1 //===-- lib/Semantics/resolve-names-utils.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 "resolve-names-utils.h"
10 #include "flang/Common/Fortran-features.h"
11 #include "flang/Common/idioms.h"
12 #include "flang/Common/indirection.h"
13 #include "flang/Evaluate/fold.h"
14 #include "flang/Evaluate/tools.h"
15 #include "flang/Evaluate/type.h"
16 #include "flang/Parser/char-block.h"
17 #include "flang/Parser/parse-tree.h"
18 #include "flang/Semantics/expression.h"
19 #include "flang/Semantics/semantics.h"
20 #include "flang/Semantics/tools.h"
21 #include <initializer_list>
22 #include <variant>
23 
24 namespace Fortran::semantics {
25 
26 using common::LanguageFeature;
27 using common::LogicalOperator;
28 using common::NumericOperator;
29 using common::RelationalOperator;
30 using IntrinsicOperator = parser::DefinedOperator::IntrinsicOperator;
31 
32 static constexpr const char *operatorPrefix{"operator("};
33 
34 static GenericKind MapIntrinsicOperator(IntrinsicOperator);
35 
36 Symbol *Resolve(const parser::Name &name, Symbol *symbol) {
37   if (symbol && !name.symbol) {
38     name.symbol = symbol;
39   }
40   return symbol;
41 }
42 Symbol &Resolve(const parser::Name &name, Symbol &symbol) {
43   return *Resolve(name, &symbol);
44 }
45 
46 parser::MessageFixedText WithIsFatal(
47     const parser::MessageFixedText &msg, bool isFatal) {
48   return parser::MessageFixedText{
49       msg.text().begin(), msg.text().size(), isFatal};
50 }
51 
52 bool IsIntrinsicOperator(
53     const SemanticsContext &context, const SourceName &name) {
54   std::string str{name.ToString()};
55   for (int i{0}; i != common::LogicalOperator_enumSize; ++i) {
56     auto names{context.languageFeatures().GetNames(LogicalOperator{i})};
57     if (std::find(names.begin(), names.end(), str) != names.end()) {
58       return true;
59     }
60   }
61   for (int i{0}; i != common::RelationalOperator_enumSize; ++i) {
62     auto names{context.languageFeatures().GetNames(RelationalOperator{i})};
63     if (std::find(names.begin(), names.end(), str) != names.end()) {
64       return true;
65     }
66   }
67   return false;
68 }
69 
70 template <typename E>
71 std::forward_list<std::string> GetOperatorNames(
72     const SemanticsContext &context, E opr) {
73   std::forward_list<std::string> result;
74   for (const char *name : context.languageFeatures().GetNames(opr)) {
75     result.emplace_front(std::string{operatorPrefix} + name + ')');
76   }
77   return result;
78 }
79 
80 std::forward_list<std::string> GetAllNames(
81     const SemanticsContext &context, const SourceName &name) {
82   std::string str{name.ToString()};
83   if (!name.empty() && name.end()[-1] == ')' &&
84       name.ToString().rfind(std::string{operatorPrefix}, 0) == 0) {
85     for (int i{0}; i != common::LogicalOperator_enumSize; ++i) {
86       auto names{GetOperatorNames(context, LogicalOperator{i})};
87       if (std::find(names.begin(), names.end(), str) != names.end()) {
88         return names;
89       }
90     }
91     for (int i{0}; i != common::RelationalOperator_enumSize; ++i) {
92       auto names{GetOperatorNames(context, RelationalOperator{i})};
93       if (std::find(names.begin(), names.end(), str) != names.end()) {
94         return names;
95       }
96     }
97   }
98   return {str};
99 }
100 
101 bool IsLogicalConstant(
102     const SemanticsContext &context, const SourceName &name) {
103   std::string str{name.ToString()};
104   return str == ".true." || str == ".false." ||
105       (context.IsEnabled(LanguageFeature::LogicalAbbreviations) &&
106           (str == ".t" || str == ".f."));
107 }
108 
109 void GenericSpecInfo::Resolve(Symbol *symbol) const {
110   if (symbol) {
111     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
