https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85970
Bug ID: 85970
Summary: Cannot move a std::unique_ptr to insert into a map
Product: gcc
Version: 7.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jose.dapena at lge dot com
Target Milestone: ---
Created attachment 44206
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44206&action=edit
Test case
Trying to insert to an std::map with value type std::unique_ptr using a move to
the initializer list fails:
std::map<std::string, std::unique_ptr<A>> map;
std::string str = "a";
std::unique_ptr<A> a = std::make_unique<A>();
// This fails
map.insert({str, std::move(a)});
But, if instead of this we do:
map.insert(std::pair<std::string, std::unique_ptr<A>>(str, std::move(a)));
It works.
This is working in LLVM libc++.
The error we get is related to trying to use the copy contructor of std::pair
and std::unique_ptr:
/usr/include/c++/7/ext/new_allocator.h:136:4: error: use of deleted function
‘std::pair<_T1, _T2>::pair(const std::pair<_T1, _T2>&) [with _T1 = const
std::__cxx11::basic_string<char>; _T2 = std::unique_ptr<A>]’
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/7/bits/stl_algobase.h:64:0,
from /usr/include/c++/7/bits/stl_tree.h:63,
from /usr/include/c++/7/map:60,
from main.cc:1:
/usr/include/c++/7/bits/stl_pair.h:292:17: note: ‘std::pair<_T1,
_T2>::pair(const std::pair<_T1, _T2>&) [with _T1 = const
std::__cxx11::basic_string<char>; _T2 = std::unique_ptr<A>]’ is implicitly
deleted because the default definition would be ill-formed:
constexpr pair(const pair&) = default;
^~~~
/usr/include/c++/7/bits/stl_pair.h:292:17: error: use of deleted function
‘std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with
_Tp = A; _Dp = std::default_delete<A>]’
In file included from /usr/include/c++/7/memory:80:0,
from main.cc:2:
/usr/include/c++/7/bits/unique_ptr.h:388:7: note: declared here
unique_ptr(const unique_ptr&) = delete;
^~~~~~~~~~
