clang-tools  6.0.0
DeleteNullPointerCheck.cpp
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1 //===--- DeleteNullPointerCheck.cpp - clang-tidy---------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "DeleteNullPointerCheck.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 
21 void DeleteNullPointerCheck::registerMatchers(MatchFinder *Finder) {
22  const auto DeleteExpr =
23  cxxDeleteExpr(has(castExpr(has(declRefExpr(
24  to(decl(equalsBoundNode("deletedPointer"))))))))
25  .bind("deleteExpr");
26 
27  const auto DeleteMemberExpr =
28  cxxDeleteExpr(has(castExpr(has(memberExpr(hasDeclaration(
29  fieldDecl(equalsBoundNode("deletedMemberPointer"))))))))
30  .bind("deleteMemberExpr");
31 
32  const auto PointerExpr = ignoringImpCasts(anyOf(
33  declRefExpr(to(decl().bind("deletedPointer"))),
34  memberExpr(hasDeclaration(fieldDecl().bind("deletedMemberPointer")))));
35 
36  const auto PointerCondition = castExpr(hasCastKind(CK_PointerToBoolean),
37  hasSourceExpression(PointerExpr));
38  const auto BinaryPointerCheckCondition =
39  binaryOperator(hasEitherOperand(castExpr(hasCastKind(CK_NullToPointer))),
40  hasEitherOperand(PointerExpr));
41 
42  Finder->addMatcher(
43  ifStmt(hasCondition(anyOf(PointerCondition, BinaryPointerCheckCondition)),
44  hasThen(anyOf(
45  DeleteExpr, DeleteMemberExpr,
46  compoundStmt(anyOf(has(DeleteExpr), has(DeleteMemberExpr)),
47  statementCountIs(1))
48  .bind("compound"))))
49  .bind("ifWithDelete"),
50  this);
51 }
52 
53 void DeleteNullPointerCheck::check(const MatchFinder::MatchResult &Result) {
54  const auto *IfWithDelete = Result.Nodes.getNodeAs<IfStmt>("ifWithDelete");
55  const auto *Compound = Result.Nodes.getNodeAs<CompoundStmt>("compound");
56 
57  auto Diag = diag(
58  IfWithDelete->getLocStart(),
59  "'if' statement is unnecessary; deleting null pointer has no effect");
60  if (IfWithDelete->getElse())
61  return;
62  // FIXME: generate fixit for this case.
63 
64  Diag << FixItHint::CreateRemoval(CharSourceRange::getTokenRange(
65  IfWithDelete->getLocStart(),
66  Lexer::getLocForEndOfToken(IfWithDelete->getCond()->getLocEnd(), 0,
67  *Result.SourceManager,
68  Result.Context->getLangOpts())));
69  if (Compound) {
70  Diag << FixItHint::CreateRemoval(
71  CharSourceRange::getTokenRange(Compound->getLBracLoc()));
72  Diag << FixItHint::CreateRemoval(
73  CharSourceRange::getTokenRange(Compound->getRBracLoc()));
74  }
75 }
76 
77 } // namespace readability
78 } // namespace tidy
79 } // namespace clang