112       details->set_kind(kind_);
113     }
114     if (parseName_) {
115       semantics::Resolve(*parseName_, symbol);
116     }
117   }
118 }
119 
120 void GenericSpecInfo::Analyze(const parser::DefinedOpName &name) {
121   kind_ = GenericKind::OtherKind::DefinedOp;
122   parseName_ = &name.v;
123   symbolName_ = name.v.source;
124 }
125 
126 void GenericSpecInfo::Analyze(const parser::GenericSpec &x) {
127   symbolName_ = x.source;
128   kind_ = std::visit(
129       common::visitors{
130           [&](const parser::Name &y) -> GenericKind {
131             parseName_ = &y;
132             symbolName_ = y.source;
133             return GenericKind::OtherKind::Name;
134           },
135           [&](const parser::DefinedOperator &y) {
136             return std::visit(
137                 common::visitors{
138                     [&](const parser::DefinedOpName &z) -> GenericKind {
139                       Analyze(z);
140                       return GenericKind::OtherKind::DefinedOp;
141                     },
142                     [&](const IntrinsicOperator &z) {
143                       return MapIntrinsicOperator(z);
144                     },
145                 },
146                 y.u);
147           },
148           [&](const parser::GenericSpec::Assignment &) -> GenericKind {
149             return GenericKind::OtherKind::Assignment;
150           },
151           [&](const parser::GenericSpec::ReadFormatted &) -> GenericKind {
152             return GenericKind::DefinedIo::ReadFormatted;
153           },
154           [&](const parser::GenericSpec::ReadUnformatted &) -> GenericKind {
155             return GenericKind::DefinedIo::ReadUnformatted;
156           },
157           [&](const parser::GenericSpec::WriteFormatted &) -> GenericKind {
158             return GenericKind::DefinedIo::WriteFormatted;
159           },
160           [&](const parser::GenericSpec::WriteUnformatted &) -> GenericKind {
161             return GenericKind::DefinedIo::WriteUnformatted;
162           },
163       },
164       x.u);
165 }
166 
167 llvm::raw_ostream &operator<<(
168     llvm::raw_ostream &os, const GenericSpecInfo &info) {
169   os << "GenericSpecInfo: kind=" << info.kind_.ToString();
170   os << " parseName="
171      << (info.parseName_ ? info.parseName_->ToString() : "null");
172   os << " symbolName="
173      << (info.symbolName_ ? info.symbolName_->ToString() : "null");
174   return os;
175 }
176 
177 // parser::DefinedOperator::IntrinsicOperator -> GenericKind
178 static GenericKind MapIntrinsicOperator(IntrinsicOperator op) {
179   switch (op) {
180     SWITCH_COVERS_ALL_CASES
181   case IntrinsicOperator::Concat:
182     return GenericKind::OtherKind::Concat;
183   case IntrinsicOperator::Power:
184     return NumericOperator::Power;
185   case IntrinsicOperator::Multiply:
186     return NumericOperator::Multiply;
187   case IntrinsicOperator::Divide:
188     return NumericOperator::Divide;
189   case IntrinsicOperator::Add:
190     return NumericOperator::Add;
191   case IntrinsicOperator::Subtract:
192     return NumericOperator::Subtract;
193   case IntrinsicOperator::AND:
194     return LogicalOperator::And;
195   case IntrinsicOperator::OR:
196     return LogicalOperator::Or;
197   case IntrinsicOperator::EQV:
198     return LogicalOperator::Eqv;
199   case IntrinsicOperator::NEQV:
200     return LogicalOperator::Neqv;
201   case IntrinsicOperator::NOT:
202     return LogicalOperator::Not;
203   case IntrinsicOperator::LT:
204     return RelationalOperator::LT;
205   case IntrinsicOperator::LE:
206     return RelationalOperator::LE;
207   case IntrinsicOperator::EQ:
208     return RelationalOperator::EQ;
209   case IntrinsicOperator::NE:
210     return RelationalOperator::NE;
