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
24using namespace clang;
25using namespace ento;
26
27namespace {
28
29class CXXSelfAssignmentChecker : public Checker<check::BeginFunction> {
30public:
31 CXXSelfAssignmentChecker();
32 void checkBeginFunction(CheckerContext &C) const;
33};
34}
35
36CXXSelfAssignmentChecker::CXXSelfAssignmentChecker() {}
37
38void CXXSelfAssignmentChecker::checkBeginFunction(CheckerContext &C) const {
39 if (!C.inTopFrame())
40 return;
41 const auto *LCtx = C.getLocationContext();
42 const auto *MD = dyn_cast<CXXMethodDecl>(Val: 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(LV: SVB.getCXXThis(D: MD, SFC: LCtx->getStackFrame()));
51 auto Param = SVB.makeLoc(region: State->getRegion(D: MD->getParamDecl(i: 0), LC: LCtx));
52 auto ParamVal = State->getSVal(LV: Param);
53
54 ProgramStateRef SelfAssignState = State->bindLoc(location: Param, V: ThisVal, LCtx);
55 const NoteTag *SelfAssignTag =
56 C.getNoteTag(Cb: [MD](PathSensitiveBugReport &BR) -> std::string {
57 SmallString<256> Msg;
58 llvm::raw_svector_ostream Out(Msg);
59 Out << "Assuming " << MD->getParamDecl(i: 0)->getName() << " == *this";
60 return std::string(Out.str());
61 });
62 C.addTransition(State: SelfAssignState, Tag: SelfAssignTag);
63
64 ProgramStateRef NonSelfAssignState = State->bindLoc(location: Param, V: ParamVal, LCtx);
65 const NoteTag *NonSelfAssignTag =
66 C.getNoteTag(Cb: [MD](PathSensitiveBugReport &BR) -> std::string {
67 SmallString<256> Msg;
68 llvm::raw_svector_ostream Out(Msg);
69 Out << "Assuming " << MD->getParamDecl(i: 0)->getName() << " != *this";
70 return std::string(Out.str());
71 });
72 C.addTransition(State: NonSelfAssignState, Tag: NonSelfAssignTag);
73}
74
75void ento::registerCXXSelfAssignmentChecker(CheckerManager &Mgr) {
76 Mgr.registerChecker<CXXSelfAssignmentChecker>();
77}
78
79bool ento::shouldRegisterCXXSelfAssignmentChecker(const CheckerManager &mgr) {
80 return true;
81}
82