[Bug libstdc++/72792] allocator_traits is too strict about rebinding

["ilg at livius dot net" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72792

--- Comment #6 from Liviu Ionescu <ilg at livius dot net> ---
> If you have real world code that is affected ...

I do, it is called µOS++, and it is a C++ RTOS with advanced memory management
features, using C++17 memory resources and C++11 standard allocators:

https://github.com/micro-os-plus/micro-os-plus-iii

It was developed on clang and GCC 5.x. When I tried GCC 6.x, it failed. Today I
took some time to understand why, and discovered the static assert in the
allocator_traits<> template.

I removed it and this solved the problem.

Now I'm working on a patch for GCC 6.x distributions, so I can run my tests on
CI servers until 6.4 will be released.

I'm a bit surprised that there were no other reports, according to my tests the
bug affected all custom allocators that use pointers to functions or pointer to
class members as template parameters. (I wrote a simple test, trying several
types of template parameters).

any estimate when the new release will be available?