Fix PR34298 - Allow std::function with an incomplete return type.
This patch fixes llvm.org/PR34298. Previously libc++ incorrectly evaluated
the __invokable trait via the converting constructor `function(Tp)` [with Tp = std::function]
whenever the copy constructor or copy assignment operator
was required. This patch further constrains that constructor to short
circut before evaluating the troublesome SFINAE when `Tp` matches
std::function.
The original patch is from Alex Lorenz.
llvm-svn: 312892
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 94d555116cbdc1522656a205f579da31f0bc14d1
diff --git a/include/functional b/include/functional
index 83a2e5a..f73c3ca 100644
--- a/include/functional
+++ b/include/functional
@@ -1597,9 +1597,11 @@
return reinterpret_cast<__base*>(p);
}
- template <class _Fp, bool = !is_same<_Fp, function>::value &&
- __invokable<_Fp&, _ArgTypes...>::value>
- struct __callable;
+ template <class _Fp, bool = __lazy_and<
+ integral_constant<bool, !is_same<__uncvref_t<_Fp>, function>::value>,
+ __invokable<_Fp&, _ArgTypes...>
+ >::value>
+ struct __callable;
template <class _Fp>
struct __callable<_Fp, true>
{
@@ -1612,6 +1614,9 @@
{
static const bool value = false;
};
+
+ template <class _Fp>
+ using _EnableIfCallable = typename enable_if<__callable<_Fp>::value>::type;
public:
typedef _Rp result_type;
@@ -1622,9 +1627,7 @@
function(nullptr_t) _NOEXCEPT : __f_(0) {}
function(const function&);
function(function&&) _NOEXCEPT;
- template<class _Fp, class = typename enable_if<
- __callable<_Fp>::value && !is_same<_Fp, function>::value
- >::type>
+ template<class _Fp, class = _EnableIfCallable<_Fp>>
function(_Fp);
#if _LIBCPP_STD_VER <= 14
@@ -1638,21 +1641,15 @@
function(allocator_arg_t, const _Alloc&, const function&);
template<class _Alloc>
function(allocator_arg_t, const _Alloc&, function&&);
- template<class _Fp, class _Alloc, class = typename enable_if<__callable<_Fp>::value>::type>
+ template<class _Fp, class _Alloc, class = _EnableIfCallable<_Fp>>
function(allocator_arg_t, const _Alloc& __a, _Fp __f);
#endif
function& operator=(const function&);
function& operator=(function&&) _NOEXCEPT;
function& operator=(nullptr_t) _NOEXCEPT;
- template<class _Fp>
- typename enable_if
- <
- __callable<typename decay<_Fp>::type>::value &&
- !is_same<typename remove_reference<_Fp>::type, function>::value,
- function&
- >::type
- operator=(_Fp&&);
+ template<class _Fp, class = _EnableIfCallable<_Fp>>
+ function& operator=(_Fp&&);
~function();
@@ -1854,13 +1851,8 @@
}
template<class _Rp, class ..._ArgTypes>
-template <class _Fp>
-typename enable_if
-<
- function<_Rp(_ArgTypes...)>::template __callable<typename decay<_Fp>::type>::value &&
- !is_same<typename remove_reference<_Fp>::type, function<_Rp(_ArgTypes...)>>::value,
- function<_Rp(_ArgTypes...)>&
->::type
+template <class _Fp, class>
+function<_Rp(_ArgTypes...)>&
function<_Rp(_ArgTypes...)>::operator=(_Fp&& __f)
{
function(_VSTD::forward<_Fp>(__f)).swap(*this);
diff --git a/include/type_traits b/include/type_traits
index 9db4d66..6c111ab 100644
--- a/include/type_traits
+++ b/include/type_traits
@@ -4339,8 +4339,8 @@
using _Result = decltype(
_VSTD::__invoke(_VSTD::declval<_Fp>(), _VSTD::declval<_Args>()...));
- static const bool value =
- conditional<
+ using type =
+ typename conditional<
!is_same<_Result, __nat>::value,
typename conditional<
is_void<_Ret>::value,
@@ -4348,7 +4348,8 @@
is_convertible<_Result, _Ret>
>::type,
false_type
- >::type::value;
+ >::type;
+ static const bool value = type::value;
};
template <class _Fp, class ..._Args>