[libc++] Implement CTAD for std::tuple
Summary:
We were using implicit deduction guides instead of explicit ones,
however the implicit ones don't do work anymore when changing the
constructors.
This commit adds the actual guides specified in the Standard to make
libc++ (1) closer to the Standard and (2) more resistent to changes
in std::tuple's constructors.
Reviewers: Quuxplusone
Subscribers: christof, jkorous, dexonsmith, libcxx-commits
Tags: #libc
Differential Revision: https://reviews.llvm.org/D65225
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@368599 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/tuple b/include/tuple
index 6506587..32bc869 100644
--- a/include/tuple
+++ b/include/tuple
@@ -69,6 +69,17 @@
void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));
};
+template <class ...T>
+tuple(T...) -> tuple<T...>; // since C++17
+template <class T1, class T2>
+tuple(pair<T1, T2>) -> tuple<T1, T2>; // since C++17
+template <class Alloc, class ...T>
+tuple(allocator_arg_t, Alloc, T...) -> tuple<T...>; // since C++17
+template <class Alloc, class T1, class T2>
+tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>; // since C++17
+template <class Alloc, class ...T>
+tuple(allocator_arg_t, Alloc, tuple<T...>) -> tuple<T...>; // since C++17
+
inline constexpr unspecified ignore;
template <class... T> tuple<V...> make_tuple(T&&...); // constexpr in C++14
@@ -943,13 +954,16 @@
};
#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
-// NOTE: These are not yet standardized, but are required to simulate the
-// implicit deduction guide that should be generated had libc++ declared the
-// tuple-like constructors "correctly"
-template <class _Alloc, class ..._Args>
-tuple(allocator_arg_t, const _Alloc&, tuple<_Args...> const&) -> tuple<_Args...>;
-template <class _Alloc, class ..._Args>
-tuple(allocator_arg_t, const _Alloc&, tuple<_Args...>&&) -> tuple<_Args...>;
+template <class ..._Tp>
+tuple(_Tp...) -> tuple<_Tp...>;
+template <class _Tp1, class _Tp2>
+tuple(pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
+template <class _Alloc, class ..._Tp>
+tuple(allocator_arg_t, _Alloc, _Tp...) -> tuple<_Tp...>;
+template <class _Alloc, class _Tp1, class _Tp2>
+tuple(allocator_arg_t, _Alloc, pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;
+template <class _Alloc, class ..._Tp>
+tuple(allocator_arg_t, _Alloc, tuple<_Tp...>) -> tuple<_Tp...>;
#endif
template <class ..._Tp>
diff --git a/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp b/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/deduct.pass.cpp
similarity index 66%
rename from test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp
rename to test/std/utilities/tuple/tuple.tuple/tuple.cnstr/deduct.pass.cpp
index 3ff089a..e903cd0 100644
--- a/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp
+++ b/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/deduct.pass.cpp
@@ -33,13 +33,15 @@
// using AT = std::allocator_arg_t
// ---------------
// (1) tuple(const Types&...) -> tuple<Types...>
-// (2) explicit tuple(const Types&...) -> tuple<Types...>
-// (3) tuple(AT, A const&, Types const&...) -> tuple<Types...>
-// (4) explicit tuple(AT, A const&, Types const&...) -> tuple<Types...>
-// (5) tuple(tuple const& t) -> decltype(t)
-// (6) tuple(tuple&& t) -> decltype(t)
-// (7) tuple(AT, A const&, tuple const& t) -> decltype(t)
-// (8) tuple(AT, A const&, tuple&& t) -> decltype(t)
+// (2) tuple(pair<T1, T2>) -> tuple<T1, T2>;
+// (3) explicit tuple(const Types&...) -> tuple<Types...>
