[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 Jonathan Wakely changed: What|Removed |Added Status|NEW |RESOLVED Target Milestone|--- |13.0 Resolution|--- |FIXED --- Comment #8 from Jonathan Wakely --- Fixed for GCC 13 by implementing the changes from https://wg21.link/P2255R2 The original example is now ill-formed.
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 --- Comment #7 from CVS Commits --- The master branch has been updated by Jonathan Wakely : https://gcc.gnu.org/g:fa9bda3ea4315a7285edbc99323e3fa7885cbbb8 commit r13-2922-gfa9bda3ea4315a7285edbc99323e3fa7885cbbb8 Author: Jonathan Wakely Date: Tue Sep 27 20:59:05 2022 +0100 libstdc++: Make INVOKE refuse to create dangling references [PR70692] This is the next part of the library changes from P2255R2. This makes INVOKE ill-formed if converting the INVOKE expression to R would bind a reference to a temporary object. The is_invocable_r trait is now false if the invocation would create a dangling reference. This is done by adding the dangling check to the __is_invocable_impl partial specialization used for INVOKE expressions. This change also slightly simplifies the nothrow checking recently added to that partial specialization. This change also removes the is_invocable_r checks from the pre-C++17 implementation of std::__invoke_r, because there is no need for it to be SFINAE-friendly. None of our C++11 and C++14 uses of INVOKE require those constraints. The std::function constructor needs to check is_invocable_r, but that's already done explicitly, so we don't need to recheck when calling __is_invoke_r in std::function::operator(). The other uses of std::__is_invoke_r do not need to be constrained and can just be ill-formed if the INVOKE expression is ill-formed. libstdc++-v3/ChangeLog: PR libstdc++/70692 * include/bits/invoke.h [__cplusplus < 201703] (__invoke_r): Remove is_invocable and is_convertible constraints. * include/std/type_traits (__is_invocable_impl::_S_conv): Use non-deduced context for parameter. (__is_invocable_impl::_S_test): Remove _Check_noex template parameter and use deduced noexcept value in its place. Add bool parameter to detect dangling references. (__is_invocable_impl::type): Adjust call to _S_test to avoid deducing unnecessary noexcept property.. (__is_invocable_impl::__nothrow_type): Rename to ... (__is_invocable_impl::__nothrow_conv): ... this. Adjust call to _S_test to deduce noexcept property. * testsuite/20_util/bind/dangling_ref.cc: New test. * testsuite/20_util/function/cons/70692.cc: New test. * testsuite/20_util/function_objects/invoke/dangling_ref.cc: New test. * testsuite/20_util/is_invocable/dangling_ref.cc: New test. * testsuite/30_threads/packaged_task/cons/dangling_ref.cc: New test.
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 Andrew Pinski changed: What|Removed |Added See Also||https://gcc.gnu.org/bugzill ||a/show_bug.cgi?id=104477 --- Comment #6 from Andrew Pinski --- (In reply to Jonathan Wakely from comment #5) > "A type trait to detect reference binding to temporary" > https://wg21.link/p2255r2 is the current direction to resolve this. Which is now recorded as PR 104477.
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 --- Comment #5 from Jonathan Wakely --- "A type trait to detect reference binding to temporary" https://wg21.link/p2255r2 is the current direction to resolve this.
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 Andrew Pinski changed: What|Removed |Added CC||gcc at hazlewoods dot net --- Comment #4 from Andrew Pinski --- *** Bug 103543 has been marked as a duplicate of this bug. ***
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 Jonathan Wakely changed: What|Removed |Added Assignee|redi at gcc dot gnu.org|unassigned at gcc dot gnu.org Status|ASSIGNED|NEW
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 --- Comment #3 from Jonathan Wakely --- This should get addressed more thoroughly by https://wg21.link/p0932
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 --- Comment #2 from Jonathan Wakely --- Bah, it seems that -Wsystem-headers doesn't get turned off again by the #pragma GCC diagnostic pop
[Bug libstdc++/70692] No warning when std::function binds a reference to a temporary
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70692 Jonathan Wakely changed: What|Removed |Added Status|UNCONFIRMED |ASSIGNED Last reconfirmed||2016-04-16 Assignee|unassigned at gcc dot gnu.org |redi at gcc dot gnu.org Ever confirmed|0 |1 --- Comment #1 from Jonathan Wakely --- Created attachment 38288 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38288=edit Untested patch. We can enable -Wsystem-headers around the relevant function, but we also need a change to to suppress the false positive -Wsign-compare warnings in there.