211   case IntrinsicOperator::GE:
212     return RelationalOperator::GE;
213   case IntrinsicOperator::GT:
214     return RelationalOperator::GT;
215   }
216 }
217 
218 class ArraySpecAnalyzer {
219 public:
220   ArraySpecAnalyzer(SemanticsContext &context) : context_{context} {}
221   ArraySpec Analyze(const parser::ArraySpec &);
222   ArraySpec Analyze(const parser::ComponentArraySpec &);
223   ArraySpec Analyze(const parser::CoarraySpec &);
224 
225 private:
226   SemanticsContext &context_;
227   ArraySpec arraySpec_;
228 
229   template <typename T> void Analyze(const std::list<T> &list) {
230     for (const auto &elem : list) {
231       Analyze(elem);
232     }
233   }
234   void Analyze(const parser::AssumedShapeSpec &);
235   void Analyze(const parser::ExplicitShapeSpec &);
236   void Analyze(const parser::AssumedImpliedSpec &);
237   void Analyze(const parser::DeferredShapeSpecList &);
238   void Analyze(const parser::AssumedRankSpec &);
239   void MakeExplicit(const std::optional<parser::SpecificationExpr> &,
240       const parser::SpecificationExpr &);
241   void MakeImplied(const std::optional<parser::SpecificationExpr> &);
242   void MakeDeferred(int);
243   Bound GetBound(const std::optional<parser::SpecificationExpr> &);
244   Bound GetBound(const parser::SpecificationExpr &);
245 };
246 
247 ArraySpec AnalyzeArraySpec(
248     SemanticsContext &context, const parser::ArraySpec &arraySpec) {
249   return ArraySpecAnalyzer{context}.Analyze(arraySpec);
250 }
251 ArraySpec AnalyzeArraySpec(
252     SemanticsContext &context, const parser::ComponentArraySpec &arraySpec) {
253   return ArraySpecAnalyzer{context}.Analyze(arraySpec);
254 }
255 ArraySpec AnalyzeCoarraySpec(
256     SemanticsContext &context, const parser::CoarraySpec &coarraySpec) {
257   return ArraySpecAnalyzer{context}.Analyze(coarraySpec);
258 }
259 
260 ArraySpec ArraySpecAnalyzer::Analyze(const parser::ComponentArraySpec &x) {
261   std::visit([this](const auto &y) { Analyze(y); }, x.u);
262   CHECK(!arraySpec_.empty());
263   return arraySpec_;
264 }
265 ArraySpec ArraySpecAnalyzer::Analyze(const parser::ArraySpec &x) {
266   std::visit(common::visitors{
267                  [&](const parser::AssumedSizeSpec &y) {
268                    Analyze(std::get<std::list<parser::ExplicitShapeSpec>>(y.t));
269                    Analyze(std::get<parser::AssumedImpliedSpec>(y.t));
270                  },
271                  [&](const parser::ImpliedShapeSpec &y) { Analyze(y.v); },
272                  [&](const auto &y) { Analyze(y); },
273              },
274       x.u);
275   CHECK(!arraySpec_.empty());
276   return arraySpec_;
277 }
278 ArraySpec ArraySpecAnalyzer::Analyze(const parser::CoarraySpec &x) {
279   std::visit(
280       common::visitors{
281           [&](const parser::DeferredCoshapeSpecList &y) { MakeDeferred(y.v); },
282           [&](const parser::ExplicitCoshapeSpec &y) {
283             Analyze(std::get<std::list<parser::ExplicitShapeSpec>>(y.t));
284             MakeImplied(
285                 std::get<std::optional<parser::SpecificationExpr>>(y.t));
286           },
287       },
288       x.u);
289   CHECK(!arraySpec_.empty());
290   return arraySpec_;
291 }
292 
293 void ArraySpecAnalyzer::Analyze(const parser::AssumedShapeSpec &x) {
294   arraySpec_.push_back(ShapeSpec::MakeAssumed(GetBound(x.v)));
295 }
296 void ArraySpecAnalyzer::Analyze(const parser::ExplicitShapeSpec &x) {
297   MakeExplicit(std::get<std::optional<parser::SpecificationExpr>>(x.t),
298       std::get<parser::SpecificationExpr>(x.t));
299 }
300 void ArraySpecAnalyzer::Analyze(const parser::AssumedImpliedSpec &x) {
301   MakeImplied(x.v);
302 }
303 void ArraySpecAnalyzer::Analyze(const parser::DeferredShapeSpecList &x) {
304   MakeDeferred(x.v);
305 }
