flang/lib/Evaluate/variable.cpp

   1 //===-- lib/Evaluate/variable.cpp -----------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "flang/Evaluate/variable.h"
  10 #include "flang/Common/idioms.h"
  11 #include "flang/Evaluate/check-expression.h"
  12 #include "flang/Evaluate/fold.h"
  13 #include "flang/Evaluate/tools.h"
  14 #include "flang/Parser/char-block.h"
  15 #include "flang/Parser/characters.h"
  16 #include "flang/Parser/message.h"
  17 #include "flang/Semantics/scope.h"
  18 #include "flang/Semantics/symbol.h"
  19 #include <type_traits>
  20
  21 using namespace Fortran::parser::literals;
  22
  23 namespace Fortran::evaluate {
  24
  25 // Constructors, accessors, mutators
  26
  27 Triplet::Triplet() : stride_{Expr<SubscriptInteger>{1}} {}
  28
  29 Triplet::Triplet(std::optional<Expr<SubscriptInteger>> &&l,
  30     std::optional<Expr<SubscriptInteger>> &&u,
  31     std::optional<Expr<SubscriptInteger>> &&s)
  32     : stride_{s ? std::move(*s) : Expr<SubscriptInteger>{1}} {
  33   if (l) {
  34     lower_.emplace(std::move(*l));
  35   }
  36   if (u) {
  37     upper_.emplace(std::move(*u));
  38   }
  39 }
  40
  41 std::optional<Expr<SubscriptInteger>> Triplet::lower() const {
  42   if (lower_) {
  43     return {lower_.value().value()};
  44   }
  45   return std::nullopt;
  46 }
  47
  48 Triplet &Triplet::set_lower(Expr<SubscriptInteger> &&expr) {
  49   lower_.emplace(std::move(expr));
  50   return *this;
  51 }
  52
  53 std::optional<Expr<SubscriptInteger>> Triplet::upper() const {
  54   if (upper_) {
  55     return {upper_.value().value()};
  56   }
  57   return std::nullopt;
  58 }
  59
  60 Triplet &Triplet::set_upper(Expr<SubscriptInteger> &&expr) {
  61   upper_.emplace(std::move(expr));
  62   return *this;
  63 }
  64
  65 Expr<SubscriptInteger> Triplet::stride() const { return stride_.value(); }
  66
  67 Triplet &Triplet::set_stride(Expr<SubscriptInteger> &&expr) {
  68   stride_.value() = std::move(expr);
  69   return *this;
  70 }
  71
  72 CoarrayRef::CoarrayRef(SymbolVector &&base, std::vector<Subscript> &&ss,
  73     std::vector<Expr<SubscriptInteger>> &&css)
  74     : base_{std::move(base)}, subscript_(std::move(ss)),
  75       cosubscript_(std::move(css)) {
  76   CHECK(!base_.empty());
  77   CHECK(!cosubscript_.empty());
  78 }
  79
  80 std::optional<Expr<SomeInteger>> CoarrayRef::stat() const {
  81   if (stat_) {
  82     return stat_.value().value();
  83   } else {
  84     return std::nullopt;
  85   }
  86 }
  87
  88 std::optional<Expr<SomeInteger>> CoarrayRef::team() const {
  89   if (team_) {
  90     return team_.value().value();
  91   } else {
  92     return std::nullopt;
  93   }
  94 }
  95
  96 CoarrayRef &CoarrayRef::set_stat(Expr<SomeInteger> &&v) {
  97   CHECK(IsVariable(v));
  98   stat_.emplace(std::move(v));
  99   return *this;
 100 }
 101
 102 CoarrayRef &CoarrayRef::set_team(Expr<SomeInteger> &&v, bool isTeamNumber) {
 103   CHECK(IsVariable(v));
 104   team_.emplace(std::move(v));
 105   teamIsTeamNumber_ = isTeamNumber;
 106   return *this;
 107 }
 108
 109 const Symbol &CoarrayRef::GetFirstSymbol() const { return base_.front(); }
 110
 111 const Symbol &CoarrayRef::GetLastSymbol() const { return base_.back(); }
 112
 113 void Substring::SetBounds(std::optional<Expr<SubscriptInteger>> &lower,
 114     std::optional<Expr<SubscriptInteger>> &upper) {
 115   if (lower) {
 116     set_lower(std::move(lower.value()));
 117   }
 118   if (upper) {
 119     set_upper(std::move(upper.value()));
 120   }
 121 }
 122
 123 Expr<SubscriptInteger> Substring::lower() const {
 124   if (lower_) {
 125     return lower_.value().value();
 126   } else {
