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| author | Patrick Palka <ppalka@redhat.com> | 2023-09-12 11:23:12 -0400 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2023-09-12 11:23:12 -0400 |
| commit | 4289f6ceefe74ea46e792692448c06197ac20c86 (patch) | |
| tree | 4e31e0b727d7077fb0e6c159c21d0fba97e94163 /libstdc++-v3 | |
| parent | f1e87aee5b7023fb4f5791c6869db705e18c2705 (diff) | |
| download | gcc-4289f6ceefe74ea46e792692448c06197ac20c86.zip gcc-4289f6ceefe74ea46e792692448c06197ac20c86.tar.gz gcc-4289f6ceefe74ea46e792692448c06197ac20c86.tar.bz2 | |
libstdc++: Fix std::bind_front perfect forwarding [PR111327]
In order to properly implement a perfect forwarding call wrapper (without
C++23 deducing 'this') we need a total of 8 operator() overloads, 4
enabled ones and 4 deleted ones, i.e. two for each const/ref qual pair,
as described in section 5.5 of P0847R6. Otherwise the wrapper may not
do the right thing if the underlying function object has a deleted
const/ref-qualified operator() overload. This patch fixes this issue in
std::bind_front.
PR libstdc++/111327
libstdc++-v3/ChangeLog:
* include/std/functional (_Bind_front::operator()): Add deleted
fallback overloads for each const/ref qualifier pair. Give the
enabled overloads dummy constraints to make each one more
specialized than the corresponding deleted overload.
* testsuite/20_util/function_objects/bind_front/111327.cc: New test.
Diffstat (limited to 'libstdc++-v3')
| -rw-r--r-- | libstdc++-v3/include/std/functional | 16 | ||||
| -rw-r--r-- | libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc | 41 |
2 files changed, 57 insertions, 0 deletions
diff --git a/libstdc++-v3/include/std/functional b/libstdc++-v3/include/std/functional index 7d1b890..c50b9e4 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 0000000..fcfb9f9c --- /dev/null +++ b/libstdc++-v3/testsuite/20_util/function_objects/bind_front/111327.cc @@ -0,0 +1,41 @@ +// PR libstdc++/111327 - std::bind_front (and std::not_fn) doesn't always +// 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))(); +} |