Defining the Rust 2024 edition

You're being facetious.

Windows code isn't portable or reusable with anything else. MacOS code isn't portable [1]. iOS anything isn't portable. Ditto Android. Every one of those platforms has a bajillion bespoke quirks and [mis]features, including mutally incompatible toolchains and build environments. The only "portable" code possible is stuff that is purely computational; everything else has to have some sort of bespoke interface to the specific platform being targeted, or you target a metaplatform (eg SDL, QT, or Unreal Engine 5) that abstracts away those platform differences for you. Even then, you're still nearly always stuck with a separate "project" for each target platform's bespoke build/toolchains.

Autotools only ever covered UNIX-ish platforms [2], which at least nominally attempted to adhere to a common specification. And autotools itself didn't magically handle those platform differences for you; all it could do is detect what was or wasn't available and adjust the build (or fail) accordingly. It was always incumbent upon to the software author to actually write non-trivial platform-specific code for themselves.

In other news, Cars can't drive on water, and trains can't fly. More than once, anyway.

[1] The GUI stuff was never portable; pure cmdline stuff is in theory, but it's grown more difficult in practice with each successive release.
[2] These days, most of the flexibility Autotools provides has been mooted due to the nearly-complete relegation of proprietary UNIXes to the dustbin of history.