Howard reported this bug, caused by a missing SFINAE constraint on a
std::chrono::time_point constructor.
I've also done a bit of simplification using alias templates.
PR libstdc++/81468
* include/std/chrono (__enable_if_is_duration)
(__disable_if_is_duration): New alias templates to simplify SFINAE.
(duration_cast, floor, ceil): Use __enable_if_is_duration.
(duration::__is_float, duration::__is_harmonic): New alias templates
to simplify SFINAE.
(duration::duration(const _Rep2&)): Use _Require, __is_float and
__is_harmonic.
(duration::duration(const duration<_Rep2, _Period2>&)): Likewise.
(__common_rep_type): Remove, replace with ...
(__common_rep_t): New alias template.
(operator*, operator/, operator%): Use __common_rep_t and
__disable_if_is_duration.
(time_point::time_point(const time_point<clock, _Dur2>&)): Add missing
constraint from LWG DR 1177.
* testsuite/20_util/duration/cons/dr1177.cc: New.
* testsuite/20_util/duration/literals/range.cc: Update dg-error line.
* testsuite/20_util/duration/requirements/typedefs_neg1.cc: Likewise.
* testsuite/20_util/duration/requirements/typedefs_neg2.cc: Likewise.
* testsuite/20_util/duration/requirements/typedefs_neg3.cc: Likewise.
* testsuite/20_util/time_point/cons/81468.cc: New.
Tested on powerp64le-linux, committed to trunk.
commit e06db0fa47676eeb386bfd1a582a005d341fb678
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Wed Sep 13 13:00:50 2017 +0100
PR libstdc++/81468 constrain std::chrono::time_point constructor
PR libstdc++/81468
* include/std/chrono (__enable_if_is_duration)
(__disable_if_is_duration): New alias templates to simplify SFINAE.
(duration_cast, floor, ceil): Use __enable_if_is_duration.
(duration::__is_float, duration::__is_harmonic): New alias templates
to simplify SFINAE.
(duration::duration(const _Rep2&)): Use _Require, __is_float and
__is_harmonic.
(duration::duration(const duration<_Rep2, _Period2>&)): Likewise.
(__common_rep_type): Remove, replace with ...
(__common_rep_t): New alias template.
(operator*, operator/, operator%): Use __common_rep_t and
__disable_if_is_duration.
(time_point::time_point(const time_point<clock, _Dur2>&)): Add
missing
constraint from LWG DR 1177.
* testsuite/20_util/duration/cons/dr1177.cc: New.
* testsuite/20_util/duration/literals/range.cc: Update dg-error
line.
* testsuite/20_util/duration/requirements/typedefs_neg1.cc:
Likewise.
* testsuite/20_util/duration/requirements/typedefs_neg2.cc:
Likewise.
* testsuite/20_util/duration/requirements/typedefs_neg3.cc:
Likewise.
* testsuite/20_util/time_point/cons/81468.cc: New.
diff --git a/libstdc++-v3/include/std/chrono b/libstdc++-v3/include/std/chrono
index 1bcbf524a7b..fc058fcd8d8 100644
--- a/libstdc++-v3/include/std/chrono
+++ b/libstdc++-v3/include/std/chrono
@@ -179,10 +179,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: std::true_type
{ };
+ template<typename _Tp>
+ using __enable_if_is_duration
+ = typename enable_if<__is_duration<_Tp>::value, _Tp>::type;
+
+ template<typename _Tp>
+ using __disable_if_is_duration
+ = typename enable_if<!__is_duration<_Tp>::value, _Tp>::type;
+
/// duration_cast
template<typename _ToDur, typename _Rep, typename _Period>
- constexpr typename enable_if<__is_duration<_ToDur>::value,
- _ToDur>::type
+ constexpr __enable_if_is_duration<_ToDur>
duration_cast(const duration<_Rep, _Period>& __d)
{
typedef typename _ToDur::period __to_period;
@@ -211,7 +218,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
# define __cpp_lib_chrono 201510
template<typename _ToDur, typename _Rep, typename _Period>
- constexpr enable_if_t<__is_duration<_ToDur>::value, _ToDur>
+ constexpr __enable_if_is_duration<_ToDur>
floor(const duration<_Rep, _Period>& __d)
{
auto __to = chrono::duration_cast<_ToDur>(__d);
@@ -221,7 +228,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
template<typename _ToDur, typename _Rep, typename _Period>
- constexpr enable_if_t<__is_duration<_ToDur>::value, _ToDur>
+ constexpr __enable_if_is_duration<_ToDur>
ceil(const duration<_Rep, _Period>& __d)
{
auto __to = chrono::duration_cast<_ToDur>(__d);
@@ -294,6 +301,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Rep, typename _Period>
struct duration
{
+ private:
+ template<typename _Rep2>
+ using __is_float = treat_as_floating_point<_Rep2>;
+
+ // _Period2 is an exact multiple of _Period
+ template<typename _Period2>
+ using __is_harmonic
+ = __bool_constant<ratio_divide<_Period2, _Period>::den == 1>;
+
+ public:
+
typedef _Rep rep;
typedef _Period period;
@@ -305,22 +323,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// 20.11.5.1 construction / copy / destroy
constexpr duration() = default;
- // NB: Make constexpr implicit. This cannot be explicitly
- // constexpr, as any UDT that is not a literal type with a
- // constexpr copy constructor will be ill-formed.
