Pushed On Thu, 31 Oct 2024 at 20:08, Jonathan Wakely <jwak...@redhat.com> wrote: > > Currently dereferencing an empty shared_ptr prints a complicated > internal type in the assertion message: > > include/bits/shared_ptr_base.h:1377: std::__shared_ptr_access<_Tp, _Lp, > <anonymous>, <anonymous> >::element_type& std::__shared_ptr_access<_Tp, _Lp, > <anonymous>, <anonymous> >::operator*() const [with _Tp = > std::filesystem::__cxx11::recursive_directory_iterator::_Dir_stack; > __gnu_cxx::_Lock_policy _Lp = __gnu_cxx::_S_atomic; bool <anonymous> = false; > bool <anonymous> = false; element_type = > std::filesystem::__cxx11::recursive_directory_iterator::_Dir_stack]: > Assertion '_M_get() != nullptr' failed. > > Users don't care about any of the _Lp and <anonymous> template > parameters, so this is unnecessarily verbose. > > We can simplify it to something that only mentions "shared_ptr_deref" > and the element type: > > include/bits/shared_ptr_base.h:1371: _Tp* std::__shared_ptr_deref(_Tp*) [with > _Tp = filesystem::__cxx11::recursive_directory_iterator::_Dir_stack]: > Assertion '__p != nullptr' failed. > > libstdc++-v3/ChangeLog: > > * include/bits/shared_ptr_base.h (__shared_ptr_deref): New > function template. > (__shared_ptr_access, __shared_ptr_access<>): Use it. > --- > Tested x86_64-linux. > > Also available for review at: > https://forge.sourceware.org/gcc/gcc-TEST/pulls/13 > > libstdc++-v3/include/bits/shared_ptr_base.h | 28 +++++++++++++-------- > 1 file changed, 17 insertions(+), 11 deletions(-) > > diff --git a/libstdc++-v3/include/bits/shared_ptr_base.h > b/libstdc++-v3/include/bits/shared_ptr_base.h > index 9a7617e7014..ee01594ce0c 100644 > --- a/libstdc++-v3/include/bits/shared_ptr_base.h > +++ b/libstdc++-v3/include/bits/shared_ptr_base.h > @@ -1337,6 +1337,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > { }; > > > + template<typename _Tp> > + [[__gnu__::__always_inline__]] > + inline _Tp* > + __shared_ptr_deref(_Tp* __p) > + { > + __glibcxx_assert(__p != nullptr); > + return __p; > + } > + > // Define operator* and operator-> for shared_ptr<T>. > template<typename _Tp, _Lock_policy _Lp, > bool = is_array<_Tp>::value, bool = is_void<_Tp>::value> > @@ -1347,10 +1356,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > element_type& > operator*() const noexcept > - { > - __glibcxx_assert(_M_get() != nullptr); > - return *_M_get(); > - } > + { return *std::__shared_ptr_deref(_M_get()); } > > element_type* > operator->() const noexcept > @@ -1392,10 +1398,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]] > element_type& > operator*() const noexcept > - { > - __glibcxx_assert(_M_get() != nullptr); > - return *_M_get(); > - } > + { return *std::__shared_ptr_deref(_M_get()); } > > [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]] > element_type* > @@ -1406,13 +1409,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > } > #endif > > +#pragma GCC diagnostic push > +#pragma GCC diagnostic ignored "-Wc++17-extensions" > element_type& > operator[](ptrdiff_t __i) const noexcept > { > - __glibcxx_assert(_M_get() != nullptr); > - __glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value); > - return _M_get()[__i]; > + if constexpr (extent<_Tp>::value) > + __glibcxx_assert(__i < extent<_Tp>::value); > + return std::__shared_ptr_deref(_M_get())[__i]; > } > +#pragma GCC diagnostic pop > > private: > element_type* > -- > 2.47.0 >
