Message ID | 20231102145522.2813330-1-jwakely@redhat.com |
---|---|
State | New |
Headers | show |
Series | libstdc++: Improve static assert messages for monadic operations | expand |
On Thu, 2 Nov 2023 at 14:55, Jonathan Wakely <jwakely@redhat.com> wrote: > > Any objections or suggestions for better wording? > > Tested x86_64-linux. Pushed to trunk. > > -- >8 -- > > The monadic operations for std::optional and std::expected make use of > internal helper traits __is_optional nad __is_expected, which are not > very user-friendly when shown in diagnostics. Add messages to the > assertions explaining the problem more clearly. > > libstdc++-v3/ChangeLog: > > * include/std/expected (expected::and_then, expected::or_else): > Add string literals to static assertions. > * include/std/optional (optional::and_then, optional::or_else): > Likewise. > --- > libstdc++-v3/include/std/expected | 64 +++++++++++++++++++++++-------- > libstdc++-v3/include/std/optional | 24 +++++++++--- > 2 files changed, 66 insertions(+), 22 deletions(-) > > diff --git a/libstdc++-v3/include/std/expected b/libstdc++-v3/include/std/expected > index a796f0b6f27..a176d4c3a78 100644 > --- a/libstdc++-v3/include/std/expected > +++ b/libstdc++-v3/include/std/expected > @@ -843,8 +843,12 @@ namespace __expected > and_then(_Fn&& __f) & > { > using _Up = __expected::__result<_Fn, _Tp&>; > - static_assert(__expected::__is_expected<_Up>); > - static_assert(is_same_v<typename _Up::error_type, _Er>); > + static_assert(__expected::__is_expected<_Up>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Up::error_type, _Er>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected with the same error_type"); > > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), _M_val); > @@ -857,8 +861,12 @@ namespace __expected > and_then(_Fn&& __f) const & > { > using _Up = __expected::__result<_Fn, const _Tp&>; > - static_assert(__expected::__is_expected<_Up>); > - static_assert(is_same_v<typename _Up::error_type, _Er>); > + static_assert(__expected::__is_expected<_Up>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Up::error_type, _Er>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected with the same error_type"); > > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), _M_val); > @@ -871,8 +879,12 @@ namespace __expected > and_then(_Fn&& __f) && > { > using _Up = __expected::__result<_Fn, _Tp&&>; > - static_assert(__expected::__is_expected<_Up>); > - static_assert(is_same_v<typename _Up::error_type, _Er>); > + static_assert(__expected::__is_expected<_Up>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Up::error_type, _Er>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected with the same error_type"); > > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), std::move(_M_val)); > @@ -886,8 +898,12 @@ namespace __expected > and_then(_Fn&& __f) const && > { > using _Up = __expected::__result<_Fn, const _Tp&&>; > - static_assert(__expected::__is_expected<_Up>); > - static_assert(is_same_v<typename _Up::error_type, _Er>); > + static_assert(__expected::__is_expected<_Up>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Up::error_type, _Er>, > + "the function passed to std::expected<T, E>::and_then " > + "must return a std::expected with the same error_type"); > > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), std::move(_M_val)); > @@ -900,8 +916,12 @@ namespace __expected > or_else(_Fn&& __f) & > { > using _Gr = __expected::__result<_Fn, _Er&>; > - static_assert(__expected::__is_expected<_Gr>); > - static_assert(is_same_v<typename _Gr::value_type, _Tp>); > + static_assert(__expected::__is_expected<_Gr>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Gr::value_type, _Tp>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected with the same value_type"); > > if (has_value()) > return _Gr(in_place, _M_val); > @@ -914,8 +934,12 @@ namespace __expected > or_else(_Fn&& __f) const & > { > using _Gr = __expected::__result<_Fn, const _Er&>; > - static_assert(__expected::__is_expected<_Gr>); > - static_assert(is_same_v<typename _Gr::value_type, _Tp>); > + static_assert(__expected::__is_expected<_Gr>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Gr::value_type, _Tp>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected with the same value_type"); > > if (has_value()) > return _Gr(in_place, _M_val); > @@ -929,8 +953,12 @@ namespace __expected > or_else(_Fn&& __f) && > { > using _Gr = __expected::__result<_Fn, _Er&&>; > - static_assert(__expected::__is_expected<_Gr>); > - static_assert(is_same_v<typename _Gr::value_type, _Tp>); > + static_assert(__expected::__is_expected<_Gr>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Gr::value_type, _Tp>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected with the same value_type"); > > if (has_value()) > return _Gr(in_place, std::move(_M_val)); > @@ -943,8 +971,12 @@ namespace __expected > or_else(_Fn&& __f) const && > { > using _Gr = __expected::__result<_Fn, const _Er&&>; > - static_assert(__expected::__is_expected<_Gr>); > - static_assert(is_same_v<typename _Gr::value_type, _Tp>); > + static_assert(__expected::__is_expected<_Gr>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected"); > + static_assert(is_same_v<typename _Gr::value_type, _Tp>, > + "the function passed to std::expected<T, E>::or_else " > + "must return a std::expected with the same value_type"); > > if (has_value()) > return _Gr(in_place, std::move(_M_val)); > diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional > index 4f75eb96f97..53450c760d9 100644 > --- a/libstdc++-v3/include/std/optional > +++ b/libstdc++-v3/include/std/optional > @@ -1048,7 +1048,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > and_then(_Fn&& __f) & > { > using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp&>>; > - static_assert(__is_optional_v<remove_cvref_t<_Up>>); > + static_assert(__is_optional_v<remove_cvref_t<_Up>>, > + "the function passed to std::optional<T>::and_then " > + "must return a std::optional"); > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), **this); > else > @@ -1060,7 +1062,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > and_then(_Fn&& __f) const & > { > using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp&>>; > - static_assert(__is_optional_v<_Up>); > + static_assert(__is_optional_v<_Up>, > + "the function passed to std::optional<T>::and_then " > + "must return a std::optional"); > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), **this); > else > @@ -1072,7 +1076,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > and_then(_Fn&& __f) && > { > using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp>>; > - static_assert(__is_optional_v<remove_cvref_t<_Up>>); > + static_assert(__is_optional_v<remove_cvref_t<_Up>>, > + "the function passed to std::optional<T>::and_then " > + "must return a std::optional"); > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); > else > @@ -1084,7 +1090,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > and_then(_Fn&& __f) const && > { > using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp>>; > - static_assert(__is_optional_v<remove_cvref_t<_Up>>); > + static_assert(__is_optional_v<remove_cvref_t<_Up>>, > + "the function passed to std::optional<T>::and_then " > + "must return a std::optional"); > if (has_value()) > return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); > else > @@ -1140,7 +1148,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > or_else(_Fn&& __f) const& > { > using _Up = invoke_result_t<_Fn>; > - static_assert( is_same_v<remove_cvref_t<_Up>, optional> ); > + static_assert(is_same_v<remove_cvref_t<_Up>, optional>, > + "the function passed to std::optional<T>::or_else " > + "must return a std::optional<T>"); > > if (has_value()) > return *this; > @@ -1153,7 +1163,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > or_else(_Fn&& __f) && > { > using _Up = invoke_result_t<_Fn>; > - static_assert( is_same_v<remove_cvref_t<_Up>, optional> ); > + static_assert(is_same_v<remove_cvref_t<_Up>, optional>, > + "the function passed to std::optional<T>::or_else " > + "must return a std::optional<T>"); > > if (has_value()) > return std::move(*this); > -- > 2.41.0 >
diff --git a/libstdc++-v3/include/std/expected b/libstdc++-v3/include/std/expected index a796f0b6f27..a176d4c3a78 100644 --- a/libstdc++-v3/include/std/expected +++ b/libstdc++-v3/include/std/expected @@ -843,8 +843,12 @@ namespace __expected and_then(_Fn&& __f) & { using _Up = __expected::__result<_Fn, _Tp&>; - static_assert(__expected::__is_expected<_Up>); - static_assert(is_same_v<typename _Up::error_type, _Er>); + static_assert(__expected::__is_expected<_Up>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected"); + static_assert(is_same_v<typename _Up::error_type, _Er>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected with the same error_type"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), _M_val); @@ -857,8 +861,12 @@ namespace __expected and_then(_Fn&& __f) const & { using _Up = __expected::__result<_Fn, const _Tp&>; - static_assert(__expected::__is_expected<_Up>); - static_assert(is_same_v<typename _Up::error_type, _Er>); + static_assert(__expected::__is_expected<_Up>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected"); + static_assert(is_same_v<typename _Up::error_type, _Er>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected with the same error_type"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), _M_val); @@ -871,8 +879,12 @@ namespace __expected and_then(_Fn&& __f) && { using _Up = __expected::__result<_Fn, _Tp&&>; - static_assert(__expected::__is_expected<_Up>); - static_assert(is_same_v<typename _Up::error_type, _Er>); + static_assert(__expected::__is_expected<_Up>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected"); + static_assert(is_same_v<typename _Up::error_type, _Er>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected with the same error_type"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), std::move(_M_val)); @@ -886,8 +898,12 @@ namespace __expected and_then(_Fn&& __f) const && { using _Up = __expected::__result<_Fn, const _Tp&&>; - static_assert(__expected::__is_expected<_Up>); - static_assert(is_same_v<typename _Up::error_type, _Er>); + static_assert(__expected::__is_expected<_Up>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected"); + static_assert(is_same_v<typename _Up::error_type, _Er>, + "the function passed to std::expected<T, E>::and_then " + "must return a std::expected with the same error_type"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), std::move(_M_val)); @@ -900,8 +916,12 @@ namespace __expected or_else(_Fn&& __f) & { using _Gr = __expected::__result<_Fn, _Er&>; - static_assert(__expected::__is_expected<_Gr>); - static_assert(is_same_v<typename _Gr::value_type, _Tp>); + static_assert(__expected::__is_expected<_Gr>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected"); + static_assert(is_same_v<typename _Gr::value_type, _Tp>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected with the same value_type"); if (has_value()) return _Gr(in_place, _M_val); @@ -914,8 +934,12 @@ namespace __expected or_else(_Fn&& __f) const & { using _Gr = __expected::__result<_Fn, const _Er&>; - static_assert(__expected::__is_expected<_Gr>); - static_assert(is_same_v<typename _Gr::value_type, _Tp>); + static_assert(__expected::__is_expected<_Gr>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected"); + static_assert(is_same_v<typename _Gr::value_type, _Tp>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected with the same value_type"); if (has_value()) return _Gr(in_place, _M_val); @@ -929,8 +953,12 @@ namespace __expected or_else(_Fn&& __f) && { using _Gr = __expected::__result<_Fn, _Er&&>; - static_assert(__expected::__is_expected<_Gr>); - static_assert(is_same_v<typename _Gr::value_type, _Tp>); + static_assert(__expected::__is_expected<_Gr>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected"); + static_assert(is_same_v<typename _Gr::value_type, _Tp>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected with the same value_type"); if (has_value()) return _Gr(in_place, std::move(_M_val)); @@ -943,8 +971,12 @@ namespace __expected or_else(_Fn&& __f) const && { using _Gr = __expected::__result<_Fn, const _Er&&>; - static_assert(__expected::__is_expected<_Gr>); - static_assert(is_same_v<typename _Gr::value_type, _Tp>); + static_assert(__expected::__is_expected<_Gr>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected"); + static_assert(is_same_v<typename _Gr::value_type, _Tp>, + "the function passed to std::expected<T, E>::or_else " + "must return a std::expected with the same value_type"); if (has_value()) return _Gr(in_place, std::move(_M_val)); diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional index 4f75eb96f97..53450c760d9 100644 --- a/libstdc++-v3/include/std/optional +++ b/libstdc++-v3/include/std/optional @@ -1048,7 +1048,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION and_then(_Fn&& __f) & { using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp&>>; - static_assert(__is_optional_v<remove_cvref_t<_Up>>); + static_assert(__is_optional_v<remove_cvref_t<_Up>>, + "the function passed to std::optional<T>::and_then " + "must return a std::optional"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), **this); else @@ -1060,7 +1062,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION and_then(_Fn&& __f) const & { using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp&>>; - static_assert(__is_optional_v<_Up>); + static_assert(__is_optional_v<_Up>, + "the function passed to std::optional<T>::and_then " + "must return a std::optional"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), **this); else @@ -1072,7 +1076,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION and_then(_Fn&& __f) && { using _Up = remove_cvref_t<invoke_result_t<_Fn, _Tp>>; - static_assert(__is_optional_v<remove_cvref_t<_Up>>); + static_assert(__is_optional_v<remove_cvref_t<_Up>>, + "the function passed to std::optional<T>::and_then " + "must return a std::optional"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); else @@ -1084,7 +1090,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION and_then(_Fn&& __f) const && { using _Up = remove_cvref_t<invoke_result_t<_Fn, const _Tp>>; - static_assert(__is_optional_v<remove_cvref_t<_Up>>); + static_assert(__is_optional_v<remove_cvref_t<_Up>>, + "the function passed to std::optional<T>::and_then " + "must return a std::optional"); if (has_value()) return std::__invoke(std::forward<_Fn>(__f), std::move(**this)); else @@ -1140,7 +1148,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION or_else(_Fn&& __f) const& { using _Up = invoke_result_t<_Fn>; - static_assert( is_same_v<remove_cvref_t<_Up>, optional> ); + static_assert(is_same_v<remove_cvref_t<_Up>, optional>, + "the function passed to std::optional<T>::or_else " + "must return a std::optional<T>"); if (has_value()) return *this; @@ -1153,7 +1163,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION or_else(_Fn&& __f) && { using _Up = invoke_result_t<_Fn>; - static_assert( is_same_v<remove_cvref_t<_Up>, optional> ); + static_assert(is_same_v<remove_cvref_t<_Up>, optional>, + "the function passed to std::optional<T>::or_else " + "must return a std::optional<T>"); if (has_value()) return std::move(*this);