The <new> header is needed by std::function to use placement new, so
include it in <bits/std_function.h> instead of in <functional>.
libstdc++-v3/ChangeLog:
* include/bits/std_function.h: Include <new> but do not include
<bits/stl_function.h>.
* include/std/functional: Do not include <new>.
Adjust the deduction guides for std::function and std::packaged_task to
work with static call operators. This finishes the implementation of
P1169R4 for C++23.
libstdc++-v3/ChangeLog:
PR c++/106651
* include/bits/std_function.h (__function_guide_t): New alias
template.
[__cpp_static_call_operator] (__function_guide_static_helper):
New class template.
(function): Use __function_guide_t in deduction guide.
* include/std/future (packaged_task): Use __function_guide_t in
deduction guide.
* testsuite/20_util/function/cons/deduction_c++23.cc: New test.
* testsuite/30_threads/packaged_task/cons/deduction_c++23.cc:
New test.
This avoids "<template-parameter-2-2>" being shown in the diagnostics
for ill-formed uses of std::function constructor:
In instantiation of 'std::function<_Res(_ArgTypes ...)>::function(_Functor&&)
[with _Functor = f(f()::_Z1fv.frame*)::<lambda()>;
<template-parameter-2-2> = void; _Res = void; _ArgTypes = {}]'
Instead we get:
In instantiation of 'std::function<_Res(_ArgTypes ...)>::function(_Functor&&)
[with _Functor = f(f()::_Z1fv.frame*)::<lambda()>;
_Constraints = void; _Res = void; _ArgTypes = {}]'
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (function::function(F&&)): Give
name to defaulted template parameter, to improve diagnostics.
Use markdown for more doxygen comments.
This makes the std::function constructor use perfect forwarding, to
avoid an unnecessary move-construction of the target. This means we need
to rewrite the _Function_base::_Base_manager::_M_init_functor function
to use a forwarding reference, and so can reuse it for the clone
operation.
Also simplify the SFINAE constraints on the constructor, by combining
the !is_same_v<remove_cvref_t<F>, function> constraint into the
_Callable trait.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (_function_base::_Base_manager):
Replace _M_init_functor with a function template using a
forwarding reference, and a pair of _M_create function
templates. Reuse _M_create for the clone operation.
(function::_Decay_t): New alias template.
(function::_Callable): Simplify by using _Decay.
(function::function(F)): Change parameter to forwarding
reference, as per LWG 2447. Add noexcept-specifier. Simplify
constraints.
(function::operator=(F&&)): Add noexcept-specifier.
* testsuite/20_util/function/cons/lwg2774.cc: New test.
* testsuite/20_util/function/cons/noexcept.cc: New test.
Add static assertions to std::function, so that more user-friendly
diagnostics are given when trying to store a non-copyable target object.
These preconditions were added as "Mandates:" by LWG 2447, but I'm
committing them separately from implementing that, to allow just this
change to be backported more easily.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (function::function(F)): Add
static assertions to check constructibility requirements.
PR 101923 points out that the unconditional swap in the std::function
move constructor makes it slower than copying an empty std::function.
The copy constructor has to check for the empty case before doing
anything, and that makes it very fast for the empty case.
Adding the same check to the move constructor avoids copying the
_Any_data POD when we don't need to. We can also inline the effects of
swap, by copying each member and then zeroing the pointer members.
This makes moving an empty object at least as fast as copying an empty
object.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/101923
* include/bits/std_function.h (function(function&&)): Check for
non-empty parameter before doing any work.
The std::function::swap member swaps each data member unconditionally,
resulting in -Wmaybe-uninitialized warnings for a default constructed
object. This happens because the _M_invoker and _M_functor members are
only initialized if the function has a target.
This change ensures that all subobjects are zero-initialized on
construction.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (_Function_base): Add
default member initializers and define constructor as defaulted.
(function::_M_invoker): Add default member initializer.
The std::function code now uses std::type_info* even when RTTI is
disabled, so it should include <typeinfo> unconditionally. Without this,
Clang can't compile <functional> with -fno-rtti (it works with GCC
because std::type_info gets declared automatically by the compiler).
libstdc++-v3/ChangeLog:
PR libstdc++/97758
* include/bits/std_function.h [!__cpp_rtti]: Include <typeinfo>.
This change allows std::function::target<F>() to work even without RTTI,
using the same approach as std::any. Because we know what the manager
function would be for a given type, we can check if the stored pointer
has the expected address. If it does, we don't need to use RTTI. If it
isn't equal, we still need to do the RTTI check (when RTTI is enabled)
to handle the case where the same function has different addresses in
different shared objects.
This also changes the implementation of the manager function to return a
null pointer result when asked for the type_info of the target object.
