Implement full support for non-pointer pointers in custom allocators for string. This completes the custom pointer support for the entire library.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@185167 91177308-0d34-0410-b5e6-96231b3b80d8

test/strings/basic.string/string.access/index.pass.cpp

@@ -15,8 +15,11 @@
 #include <string>
 #include <cassert>
 
+#include "../min_allocator.h"
+
 int main()
 {
+    {
     typedef std::string S;
     S s("0123456789");
     const S& cs = s;
@@ -28,4 +31,20 @@ int main()
     assert(cs[cs.size()] == '\0');
     const S s2 = S();
     assert(s2[0] == '\0');
+    }
+#if __cplusplus >= 201103L
+    {
+    typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
+    S s("0123456789");
+    const S& cs = s;
+    for (S::size_type i = 0; i < cs.size(); ++i)
+    {
+        assert(s[i] == '0' + i);
+        assert(cs[i] == s[i]);
+    }
+    assert(cs[cs.size()] == '\0');
+    const S s2 = S();
+    assert(s2[0] == '\0');
+    }
+#endif
 }