//===-- 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-insensitive 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()3
)

    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

       << "'.  A method with the same name (same selector) is also defined in "

          "class '"

       << *MethAncestor->getClassInterface() << "' and has a return type of '"

       << ResAncestor

       << "'.  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 && 
NumMethods17
) {

    for (const auto *M : C->instance_methods()) {

      Selector S = M->getSelector();

      MapTy::iterator MI = IMeths.find(S);

      if (MI == IMeths.end() || 
MI->second == nullptr6
)

        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 CheckerManager &mgr) {

  return true;

}