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