https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69831
Bug ID: 69831
Summary: Issue with passing a reference_wrapper to a
placeholder when using a pointer to member function in
bind
Product: gcc
Version: 5.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: sniderdj at umich dot edu
Target Milestone: ---
Created attachment 37696
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37696&action=edit
the preprocessed file
When passing in a reference_wrapper to the result of a call to bind called on a
pointer to member function, no overload is resolved, although when the
reference wrapper is given to bind initially, everything works as expected.
In this short case:
#include <functional>
#include <algorithm>
#include <vector>
using namespace std;
using namespace std::placeholders;
struct foo {
foo(){}
void func(int) {}
};
int main() {
vector<reference_wrapper<foo>> v;
foo inst;
reference_wrapper<foo> rw = inst;
auto b1 = bind(&foo::func, rw, 0); // okay
b1();
auto b2 = bind(&foo::func, _1, 0); // bad
b2(rw);
}
The first call to bind works fine, as expected, but on the last line, where the
second bind object is called with the reference_wrapper, the compiler rejects
all possible overloads, even though it appears as at least one should match.
command: gcc -v -save-temps -std=c++14 bug.cpp
the result of the command:
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
5.3.0-3ubuntu1~14.04' --with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=gcc4-compatible --disable-libstdcxx-dual-abi
--enable-gnu-unique-object --disable-vtable-verify --enable-libmpx
--enable-plugin --with-system-zlib --disable-browser-plugin
--enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 5.3.0 20151204 (Ubuntu 5.3.0-3ubuntu1~14.04)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++14' '-mtune=generic'
'-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/5/cc1plus -E -quiet -v -imultiarch
x86_64-linux-gnu -D_GNU_SOURCE bug.cpp -mtune=generic -march=x86-64 -std=c++14
-fpch-preprocess -fstack-protector -Wformat -Wformat-security -o bug.ii
ignoring duplicate directory "/usr/include/x86_64-linux-gnu/c++/5"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/5/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/include/c++/5
/usr/include/x86_64-linux-gnu/c++/5
/usr/include/c++/5/backward
/usr/lib/gcc/x86_64-linux-gnu/5/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/5/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-std=c++14' '-mtune=generic'
'-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/5/cc1plus -fpreprocessed bug.ii -quiet -dumpbase
bug.cpp -mtune=generic -march=x86-64 -auxbase bug -std=c++14 -version
-fstack-protector -Wformat -Wformat-security -o bug.s
GNU C++14 (Ubuntu 5.3.0-3ubuntu1~14.04) version 5.3.0 20151204
(x86_64-linux-gnu)
compiled by GNU C version 5.3.0 20151204, GMP version 5.1.3, MPFR
version 3.1.3, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C++14 (Ubuntu 5.3.0-3ubuntu1~14.04) version 5.3.0 20151204
(x86_64-linux-gnu)
compiled by GNU C version 5.3.0 20151204, GMP version 5.1.3, MPFR
version 3.1.3, MPC version 1.0.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: bbf79e63f589fea28823afe8bbe74c79
bug.cpp: In function ‘int main()’:
bug.cpp:15:8: error: no match for call to ‘(std::_Bind<std::_Mem_fn<void
(foo::*)(int)>(std::_Placeholder<1>, int)>) (std::reference_wrapper<foo>&)’
b2(rw);
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1129:2: note: candidate: template<class ...
_Args, class _Result> _Result std::_Bind<_Functor(_Bound_args
...)>::operator()(_Args&& ...) [with _Args = {_Args ...}; _Result = _Result;
_Functor = std::_Mem_fn<void (foo::*)(int)>; _Bound_args =
{std::_Placeholder<1>, int}]
operator()(_Args&&... __args)
^
/usr/include/c++/5/functional:1129:2: note: template argument
deduction/substitution failed:
/usr/include/c++/5/functional:1125:38: error: call of ‘(std::_Mem_fn<void
(foo::*)(int)>) (std::reference_wrapper<foo>&, int&)’ is ambiguous
= decltype( std::declval<_Functor>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:582:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class&,
_Args&& ...) const [with _Args = {int&}; _Req = void; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::_Class = foo]
operator()(_Class& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:607:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::operator()(_Tp&&, _Args&& ...)
const [with _Tp = std::reference_wrapper<foo>&; _Args = {int&}; _Req = void;
_MemFunPtr = void (foo::*)(int); bool __is_mem_fn = true;
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type = void]
operator()(_Tp&& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:618:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::reference_wrapper<_Tp>, _Args&& ...) const [with
_Tp = foo; _Args = {int&}; _Req = void; _MemFunPtr = void (foo::*)(int); bool
__is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type =
void]
operator()(reference_wrapper<_Tp> __ref, _Args&&... __args) const
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1143:2: note: candidate: template<class ...
