[libc++][test] Fix noexcept assertions in variant's get tests

All constant expressions are non-potentially-throwing in C++14, but that is *not* the case in C++17. Change these tests of the `variant`-flavored overloads of `std::get` to expect the correct behavior when the compiler is not GCC or is GCC 9+.

Credit to Jonathan Wakely for providing an improved version of my initial change that validates the incorrect behavior on GCC < 9 as well as validating the correct behavior on other compilers.

Differential Revision: https://reviews.llvm.org/D61033

llvm-svn: 359220

3 files changed, 20 insertions, 6 deletions

diff --git a/libcxx/test/std/utilities/variant/variant.get/get_index.pass.cpp b/libcxx/test/std/utilities/variant/variant.get/get_index.pass.cpp
index 4b04929a6fc..4b0ae15c352 100644
--- a/libcxx/test/std/utilities/variant/variant.get/get_index.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.get/get_index.pass.cpp
@@ -37,8 +37,10 @@ void test_const_lvalue_get() {
   {
     using V = std::variant<int, const long>;
     constexpr V v(42);
-#ifndef __clang__ // Avoid https://bugs.llvm.org/show_bug.cgi?id=15481
+#ifdef TEST_WORKAROUND_CONSTEXPR_IMPLIES_NOEXCEPT
     ASSERT_NOEXCEPT(std::get<0>(v));
+#else
+    ASSERT_NOT_NOEXCEPT(std::get<0>(v));
 #endif
     ASSERT_SAME_TYPE(decltype(std::get<0>(v)), const int &);
     static_assert(std::get<0>(v) == 42, "");
@@ -53,8 +55,10 @@ void test_const_lvalue_get() {
   {
     using V = std::variant<int, const long>;
     constexpr V v(42l);
-#ifndef __clang__ // Avoid https://bugs.llvm.org/show_bug.cgi?id=15481
+#ifdef TEST_WORKAROUND_CONSTEXPR_IMPLIES_NOEXCEPT
     ASSERT_NOEXCEPT(std::get<1>(v));
+#else
+    ASSERT_NOT_NOEXCEPT(std::get<1>(v));
 #endif
     ASSERT_SAME_TYPE(decltype(std::get<1>(v)), const long &);
     static_assert(std::get<1>(v) == 42, "");
diff --git a/libcxx/test/std/utilities/variant/variant.get/get_type.pass.cpp b/libcxx/test/std/utilities/variant/variant.get/get_type.pass.cpp
index 316213ed2fa..bd9153671e2 100644
--- a/libcxx/test/std/utilities/variant/variant.get/get_type.pass.cpp
+++ b/libcxx/test/std/utilities/variant/variant.get/get_type.pass.cpp
@@ -31,24 +31,28 @@ void test_const_lvalue_get() {
   {
     using V = std::variant<int, const long>;
     constexpr V v(42);
-#ifndef __clang__ // Avoid https://bugs.llvm.org/show_bug.cgi?id=15481
+#ifdef TEST_WORKAROUND_CONSTEXPR_IMPLIES_NOEXCEPT
     ASSERT_NOEXCEPT(std::get<int>(v));
+#else
+    ASSERT_NOT_NOEXCEPT(std::get<int>(v));
 #endif
-    ASSERT_SAME_TYPE(decltype(std::get<0>(v)), const int &);
+    ASSERT_SAME_TYPE(decltype(std::get<int>(v)), const int &);
     static_assert(std::get<int>(v) == 42, "");
   }
   {
     using V = std::variant<int, const long>;
     const V v(42);
     ASSERT_NOT_NOEXCEPT(std::get<int>(v));
-    ASSERT_SAME_TYPE(decltype(std::get<0>(v)), const int &);
+    ASSERT_SAME_TYPE(decltype(std::get<int>(v)), const int &);
     assert(std::get<int>(v) == 42);
   }
   {
     using V = std::variant<int, const long>;
     constexpr V v(42l);
-#ifndef __clang__ // Avoid https://bugs.llvm.org/show_bug.cgi?id=15481
+#ifdef TEST_WORKAROUND_CONSTEXPR_IMPLIES_NOEXCEPT
     ASSERT_NOEXCEPT(std::get<const long>(v));
+#else
+    ASSERT_NOT_NOEXCEPT(std::get<const long>(v));
 #endif
     ASSERT_SAME_TYPE(decltype(std::get<const long>(v)), const long &);
     static_assert(std::get<const long>(v) == 42, "");
diff --git a/libcxx/test/support/test_workarounds.h b/libcxx/test/support/test_workarounds.h
index 14ec9686139..81350c789d4 100644
--- a/libcxx/test/support/test_workarounds.h
+++ b/libcxx/test/support/test_workarounds.h
@@ -23,4 +23,10 @@
 # endif
 #endif
 
+#if defined(TEST_COMPILER_GCC)
+# if __GNUC__ < 9
+#  define TEST_WORKAROUND_CONSTEXPR_IMPLIES_NOEXCEPT // GCC PR 87603
+# endif
+#endif
+
 #endif // SUPPORT_TEST_WORKAROUNDS_H