xref: /llvm-project/flang/lib/Evaluate/type.cpp (revision ef934174704b75c8e04830bfd4f0c0bbedde9621) 
1 //===-- lib/Evaluate/type.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/type.h"
10 #include "flang/Common/idioms.h"
11 #include "flang/Evaluate/expression.h"
12 #include "flang/Evaluate/fold.h"
13 #include "flang/Evaluate/target.h"
14 #include "flang/Parser/characters.h"
15 #include "flang/Semantics/scope.h"
16 #include "flang/Semantics/symbol.h"
17 #include "flang/Semantics/tools.h"
18 #include "flang/Semantics/type.h"
19 #include <algorithm>
20 #include <optional>
21 #include <string>
22 
23 // IsDescriptor() predicate: true when a symbol is implemented
24 // at runtime with a descriptor.
25 namespace Fortran::semantics {
26 
27 static bool IsDescriptor(const DeclTypeSpec *type) {
28   if (type) {
29     if (auto dynamicType{evaluate::DynamicType::From(*type)}) {
30       return dynamicType->RequiresDescriptor();
31     }
32   }
33   return false;
34 }
35 
36 static bool IsDescriptor(const ObjectEntityDetails &details) {
37   if (IsDescriptor(details.type())) {
38     return true;
39   }
40   for (const ShapeSpec &shapeSpec : details.shape()) {
41     const auto &lb{shapeSpec.lbound().GetExplicit()};
42     const auto &ub{shapeSpec.ubound().GetExplicit()};
43     if (!lb || !ub || !IsConstantExpr(*lb) || !IsConstantExpr(*ub)) {
44       return true;
45     }
46   }
47   return false;
48 }
49 
50 bool IsDescriptor(const Symbol &symbol) {
51   return common::visit(
52       common::visitors{
53           [&](const ObjectEntityDetails &d) {
54             return IsAllocatableOrPointer(symbol) || IsDescriptor(d);
55           },
56           [&](const ProcEntityDetails &d) { return false; },
57           [&](const EntityDetails &d) { return IsDescriptor(d.type()); },
58           [](const AssocEntityDetails &d) {
59             if (const auto &expr{d.expr()}) {
60               if (expr->Rank() > 0) {
61                 return true;
62               }
63               if (const auto dynamicType{expr->GetType()}) {
64                 if (dynamicType->RequiresDescriptor()) {
65                   return true;
66                 }
67               }
68             }
69             return false;
70           },
71           [](const SubprogramDetails &d) {
72             return d.isFunction() && IsDescriptor(d.result());
73           },
74           [](const UseDetails &d) { return IsDescriptor(d.symbol()); },
75           [](const HostAssocDetails &d) { return IsDescriptor(d.symbol()); },
76           [](const auto &) { return false; },
77       },
78       symbol.details());
79 }
80 
81 bool IsPassedViaDescriptor(const Symbol &symbol) {
82   if (!IsDescriptor(symbol)) {
83     return false;
84   }
85   if (IsAllocatableOrPointer(symbol)) {
86     return true;
87   }
88   if (const auto *object{
89           symbol.GetUltimate().detailsIf<ObjectEntityDetails>()}) {
90     if (object->isDummy()) {
91       if (object->type() &&
92           object->type()->category() == DeclTypeSpec::Character) {
93         return false;
94       }
95       if (object->IsAssumedSize()) {
96         return false;
97       }
98       bool isExplicitShape{true};
99       for (const ShapeSpec &shapeSpec : object->shape()) {
100         if (!shapeSpec.lbound().GetExplicit() ||
101             !shapeSpec.ubound().GetExplicit()) {
102           isExplicitShape = false;
103           break;
104         }
105       }
106       if (isExplicitShape) {
107         return false; // explicit shape but non-constant bounds
108       }
109     }
110   }
111   return true;
112 }