 127     return AsExpr(Constant<SubscriptInteger>{1});
 128   }
 129 }
 130
 131 Substring &Substring::set_lower(Expr<SubscriptInteger> &&expr) {
 132   lower_.emplace(std::move(expr));
 133   return *this;
 134 }
 135
 136 std::optional<Expr<SubscriptInteger>> Substring::upper() const {
 137   if (upper_) {
 138     return upper_.value().value();
 139   } else {
 140     return common::visit(
 141         common::visitors{
 142             [](const DataRef &dataRef) { return dataRef.LEN(); },
 143             [](const StaticDataObject::Pointer &object)
 144                 -> std::optional<Expr<SubscriptInteger>> {
 145               return AsExpr(Constant<SubscriptInteger>{object->data().size()});
 146             },
 147         },
 148         parent_);
 149   }
 150 }
 151
 152 Substring &Substring::set_upper(Expr<SubscriptInteger> &&expr) {
 153   upper_.emplace(std::move(expr));
 154   return *this;
 155 }
 156
 157 std::optional<Expr<SomeCharacter>> Substring::Fold(FoldingContext &context) {
 158   if (!upper_) {
 159     upper_ = upper();
 160     if (!upper_) {
 161       return std::nullopt;
 162     }
 163   }
 164   upper_.value() = evaluate::Fold(context, std::move(upper_.value().value()));
 165   std::optional<ConstantSubscript> ubi{ToInt64(upper_.value().value())};
 166   if (!ubi) {
 167     return std::nullopt;
 168   }
 169   if (!lower_) {
 170     lower_ = AsExpr(Constant<SubscriptInteger>{1});
 171   }
 172   lower_.value() = evaluate::Fold(context, std::move(lower_.value().value()));
 173   std::optional<ConstantSubscript> lbi{ToInt64(lower_.value().value())};
 174   if (!lbi) {
 175     return std::nullopt;
 176   }
 177   if (*lbi > *ubi) { // empty result; canonicalize
 178     *lbi = 1;
 179     *ubi = 0;
 180     lower_ = AsExpr(Constant<SubscriptInteger>{*lbi});
 181     upper_ = AsExpr(Constant<SubscriptInteger>{*ubi});
 182   }
 183   std::optional<ConstantSubscript> length;
 184   std::optional<Expr<SomeCharacter>> strings; // a Constant<Character>
 185   if (const auto *literal{std::get_if<StaticDataObject::Pointer>(&parent_)}) {
 186     length = (*literal)->data().size();
 187     if (auto str{(*literal)->AsString()}) {
 188       strings =
 189           Expr<SomeCharacter>(Expr<Ascii>(Constant<Ascii>{std::move(*str)}));
 190     }
 191   } else if (const auto *dataRef{std::get_if<DataRef>(&parent_)}) {
 192     if (auto expr{AsGenericExpr(DataRef{*dataRef})}) {
 193       auto folded{evaluate::Fold(context, std::move(*expr))};
 194       if (IsActuallyConstant(folded)) {
 195         if (const auto *value{UnwrapExpr<Expr<SomeCharacter>>(folded)}) {
 196           strings = *value;
 197         }
 198       }
 199     }
 200   }
 201   std::optional<Expr<SomeCharacter>> result;
 202   if (strings) {
 203     result = common::visit(
 204         [&](const auto &expr) -> std::optional<Expr<SomeCharacter>> {
 205           using Type = typename std::decay_t<decltype(expr)>::Result;
 206           if (const auto *cc{std::get_if<Constant<Type>>(&expr.u)}) {
 207             if (auto substr{cc->Substring(*lbi, *ubi)}) {
 208               return Expr<SomeCharacter>{Expr<Type>{*substr}};
 209             }
 210           }
 211           return std::nullopt;
 212         },
 213         strings->u);
 214   }
 215   if (!result) { // error cases
 216     if (*lbi < 1) {
 217       context.messages().Say(
 218           "Lower bound (%jd) on substring is less than one"_warn_en_US,
 219           static_cast<std::intmax_t>(*lbi));
 220       *lbi = 1;
 221       lower_ = AsExpr(Constant<SubscriptInteger>{1});
 222     }
 223     if (length && *ubi > *length) {
 224       context.messages().Say(