306 void ArraySpecAnalyzer::Analyze(const parser::AssumedRankSpec &) {
307   arraySpec_.push_back(ShapeSpec::MakeAssumedRank());
308 }
309 
310 void ArraySpecAnalyzer::MakeExplicit(
311     const std::optional<parser::SpecificationExpr> &lb,
312     const parser::SpecificationExpr &ub) {
313   arraySpec_.push_back(ShapeSpec::MakeExplicit(GetBound(lb), GetBound(ub)));
314 }
315 void ArraySpecAnalyzer::MakeImplied(
316     const std::optional<parser::SpecificationExpr> &lb) {
317   arraySpec_.push_back(ShapeSpec::MakeImplied(GetBound(lb)));
318 }
319 void ArraySpecAnalyzer::MakeDeferred(int n) {
320   for (int i = 0; i < n; ++i) {
321     arraySpec_.push_back(ShapeSpec::MakeDeferred());
322   }
323 }
324 
325 Bound ArraySpecAnalyzer::GetBound(
326     const std::optional<parser::SpecificationExpr> &x) {
327   return x ? GetBound(*x) : Bound{1};
328 }
329 Bound ArraySpecAnalyzer::GetBound(const parser::SpecificationExpr &x) {
330   MaybeSubscriptIntExpr expr;
331   if (MaybeExpr maybeExpr{AnalyzeExpr(context_, x.v)}) {
332     if (auto *intExpr{evaluate::UnwrapExpr<SomeIntExpr>(*maybeExpr)}) {
333       expr = evaluate::Fold(context_.foldingContext(),
334           evaluate::ConvertToType<evaluate::SubscriptInteger>(
335               std::move(*intExpr)));
336     }
337   }
338   return Bound{std::move(expr)};
339 }
340 
341 // If SAVE is set on src, set it on all members of dst
342 static void PropagateSaveAttr(
343     const EquivalenceObject &src, EquivalenceSet &dst) {
344   if (src.symbol.attrs().test(Attr::SAVE)) {
345     for (auto &obj : dst) {
346       obj.symbol.attrs().set(Attr::SAVE);
347     }
348   }
349 }
350 static void PropagateSaveAttr(const EquivalenceSet &src, EquivalenceSet &dst) {
351   if (!src.empty()) {
352     PropagateSaveAttr(src.front(), dst);
353   }
354 }
355 
356 void EquivalenceSets::AddToSet(const parser::Designator &designator) {
357   if (CheckDesignator(designator)) {
358     Symbol &symbol{*currObject_.symbol};
359     if (!currSet_.empty()) {
360       // check this symbol against first of set for compatibility
361       Symbol &first{currSet_.front().symbol};
362       CheckCanEquivalence(designator.source, first, symbol) &&
363           CheckCanEquivalence(designator.source, symbol, first);
364     }
365     auto subscripts{currObject_.subscripts};
366     if (subscripts.empty() && symbol.IsObjectArray()) {
367       // record a whole array as its first element
368       for (const ShapeSpec &spec : symbol.get<ObjectEntityDetails>().shape()) {
369         auto &lbound{spec.lbound().GetExplicit().value()};
370         subscripts.push_back(evaluate::ToInt64(lbound).value());
371       }
372     }
373     auto substringStart{currObject_.substringStart};
374     currSet_.emplace_back(
375         symbol, subscripts, substringStart, designator.source);
376     PropagateSaveAttr(currSet_.back(), currSet_);
377   }
378   currObject_ = {};
379 }
380 
381 void EquivalenceSets::FinishSet(const parser::CharBlock &source) {
382   std::set<std::size_t> existing; // indices of sets intersecting this one
383   for (auto &obj : currSet_) {
384     auto it{objectToSet_.find(obj)};
385     if (it != objectToSet_.end()) {
386       existing.insert(it->second); // symbol already in this set
387     }
388   }
389   if (existing.empty()) {
390     sets_.push_back({}); // create a new equivalence set
391     MergeInto(source, currSet_, sets_.size() - 1);
392   } else {
393     auto it{existing.begin()};
394     std::size_t dstIndex{*it};
395     MergeInto(source, currSet_, dstIndex);
396     while (++it != existing.end()) {
397       MergeInto(source, sets_[*it], dstIndex);
398     }
399   }
400   currSet_.clear();
401 }
402 
403 // Report an error if sym1 and sym2 cannot be in the same equivalence set.
