https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61636
Bug ID: 61636
Summary: generic lambda "cannot call member function without
object"
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: tower120 at gmail dot com
In the following code:
Live http://coliru.stacked-crooked.com/a/b22bb3c9cd603bc7
#include <type_traits>
#include <iostream>
template<class datatype, class FN1, class FN2>
auto if_else(std::true_type,datatype&& data, FN1 &&fn1, FN2 &&)
{return fn1(std::forward<datatype>(data));}
template<class datatype, class FN1, class FN2>
auto if_else(std::false_type,datatype&& data, FN1 &&, FN2 &&fn2)
{return fn2(std::forward<datatype>(data));}
// ---------------------------------------------------------------------
struct A{
int id= 4;
};
struct B : A{
int h = 900;
};
class Test{
template<class Ba>
int fn1(Ba &a){
std::cout << "fn1 " << a.h;
return a.h;
};
template<class A>
int fn2(A &a){
std::cout << "fn2 " << a.id;
a.id = 9;
return a.id;
};
public:
template<bool do_it>
void go(){
std::integral_constant<bool,do_it> do_first;
using datatype = typename std::conditional<do_it,B,A>::type;
datatype data;
std::cout << std::is_same<decltype(data), A>::value;
std::cout << if_else(do_first, data,
[&](auto /*B&*/ data){ // comment auto to get rid
of error
std::cout << std::endl;
std::cout << std::is_same<decltype(data), B>::value;
std::cout << std::endl;
return fn1(/*static_cast<B&>*/(data)); // static cast
not work with gcc
},
[&](A& data){ return fn2(data); }
);
}
};
int main(){
Test().template go<false>();
Test().template go<true>();
return 0;
}
I got the following error:
main.cpp:58:61: error: cannot call member function 'int Test::fn1(Ba&) [with Ba
= B]' without object
If change auto with B - works fine. And it compiles and work as is with clang.
P.S. Maybe somehow related to this
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49554
