33c27f28d1
When the result of a function never appears in a variable definition context, emit a warning. If the function has multiple result variables due to alternate ENTRY statements, any definition will suffice. The implementation of this check is tied to the general variable definability checking utility in semantics. Every variable definition context uses it to ensure that no undefinable variable is being defined. A set of defined variables is maintained in the SemanticsContext and, when the warning is enabled and no fatal error has been reported, the scope tree is traversed and all the function subprograms' results are tested for membership in that set.
57 lines
2.4 KiB
C++
57 lines
2.4 KiB
C++
//===-- lib/Semantics/definable.h -------------------------------*- C++ -*-===//
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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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#ifndef FORTRAN_SEMANTICS_DEFINABLE_H_
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#define FORTRAN_SEMANTICS_DEFINABLE_H_
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// Utilities for checking the definability of variables and pointers in context,
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// including checks for attempted definitions in PURE subprograms.
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// Fortran 2018 C1101, C1158, C1594, &c.
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#include "flang/Common/enum-set.h"
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#include "flang/Common/idioms.h"
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#include "flang/Evaluate/expression.h"
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#include "flang/Parser/char-block.h"
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#include "flang/Parser/message.h"
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#include <optional>
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namespace Fortran::semantics {
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class Symbol;
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class Scope;
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ENUM_CLASS(DefinabilityFlag,
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VectorSubscriptIsOk, // a vector subscript may appear (i.e., assignment)
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DuplicatesAreOk, // vector subscript may have duplicates
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PointerDefinition, // a pointer is being defined, not its target
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AcceptAllocatable, // treat allocatable as if it were a pointer
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SourcedAllocation, // ALLOCATE(a,SOURCE=)
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PolymorphicOkInPure, // don't check for polymorphic type in pure subprogram
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DoNotNoteDefinition) // context does not imply definition
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using DefinabilityFlags =
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common::EnumSet<DefinabilityFlag, DefinabilityFlag_enumSize>;
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// Tests a symbol or LHS variable or pointer for definability in a given scope.
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// When the entity is not definable, returns a Message suitable for attachment
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// to an error or warning message (as a "because: addendum) to explain why the
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// entity cannot be defined.
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// When the entity can be defined in that context, returns std::nullopt.
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std::optional<parser::Message> WhyNotDefinable(
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parser::CharBlock, const Scope &, DefinabilityFlags, const Symbol &);
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std::optional<parser::Message> WhyNotDefinable(parser::CharBlock, const Scope &,
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DefinabilityFlags, const evaluate::Expr<evaluate::SomeType> &);
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// If a symbol would not be definable in a pure scope, or not be usable as the
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// target of a pointer assignment in a pure scope, return a constant string
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// describing why.
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const char *WhyBaseObjectIsSuspicious(const Symbol &, const Scope &);
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} // namespace Fortran::semantics
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#endif // FORTRAN_SEMANTICS_DEFINABLE_H_
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