[Bug libstdc++/55713] std::tupleElementType incorrectly is convertible to ElementType when it is an empty class
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55713 --- Comment #1 from Andrew Pinski pinskia at gcc dot gnu.org 2012-12-16 17:49:20 UTC --- This was done for an optimization. And I think it is allowed by the C++ standard too.
[Bug libstdc++/55713] std::tupleElementType incorrectly is convertible to ElementType when it is an empty class
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55713 --- Comment #2 from Johannes Schaub schaub.johannes at googlemail dot com 2012-12-16 17:52:14 UTC --- (In reply to comment #1) This was done for an optimization. And I think it is allowed by the C++ standard too. From the feedback I received from Stackoverflow ( http://stackoverflow.com/q/13902910/34509 ) I assumed that this behavior is not permissible. There also appear to be ways to make it not behave that way (see LLVM libc++'s implementation).
[Bug libstdc++/55713] std::tupleElementType incorrectly is convertible to ElementType when it is an empty class
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55713 Jonathan Wakely redi at gcc dot gnu.org changed: What|Removed |Added Keywords||rejects-valid Status|UNCONFIRMED |NEW Last reconfirmed||2012-12-16 Ever Confirmed|0 |1 --- Comment #3 from Jonathan Wakely redi at gcc dot gnu.org 2012-12-16 20:39:51 UTC --- What stackoverflow says is not gospel, but I agree this should compile. The summary is misleading, it's not convertible, because the base class is inaccessible.
[Bug libstdc++/55713] std::tupleElementType incorrectly is convertible to ElementType when it is an empty class
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55713 Marc Glisse glisse at gcc dot gnu.org changed: What|Removed |Added CC||glisse at gcc dot gnu.org --- Comment #4 from Marc Glisse glisse at gcc dot gnu.org 2012-12-16 22:47:34 UTC --- libc++'s implementation has the drawback that a tuple of empty types is not empty (at least with the current ABI). It seems a shame that sfinae now manages to handle access control cleverly enough to disable overloads but regular code still handles access control as something that is only checked after the fact.
