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