Deleted unused labels from compiler and fixed or allowed
unused labels in tests. This patch removes some gratuitous
unused labels and turns off the warning for unused labels
that are a necessary part of tests. This will permit
setting the `unused_labels` lint to `warn`.
This commit gives each stable keyword a short entry in the "Keywords"
section in the docs for `std`. The newly added entries are a single
summary line and a note that the documentation is not yet complete. I
changed some of the existing summary lines for consistency's sake. Each
line is either a verb phrase ("name the type of a trait object" for
`dyn`), or an object ("A value of type `bool` representing logical true"
for `true`). I tried to avoid using the keyword itself or the word
"keyword" in the summary.
Later PRs can flesh out each keyword with an example of each
context in which a keyword can appear and a link to the rust book.
Keywords which are not close to stable rust such as `box` (which is
getting unstabilized) or `try` are ignored in this PR.
`const fn` is no longer coming soon (const keyword docs)
The `const` keyword [documentation](https://doc.rust-lang.org/std/keyword.const.html) mentions that `const fn`s are coming soon, but they have already been added.
Most of these will eventually be filled, but right now travis-ci enjoys
complaining about the fact that there's links that lead nowhere, so
they're gone. Hopefully someone remembers to re-add them later.
This commit also splits out linky-line-thingies into two lines, which
judging from the source code for tidy, should be enough to make it shut
up and accept me for who I am, dammit.
I think it might be used in some other things, but I'm not fluent enough
at sifting through the rust compiler's source code to find every use of
a specific keyword.
This leaves the question of how to document the `extern` keyword, what
with how much overlap it has with `crate`, but that's used with ABI
stuff so that should be fine.
Turns out writing docs on keywords that are used in multiple different
places in entirely different contexts gets a little harder. I put a
footnote on `*const` syntax just to make sure you can find it if need
be, but it might need more detail.
The whole keyword docs thing is pretty new in Rust's history and needs
some work before it's a shining gem. Here's hoping I can provide that.
I basically shoved in a bunch of the most important information from the
reference and the book, along with leaving links to both at the end. I
don't think keyword docs need to have complete detail, just all the
broad strokes, so if someone's confused about a usage of a keyword they
can look at the std documentation for that keyword.
