[libcxx] Properly convert the count arguments to the *_n algorithms before use.

Summary:
The requirement on the `Size` type passed to *_n algorithms is that it is convertible to an integral type. This means we can't use a variable of type `Size` directly. Instead we need to convert it to an integral type first.  The problem is finding out what integral type to convert it to.  `__convert_to_integral` figures out what integral type to convert it to and performs the conversion, It also promotes the resulting integral type so that it is at least as big as an integer. `__convert_to_integral` also has a special case for converting enums. This should only work on non-scoped enumerations because it does not apply an explicit conversion from the enum to its underlying type.



Reviewers: chandlerc, mclow.lists

Reviewed By: mclow.lists

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D7449

llvm-svn: 228704

1 files changed, 4 insertions, 1 deletions

diff --git a/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy_n.pass.cpp b/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy_n.pass.cpp
index f594a0bf618..1dba8847c7e 100644
--- a/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy_n.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy_n.pass.cpp
@@ -17,6 +17,9 @@
 #include <cassert>
 
 #include "test_iterators.h"
+#include "user_defined_integral.hpp"
+
+typedef UserDefinedIntegral<unsigned> UDI;
 
 template <class InIter, class OutIter>
 void
@@ -28,7 +31,7 @@ test()
         ia[i] = i;
     int ib[N] = {0};
 
-    OutIter r = std::copy_n(InIter(ia), N/2, OutIter(ib));
+    OutIter r = std::copy_n(InIter(ia), UDI(N/2), OutIter(ib));
     assert(base(r) == ib+N/2);
     for (unsigned i = 0; i < N/2; ++i)
         assert(ia[i] == ib[i]);