clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp

   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 }