 225           "Upper bound (%jd) on substring is greater than character length (%jd)"_warn_en_US,
 226           static_cast<std::intmax_t>(*ubi),
 227           static_cast<std::intmax_t>(*length));
 228       *ubi = *length;
 229       upper_ = AsExpr(Constant<SubscriptInteger>{*ubi});
 230     }
 231   }
 232   return result;
 233 }
 234
 235 DescriptorInquiry::DescriptorInquiry(
 236     const NamedEntity &base, Field field, int dim)
 237     : base_{base}, field_{field}, dimension_{dim} {
 238   const Symbol &last{base_.GetLastSymbol()};
 239   CHECK(IsDescriptor(last));
 240   CHECK(((field == Field::Len || field == Field::Rank) && dim == 0) ||
 241       (field != Field::Len && dim >= 0 && dim < last.Rank()));
 242 }
 243
 244 DescriptorInquiry::DescriptorInquiry(NamedEntity &&base, Field field, int dim)
 245     : base_{std::move(base)}, field_{field}, dimension_{dim} {
 246   const Symbol &last{base_.GetLastSymbol()};
 247   CHECK(IsDescriptor(last));
 248   CHECK((field == Field::Len && dim == 0) ||
 249       (field != Field::Len && dim >= 0 && dim < last.Rank()));
 250 }
 251
 252 // LEN()
 253 static std::optional<Expr<SubscriptInteger>> SymbolLEN(const Symbol &symbol) {
 254   const Symbol &ultimate{symbol.GetUltimate()};
 255   if (const auto *assoc{ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
 256     if (const auto *chExpr{UnwrapExpr<Expr<SomeCharacter>>(assoc->expr())}) {
 257       return chExpr->LEN();
 258     }
 259   }
 260   if (auto dyType{DynamicType::From(ultimate)}) {
 261     auto len{dyType->GetCharLength()};
 262     if (!len && ultimate.attrs().test(semantics::Attr::PARAMETER)) {
 263       // Its initializer determines the length of an implied-length named
 264       // constant.
 265       if (const auto *object{
 266               ultimate.detailsIf<semantics::ObjectEntityDetails>()}) {
 267         if (object->init()) {
 268           if (auto dyType2{DynamicType::From(*object->init())}) {
 269             len = dyType2->GetCharLength();
 270           }
 271         }
 272       }
 273     }
 274     if (len) {
 275       if (auto constLen{ToInt64(*len)}) {
 276         return Expr<SubscriptInteger>{std::max<std::int64_t>(*constLen, 0)};
 277       } else if (ultimate.owner().IsDerivedType() ||
 278           IsScopeInvariantExpr(*len)) {
 279         return AsExpr(Extremum<SubscriptInteger>{
 280             Ordering::Greater, Expr<SubscriptInteger>{0}, std::move(*len)});
 281       }
 282     }
 283   }
 284   if (IsDescriptor(ultimate) && !ultimate.owner().IsDerivedType()) {
 285     return Expr<SubscriptInteger>{
 286         DescriptorInquiry{NamedEntity{symbol}, DescriptorInquiry::Field::Len}};
 287   }
 288   return std::nullopt;
 289 }
 290
 291 std::optional<Expr<SubscriptInteger>> BaseObject::LEN() const {
 292   return common::visit(
 293       common::visitors{
 294           [](const Symbol &symbol) { return SymbolLEN(symbol); },
 295           [](const StaticDataObject::Pointer &object)
 296               -> std::optional<Expr<SubscriptInteger>> {
 297             return AsExpr(Constant<SubscriptInteger>{object->data().size()});
 298           },
 299       },
 300       u);
 301 }
 302
 303 std::optional<Expr<SubscriptInteger>> Component::LEN() const {
 304   return SymbolLEN(GetLastSymbol());
 305 }
 306
 307 std::optional<Expr<SubscriptInteger>> NamedEntity::LEN() const {
 308   return SymbolLEN(GetLastSymbol());
 309 }
 310
 311 std::optional<Expr<SubscriptInteger>> ArrayRef::LEN() const {
 312   return base_.LEN();
 313 }
 314
 315 std::optional<Expr<SubscriptInteger>> CoarrayRef::LEN() const {
 316   return SymbolLEN(GetLastSymbol());
 317 }
 318
 319 std::optional<Expr<SubscriptInteger>> DataRef::LEN() const {