duration(const duration&) = default;
- template<typename _Rep2, typename = typename
- enable_if<is_convertible<_Rep2, rep>::value
- && (treat_as_floating_point<rep>::value
- || !treat_as_floating_point<_Rep2>::value)>::type>
+ template<typename _Rep2, typename = _Require<
+ is_convertible<_Rep2, rep>,
+ __or_<__is_float<rep>, __not_<__is_float<_Rep2>>>>>
constexpr explicit duration(const _Rep2& __rep)
: __r(static_cast<rep>(__rep)) { }
- template<typename _Rep2, typename _Period2, typename = typename
- enable_if<treat_as_floating_point<rep>::value
- || (ratio_divide<_Period2, period>::den == 1
- && !treat_as_floating_point<_Rep2>::value)>::type>
+ template<typename _Rep2, typename _Period2, typename = _Require<
+ __or_<__is_float<rep>,
+ __and_<__is_harmonic<_Period2>,
+ __not_<__is_float<_Rep2>>>>>>
constexpr duration(const duration<_Rep2, _Period2>& __d)
: __r(duration_cast<duration>(__d).count()) { }
@@ -455,18 +469,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __cd(__cd(__lhs).count() - __cd(__rhs).count());
}
- template<typename _Rep1, typename _Rep2, bool =
- is_convertible<_Rep2,
- typename common_type<_Rep1, _Rep2>::type>::value>
- struct __common_rep_type { };
-
- template<typename _Rep1, typename _Rep2>
- struct __common_rep_type<_Rep1, _Rep2, true>
- { typedef typename common_type<_Rep1, _Rep2>::type type; };
+ // SFINAE helper to obtain common_type<_Rep1, _Rep2> only if _Rep2
+ // is implicitly convertible to it.
+ template<typename _Rep1, typename _Rep2,
+ typename _CRep = typename common_type<_Rep1, _Rep2>::type>
+ using __common_rep_t
+ = typename enable_if<is_convertible<_Rep2, _CRep>::value, _CRep>::type;
template<typename _Rep1, typename _Period, typename _Rep2>
- constexpr
- duration<typename __common_rep_type<_Rep1, _Rep2>::type, _Period>
+ constexpr duration<__common_rep_t<_Rep1, _Rep2>, _Period>
operator*(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
{
typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
@@ -475,14 +486,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
template<typename _Rep1, typename _Rep2, typename _Period>
- constexpr
- duration<typename __common_rep_type<_Rep2, _Rep1>::type, _Period>
+ constexpr duration<__common_rep_t<_Rep2, _Rep1>, _Period>
operator*(const _Rep1& __s, const duration<_Rep2, _Period>& __d)
{ return __d * __s; }
template<typename _Rep1, typename _Period, typename _Rep2>
- constexpr duration<typename __common_rep_type<_Rep1, typename
- enable_if<!__is_duration<_Rep2>::value, _Rep2>::type>::type, _Period>
+ constexpr
+ duration<__common_rep_t<_Rep1, __disable_if_is_duration<_Rep2>>, _Period>
operator/(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
{
typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
@@ -504,8 +514,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// DR 934.
