* [PATCH] libstdc++: Fix bug in std::indirect_result_t
@ 2019-12-10 16:16 Jonathan Wakely
0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2019-12-10 16:16 UTC (permalink / raw)
To: libstdc++, gcc-patches
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The alias template wasn't working because it applied iter_reference_t to
the pack of iterators before and after passing the pack to the
__indeirect_result helper.
* include/bits/iterator_concepts.h (indirect_result_t): Do not apply
iter_reference_t to parameter pack.
* testsuite/24_iterators/indirect_callable/projected.cc: New test.
Tested powerpc64le-linux, committed to trunk.
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commit c87d75745e6a133a2e8e2703cec24d09bc53c636
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Tue Dec 10 15:52:50 2019 +0000
libstdc++: Fix bug in std::indirect_result_t
The alias template wasn't working because it applied iter_reference_t to
the pack of iterators before and after passing the pack to the
__indeirect_result helper.
* include/bits/iterator_concepts.h (indirect_result_t): Do not apply
iter_reference_t to parameter pack.
* testsuite/24_iterators/indirect_callable/projected.cc: New test.
diff --git a/libstdc++-v3/include/bits/iterator_concepts.h b/libstdc++-v3/include/bits/iterator_concepts.h
index 97aed72e255..ab9851f19c4 100644
--- a/libstdc++-v3/include/bits/iterator_concepts.h
+++ b/libstdc++-v3/include/bits/iterator_concepts.h
@@ -474,18 +474,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct __iter_common_ref
: common_reference<iter_reference_t<_Tp>, iter_value_t<_Tp>&>
{ };
-
- // FIXME: needed due to PR c++/67704
- template<typename _Fn, typename... _Is>
- struct __indirect_result
- { };
-
- template<typename _Fn, typename... _Is>
- requires (readable<_Is> && ...)
- && invocable<_Fn, iter_reference_t<_Is>...>
- struct __indirect_result<_Fn, _Is...>
- : invoke_result<_Fn, iter_reference_t<_Is>...>
- { };
} // namespace __detail
template<typename _Tp>
@@ -653,15 +641,31 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
&& strict_weak_order<_Fn&, iter_common_reference_t<_I1>,
iter_common_reference_t<_I2>>;
+ namespace __detail
+ {
+ // FIXME: needed due to PR c++/67704
+ template<typename _Fn, typename... _Is>
+ struct __indirect_result
+ { };
+
+ template<typename _Fn, typename... _Is>
+ requires (readable<_Is> && ...)
+ && invocable<_Fn, iter_reference_t<_Is>...>
+ struct __indirect_result<_Fn, _Is...>
+ : invoke_result<_Fn, iter_reference_t<_Is>...>
+ { };
+ } // namespace __detail
+
template<typename _Fn, typename... _Is>
using indirect_result_t = typename
- __detail::__indirect_result<_Fn, iter_reference_t<_Is>...>::type;
+ __detail::__indirect_result<_Fn, _Is...>::type;
/// [projected], projected
template<readable _Iter, indirectly_regular_unary_invocable<_Iter> _Proj>
struct projected
{
using value_type = remove_cvref_t<indirect_result_t<_Proj&, _Iter>>;
+
indirect_result_t<_Proj&, _Iter> operator*() const; // not defined
};
diff --git a/libstdc++-v3/testsuite/24_iterators/indirect_callable/projected.cc b/libstdc++-v3/testsuite/24_iterators/indirect_callable/projected.cc
new file mode 100644
index 00000000000..2237314ddc2
--- /dev/null
+++ b/libstdc++-v3/testsuite/24_iterators/indirect_callable/projected.cc
@@ -0,0 +1,41 @@
+// Copyright (C) 2019 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 <iterator>
+
+template<typename T>
+ using PI = std::projected<T, std::identity>;
+
+static_assert(std::same_as<PI<int*>::value_type, int>);
+static_assert(std::same_as<decltype(*std::declval<const PI<int*>&>()), int&>);
+
+struct X
+{
+ using value_type = char*;
+ char* const& operator*() &;
+};
+static_assert( std::readable<X> );
+static_assert(std::same_as<PI<X>::value_type, char*>);
+static_assert(std::same_as<decltype(*std::declval<PI<X>&>()), char* const&>);
+
+struct Y;
+using PY = std::projected<const Y*, int Y::*>;
+static_assert(std::same_as<PY::value_type, int>);
+static_assert(std::same_as<decltype(*std::declval<PY&>()), const int&>);
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2019-12-10 16:16 [PATCH] libstdc++: Fix bug in std::indirect_result_t Jonathan Wakely
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