+// (4) tuple(AT, A const&, Types const&...) -> tuple<Types...>
+// (5) explicit tuple(AT, A const&, Types const&...) -> tuple<Types...>
+// (6) tuple(AT, A, pair<T1, T2>) -> tuple<T1, T2>
+// (7) tuple(tuple const& t) -> decltype(t)
+// (8) tuple(tuple&& t) -> decltype(t)
+// (9) tuple(AT, A const&, tuple const& t) -> decltype(t)
+// (10) tuple(AT, A const&, tuple&& t) -> decltype(t)
void test_primary_template()
{
const std::allocator<int> A;
@@ -52,6 +54,27 @@
ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, double, decltype(nullptr)>);
}
{ // Testing (2)
+ std::pair<int, char> p1(1, 'c');
+ std::tuple t1(p1);
+ ASSERT_SAME_TYPE(decltype(t1), std::tuple<int, char>);
+
+ std::pair<int, std::tuple<char, long, void*>> p2(1, std::tuple<char, long, void*>('c', 3l, nullptr));
+ std::tuple t2(p2);
+ ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, std::tuple<char, long, void*>>);
+
+ int i = 3;
+ std::pair<std::reference_wrapper<int>, char> p3(std::ref(i), 'c');
+ std::tuple t3(p3);
+ ASSERT_SAME_TYPE(decltype(t3), std::tuple<std::reference_wrapper<int>, char>);
+
+ std::pair<int&, char> p4(i, 'c');
+ std::tuple t4(p4);
+ ASSERT_SAME_TYPE(decltype(t4), std::tuple<int&, char>);
+
+ std::tuple t5(std::pair<int, char>(1, 'c'));
+ ASSERT_SAME_TYPE(decltype(t5), std::tuple<int, char>);
+ }
+ { // Testing (3)
using T = ExplicitTestTypes::TestType;
static_assert(!std::is_convertible<T const&, T>::value, "");
@@ -62,7 +85,7 @@
std::tuple t2(T{}, 101l, v);
ASSERT_SAME_TYPE(decltype(t2), std::tuple<T, long, T>);
}
- { // Testing (3)
+ { // Testing (4)
int x = 101;
std::tuple t1(AT, A, 42);
ASSERT_SAME_TYPE(decltype(t1), std::tuple<int>);
@@ -70,7 +93,7 @@
std::tuple t2(AT, A, 42, 0.0, x);
ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, double, int>);
}
- { // Testing (4)
+ { // Testing (5)
using T = ExplicitTestTypes::TestType;
static_assert(!std::is_convertible<T const&, T>::value, "");
@@ -81,26 +104,47 @@
std::tuple t2(AT, A, T{}, 101l, v);
ASSERT_SAME_TYPE(decltype(t2), std::tuple<T, long, T>);
}
- { // Testing (5)
+ { // Testing (6)
+ std::pair<int, char> p1(1, 'c');
+ std::tuple t1(AT, A, p1);
+ ASSERT_SAME_TYPE(decltype(t1), std::tuple<int, char>);
+
+ std::pair<int, std::tuple<char, long, void*>> p2(1, std::tuple<char, long, void*>('c', 3l, nullptr));
+ std::tuple t2(AT, A, p2);
+ ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, std::tuple<char, long, void*>>);
+
+ int i = 3;
+ std::pair<std::reference_wrapper<int>, char> p3(std::ref(i), 'c');
+ std::tuple t3(AT, A, p3);
+ ASSERT_SAME_TYPE(decltype(t3), std::tuple<std::reference_wrapper<int>, char>);
+
+ std::pair<int&, char> p4(i, 'c');
+ std::tuple t4(AT, A, p4);
+ ASSERT_SAME_TYPE(decltype(t4), std::tuple<int&, char>);
+
+ std::tuple t5(AT, A, std::pair<int, char>(1, 'c'));
+ ASSERT_SAME_TYPE(decltype(t5), std::tuple<int, char>);
+ }
+ { // Testing (7)
using Tup = std::tuple<int, decltype(nullptr)>;
const Tup t(42, nullptr);
std::tuple t1(t);
ASSERT_SAME_TYPE(decltype(t1), Tup);
}
- { // Testing (6)
+ { // Testing (8)
using Tup = std::tuple<void*, unsigned, char>;
std::tuple t1(Tup(nullptr, 42, 'a'));
ASSERT_SAME_TYPE(decltype(t1), Tup);
}
- { // Testing (7)
+ { // Testing (9)
using Tup = std::tuple<int, decltype(nullptr)>;
const Tup t(42, nullptr);
std::tuple t1(AT, A, t);
ASSERT_SAME_TYPE(decltype(t1), Tup);
}
- { // Testing (8)
+ { // Testing (10)
using Tup = std::tuple<void*, unsigned, char>;
std::tuple t1(AT, A, Tup(nullptr, 42, 'a'));
ASSERT_SAME_TYPE(decltype(t1), Tup);