_Args, class _Result> _Result std::_Bind<_Functor(_Bound_args
...)>::operator()(_Args&& ...) const [with _Args = {_Args ...}; _Result =
_Result; _Functor = std::_Mem_fn<void (foo::*)(int)>; _Bound_args =
{std::_Placeholder<1>, int}]
operator()(_Args&&... __args) const
^
/usr/include/c++/5/functional:1143:2: note: template argument
deduction/substitution failed:
/usr/include/c++/5/functional:1139:52: error: call of ‘(const std::_Mem_fn<void
(foo::*)(int)>) (std::reference_wrapper<foo>&, const int&)’ is ambiguous
typename add_const<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:582:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class&,
_Args&& ...) const [with _Args = {const int&}; _Req = void; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::_Class = foo]
operator()(_Class& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:607:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::operator()(_Tp&&, _Args&& ...)
const [with _Tp = std::reference_wrapper<foo>&; _Args = {const int&}; _Req =
void; _MemFunPtr = void (foo::*)(int); bool __is_mem_fn = true;
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type = void]
operator()(_Tp&& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:618:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::reference_wrapper<_Tp>, _Args&& ...) const [with
_Tp = foo; _Args = {const int&}; _Req = void; _MemFunPtr = void (foo::*)(int);
bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void]
operator()(reference_wrapper<_Tp> __ref, _Args&&... __args) const
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1157:2: note: candidate: template<class ...
_Args, class _Result> _Result std::_Bind<_Functor(_Bound_args
...)>::operator()(_Args&& ...) volatile [with _Args = {_Args ...}; _Result =
_Result; _Functor = std::_Mem_fn<void (foo::*)(int)>; _Bound_args =
{std::_Placeholder<1>, int}]
operator()(_Args&&... __args) volatile
^
/usr/include/c++/5/functional:1157:2: note: template argument
deduction/substitution failed:
/usr/include/c++/5/functional:1153:69: error: no match for call to ‘(volatile
std::_Mem_fn<void (foo::*)(int)>) (std::reference_wrapper<foo>&, volatile
int&)’
typename add_volatile<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:582:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class&,
_Args&& ...) const [with _Args = {volatile int&}; _Req = void; _MemFunPtr =
void (foo::*)(int); bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::_Class = foo] <near match>
operator()(_Class& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:582:2: note: passing ‘volatile
std::_Mem_fn<void (foo::*)(int)>*’ as ‘this’ argument discards qualifiers
/usr/include/c++/5/functional:589:2: note: candidate: template<class ... _Args,
class _Req> std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class&&,
_Args&& ...) const [with _Args = {_Args ...}; _Req = _Req; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true]
operator()(_Class&& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:589:2: note: template argument
deduction/substitution failed:
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1153:69: note: cannot convert
‘std::_Mu<std::_Placeholder<1>, false, true>().std::_Mu<_Arg, false,
true>::operator()<std::tuple<std::reference_wrapper<foo>&> >((*(const volatile
std::_Placeholder<1>*)std::declval<volatile std::_Placeholder<1>&>()), (* &
std::declval<std::tuple<std::reference_wrapper<foo>&>&>()))’ (type
‘std::reference_wrapper<foo>’) to type ‘std::_Mem_fn_base<void (foo::*)(int),
true>::_Class&& {aka foo&&}’
typename add_volatile<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:599:2: note: candidate: template<class ... _Args,
class _Req> std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class*,
_Args&& ...) const [with _Args = {_Args ...}; _Req = _Req; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true]
operator()(_Class* __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:599:2: note: template argument
deduction/substitution failed:
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1153:69: note: cannot convert
‘std::_Mu<std::_Placeholder<1>, false, true>().std::_Mu<_Arg, false,
true>::operator()<std::tuple<std::reference_wrapper<foo>&> >((*(const volatile
std::_Placeholder<1>*)std::declval<volatile std::_Placeholder<1>&>()), (* &
std::declval<std::tuple<std::reference_wrapper<foo>&>&>()))’ (type
‘std::reference_wrapper<foo>’) to type ‘std::_Mem_fn_base<void (foo::*)(int),
true>::_Class* {aka foo*}’
typename add_volatile<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:607:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::operator()(_Tp&&, _Args&& ...)
const [with _Tp = std::reference_wrapper<foo>&; _Args = {volatile int&}; _Req =
void; _MemFunPtr = void (foo::*)(int); bool __is_mem_fn = true;
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type = void] <near match>
operator()(_Tp&& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:607:2: note: passing ‘volatile
std::_Mem_fn<void (foo::*)(int)>*’ as ‘this’ argument discards qualifiers
/usr/include/c++/5/functional:618:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::reference_wrapper<_Tp>, _Args&& ...) const [with
_Tp = foo; _Args = {volatile int&}; _Req = void; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void] <near match>
operator()(reference_wrapper<_Tp> __ref, _Args&&... __args) const
^
/usr/include/c++/5/functional:618:2: note: passing ‘volatile
std::_Mem_fn<void (foo::*)(int)>*’ as ‘this’ argument discards qualifiers
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1171:2: note: candidate: template<class ...
