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

[CaseyCarter]

Summary

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

Fixes #41578.

[CaseyCarter]

Update conditional: the bug was closed as a duplicate of a bug which has been fixed on master. Tag with the correct bug number, and disable the workaround for GCC 9.

[jwakely]

I added a patch to https://bugs.llvm.org/show_bug.cgi?id=41578 that fixes it differently.

[mclow.lists]

XREF: https://bugs.llvm.org/show_bug.cgi?id=41578

[mclow.lists]

test/std/utilities/variant/variant.get/get_index.pass.cpp

60

You've got some copy-pasta here. 0 should be 1

[CaseyCarter]

Use Jonathan's fix, which additionally validates the existence of the bug.

[CaseyCarter]

Fix pre-existing copy pasta in variant/get_type.pass.cpp.

[EricWF]

LGTM.

Thanks for the fixes.

[mclow.lists]

Thanks, Casey.

test/std/utilities/variant/variant.get/get_index.pass.cpp

 #include <type_traits>
 #include <utility>
 #include <variant>
 
 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, "");
   }
   {
     using V = std::variant<int, const long>;
     const V v(42);
     ASSERT_NOT_NOEXCEPT(std::get<0>(v));
     ASSERT_SAME_TYPE(decltype(std::get<0>(v)), const int &);
     assert(std::get<0>(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<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, "");
   }
   {
     using V = std::variant<int, const long>;
     const V v(42l);
     ASSERT_NOT_NOEXCEPT(std::get<1>(v));

test/std/utilities/variant/variant.get/get_type.pass.cpp

 #include <type_traits>
 #include <utility>
 #include <variant>
 
 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, "");
   }
   {
     using V = std::variant<int, const long>;
     const V v(42l);
     ASSERT_NOT_NOEXCEPT(std::get<const long>(v));

test/support/test_workarounds.h

 
 #if defined(TEST_COMPILER_C1XX)
 # define TEST_WORKAROUND_C1XX_BROKEN_IS_TRIVIALLY_COPYABLE // VSO#117743
 # ifndef _MSC_EXTENSIONS
 #  define TEST_WORKAROUND_C1XX_BROKEN_ZA_CTOR_CHECK // VSO#119998
 # 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