113 } // namespace Fortran::semantics
114 
115 namespace Fortran::evaluate {
116 
117 DynamicType::DynamicType(int k, const semantics::ParamValue &pv)
118     : category_{TypeCategory::Character}, kind_{k} {
119   CHECK(IsValidKindOfIntrinsicType(category_, kind_));
120   if (auto n{ToInt64(pv.GetExplicit())}) {
121     knownLength_ = *n > 0 ? *n : 0;
122   } else {
123     charLengthParamValue_ = &pv;
124   }
125 }
126 
127 template <typename A> inline bool PointeeComparison(const A *x, const A *y) {
128   return x == y || (x && y && *x == *y);
129 }
130 
131 bool DynamicType::operator==(const DynamicType &that) const {
132   return category_ == that.category_ && kind_ == that.kind_ &&
133       PointeeComparison(charLengthParamValue_, that.charLengthParamValue_) &&
134       knownLength().has_value() == that.knownLength().has_value() &&
135       (!knownLength() || *knownLength() == *that.knownLength()) &&
136       PointeeComparison(derived_, that.derived_);
137 }
138 
139 std::optional<Expr<SubscriptInteger>> DynamicType::GetCharLength() const {
140   if (category_ == TypeCategory::Character) {
141     if (knownLength()) {
142       return AsExpr(Constant<SubscriptInteger>(*knownLength()));
143     } else if (charLengthParamValue_) {
144       if (auto length{charLengthParamValue_->GetExplicit()}) {
145         return ConvertToType<SubscriptInteger>(std::move(*length));
146       }
147     }
148   }
149   return std::nullopt;
150 }
151 
152 std::size_t DynamicType::GetAlignment(
153     const TargetCharacteristics &targetCharacteristics) const {
154   if (category_ == TypeCategory::Derived) {
155     switch (GetDerivedTypeSpec().category()) {
156       SWITCH_COVERS_ALL_CASES
157     case semantics::DerivedTypeSpec::Category::DerivedType:
158       if (derived_ && derived_->scope()) {
159         return derived_->scope()->alignment().value_or(1);
160       }
161       break;
162     case semantics::DerivedTypeSpec::Category::IntrinsicVector:
163     case semantics::DerivedTypeSpec::Category::PairVector:
164     case semantics::DerivedTypeSpec::Category::QuadVector:
165       if (derived_ && derived_->scope()) {
166         return derived_->scope()->size();
167       } else {
168         common::die("Missing scope for Vector type.");
169       }
170     }
171   } else {
172     return targetCharacteristics.GetAlignment(category_, kind_);
173   }
174   return 1; // needs to be after switch to dodge a bogus gcc warning
175 }
176 
177 std::optional<Expr<SubscriptInteger>> DynamicType::MeasureSizeInBytes(
178     FoldingContext &context, bool aligned,
179     std::optional<std::int64_t> charLength) const {
180   switch (category_) {
181   case TypeCategory::Integer:
182   case TypeCategory::Real:
183   case TypeCategory::Complex:
184   case TypeCategory::Logical:
185     return Expr<SubscriptInteger>{
186         context.targetCharacteristics().GetByteSize(category_, kind_)};
187   case TypeCategory::Character:
188     if (auto len{charLength ? Expr<SubscriptInteger>{Constant<SubscriptInteger>{
189                                   *charLength}}
190                             : GetCharLength()}) {
191       return Fold(context,
192           Expr<SubscriptInteger>{
193               context.targetCharacteristics().GetByteSize(category_, kind_)} *
194               std::move(*len));
195     }
196     break;
197   case TypeCategory::Derived:
198     if (!IsPolymorphic() && derived_ && derived_->scope()) {
199       auto size{derived_->scope()->size()};
200       auto align{aligned ? derived_->scope()->alignment().value_or(0) : 0};