404 bool EquivalenceSets::CheckCanEquivalence(
405     const parser::CharBlock &source, const Symbol &sym1, const Symbol &sym2) {
406   std::optional<parser::MessageFixedText> msg;
407   const DeclTypeSpec *type1{sym1.GetType()};
408   const DeclTypeSpec *type2{sym2.GetType()};
409   bool isNum1{IsNumericSequenceType(type1)};
410   bool isNum2{IsNumericSequenceType(type2)};
411   bool isChar1{IsCharacterSequenceType(type1)};
412   bool isChar2{IsCharacterSequenceType(type2)};
413   if (sym1.attrs().test(Attr::PROTECTED) &&
414       !sym2.attrs().test(Attr::PROTECTED)) { // C8114
415     msg = "Equivalence set cannot contain '%s'"
416           " with PROTECTED attribute and '%s' without"_err_en_US;
417   } else if (isNum1) {
418     if (isChar2) {
419       if (context_.ShouldWarn(
420               LanguageFeature::EquivalenceNumericWithCharacter)) {
421         msg = "Equivalence set contains '%s' that is numeric sequence "
422               "type and '%s' that is character"_en_US;
423       }
424     } else if (!isNum2) { // C8110
425       msg = "Equivalence set cannot contain '%s'"
426             " that is numeric sequence type and '%s' that is not"_err_en_US;
427     }
428   } else if (isChar1) {
429     if (isNum2) {
430       if (context_.ShouldWarn(
431               LanguageFeature::EquivalenceNumericWithCharacter)) {
432         msg = "Equivalence set contains '%s' that is character sequence "
433               "type and '%s' that is numeric"_en_US;
434       }
435     } else if (!isChar2) { // C8111
436       msg = "Equivalence set cannot contain '%s'"
437             " that is character sequence type and '%s' that is not"_err_en_US;
438     }
439   } else if (!isNum2 && !isChar2 && *type1 != *type2) { // C8112, C8113
440     msg = "Equivalence set cannot contain '%s' and '%s' with different types"
441           " that are neither numeric nor character sequence types"_err_en_US;
442   }
443   if (msg) {
444     context_.Say(source, std::move(*msg), sym1.name(), sym2.name());
445     return false;
446   }
447   return true;
448 }
449 
450 // Move objects from src to sets_[dstIndex]
451 void EquivalenceSets::MergeInto(const parser::CharBlock &source,
452     EquivalenceSet &src, std::size_t dstIndex) {
453   EquivalenceSet &dst{sets_[dstIndex]};
454   PropagateSaveAttr(dst, src);
455   for (const auto &obj : src) {
456     dst.push_back(obj);
457     objectToSet_[obj] = dstIndex;
458   }
459   PropagateSaveAttr(src, dst);
460   src.clear();
461 }
462 
463 // If set has an object with this symbol, return it.
464 const EquivalenceObject *EquivalenceSets::Find(
465     const EquivalenceSet &set, const Symbol &symbol) {
466   for (const auto &obj : set) {
467     if (obj.symbol == symbol) {
468       return &obj;
469     }
470   }
471   return nullptr;
472 }
473 
474 bool EquivalenceSets::CheckDesignator(const parser::Designator &designator) {
475   return std::visit(
476       common::visitors{
477           [&](const parser::DataRef &x) {
478             return CheckDataRef(designator.source, x);
479           },
480           [&](const parser::Substring &x) {
481             const auto &dataRef{std::get<parser::DataRef>(x.t)};
482             const auto &range{std::get<parser::SubstringRange>(x.t)};
483             bool ok{CheckDataRef(designator.source, dataRef)};
484             if (const auto &lb{std::get<0>(range.t)}) {
485               ok &= CheckSubstringBound(lb->thing.thing.value(), true);
486             } else {
487               currObject_.substringStart = 1;
488             }
489             if (const auto &ub{std::get<1>(range.t)}) {
490               ok &= CheckSubstringBound(ub->thing.thing.value(), false);
491             }
492             return ok;
493           },
494       },
495       designator.u);
496 }
497 
498 bool EquivalenceSets::CheckDataRef(
499     const parser::CharBlock &source, const parser::DataRef &x) {
500   return std::visit(
501       common::visitors{
502           [&](const parser::Name &name) { return CheckObject(name); },
503           [&](const common::Indirection<parser::StructureComponent> &) {
504             context_.Say(source, // C8107
505                 "Derived type component '%s' is not allowed in an equivalence set"_err_en_US,
506                 source);
