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// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_REFCOUNTED_H_
#define BASE_REFCOUNTED_H_
namespace base {
template <typename T>
class RefCounted {
public:
RefCounted() {}
protected:
~RefCounted() {}
};
template <typename T>
class RefCountedThreadSafe {
public:
RefCountedThreadSafe() {}
protected:
~RefCountedThreadSafe() {}
};
} // namespace base
// Ignore classes whose inheritance tree ends in WebKit's RefCounted base
// class. Though prone to error, this pattern is very prevalent in WebKit
// code, so do not issue any warnings.
namespace WebKit {
template <typename T>
class RefCounted {
public:
RefCounted() {}
~RefCounted() {}
};
} // namespace WebKit
// Unsafe; should error.
class PublicRefCountedDtorInHeader
: public base::RefCounted<PublicRefCountedDtorInHeader> {
public:
PublicRefCountedDtorInHeader() {}
~PublicRefCountedDtorInHeader() {}
private:
friend class base::RefCounted<PublicRefCountedDtorInHeader>;
};
// Unsafe; should error.
class PublicRefCountedThreadSafeDtorInHeader
: public base::RefCountedThreadSafe<
PublicRefCountedThreadSafeDtorInHeader> {
public:
PublicRefCountedThreadSafeDtorInHeader() {}
~PublicRefCountedThreadSafeDtorInHeader() {}
private:
friend class base::RefCountedThreadSafe<
PublicRefCountedThreadSafeDtorInHeader>;
};
// Unsafe; should error.
class ProtectedRefCountedDtorInHeader
: public base::RefCounted<ProtectedRefCountedDtorInHeader> {
public:
ProtectedRefCountedDtorInHeader() {}
protected:
~ProtectedRefCountedDtorInHeader() {}
private:
friend class base::RefCounted<ProtectedRefCountedDtorInHeader>;
};
// Safe; should not have errors
class ProtectedRefCountedVirtualDtorInHeader
: public base::RefCounted<ProtectedRefCountedVirtualDtorInHeader> {
public:
ProtectedRefCountedVirtualDtorInHeader() {}
protected:
virtual ~ProtectedRefCountedVirtualDtorInHeader() {}
private:
friend class base::RefCounted<ProtectedRefCountedVirtualDtorInHeader>;
};
// Safe; should not have errors.
class PrivateRefCountedDtorInHeader
: public base::RefCounted<PrivateRefCountedDtorInHeader> {
public:
PrivateRefCountedDtorInHeader() {}
private:
~PrivateRefCountedDtorInHeader() {}
friend class base::RefCounted<PrivateRefCountedDtorInHeader>;
};
// Unsafe; A grandchild class ends up exposing their parent and grandparent's
// destructors.
class DerivedProtectedToPublicInHeader
: public ProtectedRefCountedVirtualDtorInHeader {
public:
DerivedProtectedToPublicInHeader() {}
~DerivedProtectedToPublicInHeader() override {}
};
// Unsafe; A grandchild ends up implicitly exposing their parent and
// grantparent's destructors.
class ImplicitDerivedProtectedToPublicInHeader
: public ProtectedRefCountedVirtualDtorInHeader {
public:
ImplicitDerivedProtectedToPublicInHeader() {}
};
// Unsafe-but-ignored; should not have errors.
class WebKitPublicDtorInHeader
: public WebKit::RefCounted<WebKitPublicDtorInHeader> {
public:
WebKitPublicDtorInHeader() {}
~WebKitPublicDtorInHeader() {}
};
// Unsafe-but-ignored; should not have errors.
class WebKitDerivedPublicDtorInHeader
: public WebKitPublicDtorInHeader {
public:
WebKitDerivedPublicDtorInHeader() {}
~WebKitDerivedPublicDtorInHeader() {}
};
class APublicInterface {
public:
virtual ~APublicInterface() {}
virtual void DoFoo() = 0;
};
// Unsafe. "ImplementsAPublicInterface* foo" can be deleted via
// "delete (APublicInterface*)foo;".
class ImplementsAPublicInterface
: public APublicInterface,
public base::RefCounted<ImplementsAPublicInterface> {
public:
void DoFoo() override {}
protected:
~ImplementsAPublicInterface() override {}
private:
friend class base::RefCounted<ImplementsAPublicInterface>;
};
class AnImplicitInterface {
public:
virtual void DoBar() {}
};
// Unsafe.
class ImplementsAnImplicitInterface
: public AnImplicitInterface,
public base::RefCounted<ImplementsAnImplicitInterface> {
public:
void DoBar() override {}
private:
friend class base::RefCounted<ImplementsAnImplicitInterface>;
~ImplementsAnImplicitInterface() {}
};
// Safe. Private inheritance does not expose the base destructor.
class PrivatelyImplementsAPublicInterface
: private APublicInterface,
public base::RefCounted<PrivatelyImplementsAPublicInterface> {
public:
void DoFoo() override {}
private:
friend class base::RefCounted<PrivatelyImplementsAPublicInterface>;
~PrivatelyImplementsAPublicInterface() override {}
};
// Unsafe.
class BaseInterface {
public:
virtual ~BaseInterface() {}
virtual void DoFoo() {}
};
class DerivedInterface : public BaseInterface {
protected:
~DerivedInterface() override {}
};
class SomeOtherInterface {
public:
virtual ~SomeOtherInterface() {}
virtual void DoBar() {}
};
class RefcountedType : public base::RefCounted<RefcountedType> {
protected:
~RefcountedType() {}
private:
friend class base::RefCounted<RefcountedType>;
};
class UnsafeInheritanceChain
: public DerivedInterface,
public SomeOtherInterface,
public RefcountedType {
public:
// DerivedInterface
void DoFoo() override {}
// SomeOtherInterface
void DoBar() override {}
protected:
~UnsafeInheritanceChain() override {}
};
#endif // BASE_REFCOUNTED_H_
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