7efec1a40a
Definability checking is unconditionally flagging the use of a polymorphic variable as an actual argument for a procedure reference in a PURE subprogram unless the corresponding dummy is INTENT(IN). This isn't necessary, since an INTENT(OUT) polymorphic dummy is already caught as an error in the definition of the callee, which must also be PURE; and an INTENT(IN OUT) or intent-free dummy is allowed to be passed a polymorphic actual in a PURE context, with any attempt to deallocate it being caught in the callee. So add a flag to the definability checker to disable the "polymorphic definition in PURE context" check when using it to check actual arguments. Differential Revision: https://reviews.llvm.org/D139044
248 lines
9.7 KiB
C++
248 lines
9.7 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(
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const evaluate::DataRef &dataRef, bool isPointerDefinition) {
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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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return GetRelevantSymbol(component->base(), 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 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(
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at, scope, flags, GetRelevantSymbol(*dataRef, isPointerDefinition));
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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 (!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 (!flags.test(DefinabilityFlag::PolymorphicOkInPure) &&
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FindPureProcedureContaining(scope)) {
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if (auto dyType{evaluate::DynamicType::From(ultimate)}) {
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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, original);
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}
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if (const DerivedTypeSpec * derived{GetDerivedTypeSpec(dyType)}) {
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if (auto bad{FindPolymorphicAllocatableNonCoarrayUltimateComponent(
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*derived)}) {
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return BlameSymbol(at,
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"'%s' has polymorphic non-coarray 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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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(
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dataRef, flags.test(DefinabilityFlag::PointerDefinition))};
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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)};
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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 (!flags.test(DefinabilityFlag::VectorSubscriptIsOk) &&
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evaluate::HasVectorSubscript(expr)) {
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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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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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}
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if (evaluate::IsVariable(expr)) {
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return std::nullopt; // result of function returning a pointer - ok
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}
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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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}
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return parser::Message{
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at, "'%s' is not a variable or pointer"_because_en_US, expr.AsFortran()};
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}
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} // namespace Fortran::semantics
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