1 files changed, 84 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp
new file mode 100644
index 000000000000..9a49200545e3
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/ObjCPropertyChecker.cpp
@@ -0,0 +1,84 @@
+//==- ObjCPropertyChecker.cpp - Check ObjC properties ------------*- C++ -*-==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+//  This checker finds issues with Objective-C properties.
+//  Currently finds only one kind of issue:
+//  - Find synthesized properties with copy attribute of mutable NS collection
+//    types. Calling -copy on such collections produces an immutable copy,
+//    which contradicts the type of the property.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+
+using namespace clang;
+using namespace ento;
+
+namespace {
+class ObjCPropertyChecker
+    : public Checker<check::ASTDecl<ObjCPropertyDecl>> {
+  void checkCopyMutable(const ObjCPropertyDecl *D, BugReporter &BR) const;
+
+public:
+  void checkASTDecl(const ObjCPropertyDecl *D, AnalysisManager &Mgr,
+                    BugReporter &BR) const;
+};
+} // end anonymous namespace.
+
+void ObjCPropertyChecker::checkASTDecl(const ObjCPropertyDecl *D,
+                                       AnalysisManager &Mgr,
+                                       BugReporter &BR) const {
+  checkCopyMutable(D, BR);
+}
+
+void ObjCPropertyChecker::checkCopyMutable(const ObjCPropertyDecl *D,
+                                           BugReporter &BR) const {
+  if (D->isReadOnly() || D->getSetterKind() != ObjCPropertyDecl::Copy)
+    return;
+
+  QualType T = D->getType();
+  if (!T->isObjCObjectPointerType())
+    return;
+
+  const std::string &PropTypeName(T->getPointeeType().getCanonicalType()
+                                                     .getUnqualifiedType()
+                                                     .getAsString());
+  if (!StringRef(PropTypeName).startswith("NSMutable"))
+    return;
+
+  const ObjCImplDecl *ImplD = nullptr;
+  if (const ObjCInterfaceDecl *IntD =
+          dyn_cast<ObjCInterfaceDecl>(D->getDeclContext())) {
+    ImplD = IntD->getImplementation();
+  } else if (auto *CatD = dyn_cast<ObjCCategoryDecl>(D->getDeclContext())) {
+    ImplD = CatD->getClassInterface()->getImplementation();
+  }
+
+  if (!ImplD || ImplD->HasUserDeclaredSetterMethod(D))
+    return;
+
+  SmallString<128> Str;
+  llvm::raw_svector_ostream OS(Str);
+  OS << "Property of mutable type '" << PropTypeName
+     << "' has 'copy' attribute; an immutable object will be stored instead";
+
+  BR.EmitBasicReport(
+      D, this, "Objective-C property misuse", "Logic error", OS.str(),
+      PathDiagnosticLocation::createBegin(D, BR.getSourceManager()),
+      D->getSourceRange());
+}
+
+void ento::registerObjCPropertyChecker(CheckerManager &Mgr) {
+  Mgr.registerChecker<ObjCPropertyChecker>();
+}
+
+bool ento::shouldRegisterObjCPropertyChecker(const LangOptions &LO) {
+  return true;
+}