201       auto alignedSize{align > 0 ? ((size + align - 1) / align) * align : size};
202       return Expr<SubscriptInteger>{
203           static_cast<ConstantSubscript>(alignedSize)};
204     }
205     break;
206   }
207   return std::nullopt;
208 }
209 
210 bool DynamicType::IsAssumedLengthCharacter() const {
211   return category_ == TypeCategory::Character && charLengthParamValue_ &&
212       charLengthParamValue_->isAssumed();
213 }
214 
215 bool DynamicType::IsNonConstantLengthCharacter() const {
216   if (category_ != TypeCategory::Character) {
217     return false;
218   } else if (knownLength()) {
219     return false;
220   } else if (!charLengthParamValue_) {
221     return true;
222   } else if (const auto &expr{charLengthParamValue_->GetExplicit()}) {
223     return !IsConstantExpr(*expr);
224   } else {
225     return true;
226   }
227 }
228 
229 bool DynamicType::IsTypelessIntrinsicArgument() const {
230   return category_ == TypeCategory::Integer && kind_ == TypelessKind;
231 }
232 
233 const semantics::DerivedTypeSpec *GetDerivedTypeSpec(
234     const std::optional<DynamicType> &type) {
235   return type ? GetDerivedTypeSpec(*type) : nullptr;
236 }
237 
238 const semantics::DerivedTypeSpec *GetDerivedTypeSpec(const DynamicType &type) {
239   if (type.category() == TypeCategory::Derived &&
240       !type.IsUnlimitedPolymorphic()) {
241     return &type.GetDerivedTypeSpec();
242   } else {
243     return nullptr;
244   }
245 }
246 
247 static const semantics::Symbol *FindParentComponent(
248     const semantics::DerivedTypeSpec &derived) {
249   const semantics::Symbol &typeSymbol{derived.typeSymbol()};
250   const semantics::Scope *scope{derived.scope()};
251   if (!scope) {
252     scope = typeSymbol.scope();
253   }
254   if (scope) {
255     const auto &dtDetails{typeSymbol.get<semantics::DerivedTypeDetails>()};
256     // TODO: Combine with semantics::DerivedTypeDetails::GetParentComponent
257     if (auto extends{dtDetails.GetParentComponentName()}) {
258       if (auto iter{scope->find(*extends)}; iter != scope->cend()) {
259         if (const semantics::Symbol & symbol{*iter->second};
260             symbol.test(semantics::Symbol::Flag::ParentComp)) {
261           return &symbol;
262         }
263       }
264     }
265   }
266   return nullptr;
267 }
268 
269 const semantics::DerivedTypeSpec *GetParentTypeSpec(
270     const semantics::DerivedTypeSpec &derived) {
271   if (const semantics::Symbol * parent{FindParentComponent(derived)}) {
272     return &parent->get<semantics::ObjectEntityDetails>()
273                 .type()
274                 ->derivedTypeSpec();
275   } else {
276     return nullptr;
277   }
278 }
279 
280 // Compares two derived type representations to see whether they both
281 // represent the "same type" in the sense of section 7.5.2.4.
282 using SetOfDerivedTypePairs =
283     std::set<std::pair<const semantics::DerivedTypeSpec *,
284         const semantics::DerivedTypeSpec *>>;
285 
286 static bool AreSameComponent(const semantics::Symbol &x,
287     const semantics::Symbol &y,
288     SetOfDerivedTypePairs & /* inProgress - not yet used */) {
289   if (x.attrs() != y.attrs()) {
290     return false;
291   }
292   if (x.attrs().test(semantics::Attr::PRIVATE)) {
293     return false;
294   }
295   // TODO: compare types, parameters, bounds, &c.
296   return x.has<semantics::ObjectEntityDetails>() ==
297       y.has<semantics::ObjectEntityDetails>();
298 }
299 
300 // TODO: These utilities were cloned out of Semantics to avoid a cyclic
301 // dependency and should be repackaged into then "namespace semantics"
302 // part of Evaluate/tools.cpp.
