dim created this revision.
dim added reviewers: EricWF, mclow.lists.
Herald added a subscriber: krytarowski.
After https://reviews.llvm.org/rL319736 for https://reviews.llvm.org/D28253
(which fixes PR28929), gcc cannot compile `<memory>` anymore in pre-C+11 modes,
complaining:
In file included from /usr/include/c++/v1/memory:648:0,
from test.cpp:1:
/usr/include/c++/v1/memory: In static member function 'static
std::__1::shared_ptr<_Tp> std::__1::shared_ptr<_Tp>::make_shared(_A0&, _A1&,
_A2&)':
/usr/include/c++/v1/memory:4365:5: error: wrong number of template arguments
(4, should be at least 1)
static_assert((is_constructible<_Tp, _A0, _A1, _A2>::value), "Can't
construct object in make_shared" );
^
In file included from /usr/include/c++/v1/memory:649:0,
from test.cpp:1:
/usr/include/c++/v1/type_traits:3198:29: note: provided for 'template<class
_Tp, class _A0, class _A1> struct std::__1::is_constructible'
struct _LIBCPP_TEMPLATE_VIS is_constructible
^~~~~~~~~~~~~~~~
In file included from /usr/include/c++/v1/memory:648:0,
from test.cpp:1:
/usr/include/c++/v1/memory:4365:5: error: template argument 1 is invalid
static_assert((is_constructible<_Tp, _A0, _A1, _A2>::value), "Can't
construct object in make_shared" );
^
/usr/include/c++/v1/memory: In static member function 'static
std::__1::shared_ptr<_Tp> std::__1::shared_ptr<_Tp>::allocate_shared(const
_Alloc&, _A0&, _A1&, _A2&)':
/usr/include/c++/v1/memory:4444:5: error: wrong number of template arguments
(4, should be at least 1)
static_assert((is_constructible<_Tp, _A0, _A1, _A2>::value), "Can't
construct object in allocate_shared" );
^
In file included from /usr/include/c++/v1/memory:649:0,
from test.cpp:1:
/usr/include/c++/v1/type_traits:3198:29: note: provided for 'template<class
_Tp, class _A0, class _A1> struct std::__1::is_constructible'
struct _LIBCPP_TEMPLATE_VIS is_constructible
^~~~~~~~~~~~~~~~
In file included from /usr/include/c++/v1/memory:648:0,
from test.cpp:1:
/usr/include/c++/v1/memory:4444:5: error: template argument 1 is invalid
static_assert((is_constructible<_Tp, _A0, _A1, _A2>::value), "Can't
construct object in allocate_shared" );
^
This is also reported in https://bugs.freebsd.org/224946 (FreeBSD is apparently
one of the very few projects that regularly builds programs against libc++ with
gcc).
The reason is that the static assertions are invoking `is_constructible` with
three arguments, while gcc does not have the built-in `is_constructible`
feature, and the pre-C++11 `is_constructible` wrappers in `<type_traits>` only
provide up to two arguments.
I have added additional wrappers for three arguments, modified the
`is_constructible` entry point to take three arguments instead, and added a
simple test to is_constructible.pass.cpp.
