Make array<const T, 0> non-CopyAssignable and make swap and fill ill-formed.

The standard isn't exactly clear how std::array should handle zero-sized arrays
with const element types. In particular W.R.T. copy assignment, swap, and fill.

This patch takes the position that those operations should be ill-formed,
and makes changes to libc++ to make it so.

This follows up on commit r324182.

llvm-svn: 324185

1 files changed, 8 insertions, 0 deletions

diff --git a/libcxx/test/std/containers/sequences/array/array.data/data.pass.cpp b/libcxx/test/std/containers/sequences/array/array.data/data.pass.cpp
index 7b510c203f8..452d6b7f3ca 100644
--- a/libcxx/test/std/containers/sequences/array/array.data/data.pass.cpp
+++ b/libcxx/test/std/containers/sequences/array/array.data/data.pass.cpp
@@ -37,6 +37,14 @@ int main()
         (void)p; // to placate scan-build
     }
     {
+      typedef double T;
+      typedef std::array<const T, 0> C;
+      C c = {};
+      const T* p = c.data();
+      static_assert((std::is_same<decltype(c.data()), const T*>::value), "");
+      (void)p; // to placate scan-build
+    }
+    {
       struct NoDefault {
         NoDefault(int) {}
       };