template<typename _Rep1, typename _Period, typename _Rep2>
- constexpr duration<typename __common_rep_type<_Rep1, typename
- enable_if<!__is_duration<_Rep2>::value, _Rep2>::type>::type, _Period>
+ constexpr
+ duration<__common_rep_t<_Rep1, __disable_if_is_duration<_Rep2>>, _Period>
operator%(const duration<_Rep1, _Period>& __d, const _Rep2& __s)
{
typedef duration<typename common_type<_Rep1, _Rep2>::type, _Period>
@@ -614,7 +624,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ }
// conversions
- template<typename _Dur2>
+ template<typename _Dur2,
+ typename = _Require<is_convertible<_Dur2, _Dur>>>
constexpr time_point(const time_point<clock, _Dur2>& __t)
: __d(__t.time_since_epoch())
{ }
diff --git a/libstdc++-v3/testsuite/20_util/duration/cons/dr1177.cc
b/libstdc++-v3/testsuite/20_util/duration/cons/dr1177.cc
new file mode 100644
index 00000000000..28c881ccc79
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/duration/cons/dr1177.cc
@@ -0,0 +1,41 @@
+// Copyright (C) 2017 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++11 } }
+
+#include <chrono>
+#include <type_traits>
+
+using namespace std;
+using namespace std::chrono;
+
+// DR 1177
+static_assert(is_constructible<duration<float>, duration<double>>{},
+ "can convert duration with one floating point rep to another");
+static_assert(is_constructible<duration<float>, duration<int>>{},
+ "can convert duration with integral rep to one with floating point rep");
+static_assert(!is_constructible<duration<int>, duration<float>>{},
+ "cannot convert duration with floating point rep to one with integral
rep");
+static_assert(is_constructible<duration<int>, duration<long>>{},
+ "can convert duration with one integral rep to another");
+
+static_assert(!is_constructible<duration<int>, duration<int, ratio<2,3>>>{},
+ "cannot convert duration to one with different period");
+static_assert(is_constructible<duration<float>, duration<int, ratio<2,3>>>{},
+ "unless it has a floating-point representation");
+static_assert(is_constructible<duration<float>, duration<int, ratio<1,3>>>{},
+ "or a period that is an integral multiple of the original");
diff --git a/libstdc++-v3/testsuite/20_util/duration/literals/range.cc
b/libstdc++-v3/testsuite/20_util/duration/literals/range.cc
index b5105dff38b..36e71eea72b 100644
--- a/libstdc++-v3/testsuite/20_util/duration/literals/range.cc
+++ b/libstdc++-v3/testsuite/20_util/duration/literals/range.cc
@@ -26,6 +26,6 @@ test01()
// std::numeric_limits<int64_t>::max() == 9223372036854775807;
auto h = 9223372036854775808h;
- // { dg-error "cannot be represented" "" { target *-*-* } 880 }
+ // { dg-error "cannot be represented" "" { target *-*-* } 891 }
}
// { dg-prune-output "in constexpr expansion" } // needed for -O0
diff --git
a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc
b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc
index 17f74187098..d57f6dedd66 100644
--- a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc
+++ b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg1.cc
@@ -30,4 +30,4 @@ void test01()
test_type d; // { dg-error "required from here" }
}
-// { dg-error "rep cannot be a duration" "" { target *-*-* } 300 }
+// { dg-error "rep cannot be a duration" "" { target *-*-* } 318 }
diff --git
a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc
b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc
index 282a9dbdc85..39283b2cb74 100644
--- a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc
+++ b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg2.cc
@@ -31,5 +31,5 @@ void test01()
test_type d; // { dg-error "required from here" }
}
-// { dg-error "must be a specialization of ratio" "" { target *-*-* } 301 }
+// { dg-error "must be a specialization of ratio" "" { target *-*-* } 319 }
// { dg-prune-output "not a member" }
diff --git
a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg3.cc
b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg3.cc
index c57f9d947a5..9beaa83fbfa 100644
--- a/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg3.cc
+++ b/libstdc++-v3/testsuite/20_util/duration/requirements/typedefs_neg3.cc
@@ -32,4 +32,4 @@ void test01()
test_type d; // { dg-error "required from here" }
}
-// { dg-error "period must be positive" "" { target *-*-* } 303 }
+// { dg-error "period must be positive" "" { target *-*-* } 321 }
diff --git a/libstdc++-v3/testsuite/20_util/time_point/cons/81468.cc
b/libstdc++-v3/testsuite/20_util/time_point/cons/81468.cc
new file mode 100644
index 00000000000..30d1c4a5ac7
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/time_point/cons/81468.cc
@@ -0,0 +1,34 @@
+// Copyright (C) 2017 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++11 } }
+
+#include <chrono>
+#include <type_traits>
+
+using namespace std;
+using namespace std::chrono;
+
+template <class Duration>
+ using sys_time = time_point<system_clock, Duration>;
+
+static_assert(is_constructible<sys_time<milliseconds>, sys_time<seconds>>{},
+ "Can construct time_point from one with lower precision duration");
+
+// PR libstdc++/81468 - DR 1177
+static_assert(!is_constructible<sys_time<seconds>, sys_time<milliseconds>>{},
+ "Cannot construct time_point from one with higher precision duration");
