1 //===-- lib/Semantics/check-nullify.cpp -----------------------------------===//
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 #include "check-nullify.h"
10 #include "assignment.h"
11 #include "flang/Evaluate/expression.h"
12 #include "flang/Parser/message.h"
13 #include "flang/Parser/parse-tree.h"
14 #include "flang/Semantics/expression.h"
15 #include "flang/Semantics/tools.h"
16
17 namespace Fortran::semantics {
18
Leave(const parser::NullifyStmt & nullifyStmt)19 void NullifyChecker::Leave(const parser::NullifyStmt &nullifyStmt) {
20 CHECK(context_.location());
21 const Scope &scope{context_.FindScope(*context_.location())};
22 const Scope *pure{FindPureProcedureContaining(scope)};
23 parser::ContextualMessages messages{
24 *context_.location(), &context_.messages()};
25 for (const parser::PointerObject &pointerObject : nullifyStmt.v) {
26 std::visit(
27 common::visitors{
28 [&](const parser::Name &name) {
29 const Symbol &symbol{DEREF(name.symbol)};
30 if (context_.HasError(&symbol)) {
31 // already reported an error
32 } else if (!IsVariableName(symbol) && !IsProcName(symbol)) {
33 messages.Say(name.source,
34 "name in NULLIFY statement must be a variable or procedure pointer name"_err_en_US);
35 } else if (!IsPointer(symbol)) { // C951
36 messages.Say(name.source,
37 "name in NULLIFY statement must have the POINTER attribute"_err_en_US);
38 } else if (pure) {
39 CheckDefinabilityInPureScope(messages, symbol, scope, *pure);
40 }
41 },
42 [&](const parser::StructureComponent &structureComponent) {
43 evaluate::ExpressionAnalyzer analyzer{context_};
44 if (MaybeExpr checked{analyzer.Analyze(structureComponent)}) {
45 if (!IsPointer(*structureComponent.component.symbol)) { // C951
46 messages.Say(structureComponent.component.source,
47 "component in NULLIFY statement must have the POINTER attribute"_err_en_US);
48 } else if (pure) {
49 if (const Symbol * symbol{GetFirstSymbol(checked)}) {
50 CheckDefinabilityInPureScope(
51 messages, *symbol, scope, *pure);
52 }
53 }
54 }
55 },
56 },
57 pointerObject.u);
58 }
59 // From 9.7.3.1(1)
60 // A pointer-object shall not depend on the value,
61 // bounds, or association status of another pointer-
62 // object in the same NULLIFY statement.
63 // This restriction is the programmer's responsibilty.
64 // Some dependencies can be found compile time or at
65 // runtime, but for now we choose to skip such checks.
66 }
67 } // namespace Fortran::semantics
68