https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69293
Bug ID: 69293
Summary: scoped_allocator_adaptor::construct calls wrong
function
Product: gcc
Version: 5.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: forever14 at bk dot ru
Target Milestone: ---
There is a bug in scoped_allocator_adaptor::construct. Consider following code:
#include <iostream>
#include <memory>
#include <scoped_allocator>
struct use_arg {
template<typename Alloc>
use_arg(int i, Alloc&)
{ std::cout << i << " in use_arg()\n"; }
};
namespace std {
template <typename A> struct uses_allocator<use_arg, A>: true_type {};
} // namespace std
void test_scoped()
{
std::scoped_allocator_adaptor<std::allocator<use_arg>> sa;
auto p = sa.allocate(1);
sa.construct(p, 4);
sa.destroy(p);
sa.deallocate(p, 1);
}
int main()
{
test_scoped();
}
There will not be compilation error, but should be, since:
template <class T, class... Args>
void construct(T* p, Args&&... args);
9
(9.1)
Effects:
...
(9.3) — Otherwise, if uses_allocator<T, inner_allocator_type>::value is true
and is_construct-
ible<T, Args..., inner_allocator_type>::value is true, calls OUTERMOST_ALLOC_-
TRAITS(*this):: construct(OUTERMOST (*this), p, std::forward<Args>(args)...,
inner_allocator()).
(9.4) — Otherwise, the program is ill-formed. [ Note: An error will result if
uses_allocator evaluates
to true but the specific constructor does not take an allocator. This
definition prevents a silent
failure to pass an inner allocator to a contained element. — end note ]
In code, is_constructible<T, Args..., inner_allocator_type>::value is false,
since use_arg receives Alloc by reference, but there is no test for this case
in libstdc++.
