On Mon, 27 May 2024 at 05:37, François Dumont <frs.dum...@gmail.com> wrote: > > Here is a new version working also in C++98.
Can we use a different solution that doesn't involve an explicit template argument list for that __uninitialized_fill_n_a call? -+ this->_M_impl._M_finish = std::__uninitialized_fill_n_a ++ this->_M_impl._M_finish = ++ std::__uninitialized_fill_n_a<pointer, size_type, value_type> + (__start, __n, __value, _M_get_Tp_allocator()); Using _M_fill_initialize solves the problem :-) > > Note that I have this failure: > > FAIL: 23_containers/vector/types/1.cc -std=gnu++98 (test for excess errors) > > but it's already failing on master, my patch do not change anything. Yes, that's been failing for ages. > > Tested under Linux x64, > > still ok to commit ? > > François > > On 24/05/2024 16:17, Jonathan Wakely wrote: > > On Thu, 23 May 2024 at 18:38, François Dumont <frs.dum...@gmail.com> wrote: > >> > >> On 23/05/2024 15:31, Jonathan Wakely wrote: > >>> On 23/05/24 06:55 +0200, François Dumont wrote: > >>>> As explained in this email: > >>>> > >>>> https://gcc.gnu.org/pipermail/libstdc++/2024-April/058552.html > >>>> > >>>> I experimented -Wfree-nonheap-object because of my enhancements on > >>>> algos. > >>>> > >>>> So here is a patch to extend the usage of the _Guard type to other > >>>> parts of vector. > >>> Nice, that fixes the warning you were seeing? > >> Yes ! I indeed forgot to say so :-) > >> > >> > >>> We recently got a bug report about -Wfree-nonheap-object in > >>> std::vector, but that is coming from _M_realloc_append which already > >>> uses the RAII guard :-( > >>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115016 > >> Note that I also had to move call to __uninitialized_copy_a before > >> assigning this->_M_impl._M_start so get rid of the -Wfree-nonheap-object > >> warn. But _M_realloc_append is already doing potentially throwing > >> operations before assigning this->_M_impl so it must be something else. > >> > >> Though it made me notice another occurence of _Guard in this method. Now > >> replaced too in this new patch. > >> > >> libstdc++: Use RAII to replace try/catch blocks > >> > >> Move _Guard into std::vector declaration and use it to guard all > >> calls to > >> vector _M_allocate. > >> > >> Doing so the compiler has more visibility on what is done with the > >> pointers > >> and do not raise anymore the -Wfree-nonheap-object warning. > >> > >> libstdc++-v3/ChangeLog: > >> > >> * include/bits/vector.tcc (_Guard): Move all the nested > >> duplicated class... > >> * include/bits/stl_vector.h (_Guard_alloc): ...here. > >> (_M_allocate_and_copy): Use latter. > >> (_M_initialize_dispatch): Likewise and set _M_finish first > >> from the result > >> of __uninitialize_fill_n_a that can throw. > >> (_M_range_initialize): Likewise. > >> > >>>> diff --git a/libstdc++-v3/include/bits/stl_vector.h > >>>> b/libstdc++-v3/include/bits/stl_vector.h > >>>> index 31169711a48..4ea74e3339a 100644 > >>>> --- a/libstdc++-v3/include/bits/stl_vector.h > >>>> +++ b/libstdc++-v3/include/bits/stl_vector.h > >>>> @@ -1607,6 +1607,39 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER > >>>> clear() _GLIBCXX_NOEXCEPT > >>>> { _M_erase_at_end(this->_M_impl._M_start); } > >>>> > >>>> + private: > >>>> + // RAII guard for allocated storage. > >>>> + struct _Guard > >>> If it's being defined at class scope instead of locally in a member > >>> function, I think a better name would be good. Maybe _Ptr_guard or > >>> _Dealloc_guard or something. > >> _Guard_alloc chosen. > >>>> + { > >>>> + pointer _M_storage; // Storage to deallocate > >>>> + size_type _M_len; > >>>> + _Base& _M_vect; > >>>> + > >>>> + _GLIBCXX20_CONSTEXPR > >>>> + _Guard(pointer __s, size_type __l, _Base& __vect) > >>>> + : _M_storage(__s), _M_len(__l), _M_vect(__vect) > >>>> + { } > >>>> + > >>>> + _GLIBCXX20_CONSTEXPR > >>>> + ~_Guard() > >>>> + { > >>>> + if (_M_storage) > >>>> + _M_vect._M_deallocate(_M_storage, _M_len); > >>>> + } > >>>> + > >>>> + _GLIBCXX20_CONSTEXPR > >>>> + pointer > >>>> + _M_release() > >>>> + { > >>>> + pointer __res = _M_storage; > >>>> + _M_storage = 0; > >>> I don't think the NullablePointer requirements include assigning 0, > >>> only from nullptr, which isn't valid in C++98. > >>> > >>> https://en.cppreference.com/w/cpp/named_req/NullablePointer > >>> > >>> Please use _M_storage = pointer() instead. > >> I forgot about user fancy pointer, fixed. > >> > >> > >>>> + return __res; > >>>> + } > >>>> + > >>>> + private: > >>>> + _Guard(const _Guard&); > >>>> + }; > >>>> + > >>>> protected: > >>>> /** > >>>> * Memory expansion handler. Uses the member allocation > >>>> function to > >>>> @@ -1618,18 +1651,10 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER > >>>> _M_allocate_and_copy(size_type __n, > >>>> _ForwardIterator __first, _ForwardIterator __last) > >>>> { > >>>> - pointer __result = this->_M_allocate(__n); > >>>> - __try > >>>> - { > >>>> - std::__uninitialized_copy_a(__first, __last, __result, > >>>> - _M_get_Tp_allocator()); > >>>> - return __result; > >>>> - } > >>>> - __catch(...) > >>>> - { > >>>> - _M_deallocate(__result, __n); > >>>> - __throw_exception_again; > >>>> - } > >>>> + _Guard __guard(this->_M_allocate(__n), __n, *this); > >>>> + std::__uninitialized_copy_a > >>>> + (__first, __last, __guard._M_storage, _M_get_Tp_allocator()); > >>>> + return __guard._M_release(); > >>>> } > >>>> > >>>> > >>>> @@ -1642,13 +1667,15 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER > >>>> // 438. Ambiguity in the "do the right thing" clause > >>>> template<typename _Integer> > >>>> void > >>>> - _M_initialize_dispatch(_Integer __n, _Integer __value, __true_type) > >>>> + _M_initialize_dispatch(_Integer __int_n, _Integer __value, > >>>> __true_type) > >>>> { > >>>> - this->_M_impl._M_start = _M_allocate(_S_check_init_len( > >>>> - static_cast<size_type>(__n), _M_get_Tp_allocator())); > >>>> - this->_M_impl._M_end_of_storage = > >>>> - this->_M_impl._M_start + static_cast<size_type>(__n); > >>>> - _M_fill_initialize(static_cast<size_type>(__n), __value); > >>> Please fix the comment on _M_fill_initialize if you're removing the > >>> use of it here. > >> Already done in this initial patch proposal, see below. > >> > >>>> + const size_type __n = static_cast<size_type>(__int_n); > >>>> + _Guard __guard(_M_allocate(_S_check_init_len( > >>>> + __n, _M_get_Tp_allocator())), __n, *this); > >>> I think this would be easier to read if the _S_check_init_len call was > >>> done first, and maybe the allocation too, since we are going to need a > >>> local __start later anyway. So maybe like this: > >>> > >>> template<typename _Integer> > >>> void > >>> _M_initialize_dispatch(_Integer __ni, _Integer __value, __true_type) > >>> { > >>> const size_type __n = static_cast<size_type>(__ni); > >>> pointer __start = _M_allocate(_S_check_init_len(__n), > >>> _M_get_Tp_allocator()); > >>> _Guard __guard(__start, __n, *this); > >>> this->_M_impl._M_start = __start; > >>> _M_fill_initialize(__n, __value); > >>> this->_M_impl._M_end_of_storage = __start + __n; > >>> (void) __guard._M_release(); > >>> } > >>> > >>> Or inline the __uninitialized_fill_n_a call if you want to (but then > >>> fix the comment on _M_fill_initialize). Inlining it does make this > >>> function more consistent with the next one, which calls > >>> __uninitialized_copy_a directly. > >> Yes, this is why I called __uninitialized_fill_n_a instead and also to > >> do so *before* assigning _M_impl._M_start. > >> > >> > >>>> - // Called by the first initialize_dispatch above and by the > >>>> - // vector(n,value,a) constructor. > >>>> + // Called by the vector(n,value,a) constructor. > >> See, it's here :-) > > Doh! Sorry, I'm not sure how I missed that. > > > >> Ok to commit ? > > OK for trunk, thanks! > >
