e9a8ab004c
Many semantic checks for constraints related to PURE subprograms can be implemented in terms of Semantics' "definable.h" utilities, slightly expanded. Replace some particular PURE constraint checks with calls to WhyNotDefinable(), except for cases that had better specific error messages, and start checking some missing constraints with DEALLOCATE statements and local variable declarations. Differential Revision: https://reviews.llvm.org/D147389
308 lines
13 KiB
C++
308 lines
13 KiB
C++
//===-- lib/Semantics/definable.cpp ---------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "definable.h"
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#include "flang/Evaluate/tools.h"
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#include "flang/Semantics/tools.h"
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using namespace Fortran::parser::literals;
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namespace Fortran::semantics {
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template <typename... A>
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static parser::Message BlameSymbol(parser::CharBlock at,
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const parser::MessageFixedText &text, const Symbol &original, A &&...x) {
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parser::Message message{at, text, original.name(), std::forward<A>(x)...};
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message.set_severity(parser::Severity::Because);
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evaluate::AttachDeclaration(message, original);
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return message;
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}
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static bool IsPointerDummyOfPureFunction(const Symbol &x) {
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return IsPointerDummy(x) && FindPureProcedureContaining(x.owner()) &&
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x.owner().symbol() && IsFunction(*x.owner().symbol());
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}
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// See C1594, first paragraph. These conditions enable checks on both
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// left-hand and right-hand sides in various circumstances.
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const char *WhyBaseObjectIsSuspicious(const Symbol &x, const Scope &scope) {
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if (IsHostAssociatedIntoSubprogram(x, scope)) {
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return "host-associated";
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} else if (IsUseAssociated(x, scope)) {
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return "USE-associated";
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} else if (IsPointerDummyOfPureFunction(x)) {
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return "a POINTER dummy argument of a pure function";
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} else if (IsIntentIn(x)) {
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return "an INTENT(IN) dummy argument";
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} else if (FindCommonBlockContaining(x)) {
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return "in a COMMON block";
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} else {
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return nullptr;
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}
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}
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// Checks C1594(1,2); false if check fails
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static std::optional<parser::Message> CheckDefinabilityInPureScope(
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SourceName at, const Symbol &original, const Symbol &ultimate,
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const Scope &context, const Scope &pure) {
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if (pure.symbol()) {
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if (const char *why{WhyBaseObjectIsSuspicious(ultimate, context)}) {
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return BlameSymbol(at,
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"'%s' may not be defined in pure subprogram '%s' because it is %s"_en_US,
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original, pure.symbol()->name(), why);
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}
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}
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return std::nullopt;
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}
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// When a DataRef contains pointers, gets the rightmost one (unless it is
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// the entity being defined, in which case the last pointer above it);
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// otherwise, returns the leftmost symbol. The resulting symbol is the
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// relevant base object for definabiliy checking. Examples:
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// ptr1%ptr2 => ... -> ptr1
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// nonptr%ptr => ... -> nonptr
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// nonptr%ptr = ... -> ptr
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// ptr1%ptr2 = ... -> ptr2
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// ptr1%ptr2%nonptr = ... -> ptr2
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// nonptr1%nonptr2 = ... -> nonptr1
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static const Symbol &GetRelevantSymbol(const evaluate::DataRef &dataRef,
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bool isPointerDefinition, bool acceptAllocatable) {
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if (isPointerDefinition) {
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if (const auto *component{std::get_if<evaluate::Component>(&dataRef.u)}) {
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if (IsPointer(component->GetLastSymbol()) ||
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(acceptAllocatable && IsAllocatable(component->GetLastSymbol()))) {
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return GetRelevantSymbol(component->base(), false, false);
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}
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}
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}
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if (const Symbol * lastPointer{GetLastPointerSymbol(dataRef)}) {
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return *lastPointer;
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} else {
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return dataRef.GetFirstSymbol();
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}
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}
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// Check the leftmost (or only) symbol from a data-ref or expression.
