Implement LWG 2946, 3075 and 3076. Reviewed as https://reviews.llvm.org/D48616

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@336132 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp

@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+// XFAIL: libcpp-no-deduction-guides
+
+// template<class InputIterator>
+//   basic_string(InputIterator begin, InputIterator end,
+//   const Allocator& a = Allocator());
+
+// template<class charT,
+//          class traits,
+//          class Allocator = allocator<charT>
+//          >
+// basic_string(basic_string_view<charT, traits>, const Allocator& = Allocator())
+//   -> basic_string<charT, traits, Allocator>;
+//
+//  The deduction guide shall not participate in overload resolution if Allocator
+//  is a type that does not qualify as an allocator.
+
+
+#include <string>
+#include <string_view>
+#include <iterator>
+#include <cassert>
+#include <cstddef>
+
+int main()
+{
+    {
+    std::string_view sv = "12345678901234";
+    std::basic_string s1{sv, 23}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
+    }
+}