507             return false;
508           },
509           [&](const common::Indirection<parser::ArrayElement> &elem) {
510             bool ok{CheckDataRef(source, elem.value().base)};
511             for (const auto &subscript : elem.value().subscripts) {
512               ok &= std::visit(
513                   common::visitors{
514                       [&](const parser::SubscriptTriplet &) {
515                         context_.Say(source, // C924, R872
516                             "Array section '%s' is not allowed in an equivalence set"_err_en_US,
517                             source);
518                         return false;
519                       },
520                       [&](const parser::IntExpr &y) {
521                         return CheckArrayBound(y.thing.value());
522                       },
523                   },
524                   subscript.u);
525             }
526             return ok;
527           },
528           [&](const common::Indirection<parser::CoindexedNamedObject> &) {
529             context_.Say(source, // C924 (R872)
530                 "Coindexed object '%s' is not allowed in an equivalence set"_err_en_US,
531                 source);
532             return false;
533           },
534       },
535       x.u);
536 }
537 
538 static bool InCommonWithBind(const Symbol &symbol) {
539   if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
540     const Symbol *commonBlock{details->commonBlock()};
541     return commonBlock && commonBlock->attrs().test(Attr::BIND_C);
542   } else {
543     return false;
544   }
545 }
546 
547 // If symbol can't be in equivalence set report error and return false;
548 bool EquivalenceSets::CheckObject(const parser::Name &name) {
549   if (!name.symbol) {
550     return false; // an error has already occurred
551   }
552   currObject_.symbol = name.symbol;
553   parser::MessageFixedText msg{"", 0};
554   const Symbol &symbol{*name.symbol};
555   if (symbol.owner().IsDerivedType()) { // C8107
556     msg = "Derived type component '%s'"
557           " is not allowed in an equivalence set"_err_en_US;
558   } else if (IsDummy(symbol)) { // C8106
559     msg = "Dummy argument '%s' is not allowed in an equivalence set"_err_en_US;
560   } else if (symbol.IsFuncResult()) { // C8106
561     msg = "Function result '%s' is not allow in an equivalence set"_err_en_US;
562   } else if (IsPointer(symbol)) { // C8106
563     msg = "Pointer '%s' is not allowed in an equivalence set"_err_en_US;
564   } else if (IsAllocatable(symbol)) { // C8106
565     msg = "Allocatable variable '%s'"
566           " is not allowed in an equivalence set"_err_en_US;
567   } else if (symbol.Corank() > 0) { // C8106
568     msg = "Coarray '%s' is not allowed in an equivalence set"_err_en_US;
569   } else if (symbol.has<UseDetails>()) { // C8115
570     msg = "Use-associated variable '%s'"
571           " is not allowed in an equivalence set"_err_en_US;
572   } else if (symbol.attrs().test(Attr::BIND_C)) { // C8106
573     msg = "Variable '%s' with BIND attribute"
574           " is not allowed in an equivalence set"_err_en_US;
575   } else if (symbol.attrs().test(Attr::TARGET)) { // C8108
576     msg = "Variable '%s' with TARGET attribute"
577           " is not allowed in an equivalence set"_err_en_US;
578   } else if (IsNamedConstant(symbol)) { // C8106
579     msg = "Named constant '%s' is not allowed in an equivalence set"_err_en_US;
580   } else if (InCommonWithBind(symbol)) { // C8106
581     msg = "Variable '%s' in common block with BIND attribute"
582           " is not allowed in an equivalence set"_err_en_US;
583   } else if (const auto *type{symbol.GetType()}) {
584     if (const auto *derived{type->AsDerived()}) {
585       if (const auto *comp{FindUltimateComponent(
586               *derived, IsAllocatableOrPointer)}) { // C8106
587         msg = IsPointer(*comp)
588             ? "Derived type object '%s' with pointer ultimate component"
589               " is not allowed in an equivalence set"_err_en_US
590             : "Derived type object '%s' with allocatable ultimate component"
591               " is not allowed in an equivalence set"_err_en_US;
592       } else if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
593         msg = "Nonsequence derived type object '%s'"