 320   return common::visit(common::visitors{
 321                            [](SymbolRef symbol) { return SymbolLEN(symbol); },
 322                            [](const auto &x) { return x.LEN(); },
 323                        },
 324       u);
 325 }
 326
 327 std::optional<Expr<SubscriptInteger>> Substring::LEN() const {
 328   if (auto top{upper()}) {
 329     return AsExpr(Extremum<SubscriptInteger>{Ordering::Greater,
 330         AsExpr(Constant<SubscriptInteger>{0}),
 331         *std::move(top) - lower() + AsExpr(Constant<SubscriptInteger>{1})});
 332   } else {
 333     return std::nullopt;
 334   }
 335 }
 336
 337 template <typename T>
 338 std::optional<Expr<SubscriptInteger>> Designator<T>::LEN() const {
 339   if constexpr (T::category == TypeCategory::Character) {
 340     return common::visit(common::visitors{
 341                              [](SymbolRef symbol) { return SymbolLEN(symbol); },
 342                              [](const auto &x) { return x.LEN(); },
 343                          },
 344         u);
 345   } else {
 346     common::die("Designator<non-char>::LEN() called");
 347     return std::nullopt;
 348   }
 349 }
 350
 351 std::optional<Expr<SubscriptInteger>> ProcedureDesignator::LEN() const {
 352   using T = std::optional<Expr<SubscriptInteger>>;
 353   return common::visit(
 354       common::visitors{
 355           [](SymbolRef symbol) -> T { return SymbolLEN(symbol); },
 356           [](const common::CopyableIndirection<Component> &c) -> T {
 357             return c.value().LEN();
 358           },
 359           [](const SpecificIntrinsic &i) -> T {
 360             // Some cases whose results' lengths can be determined
 361             // from the lengths of their arguments are handled in
 362             // ProcedureRef::LEN() before coming here.
 363             if (const auto &result{i.characteristics.value().functionResult}) {
 364               if (const auto *type{result->GetTypeAndShape()}) {
 365                 if (auto length{type->type().GetCharLength()}) {
 366                   return std::move(*length);
 367                 }
 368               }
 369             }
 370             return std::nullopt;
 371           },
 372       },
 373       u);
 374 }
 375
 376 // Rank()
 377 int BaseObject::Rank() const {
 378   return common::visit(common::visitors{
 379                            [](SymbolRef symbol) { return symbol->Rank(); },
 380                            [](const StaticDataObject::Pointer &) { return 0; },
 381                        },
 382       u);
 383 }
 384
 385 int Component::Rank() const {
 386   if (int rank{symbol_->Rank()}; rank > 0) {
 387     return rank;
 388   }
 389   return base().Rank();
 390 }
 391
 392 int NamedEntity::Rank() const {
 393   return common::visit(common::visitors{
 394                            [](const SymbolRef s) { return s->Rank(); },
 395                            [](const Component &c) { return c.Rank(); },
 396                        },
 397       u_);
 398 }
 399
 400 int Subscript::Rank() const {
 401   return common::visit(common::visitors{
 402                            [](const IndirectSubscriptIntegerExpr &x) {
 403                              return x.value().Rank();
 404                            },
 405                            [](const Triplet &) { return 1; },
 406                        },
 407       u);
 408 }
 409
 410 int ArrayRef::Rank() const {
 411   int rank{0};
 412   for (const auto &expr : subscript_) {
 413     rank += expr.Rank();
 414   }
 415   if (rank > 0) {
 416     return rank;
 417   } else if (const Component * component{base_.UnwrapComponent()}) {
 418     return component->base().Rank();
