[Guvante]

Feature complete is a pretty hard goal to reach. It sounds like "added all the features" but is closer to "bug compatible across compilers" (not saying there are bugs just that recent versions have removed a lot of wiggle room for implementations)

Also modules was a lot and was kind of the reason it took so long. They are wonderful and I want them but proper implementations (even with many details being implementation defined) required a lot of work to figure out.

Most of the time all the compilers get ahead of the actual release but in that case there were so many uncertainties only rough implementations were available beforehand and then post release they had to make adjustments to how they handled incremental compilation in a user facing way effectively.