`IndexMut` on mutable vectors.
This fixes a bug whereby the mutability fixups for method behavior were
not kicking in after autoderef failed to happen at any level. It also
adds support for `Index` to the fixer-upper.
Closes#12825.
Previously it had some uninituitive conditionals due to the interaction
with the Rand construction and Clone reinitialisation to create
sequential identifying numbers. This replaces all that with just
constructing the DropCounters with the appropriate identifiers.
This wasn’t really consistent with other things; the last section of the
import was not highlighted in any other case.
Also `use {foo, bar};` was having the foo and bar not highlighted, where
they would have been as separate statements.
The Sieve algorithm only requires checking all elements up to and including the square root of the maximum prime you're looking for. After that, the remaining elements are guaranteed to be prime.
The Windows-specific instruction under 'Quick Start' linked the wiki article on getting started developing Rust itself, but the quick start is just about obtaining a working Rust installation. The actual wiki page with Windows-specific instructions was difficult to find.
The most important thing to note on Windows is that you need mingw-builds, and it is totally not obvious. The only place where I have seen it mentioned is the wiki page, which was difficult to find before.
----
To reproduce issue on commit ba246100ca
it does not suffice to add just `check-build-compiletest` to
`check-secondary`; one must also ensure that `check-build-compiletest`
precedes the satisification of the `check` rule.
Otherwise hidden dependencies of `compiletest` would end up getting
satisfied when make builds `rustc` at each stage in order to
eventually run `check-stage2`.
So to handle that I moved `check-secondary` before `check` in the
`check-all` rule that bors uses, and for good measure, I also put
`check-build-compiltest` at the front of the `check-secondary` rule's
dependencies.
My understanding is that running `check-secondary` should be
relatively cheap, and thus such a reordering will not hurt bors.
----
Fix#17883.
This improves the spectralnorm shootout benchmark through a few vectors after
looking at the leading C implementation:
* The simd-based f64x2 is now used to parallelize a few computations
* RWLock usage has been removed. A custom `parallel` function was added as a
form of stack-based fork-join parallelism. I found that the contention on the
locks was high as well as hindering other optimizations.
This does, however, introduce one `unsafe` block into the benchmarks, which
previously had none.
In terms of timings, the before and after numbers are:
```
$ time ./shootout-spectralnorm-before
./shootout-spectralnorm-before 2.07s user 0.71s system 324% cpu 0.857 total
$ time ./shootout-spectralnorm-before 5500
./shootout-spectralnorm-before 5500 11.88s user 1.13s system 459% cpu 2.830 total
$ time ./shootout-spectralnorm-after
./shootout-spectralnorm-after 0.58s user 0.01s system 280% cpu 0.210 tota
$ time ./shootout-spectralnorm-after 5500
./shootout-spectralnorm-after 5500 3.55s user 0.01s system 455% cpu 0.783 total
```
Function arguments are (hopefully!) the last places where allocas don't
get proper markers for the end of their lifetimes. This means that this
code using 64 bytes of stack for the function arguments:
````rust
std::io::println("1");
std::io::println("2");
std::io::println("3");
std::io::println("4");
````
But with the proper lifetime markers, the slots can be reused, and
the arguments only need 16 bytes of stack.
All deprecation warnings have been converted to errors. This includes
the warning for multiple cfgs on one item. We'll leave that as an error
for some period of time to ensure that all uses are updated before the
behavior changes from "or" to "and".
