Given that it's not really that uncommon to see something like `pub(crate) async fn foo() ...`, the concern of function signatures starting to get unwieldy feels a lot more concrete than hypotheticals about a "sea of keywords". From looking at the list of keywords in the language currently (listed here: https://doc.rust-lang.org/std/#keywords), I don't really see a whole lot that I think the average Rust programmer would say is a burden to have to remember. At most, `union` and `unsafe` are probably ones that most Rust programmers are not going to need to use directly, and `SelfTy` might look a bit confusing at first due to the fact that the keyword itself is spelled `Self` (and presumably listed in that way to make it easier to differentiate from the `self` entry in the documentation), but even including those I'd argue that probably over half aren't specific to Rust.
As for being in the documentation, I'd argue that might even be an explicit non-goal; it's not clear to me why that should be something considered part of the API. If someone updates their tail recursive function to manually loop instead (or vice-versa), it doesn't seem like that should necessitate the documentation being updated.
As for being in the documentation, I'd argue that might even be an explicit non-goal; it's not clear to me why that should be something considered part of the API. If someone updates their tail recursive function to manually loop instead (or vice-versa), it doesn't seem like that should necessitate the documentation being updated.