That is the ultimate problem of batteries includes vs a small standard library distilled into a specific example.
People used to tout Python's "batteries included" line as positive almost universally a decade and more ago. Then better replacements were developed, and those batteries started looking less appealing.
There's really no escaping that while including any base functionality. Either you include it and portions will be stale later as better interfaces and paradigms are developed, or you don't, and you risk slower adoption and harder usability as people need to figure out solutions for common tasks, even if that solution is as simple as find the crate that provides it. Because eventually that becomes a problem not of finding the crate, but finding the best crate out of the multiple that exist, which itself causes fragmentation of the common developer experience (and thus makes it harder to share knowledge and have a good community).
Trustworthy is another thing altogether though. How do you handle this process in C and C++? Both of those languages have fairly spartan standard libraries as well.
I just did our license audit and 100% of our shipped deps were Apache | MIT. If you can clear those two licenses with legal, you should be good to go for virtually any crate.
Might be worth releasing my one liner for this if anyone else finds it useful.
And you usually see them cursing the platforms that don't care about POSIX support.
And ISO C++ has repented themselves from following C's footsteps and have been improving the standard library since C++11, mostly by integrating boost libraries.
Also, while some of your historical context is interesting, I don't really appreciate your editorialization, which I often find is off the mark personally.
So in reality POSIX complements libc as C's "runtime platform", even though ISO C never considered to make libc that big.
My historical context is how I experienced how things went, throughout the media we had available at the time.
I surely welcome factual corrections when I fail off the mark.
Everyone benefits from learning proper history facts.
I wasn't. Even with POSIX, it is spartan by today's standards. Look at the standard libraries of Python and Go. POSIX doesn't have JSON (de)serialization, HTTP servers, XML parsing and a whole boatload of other crap. So I don't think there is anything wrong with my characterization.
With that said, if `syn` finds itself in a spot where it needs to do a breaking change release for a new language feature, then that would be tricky. It sounds like syn's architecture is pretty flexible (non-exhaustive enums), but it's not clear to me that it could support all possible language additions without breaking changes.