public inbox for libstdc++-cvs@sourceware.org
help / color / mirror / Atom feed
From: Jonathan Wakely <redi@gcc.gnu.org>
To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org
Subject: [gcc r10-10028] libstdc++: Change [cmp.alg] assertions to constraints
Date: Wed, 11 Aug 2021 16:35:24 +0000 (GMT) [thread overview]
Message-ID: <20210811163524.777F83982417@sourceware.org> (raw)
https://gcc.gnu.org/g:29000237a736778e01aa3468245f6b95b02af0a5
commit r10-10028-g29000237a736778e01aa3468245f6b95b02af0a5
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Mon Jun 14 12:25:43 2021 +0100
libstdc++: Change [cmp.alg] assertions to constraints
This moves the same_as<decay_t<_Tp>, decay_t<_Up>> checks from the
[cmp.alg] function bodies into their constraints.
Also add a test for the compare_xxx_order_fallback algorithms.
libstdc++-v3/ChangeLog:
* libsupc++/compare (__decayed_same_as): New helper concept.
(strong_order, weak_order, partial_order): Constrain with new
concept instead of using static_assert.
(compare_strong_order_fallback, compare_weak_order_fallback)
(compare_partial_order_fallback): Likewise. Do not deduce return
types. Remove redundant if-constexpr checks.
* testsuite/18_support/comparisons/algorithms/fallback.cc: New test.
(cherry picked from commit e2c79b968ff95421c31a5a9a1b80b11321fe70d2)
Diff:
---
libstdc++-v3/libsupc++/compare | 39 ++++++++------------
.../18_support/comparisons/algorithms/fallback.cc | 42 ++++++++++++++++++++++
2 files changed, 57 insertions(+), 24 deletions(-)
diff --git a/libstdc++-v3/libsupc++/compare b/libstdc++-v3/libsupc++/compare
index bd9c3b2352b..97c8f29f53a 100644
--- a/libstdc++-v3/libsupc++/compare
+++ b/libstdc++-v3/libsupc++/compare
@@ -600,6 +600,9 @@ namespace std
// FIXME: || floating_point<remove_reference_t<_Tp>>
|| __cmp3way<strong_ordering, _Tp, _Up>;
+ template<typename _Tp, typename _Up>
+ concept __decayed_same_as = same_as<decay_t<_Tp>, decay_t<_Up>>;
+
class _Strong_order
{
template<typename _Tp, typename _Up>
@@ -620,14 +623,12 @@ namespace std
friend class _Strong_fallback;
public:
- template<typename _Tp, typename _Up>
+ template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __strongly_ordered<_Tp, _Up>
constexpr strong_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
- static_assert(same_as<decay_t<_Tp>, decay_t<_Up>>);
-
/* FIXME:
if constexpr (floating_point<decay_t<_Tp>>)
return __cmp_cust::__fp_strong_order(__e, __f);
@@ -669,14 +670,12 @@ namespace std
friend class _Weak_fallback;
public:
- template<typename _Tp, typename _Up>
+ template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __weakly_ordered<_Tp, _Up>
constexpr weak_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
- static_assert(same_as<decay_t<_Tp>, decay_t<_Up>>);
-
if constexpr (floating_point<decay_t<_Tp>>)
return __cmp_cust::__fp_weak_ordering(__e, __f);
else if constexpr (__adl_weak<_Tp, _Up>)
@@ -716,14 +715,12 @@ namespace std
friend class _Partial_fallback;
public:
- template<typename _Tp, typename _Up>
+ template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __partially_ordered<_Tp, _Up>
constexpr partial_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
- static_assert(same_as<decay_t<_Tp>, decay_t<_Up>>);
-
if constexpr (__adl_partial<_Tp, _Up>)
return partial_ordering(partial_order(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f)));
@@ -759,18 +756,16 @@ namespace std
}
public:
- template<typename _Tp, typename _Up>
+ template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __strongly_ordered<_Tp, _Up> || __op_eq_lt<_Tp, _Up>
- constexpr decltype(auto)
+ constexpr strong_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
