Implement LWG#2566: Requirements on the first template parameter of container adaptors

llvm-svn: 263450
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: c1fe2c43290efca9c3aba9e1ccabeceb2e6d8606
diff --git a/include/stack b/include/stack
index 2992b09..64fd652 100644
--- a/include/stack
+++ b/include/stack
@@ -112,7 +112,8 @@
     typedef typename container_type::reference       reference;
     typedef typename container_type::const_reference const_reference;
     typedef typename container_type::size_type       size_type;
-
+    static_assert((is_same<_Tp, value_type>::value), "" );
+    
 protected:
     container_type c;