Author
anonymous
about 7 years ago
Language
Compiler
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Author
anonymous
about 7 years ago
$ prog.cc: In lambda function:
prog.cc:11:27: error: inconsistent types 'std::nullopt_t' and 'std::optional<int>' deduced for lambda return type
return std::optional(2);
^
prog.cc:11:27: error: no matching function for call to 'std::nullopt_t::nullopt_t(std::optional<int>)'
In file included from /opt/wandbox/gcc-head/include/c++/9.0.0/bits/node_handle.h:39,
from /opt/wandbox/gcc-head/include/c++/9.0.0/bits/hashtable.h:37,
from /opt/wandbox/gcc-head/include/c++/9.0.0/unordered_map:46,
from /opt/wandbox/gcc-head/include/c++/9.0.0/functional:61,
from prog.cc:1:
/opt/wandbox/gcc-head/include/c++/9.0.0/optional:70:24: note: candidate: 'constexpr std::nullopt_t::nullopt_t(std::nullopt_t::_Construct)'
explicit constexpr nullopt_t(_Construct) { }
^~~~~~~~~
/opt/wandbox/gcc-head/include/c++/9.0.0/optional:70:24: note: no known conversion for argument 1 from 'std::optional<int>' to 'std::nullopt_t::_Construct'
/opt/wandbox/gcc-head/include/c++/9.0.0/optional:60:10: note: candidate: 'constexpr std::nullopt_t::nullopt_t(const std::nullopt_t&)'
struct nullopt_t
^~~~~~~~~
/opt/wandbox/gcc-head/include/c++/9.0.0/optional:60:10: note: no known conversion for argument 1 from 'std::optional<int>' to 'const std::nullopt_t&'
/opt/wandbox/gcc-head/include/c++/9.0.0/optional:60:10: note: candidate: 'constexpr std::nullopt_t::nullopt_t(std::nullopt_t&&)'
/opt/wandbox/gcc-head/include/c++/9.0.0/optional:60:10: note: no known conversion for argument 1 from 'std::optional<int>' to 'std::nullopt_t&&'
prog.cc: In function 'int main()':
prog.cc:18:24: error: static assertion failed: return type is still std::nullopt_t
static_assert(std::is_same<return_type, std::optional<int>>{},
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prog.cc:21:27: error: 'struct std::nullopt_t' has no member named 'value'
std::cout << lambda().value() << '\n';
^~~~~
Exit Code:
1