| Message ID | 20230912010852.1027184-2-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/3] libstdc++: Remove std::bind_front specialization for no bound args | expand |
On Tue, 12 Sept 2023 at 02:09, Patrick Palka via Libstdc++ <libstdc++@gcc.gnu.org> wrote: > > In order to properly implement a perfect forwarding call wrapper > (before 'deducing this' at least) we need a total of 8 operator() > overloads, 4 main ones and 4 deleted ones for each const/ref qual pair, > as described in section 5.5 of P0847R6. Otherwise the wrapper may > not perfectly forward according to the value category and constness > of the wrapped object. This patch fixes this bug in std::bind_front. OK for trunk, thanks. > > PR libstdc++/111327 > > libstdc++-v3/ChangeLog: > > * include/std/functional (_Bind_front::operator()): Add deleted > fallback overloads for each const/ref qualifier pair. Give the > main overloads dummy constraints to make them more specialized > than the deleted overloads. > * testsuite/20_util/function_objects/bind_front/111327.cc: New test. > --- > libstdc++-v3/include/std/functional | 16 ++++++++ > .../function_objects/bind_front/111327.cc | 41 +++++++++++++++++++ > 2 files changed, 57 insertions(+) > create mode 100644 libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc > > diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional > index 7d1b890bb4e..c50b9e4d365 100644 > --- a/libstdc++-v3/include/std/functional > +++ b/libstdc++-v3/include/std/functional > @@ -938,6 +938,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > ~_Bind_front() = default; > > template<typename... _CallArgs> > + requires true > constexpr > invoke_result_t<_Fd&, _BoundArgs&..., _CallArgs...> > operator()(_CallArgs&&... __call_args) & > @@ -948,6 +949,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > } > > template<typename... _CallArgs> > + requires true > constexpr > invoke_result_t<const _Fd&, const _BoundArgs&..., _CallArgs...> > operator()(_CallArgs&&... __call_args) const & > @@ -959,6 +961,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > } > > template<typename... _CallArgs> > + requires true > constexpr > invoke_result_t<_Fd, _BoundArgs..., _CallArgs...> > operator()(_CallArgs&&... __call_args) && > @@ -969,6 +972,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > } > > template<typename... _CallArgs> > + requires true > constexpr > invoke_result_t<const _Fd, const _BoundArgs..., _CallArgs...> > operator()(_CallArgs&&... __call_args) const && > @@ -979,6 +983,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > std::forward<_CallArgs>(__call_args)...); > } > > + template<typename... _CallArgs> > + void operator()(_CallArgs&&...) & = delete; > + > + template<typename... _CallArgs> > + void operator()(_CallArgs&&...) const & = delete; > + > + template<typename... _CallArgs> > + void operator()(_CallArgs&&...) && = delete; > + > + template<typename... _CallArgs> > + void operator()(_CallArgs&&...) const && = delete; > + > private: > using _BoundIndices = index_sequence_for<_BoundArgs...>; > > diff --git a/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc b/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc > new file mode 100644 > index 00000000000..6eb51994476 > --- /dev/null > +++ b/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc > @@ -0,0 +1,41 @@ > +// PR libstdc++/111327 - std::bind_front doesn't perfectly forward according > +// to value category of the call wrapper object > +// { dg-options "-std=gnu++20" } > +// { dg-do compile { target c++20 } } > + > +#include <functional> > +#include <utility> > + > +struct F { > + void operator()(...) & = delete; > + void operator()(...) const &; > +}; > + > +struct G { > + void operator()(...) && = delete; > + void operator()(...) const &&; > +}; > + > +int main() { > + auto f0 = std::bind_front(F{}); > + f0(); // { dg-error "deleted" } > + std::move(f0)(); > + std::as_const(f0)(); > + std::move(std::as_const(f0))(); > + > + auto g0 = std::bind_front(G{}); > + g0(); // { dg-error "deleted" } > + std::move(g0)(); // { dg-error "deleted" } > + std::move(std::as_const(g0))(); > + > + auto f1 = std::bind_front(F{}, 42); > + f1(); // { dg-error "deleted" } > + std::move(f1)(); > + std::as_const(f1)(); > + std::move(std::as_const(f1))(); > + > + auto g1 = std::bind_front(G{}, 42); > + g1(); // { dg-error "deleted" } > + std::move(g1)(); // { dg-error "deleted" } > + std::move(std::as_const(g1))(); > +} > -- > 2.42.0.158.g94e83dcf5b >
diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional index 7d1b890bb4e..c50b9e4d365 100644 --- a/libstdc++-v3/include/std/functional +++ b/libstdc++-v3/include/std/functional @@ -938,6 +938,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION ~_Bind_front() = default; template<typename... _CallArgs> + requires true constexpr invoke_result_t<_Fd&, _BoundArgs&..., _CallArgs...> operator()(_CallArgs&&... __call_args) & @@ -948,6 +949,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } template<typename... _CallArgs> + requires true constexpr invoke_result_t<const _Fd&, const _BoundArgs&..., _CallArgs...> operator()(_CallArgs&&... __call_args) const & @@ -959,6 +961,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } template<typename... _CallArgs> + requires true constexpr invoke_result_t<_Fd, _BoundArgs..., _CallArgs...> operator()(_CallArgs&&... __call_args) && @@ -969,6 +972,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } template<typename... _CallArgs> + requires true constexpr invoke_result_t<const _Fd, const _BoundArgs..., _CallArgs...> operator()(_CallArgs&&... __call_args) const && @@ -979,6 +983,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION std::forward<_CallArgs>(__call_args)...); } + template<typename... _CallArgs> + void operator()(_CallArgs&&...) & = delete; + + template<typename... _CallArgs> + void operator()(_CallArgs&&...) const & = delete; + + template<typename... _CallArgs> + void operator()(_CallArgs&&...) && = delete; + + template<typename... _CallArgs> + void operator()(_CallArgs&&...) const && = delete; + private: using _BoundIndices = index_sequence_for<_BoundArgs...>; diff --git a/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc b/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc new file mode 100644 index 00000000000..6eb51994476 --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc @@ -0,0 +1,41 @@ +// PR libstdc++/111327 - std::bind_front doesn't perfectly forward according +// to value category of the call wrapper object +// { dg-options "-std=gnu++20" } +// { dg-do compile { target c++20 } } + +#include <functional> +#include <utility> + +struct F { + void operator()(...) & = delete; + void operator()(...) const &; +}; + +struct G { + void operator()(...) && = delete; + void operator()(...) const &&; +}; + +int main() { + auto f0 = std::bind_front(F{}); + f0(); // { dg-error "deleted" } + std::move(f0)(); + std::as_const(f0)(); + std::move(std::as_const(f0))(); + + auto g0 = std::bind_front(G{}); + g0(); // { dg-error "deleted" } + std::move(g0)(); // { dg-error "deleted" } + std::move(std::as_const(g0))(); + + auto f1 = std::bind_front(F{}, 42); + f1(); // { dg-error "deleted" } + std::move(f1)(); + std::as_const(f1)(); + std::move(std::as_const(f1))(); + + auto g1 = std::bind_front(G{}, 42); + g1(); // { dg-error "deleted" } + std::move(g1)(); // { dg-error "deleted" } + std::move(std::as_const(g1))(); +}