Author
anonymous
about 4 years ago
Language
C++
Compiler
gcc HEAD 12.0.0 20210423 (experimental)
Options
Warnings
Boost 1.73.0
C++2b(GNU)
no pedantic
Author
anonymous
about 4 years ago
$ g++ prog.cc -Wall -Wextra -I/opt/wandbox/boost-1.73.0/gcc-head/include -std=gnu++2b prog.cc:22:7: error: 'template<class Fn, class T> T Widget::doIt(Fn&&)' cannot be overloaded with 'template<class Fn, class T> T Widget::doIt(Fn&&)'
22 | T doIt(Fn&& fn)
| ^~~~
prog.cc:16:7: note: previous declaration 'template<class Fn, class T> T Widget::doIt(Fn&&)'
16 | T doIt(Fn&& fn)
| ^~~~
prog.cc: In function 'int main()':
prog.cc:49:11: error: no matching function for call to 'Widget::doIt(main()::<lambda(Widget2*)>)'
49 | w.doIt([](Widget2*){
| ~~~~~~^~~~~~~~~~~~~~
50 | std::cout << "there will be a 2 here";
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
51 | });
| ~~
prog.cc:16:7: note: candidate: 'template<class Fn, class T> T Widget::doIt(Fn&&)'
16 | T doIt(Fn&& fn)
| ^~~~
prog.cc:16:7: note: template argument deduction/substitution failed:
In file included from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/12.0.0/type_traits: In substitution of 'template<class _Fn, class ... _Args> using invoke_result_t = typename std::invoke_result::type [with _Fn = main()::<lambda(Widget2*)>; _Args = {Widget*}]':
prog.cc:15:27: required from here
/opt/wandbox/gcc-head/include/c++/12.0.0/type_traits:2933:11: error: no type named 'type' in 'struct std::invoke_result<main()::<lambda(Widget2*)>, Widget*>'
2933 | using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
| ^~~~~~~~~~~~~~~
Exit Code:
1