 419   } else {
 420     return 0;
 421   }
 422 }
 423
 424 int CoarrayRef::Rank() const {
 425   if (!subscript_.empty()) {
 426     int rank{0};
 427     for (const auto &expr : subscript_) {
 428       rank += expr.Rank();
 429     }
 430     return rank;
 431   } else {
 432     return base_.back()->Rank();
 433   }
 434 }
 435
 436 int DataRef::Rank() const {
 437   return common::visit(common::visitors{
 438                            [](SymbolRef symbol) { return symbol->Rank(); },
 439                            [](const auto &x) { return x.Rank(); },
 440                        },
 441       u);
 442 }
 443
 444 int Substring::Rank() const {
 445   return common::visit(
 446       common::visitors{
 447           [](const DataRef &dataRef) { return dataRef.Rank(); },
 448           [](const StaticDataObject::Pointer &) { return 0; },
 449       },
 450       parent_);
 451 }
 452
 453 int ComplexPart::Rank() const { return complex_.Rank(); }
 454
 455 template <typename T> int Designator<T>::Rank() const {
 456   return common::visit(common::visitors{
 457                            [](SymbolRef symbol) { return symbol->Rank(); },
 458                            [](const auto &x) { return x.Rank(); },
 459                        },
 460       u);
 461 }
 462
 463 // GetBaseObject(), GetFirstSymbol(), GetLastSymbol(), &c.
 464 const Symbol &Component::GetFirstSymbol() const {
 465   return base_.value().GetFirstSymbol();
 466 }
 467
 468 const Symbol &NamedEntity::GetFirstSymbol() const {
 469   return common::visit(common::visitors{
 470                            [](SymbolRef s) -> const Symbol & { return s; },
 471                            [](const Component &c) -> const Symbol & {
 472                              return c.GetFirstSymbol();
 473                            },
 474                        },
 475       u_);
 476 }
 477
 478 const Symbol &NamedEntity::GetLastSymbol() const {
 479   return common::visit(common::visitors{
 480                            [](SymbolRef s) -> const Symbol & { return s; },
 481                            [](const Component &c) -> const Symbol & {
 482                              return c.GetLastSymbol();
 483                            },
 484                        },
 485       u_);
 486 }
 487
 488 const SymbolRef *NamedEntity::UnwrapSymbolRef() const {
 489   return common::visit(
 490       common::visitors{
 491           [](const SymbolRef &s) { return &s; },
 492           [](const Component &) -> const SymbolRef * { return nullptr; },
 493       },
 494       u_);
 495 }
 496
 497 SymbolRef *NamedEntity::UnwrapSymbolRef() {
 498   return common::visit(common::visitors{
 499                            [](SymbolRef &s) { return &s; },
 500                            [](Component &) -> SymbolRef * { return nullptr; },
 501                        },
 502       u_);
 503 }
 504
 505 const Component *NamedEntity::UnwrapComponent() const {
 506   return common::visit(
 507       common::visitors{
 508           [](SymbolRef) -> const Component * { return nullptr; },
 509           [](const Component &c) { return &c; },
 510       },
 511       u_);
 512 }
 513
 514 Component *NamedEntity::UnwrapComponent() {
 515   return common::visit(common::visitors{
 516                            [](SymbolRef &) -> Component * { return nullptr; },
 517                            [](Component &c) { return &c; },
 518                        },
 519       u_);
 520 }
 521
 522 const Symbol &ArrayRef::GetFirstSymbol() const {
 523   return base_.GetFirstSymbol();
 524 }
 525
 526 const Symbol &ArrayRef::GetLastSymbol() const { return base_.GetLastSymbol(); }
 527
 528 const Symbol &DataRef::GetFirstSymbol() const {