303 
304 static const semantics::Symbol *GetParentComponent(
305     const semantics::DerivedTypeDetails &details,
306     const semantics::Scope &scope) {
307   if (auto extends{details.GetParentComponentName()}) {
308     if (auto iter{scope.find(*extends)}; iter != scope.cend()) {
309       if (const Symbol & symbol{*iter->second};
310           symbol.test(semantics::Symbol::Flag::ParentComp)) {
311         return &symbol;
312       }
313     }
314   }
315   return nullptr;
316 }
317 
318 static const semantics::Symbol *GetParentComponent(
319     const semantics::Symbol *symbol, const semantics::Scope &scope) {
320   if (symbol) {
321     if (const auto *dtDetails{
322             symbol->detailsIf<semantics::DerivedTypeDetails>()}) {
323       return GetParentComponent(*dtDetails, scope);
324     }
325   }
326   return nullptr;
327 }
328 
329 static const semantics::DerivedTypeSpec *GetParentTypeSpec(
330     const semantics::Symbol *symbol, const semantics::Scope &scope) {
331   if (const Symbol * parentComponent{GetParentComponent(symbol, scope)}) {
332     return &parentComponent->get<semantics::ObjectEntityDetails>()
333                 .type()
334                 ->derivedTypeSpec();
335   } else {
336     return nullptr;
337   }
338 }
339 
340 static const semantics::Scope *GetDerivedTypeParent(
341     const semantics::Scope *scope) {
342   if (scope) {
343     CHECK(scope->IsDerivedType());
344     if (const auto *parent{GetParentTypeSpec(scope->GetSymbol(), *scope)}) {
345       return parent->scope();
346     }
347   }
348   return nullptr;
349 }
350 
351 static const semantics::Symbol *FindComponent(
352     const semantics::Scope *scope, parser::CharBlock name) {
353   if (!scope) {
354     return nullptr;
355   }
356   CHECK(scope->IsDerivedType());
357   auto found{scope->find(name)};
358   if (found != scope->end()) {
359     return &*found->second;
360   } else {
361     return FindComponent(GetDerivedTypeParent(scope), name);
362   }
363 }
364 
365 static bool AreTypeParamCompatible(const semantics::DerivedTypeSpec &x,
366     const semantics::DerivedTypeSpec &y, bool ignoreLenParameters) {
367   const auto *xScope{x.typeSymbol().scope()};
368   const auto *yScope{y.typeSymbol().scope()};
369   for (const auto &[paramName, value] : x.parameters()) {
370     const auto *yValue{y.FindParameter(paramName)};
371     if (!yValue) {
372       return false;
373     }
374     const auto *xParm{FindComponent(xScope, paramName)};
375     const auto *yParm{FindComponent(yScope, paramName)};
376     if (xParm && yParm) {
377       const auto *xTPD{xParm->detailsIf<semantics::TypeParamDetails>()};
378       const auto *yTPD{yParm->detailsIf<semantics::TypeParamDetails>()};
379       if (xTPD && yTPD) {
380         if (xTPD->attr() != yTPD->attr()) {
381           return false;
382         }
383         if (!ignoreLenParameters ||
384             xTPD->attr() != common::TypeParamAttr::Len) {
385           auto xExpr{value.GetExplicit()};
386           auto yExpr{yValue->GetExplicit()};
387           if (xExpr && yExpr) {
388             auto xVal{ToInt64(*xExpr)};
389             auto yVal{ToInt64(*yExpr)};
390             if (xVal && yVal && *xVal != *yVal) {
391               return false;
392             }
393           }
394         }
395       }
396     }
397   }
398   for (const auto &[paramName, _] : y.parameters()) {
399     if (!x.FindParameter(paramName)) {
400       return false; // y has more parameters than x
401     }
402   }
403   return true;
404 }
405 
406 static bool AreSameDerivedType(const semantics::DerivedTypeSpec &x,
407     const semantics::DerivedTypeSpec &y, bool ignoreTypeParameterValues,
408     bool ignoreLenParameters, SetOfDerivedTypePairs &inProgress) {
409   if (&x == &y) {
410     return true;
411   }
412   if (!ignoreTypeParameterValues &&
413       !AreTypeParamCompatible(x, y, ignoreLenParameters)) {
414     return false;
415   }
416   const auto &xSymbol{x.typeSymbol()};
417   const auto &ySymbol{y.typeSymbol()};
418   if (xSymbol == ySymbol) {
419     return true;
420   }
421   if (xSymbol.name() != ySymbol.name()) {
422     return false;
423   }
424   auto thisQuery{std::make_pair(&x, &y)};
425   if (inProgress.find(thisQuery) != inProgress.end()) {
426     return true; // recursive use of types in components
427   }
428   inProgress.insert(thisQuery);
429   const auto &xDetails{xSymbol.get<semantics::DerivedTypeDetails>()};
430   const auto &yDetails{ySymbol.get<semantics::DerivedTypeDetails>()};
431   if (!(xDetails.sequence() && yDetails.sequence()) &&
432       !(xSymbol.attrs().test(semantics::Attr::BIND_C) &&
433           ySymbol.attrs().test(semantics::Attr::BIND_C))) {
434     // PGI does not enforce this requirement; all other Fortran
435     // processors do with a hard error when violations are caught.
436     return false;
437   }
438   // Compare the component lists in their orders of declaration.
