[libcxx][test] Avoid warnings about unused variables and typedefs if _LIBCPP_VERSION is not defined (llvm#155679)

Make these tests pass with MSVC STL

Author: AlexGuteniev

libcxx/test/std/containers/container.adaptors/flat.map/flat.map.cons/move_assign_noexcept.compile.pass.cpp

@@ -51,7 +51,7 @@ struct MoveThrowsComp {
 
 void test() {
   {
-    using C = std::flat_map<int, int>;
+    using C [[maybe_unused]] = std::flat_map<int, int>;
     LIBCPP_STATIC_ASSERT(std::is_nothrow_move_assignable_v<C>);
   }
   {
@@ -73,7 +73,7 @@ void test() {
     static_assert(!std::is_nothrow_move_assignable_v<C>);
   }
   {
-    using C =
+    using C [[maybe_unused]] =
         std::flat_map<MoveOnly,
                       int,
                       std::less<MoveOnly>,
@@ -82,7 +82,7 @@ void test() {
     LIBCPP_STATIC_ASSERT(std::is_nothrow_move_assignable_v<C>);
   }
   {
-    using C =
+    using C [[maybe_unused]] =
         std::flat_map<int,
                       MoveOnly,
                       std::less<int>,
@@ -92,7 +92,7 @@ void test() {
   }
   {
     // Test with a comparator that throws on move-assignment.
-    using C = std::flat_map<int, int, MoveThrowsComp>;
+    using C [[maybe_unused]] = std::flat_map<int, int, MoveThrowsComp>;
     LIBCPP_STATIC_ASSERT(!std::is_nothrow_move_assignable_v<C>);
   }
   {

libcxx/test/std/containers/container.adaptors/flat.map/flat.map.erasure/erase_if_exceptions.pass.cpp

@@ -66,7 +66,8 @@ struct ErasurePredicate {
 };
 
 int main(int, char**) {
-  const std::pair<int, int> expected[] = {{1, 1}, {2, 2}, {3, 3}, {4, 4}, {5, 5}, {6, 6}, {7, 7}, {8, 8}};
+  [[maybe_unused]] const std::pair<int, int> expected[] = {
+      {1, 1}, {2, 2}, {3, 3}, {4, 4}, {5, 5}, {6, 6}, {7, 7}, {8, 8}};
   {
     using M = std::flat_map<ThrowingAssignment, int, ThrowingComparator>;
     for (int first_throw = 1; first_throw < 99; ++first_throw) {

libcxx/test/std/containers/container.adaptors/flat.multimap/flat.multimap.cons/move_assign_noexcept.compile.pass.cpp

@@ -51,7 +51,7 @@ struct MoveThrowsComp {
 
 void test() {
   {
-    using C = std::flat_multimap<int, int>;
+    using C [[maybe_unused]] = std::flat_multimap<int, int>;
     LIBCPP_STATIC_ASSERT(std::is_nothrow_move_assignable_v<C>);
   }
   {
@@ -73,7 +73,7 @@ void test() {
     static_assert(!std::is_nothrow_move_assignable_v<C>);
   }
   {
-    using C =
+    using C [[maybe_unused]] =
         std::flat_multimap<MoveOnly,
                            int,
                            std::less<MoveOnly>,
@@ -82,7 +82,7 @@ void test() {
     LIBCPP_STATIC_ASSERT(std::is_nothrow_move_assignable_v<C>);
   }
   {
-    using C =
+    using C [[maybe_unused]] =
         std::flat_multimap<int,
                            MoveOnly,
                            std::less<int>,
@@ -92,7 +92,7 @@ void test() {
   }
   {
     // Test with a comparator that throws on move-assignment.
-    using C = std::flat_multimap<int, int, MoveThrowsComp>;
+    using C [[maybe_unused]] = std::flat_multimap<int, int, MoveThrowsComp>;
     LIBCPP_STATIC_ASSERT(!std::is_nothrow_move_assignable_v<C>);
   }
   {

libcxx/test/std/containers/container.adaptors/flat.multimap/flat.multimap.erasure/erase_if_exceptions.pass.cpp

@@ -68,7 +68,8 @@ struct ErasurePredicate {
 };
 
 int main(int, char**) {
-  const std::pair<int, int> expected[] = {{1, 1}, {2, 2}, {3, 3}, {3, 3}, {5, 5}, {6, 6}, {7, 7}, {8, 8}};
+  [[maybe_unused]] const std::pair<int, int> expected[] = {
+      {1, 1}, {2, 2}, {3, 3}, {3, 3}, {5, 5}, {6, 6}, {7, 7}, {8, 8}};
   {
     using M = std::flat_multimap<ThrowingAssignment, int, ThrowingComparator>;
     for (int first_throw = 1; first_throw < 99; ++first_throw) {

libcxx/test/std/containers/container.adaptors/flat.set/flat.set.erasure/erase_if_exceptions.pass.cpp

@@ -66,7 +66,7 @@ struct ErasurePredicate {
 };
 
 void test() {
-  const int expected[] = {1, 2, 3, 4, 5, 6, 7, 8};
+  [[maybe_unused]] const int expected[] = {1, 2, 3, 4, 5, 6, 7, 8};
   {
     using M = std::flat_set<ThrowingAssignment, ThrowingComparator>;
     for (int first_throw = 1; first_throw < 99; ++first_throw) {