Author: ericwf Date: Wed May 10 14:35:49 2017 New Revision: 302709 URL: http://llvm.org/viewvc/llvm-project?rev=302709&view=rev Log: [libc++] Fix PR32979 - types with a private std::enable_shared_from_this base break shared_ptr
Summary: This patch fixes bugs.llvm.org/PR32979. [util.smartptr.shared.const] says: > In the constructor definitions below, enables shared_from_this with p, for a > pointer p of type Y*, means > that if Y has an unambiguous and accessible base class that is a > specialization of enable_shared_from_- > this. This means that libc++ needs to respect the access specifier of the base class, and not attempt to construct and enabled_shared_from_this base if it is private. However access specifiers don't affect overload resolution so our current implementation will attempt to construct the private base. This patch uses SFINAE to correctly detect if the shared_ptr input has an accessible enable_shared_from_this base class. Reviewers: mclow.lists Reviewed By: mclow.lists Subscribers: cfe-commits Differential Revision: https://reviews.llvm.org/D33033 Modified: libcxx/trunk/include/memory libcxx/trunk/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp Modified: libcxx/trunk/include/memory URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/memory?rev=302709&r1=302708&r2=302709&view=diff ============================================================================== --- libcxx/trunk/include/memory (original) +++ libcxx/trunk/include/memory Wed May 10 14:35:49 2017 @@ -3924,7 +3924,10 @@ private: template <class _Yp, class _OrigPtr> _LIBCPP_INLINE_VISIBILITY - void + typename enable_if<is_convertible<_OrigPtr*, + const enable_shared_from_this<_Yp>* + >::value, + void>::type __enable_weak_this(const enable_shared_from_this<_Yp>* __e, _OrigPtr* __ptr) _NOEXCEPT { @@ -3943,6 +3946,7 @@ private: template <class _Up> friend class _LIBCPP_TEMPLATE_VIS weak_ptr; }; + template<class _Tp> inline _LIBCPP_CONSTEXPR Modified: libcxx/trunk/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp?rev=302709&r1=302708&r2=302709&view=diff ============================================================================== --- libcxx/trunk/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp (original) +++ libcxx/trunk/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp Wed May 10 14:35:49 2017 @@ -49,6 +49,11 @@ struct Bar : public Foo { }; +struct PrivateBase : private std::enable_shared_from_this<PrivateBase> { + std::weak_ptr<PrivateBase> get_weak() { return weak_from_this(); } +}; + + int main() { { // https://bugs.llvm.org/show_bug.cgi?id=18843 @@ -74,6 +79,12 @@ int main() assert(p == q); assert(!p.owner_before(q) && !q.owner_before(p)); // p and q share ownership } + { + typedef std::shared_ptr<PrivateBase> APtr; + typedef std::weak_ptr<PrivateBase> WeakAPtr; + APtr a1 = std::make_shared<PrivateBase>(); + assert(a1.use_count() == 1); + } // Test LWG issue 2529. Only reset '__weak_ptr_' when it's already expired. // http://cplusplus.github.io/LWG/lwg-active.html#2529. // Test two different ways: _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