 529   return *common::visit(common::visitors{
 530                             [](SymbolRef symbol) { return &*symbol; },
 531                             [](const auto &x) { return &x.GetFirstSymbol(); },
 532                         },
 533       u);
 534 }
 535
 536 const Symbol &DataRef::GetLastSymbol() const {
 537   return *common::visit(common::visitors{
 538                             [](SymbolRef symbol) { return &*symbol; },
 539                             [](const auto &x) { return &x.GetLastSymbol(); },
 540                         },
 541       u);
 542 }
 543
 544 BaseObject Substring::GetBaseObject() const {
 545   return common::visit(common::visitors{
 546                            [](const DataRef &dataRef) {
 547                              return BaseObject{dataRef.GetFirstSymbol()};
 548                            },
 549                            [](StaticDataObject::Pointer pointer) {
 550                              return BaseObject{std::move(pointer)};
 551                            },
 552                        },
 553       parent_);
 554 }
 555
 556 const Symbol *Substring::GetLastSymbol() const {
 557   return common::visit(
 558       common::visitors{
 559           [](const DataRef &dataRef) { return &dataRef.GetLastSymbol(); },
 560           [](const auto &) -> const Symbol * { return nullptr; },
 561       },
 562       parent_);
 563 }
 564
 565 template <typename T> BaseObject Designator<T>::GetBaseObject() const {
 566   return common::visit(
 567       common::visitors{
 568           [](SymbolRef symbol) { return BaseObject{symbol}; },
 569           [](const Substring &sstring) { return sstring.GetBaseObject(); },
 570           [](const auto &x) { return BaseObject{x.GetFirstSymbol()}; },
 571       },
 572       u);
 573 }
 574
 575 template <typename T> const Symbol *Designator<T>::GetLastSymbol() const {
 576   return common::visit(
 577       common::visitors{
 578           [](SymbolRef symbol) { return &*symbol; },
 579           [](const Substring &sstring) { return sstring.GetLastSymbol(); },
 580           [](const auto &x) { return &x.GetLastSymbol(); },
 581       },
 582       u);
 583 }
 584
 585 template <typename T>
 586 std::optional<DynamicType> Designator<T>::GetType() const {
 587   if constexpr (IsLengthlessIntrinsicType<Result>) {
 588     return Result::GetType();
 589   }
 590   if constexpr (Result::category == TypeCategory::Character) {
 591     if (std::holds_alternative<Substring>(u)) {
 592       if (auto len{LEN()}) {
 593         if (auto n{ToInt64(*len)}) {
 594           return DynamicType{T::kind, *n};
 595         }
 596       }
 597       return DynamicType{TypeCategory::Character, T::kind};
 598     }
 599   }
 600   if (const Symbol * symbol{GetLastSymbol()}) {
 601     return DynamicType::From(*symbol);
 602   }
 603   return std::nullopt;
 604 }
 605
 606 static NamedEntity AsNamedEntity(const SymbolVector &x) {
 607   CHECK(!x.empty());
 608   NamedEntity result{x.front()};
 609   int j{0};
 610   for (const Symbol &symbol : x) {
 611     if (j++ != 0) {
 612       DataRef base{result.IsSymbol() ? DataRef{result.GetLastSymbol()}
 613                                      : DataRef{result.GetComponent()}};
 614       result = NamedEntity{Component{std::move(base), symbol}};
 615     }
 616   }
 617   return result;
 618 }
 619
 620 NamedEntity CoarrayRef::GetBase() const { return AsNamedEntity(base_); }
 621
 622 // Equality testing
 623
 624 // For the purposes of comparing type parameter expressions while
 625 // testing the compatibility of procedure characteristics, two
 626 // dummy arguments with the same position are considered equal.
