http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59721
Bug ID: 59721
Summary: [4.8 Regression] std::bind nested more than one level
results in infinite template substitution
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: rafal at rawicki dot org
Consider following code:
#include <functional>
#include <iostream>
struct A
{
struct B
{
struct C
{
C(): m(5){}
int m;
} c;
} b;
};
int main()
{
A::B b;
auto extractor = std::bind(&A::B::C::m, std::bind(&A::B::c,
std::placeholders::_1));
std::cout << extractor(b) << std::endl;
A a;
auto extractor2 = std::bind(&A::B::C::m, std::bind(&A::B::c,
std::bind(&A::b, std::placeholders::_1)));
std::cout << extractor2(a) << std::endl;
return 0;
}
Under g++-4.7 this code compiles correctly:
$ g++-4.7 -Wall -Wextra -std=c++11 bind.cpp -o bind && ./bind
5
5
while under g++-4.8 it generates infinite template recursion:
$ g++-4.8 -Wall -Wextra -std=c++11 bind.cpp -o bind 2>&1 | head
In file included from bind.cpp:1:0:
/usr/include/c++/4.8/functional:1138:35: error: template instantiation depth
exceeds maximum of 900 (use -ftemplate-depth= to increase the maximum)
substituting ‘template<class _Tp> typename std::add_rvalue_reference<
<template-parameter-1-1> >::type std::declval() [with _Tp = A&]’
-> decltype(__arg(declval<_Args>()...))
^
/usr/include/c++/4.8/functional:1391:40: recursively required by substitution
of ‘template<class _CVArg, class ... _Args> decltype
(__arg((declval<_Args>)()...)) std::_Mu<_Arg, true, false>::operator()(_CVArg&,
std::tuple<_Args2 ...>&) const volatile [with _CVArg = _CVArg; _Args = {_Args
...}; _Arg = std::_Bind<std::_Mem_fn<A::B A::*>(std::_Placeholder<1>)>] [with
_CVArg = const volatile std::_Bind<std::_Mem_fn<A::B
A::*>(std::_Placeholder<1>)>; _Args = {A&}]’
/usr/include/c++/4.8/functional:1391:40: required by substitution of
‘template<class _CVArg, class ... _Args, long unsigned int ..._Indexes>
decltype (__arg((declval<_Args>)()...)) std::_Mu<_Arg, true,
false>::__call(_CVArg&, std::tuple<_Args2 ...>&, const
std::_Index_tuple<_Indexes ...>&) const volatile [with _CVArg = _CVArg; _Args =
{_Args ...}; long unsigned int ..._Indexes = {_Indexes ...}; _Arg =
std::_Bind<std::_Mem_fn<A::B::C A::B::*>(std::_Bind<std::_Mem_fn<A::B
A::*>(std::_Placeholder<1>)>)>] [with _CVArg = std::_Bind<std::_Mem_fn<A::B::C
A::B::*>(std::_Bind<std::_Mem_fn<A::B A::*>(std::_Placeholder<1>)>)>; _Args =
{A&}; long unsigned int ..._Indexes = {0ul}]’
/usr/include/c++/4.8/functional:1143:50: template instantiation depth exceeds
maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting
‘template<class _Tp> typename std::add_rvalue_reference<
<template-parameter-1-1> >::type std::declval() [with _Tp = A&]’
/usr/include/c++/4.8/functional:1391:40: recursively required by substitution
of ‘template<class _CVArg, class ... _Args> decltype
(__arg((declval<_Args>)()...)) std::_Mu<_Arg, true, false>::operator()(_CVArg&,
std::tuple<_Args2 ...>&) const volatile [with _CVArg = _CVArg; _Args = {_Args
...}; _Arg = std::_Bind<std::_Mem_fn<A::B A::*>(std::_Placeholder<1>)>] [with
_CVArg = const volatile std::_Bind<std::_Mem_fn<A::B
A::*>(std::_Placeholder<1>)>; _Args = {A&}]’
/usr/include/c++/4.8/functional:1391:40: required by substitution of
‘template<class _CVArg, class ... _Args, long unsigned int ..._Indexes>
decltype (__arg((declval<_Args>)()...)) std::_Mu<_Arg, true,
false>::__call(_CVArg&, std::tuple<_Args2 ...>&, const
std::_Index_tuple<_Indexes ...>&) const volatile [with _CVArg = _CVArg; _Args =
{_Args ...}; long unsigned int ..._Indexes = {_Indexes ...}; _Arg =
std::_Bind<std::_Mem_fn<A::B::C A::B::*>(std::_Bind<std::_Mem_fn<A::B
A::*>(std::_Placeholder<1>)>)>] [with _CVArg = std::_Bind<std::_Mem_fn<A::B::C
A::B::*>(std::_Bind<std::_Mem_fn<A::B A::*>(std::_Placeholder<1>)>)>; _Args =
{A&}; long unsigned int ..._Indexes = {0ul}]’
/usr/include/c++/4.8/functional:1143:50: template instantiation depth exceeds
maximum of 900 (use -ftemplate-depth= to increase the maximum) substituting
‘template<class _Tp> typename std::add_rvalue_reference<
<template-parameter-1-1> >::type std::declval() [with _Tp = A&]’
My g++ is:
$ g++-4.8 --version
g++-4.8 (Ubuntu/Linaro 4.8.2-8) 4.8.2
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