1 //===-- lib/Semantics/definable.h -------------------------------*- C++ -*-===// 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 #ifndef FORTRAN_SEMANTICS_DEFINABLE_H_ 10 #define FORTRAN_SEMANTICS_DEFINABLE_H_ 11 12 // Utilities for checking the definability of variables and pointers in context, 13 // including checks for attempted definitions in PURE subprograms. 14 // Fortran 2018 C1101, C1158, C1594, &c. 15 16 #include "flang/Common/enum-set.h" 17 #include "flang/Common/idioms.h" 18 #include "flang/Evaluate/expression.h" 19 #include "flang/Parser/char-block.h" 20 #include "flang/Parser/message.h" 21 #include <optional> 22 23 namespace Fortran::semantics { 24 25 class Symbol; 26 class Scope; 27 28 ENUM_CLASS(DefinabilityFlag, 29 VectorSubscriptIsOk, // a vector subscript may appear (i.e., assignment) 30 DuplicatesAreOk, // vector subscript may have duplicates 31 PointerDefinition, // a pointer is being defined, not its target 32 AcceptAllocatable, // treat allocatable as if it were a pointer 33 SourcedAllocation, // ALLOCATE(a,SOURCE=) 34 PolymorphicOkInPure, // don't check for polymorphic type in pure subprogram 35 DoNotNoteDefinition, // context does not imply definition 36 AllowEventLockOrNotifyType) 37 38 using DefinabilityFlags = 39 common::EnumSet<DefinabilityFlag, DefinabilityFlag_enumSize>; 40 41 // Tests a symbol or LHS variable or pointer for definability in a given scope. 42 // When the entity is not definable, returns a Message suitable for attachment 43 // to an error or warning message (as a "because: addendum) to explain why the 44 // entity cannot be defined. 45 // When the entity can be defined in that context, returns std::nullopt. 46 std::optional<parser::Message> WhyNotDefinable( 47 parser::CharBlock, const Scope &, DefinabilityFlags, const Symbol &); 48 std::optional<parser::Message> WhyNotDefinable(parser::CharBlock, const Scope &, 49 DefinabilityFlags, const evaluate::Expr<evaluate::SomeType> &); 50 51 // If a symbol would not be definable in a pure scope, or not be usable as the 52 // target of a pointer assignment in a pure scope, return a constant string 53 // describing why. 54 const char *WhyBaseObjectIsSuspicious(const Symbol &, const Scope &); 55 56 } // namespace Fortran::semantics 57 #endif // FORTRAN_SEMANTICS_DEFINABLE_H_ 58