1 //===--- DeleteNullPointerCheck.cpp - clang-tidy---------------------------===//
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 "DeleteNullPointerCheck.h"
10 #include "../utils/LexerUtils.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Lex/Lexer.h"
14
15 using namespace clang::ast_matchers;
16
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20
registerMatchers(MatchFinder * Finder)21 void DeleteNullPointerCheck::registerMatchers(MatchFinder *Finder) {
22 const auto DeleteExpr =
23 cxxDeleteExpr(
24 has(declRefExpr(to(decl(equalsBoundNode("deletedPointer"))))))
25 .bind("deleteExpr");
26
27 const auto DeleteMemberExpr =
28 cxxDeleteExpr(has(memberExpr(hasDeclaration(
29 fieldDecl(equalsBoundNode("deletedMemberPointer"))))))
30 .bind("deleteMemberExpr");
31
32 const auto PointerExpr = anyOf(
33 declRefExpr(to(decl().bind("deletedPointer"))),
34 memberExpr(hasDeclaration(fieldDecl().bind("deletedMemberPointer"))));
35
36 const auto BinaryPointerCheckCondition = binaryOperator(hasOperands(
37 anyOf(cxxNullPtrLiteralExpr(), integerLiteral(equals(0))), PointerExpr));
38
39 Finder->addMatcher(
40 ifStmt(hasCondition(anyOf(PointerExpr, BinaryPointerCheckCondition)),
41 hasThen(anyOf(
42 DeleteExpr, DeleteMemberExpr,
43 compoundStmt(anyOf(has(DeleteExpr), has(DeleteMemberExpr)),
44 statementCountIs(1))
45 .bind("compound"))))
46 .bind("ifWithDelete"),
47 this);
48 }
49
check(const MatchFinder::MatchResult & Result)50 void DeleteNullPointerCheck::check(const MatchFinder::MatchResult &Result) {
51 const auto *IfWithDelete = Result.Nodes.getNodeAs<IfStmt>("ifWithDelete");
52 const auto *Compound = Result.Nodes.getNodeAs<CompoundStmt>("compound");
53
54 auto Diag = diag(
55 IfWithDelete->getBeginLoc(),
56 "'if' statement is unnecessary; deleting null pointer has no effect");
57 if (IfWithDelete->getElse())
58 return;
59 // FIXME: generate fixit for this case.
60
61 Diag << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(
62 IfWithDelete->getBeginLoc(),
63 utils::lexer::getPreviousToken(IfWithDelete->getThen()->getBeginLoc(),
64 *Result.SourceManager,
65 Result.Context->getLangOpts())
66 .getLocation()));
67
68 if (Compound) {
69 Diag << FixItHint::CreateRemoval(
70 CharSourceRange::getTokenRange(Compound->getLBracLoc()));
71 Diag << FixItHint::CreateRemoval(
72 CharSourceRange::getTokenRange(Compound->getRBracLoc()));
73 }
74 }
75
76 } // namespace readability
77 } // namespace tidy
78 } // namespace clang
79