[Bug c++/94141] c++20 rewritten operator== recursive call mixing friend and external operators for template class

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94141

Andrew Pinski  changed:

   What|Removed |Added

   Last reconfirmed|2020-05-21 00:00:00 |2021-8-4

--- Comment #5 from Andrew Pinski  ---
(In reply to Marc Glisse from comment #1)
> It looks like clang-10+ also generates an infinite loop on this code.

clang 12+ now does not produce an infinite loop.

GCC trunk still does though.

[Bug c++/94141] c++20 rewritten operator== recursive call mixing friend and external operators for template class

[Laurent.Rineau__gcc at normalesup dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94141

--- Comment #4 from Laurent Rineau  
---
(In reply to Marc Glisse from comment #3)
> It seems that this is as currently specified in C++20, but that some people
> are going to try and change the rules to avoid breaking code like this.

Do you have reference to the discussion on the subject?

[Bug c++/94141] c++20 rewritten operator== recursive call mixing friend and external operators for template class

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94141

Marc Glisse  changed:

   What|Removed |Added

   Last reconfirmed||2020-05-21
 Status|UNCONFIRMED |SUSPENDED
 Ever confirmed|0   |1

--- Comment #3 from Marc Glisse  ---
It seems that this is as currently specified in C++20, but that some people are
going to try and change the rules to avoid breaking code like this.

[Bug c++/94141] c++20 rewritten operator== recursive call mixing friend and external operators for template class

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94141

--- Comment #2 from Marc Glisse  ---
Ah, maybe the friend function is not quite a template, so the generated swapped
function is not a template either, and thus it has priority over a template if
both are exact matches?

This is going to break a number of users of boost/operators.hpp, and possibly
other mixins using a similar technique.

[Bug c++/94141] c++20 rewritten operator== recursive call mixing friend and external operators for template class

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94141

--- Comment #1 from Marc Glisse  ---
It looks like clang-10+ also generates an infinite loop on this code. Does the
standard really give priority to some implicit function over a user-defined one
that is an exact match?