This not only avoids a warning with -Wswitch -Wsystem-headers, but also
avoids prevents std::function::target_type() from dereferencing an
uninitialized pointer when the linker keeps an instantiation of the
manager function that was compiled without RTTI.
Finally, this fixes a bug in the non-const overload of function::target
where calling it with a function type F was ill-formed, due to
attempting to use const_cast<F*>(ptr). The standard only allows
const_cast<T*> when T is an object type. The solution is to use
*const_cast<F**>(&ptr) instead, because F* is an object type even if F
isn't. I've also used _GLIBCXX17_CONSTEXPR in function::target so that
it doesn't bother instantiating anything for types that can never be a
valid target.
libstdc++-v3/ChangeLog:
* include/bits/std_function.h (_Function_handler<void, void>):
Define explicit specialization used for invalid target types.
(_Base_manager::_M_manager) [!__cpp_rtti]: Return null.
(function::target_type()): Check for null pointer.
(function::target()): Define unconditionall. Fix bug with
const_cast of function pointer type.
(function::target() const): Define unconditionally, but
only use RTTI if enabled.
* testsuite/20_util/function/target_no_rtti.cc: New test.
Some more C++20 changes from P1614R2, "The Mothership has Landed".
This removes all redundant equality and inequality operators in the
Utilities clause, as they can be synthesized from the remaining equality
operators.
It also removes the single redundant operator in the Localization
clause, because it didn't seem worth doing in a separate commit.
* include/bits/allocator.h (operator!=): Do not define for C++20.
* include/bits/locale_classes.h (operator!=): Likewise.
* include/bits/std_function.h (operator==(nullptr_t, const function&))
(operator!=(const function&, nullptr_t))
(operator!=(nullptr_t, const function&)): Likewise.
* include/ext/bitmap_allocator.h (operator!=): Likewise.
* include/ext/debug_allocator.h (operator!=): Likewise.
* include/ext/extptr_allocator.h (operator!=): Likewise.
* include/ext/malloc_allocator.h (operator!=): Likewise.
* include/ext/mt_allocator.h (operator!=): Likewise.
* include/ext/new_allocator.h (operator!=): Likewise.
* include/ext/pool_allocator.h (operator!=): Likewise.
* include/ext/throw_allocator.h (operator!=): Likewise.
* include/std/bitset (bitset::operator!=): Likewise.
* include/std/memory_resource (operator!=): Likewise.
* include/std/scoped_allocator (operator!=): Likewise.
In C++17 a function can return a prvalue of a type that cannot be moved
or copied. The current implementation of std::is_invocable_r uses
std::is_convertible to test the conversion to R required by INVOKE<R>.
That fails for non-copyable prvalues, because std::is_convertible is
defined in terms of std::declval which uses std::add_rvalue_reference.
In C++17 conversion from R to R involves no copies and so is not the
same as conversion from R&& to R.
This commit changes std::is_invocable_r to check the conversion without
using std::is_convertible.
std::function also contains a similar check using std::is_convertible,
which can be fixed by simply reusing std::is_invocable_r (but because
std::is_invocable_r is not defined for C++11 it uses the underlying
std::__is_invocable_impl trait directly).
PR libstdc++/91456
* include/bits/std_function.h (__check_func_return_type): Remove.
(function::_Callable): Use std::__is_invocable_impl instead of
__check_func_return_type.
* include/std/type_traits (__is_invocable_impl): Add another defaulted
template parameter. Define a separate partial specialization for
INVOKE and INVOKE<void>. For INVOKE<R> replace is_convertible check
with a check that models delayed temporary materialization.
* testsuite/20_util/function/91456.cc: New test.
* testsuite/20_util/is_invocable/91456.cc: New test.
From-SVN: r274542
As well as simpifying the code by removing duplication, this means that
we only need to touch std::__invoke_r if we need to implement changes to
INVOKE<R>, such as those in P0932R0.
* include/bits/std_function.h (_Simple_type_wrapper): Remove.
(_Function_handler): Remove partial specializations for void return
types and pointers to member.
(_Function_handler::_M_manager): Adapt to removal of
_Simple_type_wrapper.
(_Function_handler::_M_invoke): Use __invoke_r instead of __invoke.
* include/std/functional (_Bind_result::__enable_if_void)
(_Bind_result::__disable_if_void): Remove sfinae helpers.
(_Bind_result::__call): Use __invoke_r and remove overloads for void
return types.
* include/std/future (__future_base::_Task_state::_M_run)
(__future_base::_Task_state::_M_run_delayed): Use __invoke_r and
change return type of lambda expressions.