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static std::optional<parser::Message> WhyNotDefinableBase(parser::CharBlock at,
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const Scope &scope, DefinabilityFlags flags, const Symbol &original) {
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const Symbol &ultimate{original.GetUltimate()};
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bool isPointerDefinition{flags.test(DefinabilityFlag::PointerDefinition)};
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bool acceptAllocatable{flags.test(DefinabilityFlag::AcceptAllocatable)};
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bool isTargetDefinition{!isPointerDefinition && IsPointer(ultimate)};
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if (const auto *association{ultimate.detailsIf<AssocEntityDetails>()}) {
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if (association->rank().has_value()) {
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return std::nullopt; // SELECT RANK always modifiable variable
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} else if (!IsVariable(association->expr())) {
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return BlameSymbol(at,
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"'%s' is construct associated with an expression"_en_US, original);
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} else if (evaluate::HasVectorSubscript(association->expr().value())) {
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return BlameSymbol(at,
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"Construct association '%s' has a vector subscript"_en_US, original);
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} else if (auto dataRef{evaluate::ExtractDataRef(
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*association->expr(), true, true)}) {
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return WhyNotDefinableBase(at, scope, flags,
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GetRelevantSymbol(*dataRef, isPointerDefinition, acceptAllocatable));
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}
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}
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if (isTargetDefinition) {
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} else if (!isPointerDefinition && !IsVariableName(ultimate)) {
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return BlameSymbol(at, "'%s' is not a variable"_en_US, original);
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} else if (IsProtected(ultimate) && IsUseAssociated(original, scope)) {
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return BlameSymbol(at, "'%s' is protected in this scope"_en_US, original);
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} else if (IsIntentIn(ultimate)) {
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return BlameSymbol(
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at, "'%s' is an INTENT(IN) dummy argument"_en_US, original);
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}
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if (const Scope * pure{FindPureProcedureContaining(scope)}) {
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// Additional checking for pure subprograms.
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if (!isTargetDefinition) {
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if (auto msg{CheckDefinabilityInPureScope(
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at, original, ultimate, scope, *pure)}) {
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return msg;
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}
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}
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if (const Symbol *
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visible{FindExternallyVisibleObject(
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ultimate, *pure, isPointerDefinition)}) {
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return BlameSymbol(at,
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"'%s' is externally visible via '%s' and not definable in a pure subprogram"_en_US,
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original, visible->name());
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}
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}
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return std::nullopt;
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}
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static std::optional<parser::Message> WhyNotDefinableLast(parser::CharBlock at,
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const Scope &scope, DefinabilityFlags flags, const Symbol &original) {
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const Symbol &ultimate{original.GetUltimate()};
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if (flags.test(DefinabilityFlag::PointerDefinition)) {
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if (flags.test(DefinabilityFlag::AcceptAllocatable)) {
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if (!IsAllocatableOrPointer(ultimate)) {
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return BlameSymbol(
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at, "'%s' is neither a pointer nor an allocatable"_en_US, original);
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}
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} else if (!IsPointer(ultimate)) {
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return BlameSymbol(at, "'%s' is not a pointer"_en_US, original);
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}
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return std::nullopt; // pointer assignment - skip following checks
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}
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if (IsOrContainsEventOrLockComponent(ultimate)) {
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return BlameSymbol(at,
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"'%s' is an entity with either an EVENT_TYPE or LOCK_TYPE"_en_US,
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original);
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}
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if (FindPureProcedureContaining(scope)) {
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if (auto dyType{evaluate::DynamicType::From(ultimate)}) {
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if (!flags.test(DefinabilityFlag::PolymorphicOkInPure)) {
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if (dyType->IsPolymorphic()) { // C1596
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return BlameSymbol(at,
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"'%s' is polymorphic in a pure subprogram"_because_en_US,
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original);
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}
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}
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if (const Symbol * impure{HasImpureFinal(ultimate)}) {
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return BlameSymbol(at,
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"'%s' has an impure FINAL procedure '%s'"_because_en_US, original,
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impure->name());
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}
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if (const DerivedTypeSpec * derived{GetDerivedTypeSpec(dyType)}) {
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if (!flags.test(DefinabilityFlag::PolymorphicOkInPure)) {
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if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
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return BlameSymbol(at,
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"'%s' has polymorphic component '%s' in a pure subprogram"_because_en_US,
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original, bad.BuildResultDesignatorName());
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}
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}
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}
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}
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}
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return std::nullopt;
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}
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// Checks a data-ref
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static std::optional<parser::Message> WhyNotDefinable(parser::CharBlock at,
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const Scope &scope, DefinabilityFlags flags,
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const evaluate::DataRef &dataRef) {
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const Symbol &base{GetRelevantSymbol(dataRef,
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flags.test(DefinabilityFlag::PointerDefinition),
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flags.test(DefinabilityFlag::AcceptAllocatable))};
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if (auto whyNot{WhyNotDefinableBase(at, scope, flags, base)}) {
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return whyNot;
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} else {
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return WhyNotDefinableLast(at, scope, flags, dataRef.GetLastSymbol());
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}
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}
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// Checks a NOPASS procedure pointer component
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static std::optional<parser::Message> WhyNotDefinable(parser::CharBlock at,
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const Scope &scope, DefinabilityFlags flags,
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const evaluate::Component &component) {
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const evaluate::DataRef &dataRef{component.base()};
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const Symbol &base{GetRelevantSymbol(dataRef, false, false)};
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DefinabilityFlags baseFlags{flags};
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baseFlags.reset(DefinabilityFlag::PointerDefinition);
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return WhyNotDefinableBase(at, scope, baseFlags, base);
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}
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std::optional<parser::Message> WhyNotDefinable(parser::CharBlock at,
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const Scope &scope, DefinabilityFlags flags, const Symbol &original) {
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if (auto base{WhyNotDefinableBase(at, scope, flags, original)}) {
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return base;
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}
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return WhyNotDefinableLast(at, scope, flags, original);
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}
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std::optional<parser::Message> WhyNotDefinable(parser::CharBlock at,
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const Scope &scope, DefinabilityFlags flags,
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const evaluate::Expr<evaluate::SomeType> &expr) {
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if (auto dataRef{evaluate::ExtractDataRef(expr, true, true)}) {
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if (evaluate::HasVectorSubscript(expr)) {
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if (flags.test(DefinabilityFlag::VectorSubscriptIsOk)) {
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if (auto type{expr.GetType()}) {
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if (!type->IsUnlimitedPolymorphic() &&
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type->category() == TypeCategory::Derived) {
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// Seek the FINAL subroutine that should but cannot be called
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// for this definition of an array with a vector-valued subscript.
