Add tests for class template deduction on std::tuple.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@304967 91177308-0d34-0410-b5e6-96231b3b80d8

include/tuple

@@ -929,6 +929,16 @@ public:
     void swap(tuple&) _NOEXCEPT {}
 };
 
+#ifdef __cpp_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...>;
+#endif
+
 template <class ..._Tp>
 inline _LIBCPP_INLINE_VISIBILITY
 typename enable_if

test/std/utilities/tuple/tuple.tuple/tuple.cnstr/implicit_deduction_guides.pass.cpp

@@ -0,0 +1,150 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+// UNSUPPORTED: libcpp-no-deduction-guides
+
+// <string>
+
+// Test that the constructors offered by std::basic_string are formulated
+// so they're compatible with implicit deduction guides.
+
+#include <tuple>
+#include <memory>
+#include <cassert>
+
+#include "test_macros.h"
+#include "archetypes.hpp"
+
+
+// Overloads
+//  using A = Allocator
+//  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)
+void test_primary_template()
+{
+  const std::allocator<int> A;
+  const auto AT = std::allocator_arg;
+  { // Testing (1)
+    int x = 101;
+    std::tuple t1(42);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<int>);
+    std::tuple t2(x, 0.0, nullptr);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, double, decltype(nullptr)>);
+  }
+  { // Testing (2)
+    using T = ExplicitTestTypes::TestType;
+    static_assert(!std::is_convertible<T const&, T>::value, "");
+
+    std::tuple t1(T{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<T>);
+
+    const T v{};
+    std::tuple t2(T{}, 101l, v);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<T, long, T>);
+  }
+  { // Testing (3)
+    int x = 101;
+    std::tuple t1(AT, A, 42);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<int>);
+
+    std::tuple t2(AT, A, 42, 0.0, x);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<int, double, int>);
+  }
+  { // Testing (4)
+    using T = ExplicitTestTypes::TestType;
+    static_assert(!std::is_convertible<T const&, T>::value, "");
+
+    std::tuple t1(AT, A, T{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<T>);
+
+    const T v{};
+    std::tuple t2(AT, A, T{}, 101l, v);
+    ASSERT_SAME_TYPE(decltype(t2), std::tuple<T, long, T>);
+  }
+  { // Testing (5)
+    using Tup = std::tuple<int, decltype(nullptr)>;
+    const Tup t(42, nullptr);
+
+    std::tuple t1(t);
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+  { // Testing (6)
+    using Tup = std::tuple<void*, unsigned, char>;
+    std::tuple t1(Tup(nullptr, 42, 'a'));
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+  { // Testing (7)
+    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)
+    using Tup = std::tuple<void*, unsigned, char>;
+    std::tuple t1(AT, A, Tup(nullptr, 42, 'a'));
+    ASSERT_SAME_TYPE(decltype(t1), Tup);
+  }
+}
+
+// Overloads
+//  using A = Allocator
+//  using AT = std::allocator_arg_t
+// ---------------
+// (1)  tuple() -> tuple<>
+// (2)  tuple(AT, A const&) -> tuple<>
+// (3)  tuple(tuple const&) -> tuple<>
+// (4)  tuple(tuple&&) -> tuple<>
+// (5)  tuple(AT, A const&, tuple const&) -> tuple<>
+// (6)  tuple(AT, A const&, tuple&&) -> tuple<>
+void test_empty_specialization()
+{
+  std::allocator<int> A;
+  const auto AT = std::allocator_arg;
+  { // Testing (1)
+    std::tuple t1{};
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (2)
+    std::tuple t1{AT, A};
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (3)
+    const std::tuple<> t{};
+    std::tuple t1(t);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (4)
+    std::tuple t1(std::tuple<>{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (5)
+    const std::tuple<> t{};
+    std::tuple t1(AT, A, t);
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+  { // Testing (6)
+    std::tuple t1(AT, A, std::tuple<>{});
+    ASSERT_SAME_TYPE(decltype(t1), std::tuple<>);
+  }
+}
+
+int main() {
+  test_primary_template();
+  test_empty_specialization();
+}