[libcxx] r321963 - Add pre-C++11 is_constructible wrappers for 3 arguments
Hans Wennborg via cfe-commits
cfe-commits at lists.llvm.org
Wed Jan 17 06:28:16 PST 2018
Merged to 6.0 in r322659.
On Sun, Jan 7, 2018 at 5:45 PM, Dimitry Andric via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
> Author: dim
> Date: Sun Jan 7 08:45:11 2018
> New Revision: 321963
>
> URL: http://llvm.org/viewvc/llvm-project?rev=321963&view=rev
> Log:
> Add pre-C++11 is_constructible wrappers for 3 arguments
>
> Summary:
> After rL319736 for 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.
>
> Reviewers: EricWF, mclow.lists
>
> Reviewed By: EricWF
>
> Subscribers: krytarowski, cfe-commits, emaste
>
> Differential Revision: https://reviews.llvm.org/D41805
>
> Modified:
> libcxx/trunk/include/type_traits
> libcxx/trunk/test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp
>
> Modified: libcxx/trunk/include/type_traits
> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/type_traits?rev=321963&r1=321962&r2=321963&view=diff
> ==============================================================================
> --- libcxx/trunk/include/type_traits (original)
> +++ libcxx/trunk/include/type_traits Sun Jan 7 08:45:11 2018
> @@ -3172,6 +3172,14 @@ template <class _A0, class _A1>
> 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 @@ struct __is_constructible2_imp // false,
> >::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 @@ struct __is_constructible2_imp<true, _Tp
> : 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 @@ struct __is_constructible2_void_check
> _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 @@ struct __is_constructible2_void_check<tr
> : 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 @@ struct _LIBCPP_TEMPLATE_VIS is_construct
> _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 @@ struct __is_constructible2_imp<false, _A
> : 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>
> @@ -3317,6 +3366,11 @@ struct __is_constructible2_imp<false, _A
> : public false_type
> {};
>
> +template <class _Ap, class _A0, class _A1, class _A2>
> +struct __is_constructible3_imp<false, _Ap[], _A0, _A1, _A2>
> + : public false_type
> + {};
> +
> #endif // __has_feature(is_constructible)
>
>
>
> Modified: libcxx/trunk/test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp
> URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp?rev=321963&r1=321962&r2=321963&view=diff
> ==============================================================================
> --- libcxx/trunk/test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp (original)
> +++ libcxx/trunk/test/std/utilities/meta/meta.unary/meta.unary.prop/is_constructible.pass.cpp Sun Jan 7 08:45:11 2018
> @@ -30,6 +30,7 @@ struct A
> {
> explicit A(int);
> A(int, double);
> + A(int, long, double);
> #if TEST_STD_VER >= 11
> private:
> #endif
> @@ -106,6 +107,16 @@ void test_is_constructible()
> #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 @@ int main()
> 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> ();
>
>
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