },
	[](const auto &x) { return &x.GetLastSymbol(); },
	},
	u);
	}

	BaseObject Substring::GetBaseObject() const {
	return std::visit(common::visitors{
	[](const DataRef &dataRef) {
	return BaseObject{dataRef.GetFirstSymbol()};
	},
	[](StaticDataObject::Pointer pointer) {
	return BaseObject{std::move(pointer)};
	},
	},
	parent_);
	}

	const Symbol *Substring::GetLastSymbol() const {
	return std::visit(
	common::visitors{
	[](const DataRef &dataRef) { return &dataRef.GetLastSymbol(); },
	[](const auto &) -> const Symbol * { return nullptr; },
	},
	parent_);
	}

	template <typename T> BaseObject Designator<T>::GetBaseObject() const {
	return std::visit(
	common::visitors{
	[](SymbolRef symbol) { return BaseObject{symbol}; },
	[](const Substring &sstring) { return sstring.GetBaseObject(); },
	[](const auto &x) {
	#if !__clang__ && __GNUC__ == 7 && __GNUC_MINOR__ == 2
	if constexpr (std::is_same_v<std::decay_t<decltype(x)>,
	Substring>) {
	return x.GetBaseObject();
	} else
	#endif
	return BaseObject{x.GetFirstSymbol()};
	},
	},
	u);
	}

	template <typename T> const Symbol *Designator<T>::GetLastSymbol() const {
	return std::visit(
	common::visitors{
	[](SymbolRef symbol) { return &*symbol; },
	[](const Substring &sstring) { return sstring.GetLastSymbol(); },
	[](const auto &x) {
	#if !__clang__ && __GNUC__ == 7 && __GNUC_MINOR__ == 2
	if constexpr (std::is_same_v<std::decay_t<decltype(x)>,
	Substring>) {
	return x.GetLastSymbol();
	} else
	#endif
	return &x.GetLastSymbol();
	},
	},
	u);
	}

	template <typename T>
	std::optional<DynamicType> Designator<T>::GetType() const {
	if constexpr (IsLengthlessIntrinsicType<Result>) {
	return Result::GetType();
	} else if (const Symbol * symbol{GetLastSymbol()}) {
	return DynamicType::From(*symbol);
	} else if constexpr (Result::category == TypeCategory::Character) {
	if (const Substring * substring{std::get_if<Substring>(&u)}) {
	const auto *parent{substring->GetParentIf<StaticDataObject::Pointer>()};
	CHECK(parent);
	return DynamicType{TypeCategory::Character, (*parent)->itemBytes()};
	}
	}
	return std::nullopt;
	}

	static NamedEntity AsNamedEntity(const SymbolVector &x) {
	CHECK(!x.empty());
	NamedEntity result{x.front()};
	int j{0};
	for (const Symbol &symbol : x) {
	if (j++ != 0) {
	DataRef base{result.IsSymbol() ? DataRef{result.GetLastSymbol()}
	: DataRef{result.GetComponent()}};
	result = NamedEntity{Component{std::move(base), symbol}};
	}
	}
	return result;
	}

	NamedEntity CoarrayRef::GetBase() const { return AsNamedEntity(base_); }

	// Equality testing

	// For the purposes of comparing type parameter expressions while
	// testing the compatibility of procedure characteristics, two
	// object dummy arguments with the same name are considered equal.
	static bool AreSameSymbol(const Symbol &x, const Symbol &y) {
	if (&x == &y) {
	return true;
	}
	if (x.name() == y.name()) {
	if (const auto *xObject{x.detailsIf<semantics::ObjectEntityDetails>()}) {
	if (const auto *yObject{y.detailsIf<semantics::ObjectEntityDetails>()}) {
	return xObject->isDummy() && yObject->isDummy();
	}
	}
	}
	return false;
	}

	// Implements operator==() for a union type, using special case handling
	// for Symbol references.
	template <typename A> static bool TestVariableEquality(const A &x, const A &y) {
	const SymbolRef *xSymbol{std::get_if<SymbolRef>(&x.u)};
	if (const SymbolRef * ySymbol{std::get_if<SymbolRef>(&y.u)}) {
	return xSymbol && AreSameSymbol(xSymbol, ySymbol);
	} else {
	return x.u == y.u;
	}
	}

	bool BaseObject::operator==(const BaseObject &that) const {
	return TestVariableEquality(*this, that);
	}
	bool Component::operator==(const Component &that) const {
	return base_ == that.base_ && &symbol_ == &that.symbol_;
	}
	bool NamedEntity::operator==(const NamedEntity &that) const {
	if (IsSymbol()) {
	return that.IsSymbol() &&
	AreSameSymbol(GetFirstSymbol(), that.GetFirstSymbol());
	} else {
	return !that.IsSymbol() && GetComponent() == that.GetComponent();
	}
	}
	bool TypeParamInquiry::operator==(const TypeParamInquiry &that) const {
	return &parameter_ == &that.parameter_ && base_ == that.base_;
	}
	bool Triplet::operator==(const Triplet &that) const {
	return lower_ == that.lower_ && upper_ == that.upper_ &&
	stride_ == that.stride_;
	}
	bool Subscript::operator==(const Subscript &that) const { return u == that.u; }
	bool ArrayRef::operator==(const ArrayRef &that) const {
	return base_ == that.base_ && subscript_ == that.subscript_;
	}
	bool CoarrayRef::operator==(const CoarrayRef &that) const {
	return base_ == that.base_ && subscript_ == that.subscript_ &&
	cosubscript_ == that.cosubscript_ && stat_ == that.stat_ &&
	team_ == that.team_ && teamIsTeamNumber_ == that.teamIsTeamNumber_;
	}
	bool DataRef::operator==(const DataRef &that) const {
	return TestVariableEquality(*this, that);
	}
	bool Substring::operator==(const Substring &that) const {
	return parent_ == that.parent_ && lower_ == that.lower_ &&
	upper_ == that.upper_;
	}
	bool ComplexPart::operator==(const ComplexPart &that) const {
	return part_ == that.part_ && complex_ == that.complex_;
	}
	bool ProcedureRef::operator==(const ProcedureRef &that) const {
	return proc_ == that.proc_ && arguments_ == that.arguments_;
	}
	template <typename T>
	bool Designator<T>::operator==(const Designator<T> &that) const {
	return TestVariableEquality(*this, that);
	}
	bool DescriptorInquiry::operator==(const DescriptorInquiry &that) const {
	return field_ == that.field_ && base_ == that.base_ &&
	dimension_ == that.dimension_;
	}

	INSTANTIATE_VARIABLE_TEMPLATES
	} // namespace Fortran::evaluate

	template class Fortran::common::Indirection<Fortran::evaluate::Component, true>;