clang-tools-extra/clang-tidy/readability/DeleteNullPointerCheck.cpp

   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
  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
  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