 627 static std::optional<int> GetDummyArgPosition(const Symbol &original) {
 628   const Symbol &symbol(original.GetUltimate());
 629   if (IsDummy(symbol)) {
 630     if (const Symbol * proc{symbol.owner().symbol()}) {
 631       if (const auto *subp{proc->detailsIf<semantics::SubprogramDetails>()}) {
 632         int j{0};
 633         for (const Symbol *arg : subp->dummyArgs()) {
 634           if (arg == &symbol) {
 635             return j;
 636           }
 637           ++j;
 638         }
 639       }
 640     }
 641   }
 642   return std::nullopt;
 643 }
 644
 645 static bool AreSameSymbol(const Symbol &x, const Symbol &y) {
 646   if (&x == &y) {
 647     return true;
 648   }
 649   if (auto xPos{GetDummyArgPosition(x)}) {
 650     if (auto yPos{GetDummyArgPosition(y)}) {
 651       return *xPos == *yPos;
 652     }
 653   }
 654   return false;
 655 }
 656
 657 // Implements operator==() for a union type, using special case handling
 658 // for Symbol references.
 659 template <typename A> static bool TestVariableEquality(const A &x, const A &y) {
 660   const SymbolRef *xSymbol{std::get_if<SymbolRef>(&x.u)};
 661   if (const SymbolRef * ySymbol{std::get_if<SymbolRef>(&y.u)}) {
 662     return xSymbol && AreSameSymbol(*xSymbol, *ySymbol);
 663   } else {
 664     return x.u == y.u;
 665   }
 666 }
 667
 668 bool BaseObject::operator==(const BaseObject &that) const {
 669   return TestVariableEquality(*this, that);
 670 }
 671 bool Component::operator==(const Component &that) const {
 672   return base_ == that.base_ && &*symbol_ == &*that.symbol_;
 673 }
 674 bool NamedEntity::operator==(const NamedEntity &that) const {
 675   if (IsSymbol()) {
 676     return that.IsSymbol() &&
 677         AreSameSymbol(GetFirstSymbol(), that.GetFirstSymbol());
 678   } else {
 679     return !that.IsSymbol() && GetComponent() == that.GetComponent();
 680   }
 681 }
 682 bool TypeParamInquiry::operator==(const TypeParamInquiry &that) const {
 683   return &*parameter_ == &*that.parameter_ && base_ == that.base_;
 684 }
 685 bool Triplet::operator==(const Triplet &that) const {
 686   return lower_ == that.lower_ && upper_ == that.upper_ &&
 687       stride_ == that.stride_;
 688 }
 689 bool Subscript::operator==(const Subscript &that) const { return u == that.u; }
 690 bool ArrayRef::operator==(const ArrayRef &that) const {
 691   return base_ == that.base_ && subscript_ == that.subscript_;
 692 }
 693 bool CoarrayRef::operator==(const CoarrayRef &that) const {
 694   return base_ == that.base_ && subscript_ == that.subscript_ &&
 695       cosubscript_ == that.cosubscript_ && stat_ == that.stat_ &&
 696       team_ == that.team_ && teamIsTeamNumber_ == that.teamIsTeamNumber_;
 697 }
 698 bool DataRef::operator==(const DataRef &that) const {
 699   return TestVariableEquality(*this, that);
 700 }
 701 bool Substring::operator==(const Substring &that) const {
 702   return parent_ == that.parent_ && lower_ == that.lower_ &&
 703       upper_ == that.upper_;
 704 }
 705 bool ComplexPart::operator==(const ComplexPart &that) const {
 706   return part_ == that.part_ && complex_ == that.complex_;
 707 }
 708 bool ProcedureRef::operator==(const ProcedureRef &that) const {
 709   return proc_ == that.proc_ && arguments_ == that.arguments_;
 710 }
 711 template <typename T>
 712 bool Designator<T>::operator==(const Designator<T> &that) const {
 713   return TestVariableEquality(*this, that);
 714 }
 715 bool DescriptorInquiry::operator==(const DescriptorInquiry &that) const {
 716   return field_ == that.field_ && base_ == that.base_ &&
 717       dimension_ == that.dimension_;
 718 }
 719
 720 #ifdef _MSC_VER // disable bogus warning about missing definitions
 721 #pragma warning(disable : 4661)
 722 #endif
 723 INSTANTIATE_VARIABLE_TEMPLATES
 724 } // namespace Fortran::evaluate
 725
 726 template class Fortran::common::Indirection<Fortran::evaluate::Component, true>;