There are several that are unused and can be removed.

And there are some calls to `to_string`, which can be expressed more
nicely as a `foo_to_string` call, and then `to_string` need not be
`pub`. (This requires adding `pat_to_string`).

- Remove an out-of-date comment. (There is no `PpAnn` implementation for `hir::Crate`.)
- Remove a low-value comment.
- And break a very long comment.

Remove and inline `new_from_input`, because it has a single call site.
And move `attrs` into the earlier `impl` block.

This PR fixes an issues where rustc would ignore subsequent
`#[diagnostic::on_unimplemented]` attributes. The [corresponding
RFC](https://rust-lang.github.io/rfcs/3368-diagnostic-attribute-namespace.html)
specifies that the first matching instance of each option is used.
Invalid attributes are linted and otherwise ignored.

This is the only BCB that `TraverseCoverageGraphWithLoops::next` works with, so
calling it `next_bcb` just makes the code less clear.

The previous code was storing the worklist in a vector, and then selectively
adding items to the start or end of the vector. That's a perfect use-case for a
double-ended queue.

This change also reveals that the existing code was a bit confused about which
end of the worklist is the front or back. For now, items are always removed
from the front of the queue (instead of the back), and code that adds items to
the queue has been flipped, to preserve the existing behaviour.

Having to keep passing in a graph reference was a holdover from when the graph
was partly mutated during traversal. As of rust-lang#114354 that is no longer necessary,
so we can simplify the traversal code by storing a graph reference as a field
in `TraverseCoverageGraphWithLoops`.

As long as we store the loop header BCB, we can look up its incoming loop
backedges as needed.

…mpiler-errors

Add unstable book page for the no-jump-tables codegen option

See tracking issue: rust-lang#116592

…e1-dead

`rustc_hir_pretty` cleanups

Just some improvements I found while looking through this code.

r? ``@fee1-dead``

…ed_improvements, r=compiler-errors

Handle several `#[diagnostic::on_unimplemented]` attributes correctly

This PR fixes an issues where rustc would ignore subsequent `#[diagnostic::on_unimplemented]` attributes. The [corresponding RFC](https://rust-lang.github.io/rfcs/3368-diagnostic-attribute-namespace.html) specifies that the first matching instance of each option is used. Invalid attributes are linted and otherwise ignored.

coverage: Clarify loop-edge detection and graph traversal

This is a collection of improvements to two semi-related pieces of code:

- The code in `counters` that detects which graph edges don't exit a loop, and would therefore be good candidates to have their coverage computed as an expression rather than having a physical counter.
- The code in `graph` that traverses the coverage BCB graph in a particular order, and tracks loops and loop edges along the way (which is relevant to the above).

I was originally only planning to make the `graph` changes, but there was going to be a lot of indentation churn in `counters` anyway, and once I started looking I noticed a lot of opportunities for simplification.

---

`@rustbot` label +A-code-coverage

Fix mips platform support entries.

The table entries for these MIPS entries were broken because they had the wrong number of columns (from rust-lang#116503). Additionally, there was a conflict with rust-lang#115238, which made the same change (but on different lines, so git didn't complain).