From-SVN: r271174
Avoid creating arbitrarily large objects on the stack when emplacing
trivially copyable objects into a variant. Currently we provide the
strong exception-safety guarantee for all trivially copyable types, by
constructing a second variant and then doing a non-throwing move
assignment from the temporary. This patch restricts that behaviour to
trivially copyable types that are no larger than 256 bytes. For larger
types the object will be emplaced directly into the variant, and if its
initialization throws then the variant becomes valueless.
Also implement Antony Polukhin's suggestion to whitelist specific types
that are not trivially copyable but can be efficiently move-assigned.
Emplacing those types will never cause a variant to become valueless.
The whitelisted types are: std::shared_ptr, std::weak_ptr,
std::unique_ptr, std::function, and std::any. Additionally,
std::basic_string, std::vector, and __gnu_debug::vector are whitelisted
if their allocator traits give them a non-throwing move assignment
operator. Specifically, this means std::string is whitelisted, but
std::pmr::string is not.
As part of this patch, additional if-constexpr branches are added for
the cases where the initialization is known to be non-throwing (so the
overhead of the try-catch block can be avoided) and where a scalar is
being produced by a potentially-throwing conversion operator (so that
the overhead of constructing and move-assigning a variant is avoided).
These changes should have no semantic effect, just better codegen.
PR libstdc++/87431 (again)
* include/bits/basic_string.h (__variant::_Never_valueless_alt):
Define partial specialization for basic_string.
* include/bits/shared_ptr.h (_Never_valueless_alt): Likewise for
shared_ptr and weak_ptr.
* include/bits/std_function.h (_Never_valueless_alt): Likewise for
function.
* include/bits/stl_vector.h (_Never_valueless_alt): Likewise for
vector.
* include/bits/unique_ptr.h (_Never_valueless_alt): Likewise for
unique_ptr.
* include/debug/vector (_Never_valueless_alt): Likewise for debug
vector.
* include/std/any (_Never_valueless_alt): Define explicit
specialization for any.
* include/std/variant (_Never_valueless_alt): Define primary template.
(__never_valueless): Use _Never_valueless_alt instead of
is_trivially_copyable.
(variant::emplace<N>(Args&&...)): Add special case for non-throwing
initializations to avoid try-catch overhead. Add special case for
scalars produced by potentially-throwing conversions. Use
_Never_valueless_alt instead of is_trivially_copyable for the
remaining strong exception-safety cases.
(variant::emplace<N>(initializer_list<U>, Args&&...)): Likewise.
* testsuite/20_util/variant/87431.cc: Run both test functions.
* testsuite/20_util/variant/exception_safety.cc: New test.
* testsuite/20_util/variant/run.cc: Use pmr::string instead of string,
so the variant becomes valueless.
From-SVN: r270170
To satisfy the CopyConstructible requirement a callable object stored in
a std::function must behave the same when copied from a const or
non-const source. If copying a non-const object doesn't produce an
equivalent copy then the behaviour is undefined. But we can make our
std::function more tolerant of such objects by ensuring we always copy
from a const lvalue.
Additionally use an if constexpr statement in the _M_get_pointer
function to avoid unnecessary instantiations in the discarded branch.
* include/bits/std_function.h (_Base_manager::_M_get_pointer):
Use constexpr if in C++17 mode.
(_Base_manager::_M_clone(_Any_data&, const _Any_data&, true_type)):
Copy from const object.
* testsuite/20_util/function/cons/non_copyconstructible.cc: New.
From-SVN: r260080
PR libstdc++/83427
* include/bits/refwrap.h (_Maybe_unary_or_binary_function): Move here
from <bits/std_function.h>.
(_Mem_fn_traits_base, _Mem_fn_traits): Move here, from <functional>.
(_Weak_result_type_impl, _Reference_wrapper_base): Deduce noexcept
for function types. Remove partial specializations for member
functions.
(_Weak_result_type_impl): Remove unused partial specializations for
non-referenceable function types and for references to functions.
(_Weak_result_type_memfun, _Reference_wrapper_base_memfun): New
helpers to handle member functions via _Mem_fn_traits.
(_Weak_result_type, reference_wrapper): Derive from new helpers.
* include/bits/std_function.h (_Maybe_unary_or_binary_function): Move
to <bits/refwrap.h>.
* include/std/functional (_Pack, _AllConvertible, _NotSame): Remove.
(_Mem_fn_traits_base, _Mem_fn_traits): Move to <bits/refwrap.h>.
* testsuite/20_util/bind/83427.cc: New test.
* testsuite/20_util/bind/refqual.cc: Add noexcept to functions and
check for weak result types.
* testsuite/20_util/reference_wrapper/83427.cc: New test.
From-SVN: r255651
Jakub Jelinek