1 //==- ObjCPropertyChecker.cpp - Check ObjC properties ------------*- 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 checker finds issues with Objective-C properties.
10 //  Currently finds only one kind of issue:
11 //  - Find synthesized properties with copy attribute of mutable NS collection
12 //    types. Calling -copy on such collections produces an immutable copy,
13 //    which contradicts the type of the property.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
18 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
19 #include "clang/StaticAnalyzer/Core/Checker.h"
20 
21 using namespace clang;
22 using namespace ento;
23 
24 namespace {
25 class ObjCPropertyChecker
26     : public Checker<check::ASTDecl<ObjCPropertyDecl>> {
27   void checkCopyMutable(const ObjCPropertyDecl *D, BugReporter &BR) const;
28 
29 public:
30   void checkASTDecl(const ObjCPropertyDecl *D, AnalysisManager &Mgr,
31                     BugReporter &BR) const;
32 };
33 } // end anonymous namespace.
34 
35 void ObjCPropertyChecker::checkASTDecl(const ObjCPropertyDecl *D,
36                                        AnalysisManager &Mgr,
37                                        BugReporter &BR) const {
38   checkCopyMutable(D, BR);
39 }
40 
41 void ObjCPropertyChecker::checkCopyMutable(const ObjCPropertyDecl *D,
42                                            BugReporter &BR) const {
43   if (D->isReadOnly() || D->getSetterKind() != ObjCPropertyDecl::Copy)
44     return;
45 
46   QualType T = D->getType();
47   if (!T->isObjCObjectPointerType())
48     return;
49 
50   const std::string &PropTypeName(T->getPointeeType().getCanonicalType()
51                                                      .getUnqualifiedType()
52                                                      .getAsString());
53   if (!StringRef(PropTypeName).startswith("NSMutable"))
54     return;
55 
56   const ObjCImplDecl *ImplD = nullptr;
57   if (const ObjCInterfaceDecl *IntD =
58           dyn_cast<ObjCInterfaceDecl>(D->getDeclContext())) {
59     ImplD = IntD->getImplementation();
60   } else if (auto *CatD = dyn_cast<ObjCCategoryDecl>(D->getDeclContext())) {
61     ImplD = CatD->getClassInterface()->getImplementation();
62   }
63 
64   if (!ImplD || ImplD->HasUserDeclaredSetterMethod(D))
65     return;
66 
67   SmallString<128> Str;
68   llvm::raw_svector_ostream OS(Str);
69   OS << "Property of mutable type '" << PropTypeName
70      << "' has 'copy' attribute; an immutable object will be stored instead";
71 
72   BR.EmitBasicReport(
73       D, this, "Objective-C property misuse", "Logic error", OS.str(),
74       PathDiagnosticLocation::createBegin(D, BR.getSourceManager()),
75       D->getSourceRange());
76 }
77 
78 void ento::registerObjCPropertyChecker(CheckerManager &Mgr) {
79   Mgr.registerChecker<ObjCPropertyChecker>();
80 }
81 
82 bool ento::shouldRegisterObjCPropertyChecker(const CheckerManager &mgr) {
83   return true;
84 }
85