439   auto xEnd{xDetails.componentNames().cend()};
440   auto yComponentName{yDetails.componentNames().cbegin()};
441   auto yEnd{yDetails.componentNames().cend()};
442   for (auto xComponentName{xDetails.componentNames().cbegin()};
443        xComponentName != xEnd; ++xComponentName, ++yComponentName) {
444     if (yComponentName == yEnd || *xComponentName != *yComponentName ||
445         !xSymbol.scope() || !ySymbol.scope()) {
446       return false;
447     }
448     const auto xLookup{xSymbol.scope()->find(*xComponentName)};
449     const auto yLookup{ySymbol.scope()->find(*yComponentName)};
450     if (xLookup == xSymbol.scope()->end() ||
451         yLookup == ySymbol.scope()->end() ||
452         !AreSameComponent(*xLookup->second, *yLookup->second, inProgress)) {
453       return false;
454     }
455   }
456   return yComponentName == yEnd;
457 }
458 
459 bool AreSameDerivedType(
460     const semantics::DerivedTypeSpec &x, const semantics::DerivedTypeSpec &y) {
461   SetOfDerivedTypePairs inProgress;
462   return AreSameDerivedType(x, y, false, false, inProgress);
463 }
464 
465 static bool AreCompatibleDerivedTypes(const semantics::DerivedTypeSpec *x,
466     const semantics::DerivedTypeSpec *y, bool isPolymorphic,
467     bool ignoreTypeParameterValues, bool ignoreLenTypeParameters) {
468   if (!x || !y) {
469     return false;
470   } else {
471     SetOfDerivedTypePairs inProgress;
472     if (AreSameDerivedType(*x, *y, ignoreTypeParameterValues,
473             ignoreLenTypeParameters, inProgress)) {
474       return true;
475     } else {
476       return isPolymorphic &&
477           AreCompatibleDerivedTypes(x, GetParentTypeSpec(*y), true,
478               ignoreTypeParameterValues, ignoreLenTypeParameters);
479     }
480   }
481 }
482 
483 static bool AreCompatibleTypes(const DynamicType &x, const DynamicType &y,
484     bool ignoreTypeParameterValues, bool ignoreLengths) {
485   if (x.IsUnlimitedPolymorphic()) {
486     return true;
487   } else if (y.IsUnlimitedPolymorphic()) {
488     return false;
489   } else if (x.category() != y.category()) {
490     return false;
491   } else if (x.category() == TypeCategory::Character) {
492     const auto xLen{x.knownLength()};
493     const auto yLen{y.knownLength()};
494     return x.kind() == y.kind() &&
495         (ignoreLengths || !xLen || !yLen || *xLen == *yLen);
496   } else if (x.category() != TypeCategory::Derived) {
497     return x.kind() == y.kind();
498   } else {
499     const auto *xdt{GetDerivedTypeSpec(x)};
500     const auto *ydt{GetDerivedTypeSpec(y)};
501     return AreCompatibleDerivedTypes(
502         xdt, ydt, x.IsPolymorphic(), ignoreTypeParameterValues, false);
503   }
504 }
505 
506 // See 7.3.2.3 (5) & 15.5.2.4
507 bool DynamicType::IsTkCompatibleWith(const DynamicType &that) const {
508   return AreCompatibleTypes(*this, that, false, true);
509 }
510 
511 bool DynamicType::IsTkCompatibleWith(
512     const DynamicType &that, common::IgnoreTKRSet ignoreTKR) const {
513   if (ignoreTKR.test(common::IgnoreTKR::Type) &&
514       (category() == TypeCategory::Derived ||
515           that.category() == TypeCategory::Derived ||
516           category() != that.category())) {
517     return true;
518   } else if (ignoreTKR.test(common::IgnoreTKR::Kind) &&
519       category() == that.category()) {
520     return true;
521   } else {
522     return AreCompatibleTypes(*this, that, false, true);
523   }
524 }
525 
526 bool DynamicType::IsTkLenCompatibleWith(const DynamicType &that) const {
527   return AreCompatibleTypes(*this, that, false, false);
528 }
529 
530 // 16.9.165
531 std::optional<bool> DynamicType::SameTypeAs(const DynamicType &that) const {
532   bool x{AreCompatibleTypes(*this, that, true, true)};
533   bool y{AreCompatibleTypes(that, *this, true, true)};
534   if (!x && !y) {
535     return false;
536   } else if (x && y && !IsPolymorphic() && !that.IsPolymorphic()) {
537     return true;
538   } else {
539     return std::nullopt;
540   }
541 }
542 
543 // 16.9.76
544 std::optional<bool> DynamicType::ExtendsTypeOf(const DynamicType &that) const {
545   if (IsUnlimitedPolymorphic() || that.IsUnlimitedPolymorphic()) {
546     return std::nullopt; // unknown
547   }
548   const auto *thisDts{evaluate::GetDerivedTypeSpec(*this)};
549   const auto *thatDts{evaluate::GetDerivedTypeSpec(that)};
550   if (!thisDts || !thatDts) {
551     return std::nullopt;
552   } else if (!AreCompatibleDerivedTypes(thatDts, thisDts, true, true, true)) {
553     // Note that I check *thisDts, not its parent, so that EXTENDS_TYPE_OF()
554     // is .true. when they are the same type.  This is technically
555     // an implementation-defined case in the standard, but every other
556     // compiler works this way.
