1/* Policies for result and outcome
2(C) 2018-2024 Niall Douglas <http://www.nedproductions.biz/> (4 commits)
3File Created: Sep 2018
4
5
6Boost Software License - Version 1.0 - August 17th, 2003
7
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29*/
30
31#ifndef BOOST_OUTCOME_POLICY_FAIL_TO_COMPILE_OBSERVERS_HPP
32#define BOOST_OUTCOME_POLICY_FAIL_TO_COMPILE_OBSERVERS_HPP
33
34#include "base.hpp"
35
36BOOST_OUTCOME_V2_NAMESPACE_EXPORT_BEGIN
37
38#define BOOST_OUTCOME_FAIL_TO_COMPILE_OBSERVERS_MESSAGE \
39 "Attempt to wide observe value, error or " \
40 "exception for a basic_result/basic_outcome given an EC or EP type which is not void, and for whom " \
41 "trait::is_error_code_available<EC>, trait::is_exception_ptr_available<EC>, and trait::is_exception_ptr_available<EP> " \
42 "are all false. Please specify a NoValuePolicy to tell basic_result/basic_outcome what to do, or else use " \
43 "a more specific convenience type alias such as unchecked<T, E> to indicate you want the wide " \
44 "observers to be narrow, or checked<T, E> to indicate you always want an exception throw etc."
45
46namespace policy
47{
48 struct fail_to_compile_observers : base
49 {
50 template <class Impl> static constexpr void wide_value_check(Impl && /* unused */) { static_assert(!std::is_same<Impl, Impl>::value, BOOST_OUTCOME_FAIL_TO_COMPILE_OBSERVERS_MESSAGE); }
51 template <class Impl> static constexpr void wide_error_check(Impl && /* unused */) { static_assert(!std::is_same<Impl, Impl>::value, BOOST_OUTCOME_FAIL_TO_COMPILE_OBSERVERS_MESSAGE); }
52 template <class Impl> static constexpr void wide_exception_check(Impl && /* unused */) { static_assert(!std::is_same<Impl, Impl>::value, BOOST_OUTCOME_FAIL_TO_COMPILE_OBSERVERS_MESSAGE); }
53 };
54} // namespace policy
55
56#undef BOOST_OUTCOME_FAIL_TO_COMPILE_OBSERVERS_MESSAGE
57
58BOOST_OUTCOME_V2_NAMESPACE_END
59
60#endif
61

source code of boost/libs/outcome/include/boost/outcome/policy/fail_to_compile_observers.hpp