573fc6187b
The infrastructure in semantics that is used to check that the left-hand sides of normal assignment statements are really definable variables was not being used to check whether the LHSs of pointer assignments are modifiable, and so most cases of unmodifiable pointers are left undiagnosed. Rework the semantics checking for pointer assignments, NULLIFY statements, pointer dummy arguments, &c. so that cases of unmodifiable pointers are properly caught. This has been done by extracting all the various definability checking code that has been implemented for different contexts in Fortran into one new facility. The new consolidated definability checking code returns messages meant to be attached as "because: " explanations to context-dependent errors like "left-hand side of assignment is not definable". These new error message texts and their attached explanations affect many existing tests, which have been updated. The testing infrastructure was extended by another patch to properly compare warnings and explanatory messages, which had been ignored until recently. Differential Revision: https://reviews.llvm.org/D136979
63 lines
2.5 KiB
C++
63 lines
2.5 KiB
C++
//===-- lib/Semantics/check-nullify.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 "check-nullify.h"
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#include "definable.h"
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#include "flang/Evaluate/expression.h"
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#include "flang/Parser/message.h"
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#include "flang/Parser/parse-tree.h"
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#include "flang/Semantics/expression.h"
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#include "flang/Semantics/tools.h"
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namespace Fortran::semantics {
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void NullifyChecker::Leave(const parser::NullifyStmt &nullifyStmt) {
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CHECK(context_.location());
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const Scope &scope{context_.FindScope(*context_.location())};
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for (const parser::PointerObject &pointerObject : nullifyStmt.v) {
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common::visit(
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common::visitors{
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[&](const parser::Name &name) {
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if (name.symbol) {
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if (auto whyNot{WhyNotDefinable(name.source, scope,
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DefinabilityFlags{DefinabilityFlag::PointerDefinition},
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*name.symbol)}) {
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context_.messages()
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.Say(name.source,
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"'%s' may not appear in NULLIFY"_err_en_US,
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name.source)
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.Attach(std::move(*whyNot));
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}
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}
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},
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[&](const parser::StructureComponent &structureComponent) {
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const auto &component{structureComponent.component};
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SourceName at{component.source};
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if (const auto *checkedExpr{GetExpr(context_, pointerObject)}) {
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if (auto whyNot{WhyNotDefinable(at, scope,
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DefinabilityFlags{DefinabilityFlag::PointerDefinition},
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*checkedExpr)}) {
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context_.messages()
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.Say(at, "'%s' may not appear in NULLIFY"_err_en_US, at)
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.Attach(std::move(*whyNot));
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}
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}
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},
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},
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pointerObject.u);
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}
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// From 9.7.3.1(1)
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// A pointer-object shall not depend on the value,
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// bounds, or association status of another pointer-
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// object in the same NULLIFY statement.
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// This restriction is the programmer's responsibility.
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// Some dependencies can be found compile time or at
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// runtime, but for now we choose to skip such checks.
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}
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} // namespace Fortran::semantics
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