libstdc++: LWG 3292 iota_view is under-constrained
authorPatrick Palka <ppalka@redhat.com>
Mon, 24 Feb 2020 22:01:29 +0000 (17:01 -0500)
committerPatrick Palka <ppalka@redhat.com>
Tue, 25 Feb 2020 17:39:51 +0000 (12:39 -0500)
libstdc++-v3/ChangeLog:

LWG 3292 iota_view is under-constrained
* include/std/ranges (iota_view): Require that _Winc models semiregular
  as per LWG 3292.
* testsuite/std/ranges/iota/lwg3292_neg.cc: New test.

libstdc++-v3/ChangeLog
libstdc++-v3/include/std/ranges
libstdc++-v3/testsuite/std/ranges/iota/lwg3292_neg.cc [new file with mode: 0644]

index 2adf9cba26fc8adb8947ca6308184b4aea579a63..046d50de6d1755984e6d9a6520814ab7a254be31 100644 (file)
@@ -1,3 +1,10 @@
+2020-02-25  Patrick Palka  <ppalka@redhat.com>
+
+       LWG 3292 iota_view is under-constrained
+       * include/std/ranges (iota_view): Require that _Winc models semiregular
+         as per LWG 3292.
+       * testsuite/std/ranges/iota/lwg3292_neg.cc: New test.
+
 2020-02-25  Jonathan Wakely  <jwakely@redhat.com>
 
        * include/bits/ranges_algobase.h (__copy_or_move): Do not use memmove
index 0b2057c966152a89c7b78289d09caf7e20eeaeb8..ab8fbaca38f6c36058bcaaf4c7ded1111a6c0422 100644 (file)
@@ -615,6 +615,7 @@ namespace ranges
   template<weakly_incrementable _Winc,
           semiregular _Bound = unreachable_sentinel_t>
     requires std::__detail::__weakly_eq_cmp_with<_Winc, _Bound>
+      && semiregular<_Winc>
     class iota_view : public view_interface<iota_view<_Winc, _Bound>>
     {
     private:
diff --git a/libstdc++-v3/testsuite/std/ranges/iota/lwg3292_neg.cc b/libstdc++-v3/testsuite/std/ranges/iota/lwg3292_neg.cc
new file mode 100644 (file)
index 0000000..80c3927
--- /dev/null
@@ -0,0 +1,40 @@
+// Copyright (C) 2020 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-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <sstream>
+#include <ranges>
+
+namespace ranges = std::ranges;
+namespace views = std::views;
+
+void
+test01()
+{
+  std::istringstream s("1 2 3 4 5");
+  auto v = ranges::istream_view<int>(s);
+  auto i = v.begin();
+  static_assert(!std::semiregular<decltype(i)>);
+  auto o = views::iota(std::move(i));
+  static_assert(false); // { dg-error "" }
+}
+
+// { dg-prune-output "no match" }
+// { dg-prune-output "deduction failed" }
+// { dg-prune-output "constraint failure" }