557     if (IsPolymorphic() &&
558         AreCompatibleDerivedTypes(thisDts, thatDts, true, true, true)) {
559       // 'that' is *this or an extension of *this, and so runtime *this
560       // could be an extension of 'that'
561       return std::nullopt;
562     } else {
563       return false;
564     }
565   } else if (that.IsPolymorphic()) {
566     return std::nullopt; // unknown
567   } else {
568     return true;
569   }
570 }
571 
572 std::optional<DynamicType> DynamicType::From(
573     const semantics::DeclTypeSpec &type) {
574   if (const auto *intrinsic{type.AsIntrinsic()}) {
575     if (auto kind{ToInt64(intrinsic->kind())}) {
576       TypeCategory category{intrinsic->category()};
577       if (IsValidKindOfIntrinsicType(category, *kind)) {
578         if (category == TypeCategory::Character) {
579           const auto &charType{type.characterTypeSpec()};
580           return DynamicType{static_cast<int>(*kind), charType.length()};
581         } else {
582           return DynamicType{category, static_cast<int>(*kind)};
583         }
584       }
585     }
586   } else if (const auto *derived{type.AsDerived()}) {
587     return DynamicType{
588         *derived, type.category() == semantics::DeclTypeSpec::ClassDerived};
589   } else if (type.category() == semantics::DeclTypeSpec::ClassStar) {
590     return DynamicType::UnlimitedPolymorphic();
591   } else if (type.category() == semantics::DeclTypeSpec::TypeStar) {
592     return DynamicType::AssumedType();
593   } else {
594     common::die("DynamicType::From(DeclTypeSpec): failed");
595   }
596   return std::nullopt;
597 }
598 
599 std::optional<DynamicType> DynamicType::From(const semantics::Symbol &symbol) {
600   return From(symbol.GetType()); // Symbol -> DeclTypeSpec -> DynamicType
601 }
602 
603 DynamicType DynamicType::ResultTypeForMultiply(const DynamicType &that) const {
604   switch (category_) {
605   case TypeCategory::Integer:
606     switch (that.category_) {
607     case TypeCategory::Integer:
608       return DynamicType{TypeCategory::Integer, std::max(kind_, that.kind_)};
609     case TypeCategory::Real:
610     case TypeCategory::Complex:
611       return that;
612     default:
613       CRASH_NO_CASE;
614     }
615     break;
616   case TypeCategory::Real:
617     switch (that.category_) {
618     case TypeCategory::Integer:
619       return *this;
620     case TypeCategory::Real:
621       return DynamicType{TypeCategory::Real, std::max(kind_, that.kind_)};
622     case TypeCategory::Complex:
623       return DynamicType{TypeCategory::Complex, std::max(kind_, that.kind_)};
624     default:
625       CRASH_NO_CASE;
626     }
627     break;
628   case TypeCategory::Complex:
629     switch (that.category_) {
630     case TypeCategory::Integer:
631       return *this;
632     case TypeCategory::Real:
633     case TypeCategory::Complex:
634       return DynamicType{TypeCategory::Complex, std::max(kind_, that.kind_)};
635     default:
636       CRASH_NO_CASE;
637     }
638     break;
639   case TypeCategory::Logical:
640     switch (that.category_) {
641     case TypeCategory::Logical:
642       return DynamicType{TypeCategory::Logical, std::max(kind_, that.kind_)};
643     default:
644       CRASH_NO_CASE;
645     }
646     break;
647   default:
648     CRASH_NO_CASE;
649   }
650   return *this;
651 }
652 
653 bool DynamicType::RequiresDescriptor() const {
654   return IsPolymorphic() || IsNonConstantLengthCharacter() ||
655       (derived_ && CountNonConstantLenParameters(*derived_) > 0);
656 }
657 
