Author
anonymous
over 8 years ago
Language
Compiler
Options
Author
anonymous
over 8 years ago
$ prog.cc: In function 'int main()':
prog.cc:19:26: error: no match for 'operator+' (operand types are 'Foo' and 'Bar')
int temp = Foo::none + Bar::none;
~~~~~~~~~~^~~~~
prog.cc:20:32: error: no match for 'operator<<' (operand types are 'std::basic_ostream<char>' and 'Foo')
std::cout << "foo::none =" << Foo::none << "\n";
~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:108:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ostream_type& (*)(std::basic_ostream<_CharT, _Traits>::__ostream_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(__ostream_type& (*__pf)(__ostream_type&))
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:108:7: note: no known conversion for argument 1 from 'Foo' to 'std::basic_ostream<char>::__ostream_type& (*)(std::basic_ostream<char>::__ostream_type&) {aka std::basic_ostream<char>& (*)(std::basic_ostream<char>&)}'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:117:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__ios_type& (*)(std::basic_ostream<_CharT, _Traits>::__ios_type&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>; std::basic_ostream<_CharT, _Traits>::__ios_type = std::basic_ios<char>]
operator<<(__ios_type& (*__pf)(__ios_type&))
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:117:7: note: no known conversion for argument 1 from 'Foo' to 'std::basic_ostream<char>::__ios_type& (*)(std::basic_ostream<char>::__ios_type&) {aka std::basic_ios<char>& (*)(std::basic_ios<char>&)}'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:127:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::ios_base& (*)(std::ios_base&)) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(ios_base& (*__pf) (ios_base&))
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:127:7: note: no known conversion for argument 1 from 'Foo' to 'std::ios_base& (*)(std::ios_base&)'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:166:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:166:7: note: no known conversion for argument 1 from 'Foo' to 'long int'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:170:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:170:7: note: no known conversion for argument 1 from 'Foo' to 'long unsigned int'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:174:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(bool) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(bool __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:174:7: note: no known conversion for argument 1 from 'Foo' to 'bool'
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:666:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:91:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(short int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:91:5: note: no known conversion for argument 1 from 'Foo' to 'short int'
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:181:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(short unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned short __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:181:7: note: no known conversion for argument 1 from 'Foo' to 'short unsigned int'
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:666:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:105:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(int) [with _CharT = char; _Traits = std::char_traits<char>]
basic_ostream<_CharT, _Traits>::
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:105:5: note: no known conversion for argument 1 from 'Foo' to 'int'
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:192:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned int __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:192:7: note: no known conversion for argument 1 from 'Foo' to 'unsigned int'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:201:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long long __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:201:7: note: no known conversion for argument 1 from 'Foo' to 'long long int'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:205:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long long unsigned int) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(unsigned long long __n)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:205:7: note: no known conversion for argument 1 from 'Foo' to 'long long unsigned int'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:220:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(double __f)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:220:7: note: no known conversion for argument 1 from 'Foo' to 'double'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:224:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(float) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(float __f)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:224:7: note: no known conversion for argument 1 from 'Foo' to 'float'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:232:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(long double) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(long double __f)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:232:7: note: no known conversion for argument 1 from 'Foo' to 'long double'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:245:7: note: candidate: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(const void*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__ostream_type = std::basic_ostream<char>]
operator<<(const void* __p)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:245:7: note: no known conversion for argument 1 from 'Foo' to 'const void*'
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:666:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:119:5: note: candidate: std::basic_ostream<_CharT, _Traits>& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostream<_CharT, _Traits>::__streambuf_type*) [with _CharT = char; _Traits = std::char_traits<char>; std::basic_ostream<_CharT, _Traits>::__streambuf_type = std::basic_streambuf<char>]
basic_ostream<_CharT, _Traits>::
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:119:5: note: no known conversion for argument 1 from 'Foo' to 'std::basic_ostream<char>::__streambuf_type* {aka std::basic_streambuf<char>*}'
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:656:5: note: candidate: template<class _Ostream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable<_Ostream&, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::ostream_type>::type std::operator<<(_Ostream&&, const _Tp&)
