1 files changed, 143 insertions, 0 deletions
diff --git a/clang/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp b/clang/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp
new file mode 100644
index 000000000000..1694c237cda4
--- /dev/null
+++ b/clang/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp
@@ -0,0 +1,143 @@
+//===-- CheckObjCInstMethSignature.cpp - Check ObjC method signatures -----===//
+//
+// 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 file defines a CheckObjCInstMethSignature, a flow-insenstive check
+//  that determines if an Objective-C class interface incorrectly redefines
+//  the method signature in a subclass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
+#include "clang/Analysis/PathDiagnostic.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Type.h"
+#include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
+#include "clang/StaticAnalyzer/Core/Checker.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+using namespace ento;
+
+static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
+                               ASTContext &C) {
+
+  // Right now don't compare the compatibility of pointers.  That involves
+  // looking at subtyping relationships.  FIXME: Future patch.
+  if (Derived->isAnyPointerType() &&  Ancestor->isAnyPointerType())
+    return true;
+
+  return C.typesAreCompatible(Derived, Ancestor);
+}
+
+static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
+                               const ObjCMethodDecl *MethAncestor,
+                               BugReporter &BR, ASTContext &Ctx,
+                               const ObjCImplementationDecl *ID,
+                               const CheckerBase *Checker) {
+
+  QualType ResDerived = MethDerived->getReturnType();
+  QualType ResAncestor = MethAncestor->getReturnType();
+
+  if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
+    std::string sbuf;
+    llvm::raw_string_ostream os(sbuf);
+
+    os << "The Objective-C class '"
+       << *MethDerived->getClassInterface()
+       << "', which is derived from class '"
+       << *MethAncestor->getClassInterface()
+       << "', defines the instance method '";
+    MethDerived->getSelector().print(os);
+    os << "' whose return type is '"
+       << ResDerived.getAsString()
+       << "'.  A method with the same name (same selector) is also defined in "
+          "class '"
+       << *MethAncestor->getClassInterface()
+       << "' and has a return type of '"
+       << ResAncestor.getAsString()
+       << "'.  These two types are incompatible, and may result in undefined "
+          "behavior for clients of these classes.";
+
+    PathDiagnosticLocation MethDLoc =
+      PathDiagnosticLocation::createBegin(MethDerived,
+                                          BR.getSourceManager());
+
+    BR.EmitBasicReport(
+        MethDerived, Checker, "Incompatible instance method return type",
+        categories::CoreFoundationObjectiveC, os.str(), MethDLoc);
+  }
+}
+
+static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
+                                       BugReporter &BR,
+                                       const CheckerBase *Checker) {
+
+  const ObjCInterfaceDecl *D = ID->getClassInterface();
+  const ObjCInterfaceDecl *C = D->getSuperClass();
+
+  if (!C)
+    return;
+
+  ASTContext &Ctx = BR.getContext();
+
+  // Build a DenseMap of the methods for quick querying.
+  typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
+  MapTy IMeths;
+  unsigned NumMethods = 0;
+
+  for (auto *M : ID->instance_methods()) {
+    IMeths[M->getSelector()] = M;
+    ++NumMethods;
+  }
+
+  // Now recurse the class hierarchy chain looking for methods with the
+  // same signatures.
+  while (C && NumMethods) {
+    for (const auto *M : C->instance_methods()) {
+      Selector S = M->getSelector();
+
+      MapTy::iterator MI = IMeths.find(S);
+
+      if (MI == IMeths.end() || MI->second == nullptr)
+        continue;
+
+      --NumMethods;
+      ObjCMethodDecl *MethDerived = MI->second;
+      MI->second = nullptr;
+
+      CompareReturnTypes(MethDerived, M, BR, Ctx, ID, Checker);
+    }
+
+    C = C->getSuperClass();
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// ObjCMethSigsChecker
+//===----------------------------------------------------------------------===//
+
+namespace {
+class ObjCMethSigsChecker : public Checker<
+                                      check::ASTDecl<ObjCImplementationDecl> > {
+public:
+  void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
+                    BugReporter &BR) const {
+    CheckObjCInstMethSignature(D, BR, this);
+  }
+};
+}
+
+void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
+  mgr.registerChecker<ObjCMethSigsChecker>();
+}
+
+bool ento::shouldRegisterObjCMethSigsChecker(const LangOptions &LO) {
+  return true;
+}