658 bool DynamicType::HasDeferredTypeParameter() const {
659   if (derived_) {
660     for (const auto &pair : derived_->parameters()) {
661       if (pair.second.isDeferred()) {
662         return true;
663       }
664     }
665   }
666   return charLengthParamValue_ && charLengthParamValue_->isDeferred();
667 }
668 
669 bool SomeKind<TypeCategory::Derived>::operator==(
670     const SomeKind<TypeCategory::Derived> &that) const {
671   return PointeeComparison(derivedTypeSpec_, that.derivedTypeSpec_);
672 }
673 
674 int SelectedCharKind(const std::string &s, int defaultKind) { // 16.9.168
675   auto lower{parser::ToLowerCaseLetters(s)};
676   auto n{lower.size()};
677   while (n > 0 && lower[0] == ' ') {
678     lower.erase(0, 1);
679     --n;
680   }
681   while (n > 0 && lower[n - 1] == ' ') {
682     lower.erase(--n, 1);
683   }
684   if (lower == "ascii") {
685     return 1;
686   } else if (lower == "ucs-2") {
687     return 2;
688   } else if (lower == "iso_10646" || lower == "ucs-4") {
689     return 4;
690   } else if (lower == "default") {
691     return defaultKind;
692   } else {
693     return -1;
694   }
695 }
696 
697 std::optional<DynamicType> ComparisonType(
698     const DynamicType &t1, const DynamicType &t2) {
699   switch (t1.category()) {
700   case TypeCategory::Integer:
701     switch (t2.category()) {
702     case TypeCategory::Integer:
703       return DynamicType{TypeCategory::Integer, std::max(t1.kind(), t2.kind())};
704     case TypeCategory::Real:
705     case TypeCategory::Complex:
706       return t2;
707     default:
708       return std::nullopt;
709     }
710   case TypeCategory::Real:
711     switch (t2.category()) {
712     case TypeCategory::Integer:
713       return t1;
714     case TypeCategory::Real:
715     case TypeCategory::Complex:
716       return DynamicType{t2.category(), std::max(t1.kind(), t2.kind())};
717     default:
718       return std::nullopt;
719     }
720   case TypeCategory::Complex:
721     switch (t2.category()) {
722     case TypeCategory::Integer:
723       return t1;
724     case TypeCategory::Real:
725     case TypeCategory::Complex:
726       return DynamicType{TypeCategory::Complex, std::max(t1.kind(), t2.kind())};
727     default:
728       return std::nullopt;
729     }
730   case TypeCategory::Character:
731     switch (t2.category()) {
732     case TypeCategory::Character:
733       return DynamicType{
734           TypeCategory::Character, std::max(t1.kind(), t2.kind())};
735     default:
736       return std::nullopt;
737     }
738   case TypeCategory::Logical:
739     switch (t2.category()) {
740     case TypeCategory::Logical:
741       return DynamicType{TypeCategory::Logical, LogicalResult::kind};
742     default:
743       return std::nullopt;
744     }
745   default:
746     return std::nullopt;
747   }
748 }
749 
750 bool IsInteroperableIntrinsicType(
751     const DynamicType &type, bool checkCharLength) {
752   switch (type.category()) {
753   case TypeCategory::Integer:
754     return true;
755   case TypeCategory::Real:
756   case TypeCategory::Complex:
757     return type.kind() >= 4; // no short or half floats
758   case TypeCategory::Logical:
759     return type.kind() == 1; // C_BOOL
760   case TypeCategory::Character:
761     if (checkCharLength && type.knownLength().value_or(0) != 1) {
762       return false;
763     }
764     return type.kind() == 1 /* C_CHAR */;
765   default:
766     // Derived types are tested in Semantics/check-declarations.cpp
767     return false;
768   }
769 }
770 
771 } // namespace Fortran::evaluate
772