re PR libstdc++/59656 (weak_ptr::lock function crashes when compiling with -fno-exceptions flag)
2014-01-28 Jonathan Wakely <jwakely@redhat.com> Kyle Lippincott <spectral@google.com> PR libstdc++/59656 * include/bits/shared_ptr.h (shared_ptr): Add new non-throwing constructor and grant friendship to weak_ptr. (weak_ptr::lock()): Use new constructor. * include/bits/shared_ptr_base.h (_Sp_counted_base::_M_add_ref_lock_nothrow()): Declare new function and define specializations. (__shared_count): Add new non-throwing constructor. (__shared_ptr): Add new non-throwing constructor and grant friendship to __weak_ptr. (__weak_ptr::lock()): Use new constructor. * testsuite/20_util/shared_ptr/cons/43820_neg.cc: Adjust dg-error. * testsuite/20_util/shared_ptr/cons/void_neg.cc: Likewise. Co-Authored-By: Kyle Lippincott <spectral@google.com> From-SVN: r207180
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@ -1,3 +1,20 @@
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2014-01-28 Jonathan Wakely <jwakely@redhat.com>
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Kyle Lippincott <spectral@google.com>
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PR libstdc++/59656
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* include/bits/shared_ptr.h (shared_ptr): Add new non-throwing
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constructor and grant friendship to weak_ptr.
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(weak_ptr::lock()): Use new constructor.
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* include/bits/shared_ptr_base.h
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(_Sp_counted_base::_M_add_ref_lock_nothrow()): Declare new function
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and define specializations.
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(__shared_count): Add new non-throwing constructor.
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(__shared_ptr): Add new non-throwing constructor and grant friendship
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to __weak_ptr.
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(__weak_ptr::lock()): Use new constructor.
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* testsuite/20_util/shared_ptr/cons/43820_neg.cc: Adjust dg-error.
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* testsuite/20_util/shared_ptr/cons/void_neg.cc: Likewise.
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2014-01-27 Jonathan Wakely <jwakely@redhat.com>
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PR libstdc++/59215
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@ -319,6 +319,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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template<typename _Tp1, typename _Alloc, typename... _Args>
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friend shared_ptr<_Tp1>
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allocate_shared(const _Alloc& __a, _Args&&... __args);
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// This constructor is non-standard, it is used by weak_ptr::lock().
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shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t)
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: __shared_ptr<_Tp>(__r, std::nothrow) { }
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friend class weak_ptr<_Tp>;
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};
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// 20.7.2.2.7 shared_ptr comparisons
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@ -492,23 +498,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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shared_ptr<_Tp>
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lock() const noexcept
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{
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#ifdef __GTHREADS
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if (this->expired())
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return shared_ptr<_Tp>();
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__try
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{
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return shared_ptr<_Tp>(*this);
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}
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__catch(const bad_weak_ptr&)
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{
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return shared_ptr<_Tp>();
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}
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#else
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return this->expired() ? shared_ptr<_Tp>() : shared_ptr<_Tp>(*this);
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#endif
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}
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{ return shared_ptr<_Tp>(*this, std::nothrow); }
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};
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// 20.7.2.3.6 weak_ptr specialized algorithms.
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@ -134,7 +134,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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void
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_M_add_ref_lock();
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bool
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_M_add_ref_lock_nothrow();
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void
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_M_release() noexcept
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{
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@ -246,6 +249,51 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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__ATOMIC_RELAXED));
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}
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template<>
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inline bool
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_Sp_counted_base<_S_single>::
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_M_add_ref_lock_nothrow()
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{
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if (_M_use_count == 0)
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return false;
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++_M_use_count;
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return true;
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}
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template<>
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inline bool
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_Sp_counted_base<_S_mutex>::
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_M_add_ref_lock_nothrow()
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{
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__gnu_cxx::__scoped_lock sentry(*this);
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if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
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{
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_M_use_count = 0;
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return false;
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}
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return true;
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}
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template<>
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inline bool
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_Sp_counted_base<_S_atomic>::
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_M_add_ref_lock_nothrow()
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{
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// Perform lock-free add-if-not-zero operation.
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_Atomic_word __count = _M_get_use_count();
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do
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{
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if (__count == 0)
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return false;
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// Replace the current counter value with the old value + 1, as
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// long as it's not changed meanwhile.
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}
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while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
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true, __ATOMIC_ACQ_REL,
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__ATOMIC_RELAXED));
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return true;
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}
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template<>
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inline void
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_Sp_counted_base<_S_single>::_M_add_ref_copy()
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@ -609,6 +657,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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// Throw bad_weak_ptr when __r._M_get_use_count() == 0.
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explicit __shared_count(const __weak_count<_Lp>& __r);
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// Does not throw if __r._M_get_use_count() == 0, caller must check.
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explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);
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~__shared_count() noexcept
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{
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if (_M_pi != nullptr)
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@ -761,15 +812,27 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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// Now that __weak_count is defined we can define this constructor:
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template<_Lock_policy _Lp>
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inline __shared_count<_Lp>:: __shared_count(const __weak_count<_Lp>& __r)
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inline
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__shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
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: _M_pi(__r._M_pi)
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{
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if (_M_pi != 0)
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if (_M_pi != nullptr)
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_M_pi->_M_add_ref_lock();
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else
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__throw_bad_weak_ptr();
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}
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// Now that __weak_count is defined we can define this constructor:
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template<_Lock_policy _Lp>
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inline
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__shared_count<_Lp>::
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__shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
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: _M_pi(__r._M_pi)
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{
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if (_M_pi != nullptr)
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if (!_M_pi->_M_add_ref_lock_nothrow())
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_M_pi = nullptr;
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}
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// Support for enable_shared_from_this.
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@ -1077,6 +1140,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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friend __shared_ptr<_Tp1, _Lp1>
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__allocate_shared(const _Alloc& __a, _Args&&... __args);
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// This constructor is used by __weak_ptr::lock() and
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// shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
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__shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
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: _M_refcount(__r._M_refcount, std::nothrow)
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{
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_M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
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}
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friend class __weak_ptr<_Tp, _Lp>;
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private:
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void*
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_M_get_deleter(const std::type_info& __ti) const noexcept
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@ -1322,31 +1395,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
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__shared_ptr<_Tp, _Lp>
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lock() const noexcept
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{
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#ifdef __GTHREADS
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// Optimization: avoid throw overhead.
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if (expired())
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return __shared_ptr<element_type, _Lp>();
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__try
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{
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return __shared_ptr<element_type, _Lp>(*this);
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}
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__catch(const bad_weak_ptr&)
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{
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// Q: How can we get here?
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// A: Another thread may have invalidated r after the
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// use_count test above.
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return __shared_ptr<element_type, _Lp>();
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}
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#else
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// Optimization: avoid try/catch overhead when single threaded.
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return expired() ? __shared_ptr<element_type, _Lp>()
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: __shared_ptr<element_type, _Lp>(*this);
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#endif
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} // XXX MT
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{ return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }
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long
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use_count() const noexcept
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{
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X* px = 0;
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std::shared_ptr<X> p1(px); // { dg-error "here" }
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// { dg-error "incomplete" "" { target *-*-* } 812 }
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// { dg-error "incomplete" "" { target *-*-* } 875 }
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std::shared_ptr<X> p9(ap()); // { dg-error "here" }
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// { dg-error "incomplete" "" { target *-*-* } 307 }
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void test01()
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{
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std::shared_ptr<void> p((void*)nullptr); // { dg-error "here" }
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// { dg-error "incomplete" "" { target *-*-* } 811 }
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// { dg-error "incomplete" "" { target *-*-* } 874 }
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}
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