From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: [committed] libstdc++: Remove constraints from std::optional monadic ops [PR102863]
Date: Thu, 21 Oct 2021 01:23:46 +0100 [thread overview]
Message-ID: <YXCzEkqqDm2TEQcS@redhat.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 577 bytes --]
The constraints on transform and and_then can cause errors when checking
satisfaction. The constraints that were present in R6 of the paper were
moved for he final F8 revision, and so should have been included in the
implementation.
libstdc++-v3/ChangeLog:
PR libstdc++/102863
* include/std/optional (optional::and_then, optional::transform):
Remove requires-clause.
* testsuite/20_util/optional/monadic/and_then.cc: Check
overload resolution doesn't cause errors.
* testsuite/20_util/optional/monadic/transform.cc: Likewise.
Tested x86_64-linux. Committed to trunk.
[-- Attachment #2: patch.txt --]
[-- Type: text/plain, Size: 4329 bytes --]
commit 0fac85a24f40ef6098b756e8e8655205f4bfbf3e
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Thu Oct 21 01:19:45 2021
libstdc++: Remove constraints from std::optional monadic ops [PR102863]
The constraints on transform and and_then can cause errors when checking
satisfaction. The constraints that were present in R6 of the paper were
moved for he final F8 revision, and so should have been included in the
implementation.
libstdc++-v3/ChangeLog:
PR libstdc++/102863
* include/std/optional (optional::and_then, optional::transform):
Remove requires-clause.
* testsuite/20_util/optional/monadic/and_then.cc: Check
overload resolution doesn't cause errors.
* testsuite/20_util/optional/monadic/transform.cc: Likewise.
diff --git a/libstdc++-v3/include/std/optional b/libstdc++-v3/include/std/optional
index eac91d3c160..783d7ca1b64 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -1048,7 +1048,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// [optional.monadic]
- template<typename _Fn> requires invocable<_Fn, _Tp&>
+ template<typename _Fn>
constexpr auto
and_then(_Fn&& __f) &
{
@@ -1060,7 +1060,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return _Up();
}
- template<typename _Fn> requires invocable<_Fn, const _Tp&>
+ template<typename _Fn>
constexpr auto
and_then(_Fn&& __f) const &
{
@@ -1072,7 +1072,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return _Up();
}
- template<typename _Fn> requires invocable<_Fn, _Tp>
+ template<typename _Fn>
constexpr auto
and_then(_Fn&& __f) &&
{
@@ -1084,7 +1084,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return _Up();
}
- template<typename _Fn> requires invocable<_Fn, const _Tp>
+ template<typename _Fn>
constexpr auto
and_then(_Fn&& __f) const &&
{
@@ -1096,7 +1096,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return _Up();
}
- template<typename _Fn> requires invocable<_Fn, _Tp&>
+ template<typename _Fn>
constexpr auto
transform(_Fn&& __f) &
{
@@ -1107,7 +1107,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return optional<_Up>();
}
- template<typename _Fn> requires invocable<_Fn, const _Tp&>
+ template<typename _Fn>
constexpr auto
transform(_Fn&& __f) const &
{
@@ -1118,7 +1118,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return optional<_Up>();
}
- template<typename _Fn> requires invocable<_Fn, _Tp>
+ template<typename _Fn>
constexpr auto
transform(_Fn&& __f) &&
{
@@ -1129,7 +1129,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return optional<_Up>();
}
- template<typename _Fn> requires invocable<_Fn, const _Tp>
+ template<typename _Fn>
constexpr auto
transform(_Fn&& __f) const &&
{
diff --git a/libstdc++-v3/testsuite/20_util/optional/monadic/and_then.cc b/libstdc++-v3/testsuite/20_util/optional/monadic/and_then.cc
index 02dcafe6c58..f69ab952643 100644
--- a/libstdc++-v3/testsuite/20_util/optional/monadic/and_then.cc
+++ b/libstdc++-v3/testsuite/20_util/optional/monadic/and_then.cc
@@ -113,8 +113,20 @@ test_forwarding()
static_assert( test_forwarding() );
+void f(int&) { }
+
+void
+test_unconstrained()
+{
+ // PR libstc++/102863 - Optional monadic ops should not be constrained
+ std::optional<int> x;
+ auto answer = x.and_then([](auto& y) { f(y); return std::optional<int>{42}; });
+ VERIFY( !answer );
+}
+
int main()
{
test_and_then();
test_forwarding();
+ test_unconstrained();
}
diff --git a/libstdc++-v3/testsuite/20_util/optional/monadic/transform.cc b/libstdc++-v3/testsuite/20_util/optional/monadic/transform.cc
index 13977b8ba8d..356c94de6d0 100644
--- a/libstdc++-v3/testsuite/20_util/optional/monadic/transform.cc
+++ b/libstdc++-v3/testsuite/20_util/optional/monadic/transform.cc
@@ -132,9 +132,21 @@ test_copy_elision()
static_assert( test_copy_elision() );
+void f(int&) { }
+
+void
+test_unconstrained()
+{
+ // PR libstc++/102863 - Optional monadic ops should not be constrained
+ std::optional<int> x;
+ auto answer = x.transform([](auto& y) { f(y); return 42; });
+ VERIFY( !answer );
+}
+
int main()
{
test_transform();
test_forwarding();
test_copy_elision();
+ test_unconstrained();
}
next reply other threads:[~2021-10-21 0:23 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 0:23 Jonathan Wakely [this message]
2021-10-21 0:25 ` Jonathan Wakely
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=YXCzEkqqDm2TEQcS@redhat.com \
--to=jwakely@redhat.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=libstdc++@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).