On Tue, Feb 18, 2025, at 8:39 AM, Christoph Grüninger via Discussion list for the autoconf build system wrote: > Dear Autoconf, > > I am interested in the state and plans for supporting C++20 modules. As far as I know, nobody is currently working on anything related to C++ 2020 in either Autoconf or Automake. I have not kept up with the evolution of the C++ language since the 2011 standard, and in particular I know absolutely nothing about the C++2020 modules feature. So what follows is necessarily very speculative. 0) According to your "arewemodulesyet" site, neither GCC nor Clang fully supports modules yet, so I would suggest that developer effort is best spent there *first.* Autotools probably *shouldn't* try to do much of anything with incompletely implemented language features; we've had bad luck with that in the past. 1) Autoconf includes logic to probe for various compiler features and for adequate support for various levels of the C and C++ standards. These probes have a bunch of problems and they currently don't include anything newer than about 2017 for either C or C++. I would be glad to see work done on fixing these probes' problems and on updating them to include the newest editions of the language standards. However, the biggest problem with them is NOT that they are out of date, but that they do not allow the package being configured to declare which edition of the language standard they want. That needs to be addressed *before* we add any more editions, because the current behavior of selecting the most recent edition the compiler supports is known to be troublesome for big important things like Postgres, and we don't want to make it worse. If you're interested in working on this yourself, or you know someone who is, I would be happy to go into more detail. As things stand, if nobody steps up to do the work, it is unlikely to get done soon. 2) Besides an "is this feature available" probe, I don't know if any support for C++ 2020 modules is even *necessary*, because I don't know how they work. If any other changes are necessary, they would probably need to happen in Automake and Libtool, not in Autoconf. zw
