A type alias to a no-value policy selected based on traits matching of T, EC and EP. It is defined as follows:

1. If EC and EP is void, choose terminate.

2. If is_error_code_available<T> true for EC, choose error_code_throw_as_system_error<T, EC, EP> for basic_outcome or error_code_throw_as_system_error<T, EC, void> for basic_result.

3. If is_exception_ptr_available<T> true for EC or EP, choose exception_ptr_rethrow<T, EC, EP> for basic_outcome or exception_ptr_rethrow<T, EC, void> for basic_result.

4. Else choose fail_to_compile_observers, which fails the build with a useful message.

Namespace: BOOST_OUTCOME_V2_NAMESPACE::policy

Header: <boost/outcome/std_result.hpp>