Fixes PR21157 'tuple: non-default constructible tuple hard failure' Thanks to Louis Dionne for the bug report and the patch.

llvm-svn: 219785

3 files changed, 56 insertions, 0 deletions

diff --git a/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/UTypes.pass.cpp b/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/UTypes.pass.cpp
index d6fbdae835a..7359d77c054 100644
--- a/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/UTypes.pass.cpp
+++ b/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/UTypes.pass.cpp
@@ -16,6 +16,7 @@
 
 #include <tuple>
 #include <cassert>
+#include <type_traits>
 
 #include "../MoveOnly.h"
 
@@ -30,6 +31,8 @@ struct A
 
 #endif
 
+struct NoDefault { NoDefault() = delete; };
+
 int main()
 {
     {
@@ -63,6 +66,14 @@ int main()
         assert(std::get<1>(t) == MoveOnly());
         assert(std::get<2>(t) == MoveOnly());
     }
+    {
+        // Make sure the _Up... constructor SFINAEs out when the types that
+        // are not explicitly initialized are not all default constructible.
+        // Otherwise, std::is_constructible would return true but instantiating
+        // the constructor would fail.
+        static_assert(!std::is_constructible<std::tuple<MoveOnly, NoDefault>, MoveOnly>(), "");
+        static_assert(!std::is_constructible<std::tuple<MoveOnly, MoveOnly, NoDefault>, MoveOnly, MoveOnly>(), "");
+    }
 #if _LIBCPP_STD_VER > 11
     {
         constexpr std::tuple<Empty> t0{Empty()};
diff --git a/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp b/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp
index 667c4dd803c..97469869dff 100644
--- a/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp
+++ b/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/alloc_UTypes.pass.cpp
@@ -22,6 +22,8 @@
 #include "../alloc_first.h"
 #include "../alloc_last.h"
 
+struct NoDefault { NoDefault() = delete; };
+
 int main()
 {
     {
@@ -68,4 +70,19 @@ int main()
         assert(std::get<1>(t) == MoveOnly());
         assert(std::get<2>(t) == MoveOnly());
     }
+    {
+        // Make sure the _Up... constructor SFINAEs out when the types that
+        // are not explicitly initialized are not all default constructible.
+        // Otherwise, std::is_constructible would return true but instantiating
+        // the constructor would fail.
+        static_assert(!std::is_constructible<
+            std::tuple<MoveOnly, NoDefault>,
+            std::allocator_arg_t, A1<int>, MoveOnly
+        >::value, "");
+
+        static_assert(!std::is_constructible<
+            std::tuple<MoveOnly, MoveOnly, NoDefault>,
+            std::allocator_arg_t, A1<int>, MoveOnly, MoveOnly
+        >::value, "");
+    }
 }
diff --git a/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp b/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp
index b72b77ee97c..9cde90da3f5 100644
--- a/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp
+++ b/libcxx/test/utilities/tuple/tuple.tuple/tuple.cnstr/default.pass.cpp
@@ -16,9 +16,23 @@
 #include <tuple>
 #include <string>
 #include <cassert>
+#include <type_traits>
 
 #include "DefaultOnly.h"
 
+struct NoDefault {
+    NoDefault() = delete;
+    explicit NoDefault(int) { }
+};
+
+struct NoExceptDefault {
+    NoExceptDefault() noexcept = default;
+};
+
+struct ThrowingDefault {
+    ThrowingDefault() { }
+};
+
 int main()
 {
     {
@@ -46,6 +60,20 @@ int main()
         assert(std::get<2>(t) == "");
         assert(std::get<3>(t) == DefaultOnly());
     }
+    {
+        // See bug #21157.
+        static_assert(!std::is_default_constructible<std::tuple<NoDefault>>(), "");
+        static_assert(!std::is_default_constructible<std::tuple<DefaultOnly, NoDefault>>(), "");
+        static_assert(!std::is_default_constructible<std::tuple<NoDefault, DefaultOnly, NoDefault>>(), "");
+    }
+    {
+        static_assert(noexcept(std::tuple<NoExceptDefault>()), "");
+        static_assert(noexcept(std::tuple<NoExceptDefault, NoExceptDefault>()), "");
+
+        static_assert(!noexcept(std::tuple<ThrowingDefault, NoExceptDefault>()), "");
+        static_assert(!noexcept(std::tuple<NoExceptDefault, ThrowingDefault>()), "");
+        static_assert(!noexcept(std::tuple<ThrowingDefault, ThrowingDefault>()), "");
+    }
 #ifndef _LIBCPP_HAS_NO_CONSTEXPR
     {
         constexpr std::tuple<> t;