[libcxx] Use a type that is always an aggregate in variant's tests

Summary:
In PR39232, we noticed that some variant tests started failing in C++2a mode
with recent Clangs, because the rules for literal types changed in C++2a. As
a result, a temporary fix was checked in (enabling the test only in C++17).

This commit is what I believe should be the long term fix: I removed the
tests that checked constexpr default-constructibility with a weird type
from the tests for index() and valueless_by_exception(), and instead I
added tests for those using an obviously literal type in the test for the
default constructor.

Reviewers: EricWF, mclow.lists

Subscribers: christof, jkorous, dexonsmith, arphaman, libcxx-commits, rsmith

Differential Revision: https://reviews.llvm.org/D54767

llvm-svn: 347568

1 files changed, 8 insertions, 12 deletions

diff --git a/libcxx/test/std/utilities/variant/variant.variant/variant.status/index.pass.cpp b/libcxx/test/std/utilities/variant/variant.variant/variant.status/index.pass.cpp
index 7ab828eb0bf..6d78de3a48b 100644
--- a/libcxx/test/std/utilities/variant/variant.variant/variant.status/index.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.variant/variant.status/index.pass.cpp
@@ -10,14 +10,6 @@
 
 // UNSUPPORTED: c++98, c++03, c++11, c++14
 
-// The following compilers don't consider a type an aggregate type (and
-// consequently not a literal type) if it has a base class at all.
-// In C++17, an aggregate type is allowed to have a base class if it's not
-// virtual, private, nor protected (e.g. ConstexprTestTypes:::NoCtors).
-// XFAIL: gcc-5, gcc-6
-// XFAIL: clang-3.5, clang-3.6, clang-3.7, clang-3.8
-// XFAIL: apple-clang-6, apple-clang-7, apple-clang-8.0
-
 // <variant>
 
 // template <class ...Types> class variant;
@@ -33,14 +25,18 @@
 #include "test_macros.h"
 #include "variant_test_helpers.hpp"
 
+
 int main() {
-#if TEST_STD_VER == 17
-  { // This test does not pass on C++20 or later; see https://bugs.llvm.org/show_bug.cgi?id=39232
-    using V = std::variant<int, ConstexprTestTypes::NoCtors>;
+  {
+    using V = std::variant<int, long>;
     constexpr V v;
     static_assert(v.index() == 0, "");
   }
-#endif
+  {
+    using V = std::variant<int, long>;
+    V v;
+    assert(v.index() == 0);
+  }
   {
     using V = std::variant<int, long>;
     constexpr V v(std::in_place_index<1>);