_Args, class _Result> _Result std::_Bind<_Functor(_Bound_args
...)>::operator()(_Args&& ...) const volatile [with _Args = {_Args ...};
_Result = _Result; _Functor = std::_Mem_fn<void (foo::*)(int)>; _Bound_args =
{std::_Placeholder<1>, int}]
operator()(_Args&&... __args) const volatile
^
/usr/include/c++/5/functional:1171:2: note: template argument
deduction/substitution failed:
/usr/include/c++/5/functional:1167:63: error: no match for call to ‘(const
volatile std::_Mem_fn<void (foo::*)(int)>) (std::reference_wrapper<foo>&, const
volatile int&)’
typename add_cv<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:582:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class&,
_Args&& ...) const [with _Args = {const volatile int&}; _Req = void; _MemFunPtr
= void (foo::*)(int); bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::_Class = foo] <near match>
operator()(_Class& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:582:2: note: passing ‘const volatile
std::_Mem_fn<void (foo::*)(int)>*’ as ‘this’ argument discards qualifiers
/usr/include/c++/5/functional:589:2: note: candidate: template<class ... _Args,
class _Req> std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class&&,
_Args&& ...) const [with _Args = {_Args ...}; _Req = _Req; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true]
operator()(_Class&& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:589:2: note: template argument
deduction/substitution failed:
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1167:63: note: cannot convert
‘std::_Mu<std::_Placeholder<1>, false, true>().std::_Mu<_Arg, false,
true>::operator()<std::tuple<std::reference_wrapper<foo>&> >((* &
std::declval<const volatile std::_Placeholder<1>&>()), (* &
std::declval<std::tuple<std::reference_wrapper<foo>&>&>()))’ (type
‘std::reference_wrapper<foo>’) to type ‘std::_Mem_fn_base<void (foo::*)(int),
true>::_Class&& {aka foo&&}’
typename add_cv<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:599:2: note: candidate: template<class ... _Args,
class _Req> std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::_Class*,
_Args&& ...) const [with _Args = {_Args ...}; _Req = _Req; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true]
operator()(_Class* __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:599:2: note: template argument
deduction/substitution failed:
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:1167:63: note: cannot convert
‘std::_Mu<std::_Placeholder<1>, false, true>().std::_Mu<_Arg, false,
true>::operator()<std::tuple<std::reference_wrapper<foo>&> >((* &
std::declval<const volatile std::_Placeholder<1>&>()), (* &
std::declval<std::tuple<std::reference_wrapper<foo>&>&>()))’ (type
‘std::reference_wrapper<foo>’) to type ‘std::_Mem_fn_base<void (foo::*)(int),
true>::_Class* {aka foo*}’
typename add_cv<_Functor>::type>::type>()(
^
In file included from bug.cpp:1:0:
/usr/include/c++/5/functional:607:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::operator()(_Tp&&, _Args&& ...)
const [with _Tp = std::reference_wrapper<foo>&; _Args = {const volatile int&};
_Req = void; _MemFunPtr = void (foo::*)(int); bool __is_mem_fn = true;
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type = void] <near match>
operator()(_Tp&& __object, _Args&&... __args) const
^
/usr/include/c++/5/functional:607:2: note: passing ‘const volatile
std::_Mem_fn<void (foo::*)(int)>*’ as ‘this’ argument discards qualifiers
/usr/include/c++/5/functional:618:2: note: candidate:
std::_Mem_fn_base<_MemFunPtr, __is_mem_fn>::result_type
std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::operator()(std::reference_wrapper<_Tp>, _Args&& ...) const [with
_Tp = foo; _Args = {const volatile int&}; _Req = void; _MemFunPtr = void
(foo::*)(int); bool __is_mem_fn = true; std::_Mem_fn_base<_MemFunPtr,
__is_mem_fn>::result_type = void] <near match>
operator()(reference_wrapper<_Tp> __ref, _Args&&... __args) const
^
/usr/include/c++/5/functional:618:2: note: passing ‘const volatile
std::_Mem_fn<void (foo::*)(int)>*’ as ‘this’ argument discards qualifiers