- static_assert(same_as<decay_t<_Tp>, decay_t<_Up>>);
-
if constexpr (__strongly_ordered<_Tp, _Up>)
return _Strong_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
- else if constexpr (__op_eq_lt<_Tp, _Up>)
+ else // __op_eq_lt<_Tp, _Up>
return static_cast<_Tp&&>(__e) == static_cast<_Up&&>(__f)
? strong_ordering::equal
: static_cast<_Tp&&>(__e) < static_cast<_Up&&>(__f)
@@ -793,18 +788,16 @@ namespace std
}
public:
- template<typename _Tp, typename _Up>
+ template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __weakly_ordered<_Tp, _Up> || __op_eq_lt<_Tp, _Up>
- constexpr decltype(auto)
+ constexpr weak_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
- static_assert(same_as<decay_t<_Tp>, decay_t<_Up>>);
-
if constexpr (__weakly_ordered<_Tp, _Up>)
return _Weak_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
- else if constexpr (__op_eq_lt<_Tp, _Up>)
+ else // __op_eq_lt<_Tp, _Up>
return static_cast<_Tp&&>(__e) == static_cast<_Up&&>(__f)
? weak_ordering::equivalent
: static_cast<_Tp&&>(__e) < static_cast<_Up&&>(__f)
@@ -827,18 +820,16 @@ namespace std
}
public:
- template<typename _Tp, typename _Up>
+ template<typename _Tp, __decayed_same_as<_Tp> _Up>
requires __partially_ordered<_Tp, _Up> || __op_eq_lt<_Tp, _Up>
- constexpr decltype(auto)
+ constexpr partial_ordering
operator()(_Tp&& __e, _Up&& __f) const
noexcept(_S_noexcept<_Tp, _Up>())
{
- static_assert(same_as<decay_t<_Tp>, decay_t<_Up>>);
-
if constexpr (__partially_ordered<_Tp, _Up>)
return _Partial_order{}(static_cast<_Tp&&>(__e),
static_cast<_Up&&>(__f));
- else if constexpr (__op_eq_lt<_Tp, _Up>)
+ else // __op_eq_lt<_Tp, _Up>
return static_cast<_Tp&&>(__e) == static_cast<_Up&&>(__f)
? partial_ordering::equivalent
: static_cast<_Tp&&>(__e) < static_cast<_Up&&>(__f)
diff --git a/libstdc++-v3/testsuite/18_support/comparisons/algorithms/fallback.cc b/libstdc++-v3/testsuite/18_support/comparisons/algorithms/fallback.cc
new file mode 100644
index 00000000000..ae458528f17
--- /dev/null
+++ b/libstdc++-v3/testsuite/18_support/comparisons/algorithms/fallback.cc
@@ -0,0 +1,42 @@
+// { dg-options "-std=gnu++20" }
+// { dg-do compile { target c++20 } }
+
+#include <compare>
+
+using std::strong_ordering;
+using std::partial_ordering;
+
+namespace adl
+{
+ struct S { };
+ void strong_ordering(const S&, const S&);
+ bool operator==(const S&, S&) { return true; }
+ bool operator<(const S&, S&) { return true; }
+}
+
+template<typename T, typename U>
+ concept has_strong_order_fallback = requires (T& t, U& u) {
+ std::compare_strong_order_fallback(t, u);
+ };
+
+template<typename T, typename U>
+ concept has_weak_order_fallback = requires (T& t, U& u) {
+ std::compare_weak_order_fallback(t, u);
+ };
+
+template<typename T, typename U>
+ concept has_partial_order_fallback = requires (T& t, U& u) {
+ std::compare_partial_order_fallback(t, u);
+ };
+
+using adl::S;
+
+static_assert( has_strong_order_fallback<S, S> );
+static_assert( has_strong_order_fallback<const S, S> );
+static_assert( ! has_strong_order_fallback<const S, const S> );
+static_assert( has_weak_order_fallback<S, S> );
+static_assert( has_weak_order_fallback<const S, S> );
+static_assert( ! has_weak_order_fallback<const S, const S> );
+static_assert( has_partial_order_fallback<S, S> );
+static_assert( has_partial_order_fallback<const S, S> );
+static_assert( ! has_partial_order_fallback<const S, const S> );
reply other threads:[~2021-08-11 16:35 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210811163524.777F83982417@sourceware.org \
--to=redi@gcc.gnu.org \
--cc=gcc-cvs@gcc.gnu.org \
--cc=libstdc++-cvs@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).