Void cast runtime-unused variables. Patch from STL@microsoft.com

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@268284 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/iterators/iterator.primitives/std.iterator.tags/bidirectional_iterator_tag.pass.cpp

@@ -17,6 +17,7 @@
 int main()
 {
     std::bidirectional_iterator_tag tag;
+    ((void)tag); // Prevent unused warning
     static_assert((std::is_base_of<std::forward_iterator_tag,
                                    std::bidirectional_iterator_tag>::value), "");
     static_assert((!std::is_base_of<std::output_iterator_tag,

test/std/iterators/iterator.primitives/std.iterator.tags/forward_iterator_tag.pass.cpp

@@ -17,6 +17,7 @@
 int main()
 {
     std::forward_iterator_tag tag;
+    ((void)tag); // Prevent unused warning
     static_assert((std::is_base_of<std::input_iterator_tag,
                                    std::forward_iterator_tag>::value), "");
     static_assert((!std::is_base_of<std::output_iterator_tag,

test/std/iterators/iterator.primitives/std.iterator.tags/input_iterator_tag.pass.cpp

@@ -17,6 +17,7 @@
 int main()
 {
     std::input_iterator_tag tag;
+    ((void)tag); // Prevent unused warning
     static_assert((!std::is_base_of<std::output_iterator_tag,
                                     std::input_iterator_tag>::value), "");
 }

test/std/iterators/iterator.primitives/std.iterator.tags/output_iterator_tag.pass.cpp

@@ -17,6 +17,7 @@
 int main()
 {
     std::output_iterator_tag tag;
+    ((void)tag); // Prevent unused warning
     static_assert((!std::is_base_of<std::input_iterator_tag,
                                     std::output_iterator_tag>::value), "");
 }

test/std/iterators/iterator.primitives/std.iterator.tags/random_access_iterator_tag.pass.cpp

@@ -17,6 +17,7 @@
 int main()
 {
     std::random_access_iterator_tag tag;
+    ((void)tag); // Prevent unused warning
     static_assert((std::is_base_of<std::bidirectional_iterator_tag,
                                    std::random_access_iterator_tag>::value), "");
     static_assert((!std::is_base_of<std::output_iterator_tag,