Changes in buildable components over time

From: Tim Haines (thaines.astro_at_[hidden])
Date: 2022-04-07 14:38:06

I've recently needed to understand which components need to be built, which
are header-only, and what versions correspond to each component (i.e., when
was it introduced, when was it removed). Combining the outputs from
'bootstrap.sh --show-libraries' since 1.39.0 and scraping the library
listings on the website as of 1.78.0, I was able to identify everything I
needed.

Surprisingly, though, it appears that coroutine2 and metaparse started out
as buildable components, but then switched to being header-only.

coroutine2
 - introduced in 1.59.0
 - first buildable in 1.59.0
 - last buildable in 1.64.0
 - available as of 1.78.0

metaparse
 - introduced in 1.61.0
 - first buildable in 1.61.0
 - last buildable in 1.65.1
 - available as of 1.78.0

I cross-referenced the release notes, but I didn't see any mention of these
components being made header-only. Is this intended behavior?

Thanks.
- Tim