Update the book to fix some edition-related bugs
I'd love to have this included in a point release if one happens, but the changes aren't worth doing a point release on their own IMO. I'd definitely like to see this backported to beta.
The most urgent changes included here are:
- Chapter 19.6, on macros (including the macro changes that just stabilized), [is cut off](https://github.com/rust-lang/book/issues/1668) because of an ill-placed newline in a comment that [pulldown-cmark interprets incorrectly](https://github.com/raphlinus/pulldown-cmark/issues/124).
- [The `Cargo.toml` shown in the Guessing Game example in Chapter 2 (and one in Chapter 14) doesn't have `edition="2018"`](https://github.com/rust-lang/book/pull/1671), which can be confusing depending on whether the readers have it in theirs or not, think they should remove it if they have it, and the rest of the chapter assumes it's there and the code doesn't compile if you don't have it.
- The redirects implemented as part of only shipping the 2018 edition of the book sometimes lead to [having to click through 2 redirect pages](https://github.com/rust-lang/book/pull/1667) when it could be just one.
There are other small corrections included that were made since the last time the book was updated, but those aren't urgent.
cc @steveklabnik
name old ns/iter new ns/iter diff ns/iter diff % speedup
iter::bench_cycle_take_ref_sum 927,152 927,194 42 0.00% x 1.00
iter::bench_cycle_take_sum 938,129 603,492 -334,637 -35.67% x 1.55
resolve: Reduce some clutter in import ambiguity errors
Noticed in https://www.reddit.com/r/rust/comments/a3pyrw/announcing_rust_131_and_rust_2018/eb8alhi/.
The first error is distracting, but unnecessary, it's a *consequence* of the ambiguity error and appears because one of the ambiguous `actix` modules (unsurprisingly) doesn't have the expected name in it.
codegen: Fix va_list - aarch64 iOS/Windows
## Summary
Fix code generated for `VaList` on Aarch64 iOS/Windows.
## Details
According to the [Apple - ARM64 Function Calling Conventions]:
> ... the type va_list is an alias for char * rather than for the struct
> type specified in the generic PCS.
The current implementation uses the generic Aarch64 structure for `VaList`
for Aarch64 iOS. Switch to using the `char *` variant of the `VaList`
and use the corresponding `emit_ptr_va_arg` for the `va_arg` intrinsic.
Windows always uses the `char *` variant of the `VaList`. Update the `va_arg`
intrinsic to use `emit_ptr_va_arg`.
[Apple - ARM64 Function Calling Conventions]: https://developer.apple.com/library/archive/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARM64FunctionCallingConventions.html
Improve the usage message for `-Z dump-mir`.
Ouput now looks like this:
```
$ rustc -Z help
...
-Z arg-align-attributes -- emit align metadata for reference arguments
-Z dump-mir=val -- dump MIR state to file.
`val` is used to select which passes and functions to dump. For example:
`all` matches all passes and functions,
`foo` matches all passes for functions whose name contains 'foo',
`foo & ConstProp` only the 'ConstProp' pass for function names containing 'foo',
`foo | bar` all passes for function names containing 'foo' or 'bar'.
-Z dump-mir-dir=val -- the directory the MIR is dumped into
...
```
Fixes#56558
use top level `fs` functions where appropriate
This commit replaces many usages of `File::open` and reading or writing
with `fs::read_to_string`, `fs::read` and `fs::write`. This reduces code
complexity, and will improve performance for most reads, since the
functions allocate the buffer to be the size of the file.
I believe that this commit will not impact behavior in any way, so some
matches will check the error kind in case the file was not valid UTF-8.
Some of these cases may not actually care about the error.
According to the Apple developer docs:
> The type va_list is an alias for char * rather than for the struct
> type specified in the generic PCS.
The current implementation uses the generic Aarch64 structure for VaList
for Aarch64 iOS.
Windows always uses the char * variant of the va_list.
This commit replaces many usages of `File::open` and reading or writing
with `fs::read_to_string`, `fs::read` and `fs::write`. This reduces code
complexity, and will improve performance for most reads, since the
functions allocate the buffer to be the size of the file.
I believe that this commit will not impact behavior in any way, so some
matches will check the error kind in case the file was not valid UTF-8.
Some of these cases may not actually care about the error.
Fix ICE with generators and NLL
Fix#55850.
This PR stops an ICE in #55850 by not panicking when a region cannot be named. However, this PR does not (yet) fix the underlying issue that the correct name for the test case provided for the issue (in this instance, `'a`) was not found.
This PR also lays a little bit of groundwork by categorizing yields separately from returns so that region naming can be specialized for this case.
r? @pnkfelix