Repository:
rCXX libc++
https://reviews.llvm.org/D41805
Files:
include/type_traits
test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp
Index: test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp
===================================================================
--- test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp
+++ test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp
@@ -30,6 +30,7 @@
{
explicit A(int);
A(int, double);
+ A(int, long, double);
#if TEST_STD_VER >= 11
private:
#endif
@@ -106,6 +107,16 @@
#endif
}
+template <class T, class A0, class A1, class A2>
+void test_is_constructible()
+{
+ static_assert(( std::is_constructible<T, A0, A1, A2>::value), "");
+ LIBCPP11_STATIC_ASSERT((std::__libcpp_is_constructible<T, A0, A1, A2>::type::value), "");
+#if TEST_STD_VER > 14
+ static_assert(( std::is_constructible_v<T, A0, A1, A2>), "");
+#endif
+}
+
template <class T>
void test_is_not_constructible()
{
@@ -146,6 +157,7 @@
test_is_constructible<int, const int> ();
test_is_constructible<A, int> ();
test_is_constructible<A, int, double> ();
+ test_is_constructible<A, int, long, double> ();
test_is_constructible<int&, int&> ();
test_is_not_constructible<A> ();
Index: include/type_traits
===================================================================
--- include/type_traits
+++ include/type_traits
@@ -3172,6 +3172,14 @@
false_type
__is_constructible2_test(__any, _A0&, _A1&);
+template <class _Tp, class _A0, class _A1, class _A2>
+decltype((_Tp(_VSTD::declval<_A0>(), _VSTD::declval<_A1>(), _VSTD::declval<_A2>()), true_type()))
+__is_constructible3_test(_Tp&, _A0&, _A1&, _A2&);
+
+template <class _A0, class _A1, class _A2>
+false_type
+__is_constructible3_test(__any, _A0&, _A1&, _A2&);
+
template <bool, class _Tp>
struct __is_constructible0_imp // false, _Tp is not a scalar
: public common_type
@@ -3196,6 +3204,14 @@
>::type
{};
+template <bool, class _Tp, class _A0, class _A1, class _A2>
+struct __is_constructible3_imp // false, _Tp is not a scalar
+ : public common_type
+ <
+ decltype(__is_constructible3_test(declval<_Tp&>(), declval<_A0>(), declval<_A1>(), declval<_A2>()))
+ >::type
+ {};
+
// handle scalars and reference types
// Scalars are default constructible, references are not
@@ -3215,6 +3231,11 @@
: public false_type
{};
+template <class _Tp, class _A0, class _A1, class _A2>
+struct __is_constructible3_imp<true, _Tp, _A0, _A1, _A2>
+ : public false_type
+ {};
+
// Treat scalars and reference types separately
template <bool, class _Tp>
@@ -3235,6 +3256,12 @@
_Tp, _A0, _A1>
{};
+template <bool, class _Tp, class _A0, class _A1, class _A2>
+struct __is_constructible3_void_check
+ : public __is_constructible3_imp<is_scalar<_Tp>::value || is_reference<_Tp>::value,
+ _Tp, _A0, _A1, _A2>
+ {};
+
// If any of T or Args is void, is_constructible should be false
template <class _Tp>
@@ -3252,17 +3279,24 @@
: public false_type
{};
+template <class _Tp, class _A0, class _A1, class _A2>
+struct __is_constructible3_void_check<true, _Tp, _A0, _A1, _A2>
+ : public false_type
+ {};
+
// is_constructible entry point
template <class _Tp, class _A0 = __is_construct::__nat,
- class _A1 = __is_construct::__nat>
+ class _A1 = __is_construct::__nat,
+ class _A2 = __is_construct::__nat>
struct _LIBCPP_TEMPLATE_VIS is_constructible
- : public __is_constructible2_void_check<is_void<_Tp>::value
+ : public __is_constructible3_void_check<is_void<_Tp>::value
|| is_abstract<_Tp>::value
|| is_function<_Tp>::value
|| is_void<_A0>::value
- || is_void<_A1>::value,
- _Tp, _A0, _A1>
+ || is_void<_A1>::value
+ || is_void<_A2>::value,
+ _Tp, _A0, _A1, _A2>
{};
template <class _Tp>
@@ -3282,6 +3316,16 @@
_Tp, _A0>
{};
+template <class _Tp, class _A0, class _A1>
+struct _LIBCPP_TEMPLATE_VIS is_constructible<_Tp, _A0, _A1, __is_construct::__nat>
+ : public __is_constructible2_void_check<is_void<_Tp>::value
+ || is_abstract<_Tp>::value
+ || is_function<_Tp>::value
+ || is_void<_A0>::value
+ || is_void<_A1>::value,
+ _Tp, _A0, _A1>
+ {};
+
// Array types are default constructible if their element type
// is default constructible
@@ -3300,6 +3344,11 @@
: public false_type
{};
+template <class _Ap, size_t _Np, class _A0, class _A1, class _A2>
+struct __is_constructible3_imp<false, _Ap[_Np], _A0, _A1, _A2>
+ : public false_type
+ {};
+
// Incomplete array types are not constructible
template <class _Ap>
@@ -3314,6 +3363,11 @@
template <class _Ap, class _A0, class _A1>
struct __is_constructible2_imp<false, _Ap[], _A0, _A1>
+ : public false_type
+ {};
+
+template <class _Ap, class _A0, class _A1, class _A2>
+struct __is_constructible3_imp<false, _Ap[], _A0, _A1, _A2>
: public false_type
{};
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