clang/lib/StaticAnalyzer/Checkers/CXXSelfAssignmentChecker.cpp

   1 //=== CXXSelfAssignmentChecker.cpp -----------------------------*- C++ -*--===//
   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 // This file defines CXXSelfAssignmentChecker, which tests all custom defined
  10 // copy and move assignment operators for the case of self assignment, thus
  11 // where the parameter refers to the same location where the this pointer
  12 // points to. The checker itself does not do any checks at all, but it
  13 // causes the analyzer to check every copy and move assignment operator twice:
  14 // once for when 'this' aliases with the parameter and once for when it may not.
  15 // It is the task of the other enabled checkers to find the bugs in these two
  16 // different cases.
  17 //
  18 //===----------------------------------------------------------------------===//
  19
  20 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
  21 #include "clang/StaticAnalyzer/Core/Checker.h"
  22 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
  23
  24 using namespace clang;
  25 using namespace ento;
  26
  27 namespace {
  28
  29 class CXXSelfAssignmentChecker : public Checker<check::BeginFunction> {
  30 public:
  31   CXXSelfAssignmentChecker();
  32   void checkBeginFunction(CheckerContext &C) const;
  33 };
  34 }
  35
  36 CXXSelfAssignmentChecker::CXXSelfAssignmentChecker() {}
  37
  38 void CXXSelfAssignmentChecker::checkBeginFunction(CheckerContext &C) const {
  39   if (!C.inTopFrame())
  40     return;
  41   const auto *LCtx = C.getLocationContext();
  42   const auto *MD = dyn_cast<CXXMethodDecl>(LCtx->getDecl());
  43   if (!MD)
  44     return;
  45   if (!MD->isCopyAssignmentOperator() && !MD->isMoveAssignmentOperator())
  46     return;
  47   auto &State = C.getState();
  48   auto &SVB = C.getSValBuilder();
  49   auto ThisVal =
  50       State->getSVal(SVB.getCXXThis(MD, LCtx->getStackFrame()));
  51   auto Param = SVB.makeLoc(State->getRegion(MD->getParamDecl(0), LCtx));
  52   auto ParamVal = State->getSVal(Param);
  53
  54   ProgramStateRef SelfAssignState = State->bindLoc(Param, ThisVal, LCtx);
  55   const NoteTag *SelfAssignTag =
  56     C.getNoteTag([MD](PathSensitiveBugReport &BR) -> std::string {
  57         SmallString<256> Msg;
  58         llvm::raw_svector_ostream Out(Msg);
  59         Out << "Assuming " << MD->getParamDecl(0)->getName() << " == *this";
  60         return std::string(Out.str());
  61       });
  62   C.addTransition(SelfAssignState, SelfAssignTag);
  63
  64   ProgramStateRef NonSelfAssignState = State->bindLoc(Param, ParamVal, LCtx);
  65   const NoteTag *NonSelfAssignTag =
  66     C.getNoteTag([MD](PathSensitiveBugReport &BR) -> std::string {
  67         SmallString<256> Msg;
  68         llvm::raw_svector_ostream Out(Msg);
  69         Out << "Assuming " << MD->getParamDecl(0)->getName() << " != *this";
  70         return std::string(Out.str());
  71       });
  72   C.addTransition(NonSelfAssignState, NonSelfAssignTag);
  73 }
  74
  75 void ento::registerCXXSelfAssignmentChecker(CheckerManager &Mgr) {
  76   Mgr.registerChecker<CXXSelfAssignmentChecker>();
  77 }
  78
  79 bool ento::shouldRegisterCXXSelfAssignmentChecker(const CheckerManager &mgr) {
  80   return true;
  81 }