PR libstdc++/84671 handle digit separators in duration literals

	PR libstdc++/84671
	* include/bits/parse_numbers.h (_Number_help): Add partial
	specialization to handle digit separators. Adjust partial
	specialization for recursion temrination to require _Pow == 1ULL.
	* testsuite/20_util/duration/literals/84671.cc: New

From-SVN: r258157

libstdc++-v3/ChangeLog

+2018-03-02  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/84671
+	* include/bits/parse_numbers.h (_Number_help): Add partial
+	specialization to handle digit separators. Adjust partial
+	specialization for recursion temrination to require _Pow == 1ULL.
+	* testsuite/20_util/duration/literals/84671.cc: New
+
 2018-02-27  Ville Voutilainen  <ville.voutilainen@gmail.com>
 
 	Implement the missing bits of LWG 2769

libstdc++-v3/include/bits/parse_numbers.h

@@ -197,10 +197,16 @@ namespace __parse_int
 		    "integer literal does not fit in unsigned long long");
     };
 
-  template<unsigned _Base, unsigned long long _Pow, char _Dig>
-    struct _Number_help<_Base, _Pow, _Dig>
+  // Skip past digit separators:
+  template<unsigned _Base, unsigned long long _Pow, char _Dig, char..._Digs>
+    struct _Number_help<_Base, _Pow, '\'', _Dig, _Digs...>
+    : _Number_help<_Base, _Pow, _Dig, _Digs...>
+    { };
+
+  // Terminating case for recursion:
+  template<unsigned _Base, char _Dig>
+    struct _Number_help<_Base, 1ULL, _Dig>
     {
-      //static_assert(_Pow == 1U, "power should be one");
       using type = __ull_constant<_Digit<_Base, _Dig>::value>;
     };
 

libstdc++-v3/testsuite/20_util/duration/literals/84671.cc

+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-do compile { target c++14 } }
+
+#include <chrono>
+
+// PR libstdc++/84671
+using namespace std::literals::chrono_literals;
+constexpr auto ns_ok = 12113ns;
+constexpr auto ns_fail = 12'11'3ns;
+static_assert(ns_ok == ns_fail, "digit separators work in duration literals");