operator<<(_Ostream&& __os, const _Tp& __x)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:656:5: note: template argument deduction/substitution failed:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream: In substitution of 'template<class _Ostream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable<_Ostream&, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::ostream_type>::type std::operator<<(_Ostream&&, const _Tp&) [with _Ostream = std::basic_ostream<char>&; _Tp = Foo]':
prog.cc:20:40: required from here
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:656:5: error: no type named 'type' in 'struct std::enable_if<false, std::basic_ostream<char>&>'
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:574:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const unsigned char*)
operator<<(basic_ostream<char, _Traits>& __out, const unsigned char* __s)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:574:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'const unsigned char*'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:569:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const signed char*)
operator<<(basic_ostream<char, _Traits>& __out, const signed char* __s)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:569:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'const signed char*'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:556:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, const char*)
operator<<(basic_ostream<char, _Traits>& __out, const char* __s)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:556:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'const char*'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:666:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:321:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const char*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const char* __s)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/ostream.tcc:321:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'const char*'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:539:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const _CharT*)
operator<<(basic_ostream<_CharT, _Traits>& __out, const _CharT* __s)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:539:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: mismatched types 'const _CharT*' and 'Foo'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:519:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, unsigned char)
operator<<(basic_ostream<char, _Traits>& __out, unsigned char __c)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:519:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'unsigned char'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:514:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, signed char)
operator<<(basic_ostream<char, _Traits>& __out, signed char __c)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:514:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'signed char'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:508:5: note: candidate: template<class _Traits> std::basic_ostream<char, _Traits>& std::operator<<(std::basic_ostream<char, _Traits>&, char)
operator<<(basic_ostream<char, _Traits>& __out, char __c)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:508:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'char'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:502:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, char)
operator<<(basic_ostream<_CharT, _Traits>& __out, char __c)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:502:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'char'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39:0,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:497:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, _CharT)
operator<<(basic_ostream<_CharT, _Traits>& __out, _CharT __c)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/ostream:497:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: deduced conflicting types for parameter '_CharT' ('char' and 'Foo')
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/bits/ios_base.h:46:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/ios:42,
from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:38,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/system_error:216:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::error_code&)
operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e)
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/system_error:216:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: cannot convert 'none' (type 'Foo') to type 'const std::error_code&'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/string:52:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/bits/locale_classes.h:40,
from /opt/wandbox/gcc-head/include/c++/7.0.1/bits/ios_base.h:41,
from /opt/wandbox/gcc-head/include/c++/7.0.1/ios:42,
from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:38,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/basic_string.h:6082:5: note: candidate: template<class _CharT, class _Traits, class _Alloc> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>&)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/bits/basic_string.h:6082:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Alloc>' and 'Foo'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
In file included from /opt/wandbox/gcc-head/include/c++/7.0.1/bits/basic_string.h:48:0,
from /opt/wandbox/gcc-head/include/c++/7.0.1/string:52,
from /opt/wandbox/gcc-head/include/c++/7.0.1/bits/locale_classes.h:40,
from /opt/wandbox/gcc-head/include/c++/7.0.1/bits/ios_base.h:41,
from /opt/wandbox/gcc-head/include/c++/7.0.1/ios:42,
from /opt/wandbox/gcc-head/include/c++/7.0.1/ostream:38,
from /opt/wandbox/gcc-head/include/c++/7.0.1/iostream:39,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/7.0.1/string_view:558:5: note: candidate: template<class _CharT, class _Traits> std::basic_ostream<_CharT, _Traits>& std::operator<<(std::basic_ostream<_CharT, _Traits>&, std::basic_string_view<_CharT, _Traits>)
operator<<(basic_ostream<_CharT, _Traits>& __os,
^~~~~~~~
/opt/wandbox/gcc-head/include/c++/7.0.1/string_view:558:5: note: template argument deduction/substitution failed:
prog.cc:20:40: note: mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'Foo'
std::cout << "foo::none =" << Foo::none << "\n";
^~~~
prog.cc:19:9: warning: unused variable 'temp' [-Wunused-variable]
int temp = Foo::none + Bar::none;
^~~~
Exit Code:
1