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// If there's an elemental FINAL subroutine, all is well; otherwise,
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// if there is a FINAL subroutine with a matching or assumed rank
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// dummy argument, there's no way to call it.
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int rank{expr.Rank()};
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const DerivedTypeSpec *spec{&type->GetDerivedTypeSpec()};
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while (spec) {
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bool anyElemental{false};
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const Symbol *anyRankMatch{nullptr};
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for (auto ref : FinalsForDerivedTypeInstantiation(*spec)) {
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const Symbol &ultimate{ref->GetUltimate()};
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anyElemental |= ultimate.attrs().test(Attr::ELEMENTAL);
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if (const auto *subp{ultimate.detailsIf<SubprogramDetails>()}) {
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if (!subp->dummyArgs().empty()) {
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if (const Symbol * arg{subp->dummyArgs()[0]}) {
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const auto *object{arg->detailsIf<ObjectEntityDetails>()};
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if (arg->Rank() == rank ||
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(object && object->IsAssumedRank())) {
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anyRankMatch = &*ref;
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}
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}
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}
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}
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}
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if (anyRankMatch && !anyElemental) {
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return parser::Message{at,
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"Variable '%s' has a vector subscript and cannot be finalized by non-elemental subroutine '%s'"_because_en_US,
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expr.AsFortran(), anyRankMatch->name()};
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}
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const auto *parent{FindParentTypeSpec(*spec)};
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spec = parent ? parent->AsDerived() : nullptr;
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}
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}
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}
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} else {
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return parser::Message{at,
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"Variable '%s' has a vector subscript"_because_en_US,
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expr.AsFortran()};
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}
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}
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if (FindPureProcedureContaining(scope) &&
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evaluate::ExtractCoarrayRef(expr)) {
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return parser::Message(at,
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"A pure subprogram may not define the coindexed object '%s'"_because_en_US,
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expr.AsFortran());
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}
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return WhyNotDefinable(at, scope, flags, *dataRef);
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} else if (evaluate::IsNullPointer(expr)) {
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return parser::Message{
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at, "'%s' is a null pointer"_because_en_US, expr.AsFortran()};
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} else if (flags.test(DefinabilityFlag::PointerDefinition)) {
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if (const auto *procDesignator{
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std::get_if<evaluate::ProcedureDesignator>(&expr.u)}) {
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// Defining a procedure pointer
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if (const Symbol * procSym{procDesignator->GetSymbol()}) {
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if (evaluate::ExtractCoarrayRef(expr)) { // C1027
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return BlameSymbol(at,
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"Procedure pointer '%s' may not be a coindexed object"_because_en_US,
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*procSym, expr.AsFortran());
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}
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if (const auto *component{procDesignator->GetComponent()}) {
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return WhyNotDefinable(at, scope, flags, *component);
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} else {
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return WhyNotDefinable(at, scope, flags, *procSym);
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}
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}
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}
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return parser::Message{
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at, "'%s' is not a definable pointer"_because_en_US, expr.AsFortran()};
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} else if (!evaluate::IsVariable(expr)) {
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return parser::Message{at,
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"'%s' is not a variable or pointer"_because_en_US, expr.AsFortran()};
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} else {
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return std::nullopt;
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}
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}
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} // namespace Fortran::semantics
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