594               " is not allowed in an equivalence set"_err_en_US;
595       }
596     } else if (IsAutomaticObject(symbol)) {
597       msg = "Automatic object '%s'"
598             " is not allowed in an equivalence set"_err_en_US;
599     }
600   }
601   if (!msg.text().empty()) {
602     context_.Say(name.source, std::move(msg), name.source);
603     return false;
604   }
605   return true;
606 }
607 
608 bool EquivalenceSets::CheckArrayBound(const parser::Expr &bound) {
609   MaybeExpr expr{
610       evaluate::Fold(context_.foldingContext(), AnalyzeExpr(context_, bound))};
611   if (!expr) {
612     return false;
613   }
614   if (expr->Rank() > 0) {
615     context_.Say(bound.source, // C924, R872
616         "Array with vector subscript '%s' is not allowed in an equivalence set"_err_en_US,
617         bound.source);
618     return false;
619   }
620   auto subscript{evaluate::ToInt64(*expr)};
621   if (!subscript) {
622     context_.Say(bound.source, // C8109
623         "Array with nonconstant subscript '%s' is not allowed in an equivalence set"_err_en_US,
624         bound.source);
625     return false;
626   }
627   currObject_.subscripts.push_back(*subscript);
628   return true;
629 }
630 
631 bool EquivalenceSets::CheckSubstringBound(
632     const parser::Expr &bound, bool isStart) {
633   MaybeExpr expr{
634       evaluate::Fold(context_.foldingContext(), AnalyzeExpr(context_, bound))};
635   if (!expr) {
636     return false;
637   }
638   auto subscript{evaluate::ToInt64(*expr)};
639   if (!subscript) {
640     context_.Say(bound.source, // C8109
641         "Substring with nonconstant bound '%s' is not allowed in an equivalence set"_err_en_US,
642         bound.source);
643     return false;
644   }
645   if (!isStart) {
646     auto start{currObject_.substringStart};
647     if (*subscript < (start ? *start : 1)) {
648       context_.Say(bound.source, // C8116
649           "Substring with zero length is not allowed in an equivalence set"_err_en_US);
650       return false;
651     }
652   } else if (*subscript != 1) {
653     currObject_.substringStart = *subscript;
654   }
655   return true;
656 }
657 
658 bool EquivalenceSets::IsCharacterSequenceType(const DeclTypeSpec *type) {
659   return IsSequenceType(type, [&](const IntrinsicTypeSpec &type) {
660     auto kind{evaluate::ToInt64(type.kind())};
661     return type.category() == TypeCategory::Character && kind &&
662         kind.value() == context_.GetDefaultKind(TypeCategory::Character);
663   });
664 }
665 
666 // Numeric or logical type of default kind or DOUBLE PRECISION or DOUBLE COMPLEX
667 bool EquivalenceSets::IsDefaultKindNumericType(const IntrinsicTypeSpec &type) {
668   if (auto kind{evaluate::ToInt64(type.kind())}) {
669     auto category{type.category()};
670     auto defaultKind{context_.GetDefaultKind(category)};
671     switch (category) {
672     case TypeCategory::Integer:
673     case TypeCategory::Logical:
674       return *kind == defaultKind;
675     case TypeCategory::Real:
676     case TypeCategory::Complex:
677       return *kind == defaultKind || *kind == context_.doublePrecisionKind();
678     default:
679       return false;
680     }
681   }
682   return false;
683 }
684 
685 bool EquivalenceSets::IsNumericSequenceType(const DeclTypeSpec *type) {
686   return IsSequenceType(type, [&](const IntrinsicTypeSpec &type) {
687     return IsDefaultKindNumericType(type);
688   });
689 }
690 
691 // Is type an intrinsic type that satisfies predicate or a sequence type
692 // whose components do.
693 bool EquivalenceSets::IsSequenceType(const DeclTypeSpec *type,
694     std::function<bool(const IntrinsicTypeSpec &)> predicate) {
695   if (!type) {
696     return false;
697   } else if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
698     return predicate(*intrinsic);
699   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
700     for (const auto &pair : *derived->typeSymbol().scope()) {
701       const Symbol &component{*pair.second};
702       if (IsAllocatableOrPointer(component) ||
703           !IsSequenceType(component.GetType(), predicate)) {
704         return false;
705       }
706     }
707     return true;
708   } else {
709     return false;
710   }
711 }
712 
713 } // namespace Fortran::semantics
714