Format libcore with rustfmt (including tests and benches)
Important: two small non-rustfmt changes that will need close review:
- I added `#[rustfmt::skip]` to two manually arranged tables in src/libcore/benches/ascii.rs; see first commit in the PR.
- I added `// ignore-tidy-filelength` to src/libcore/ptr/mod.rs because rustfmt puts it over tidy's 3000 line limit; see second commit in the PR. I filed #66891 to follow up on breaking up that file. For now though having it be formatted is more important than having it below the line limit.
---
As with my previous formatting PRs, I am avoiding causing merge conflicts in other PRs by only touches those files that are not involved in any currently open PR. Files that appear in new PRs between when this PR is opened and when it makes it to the top of the bors queue will be reverted from this PR.
The list of files involved in open PRs is determined by querying GitHub's GraphQL API [with this script](https://gist.github.com/dtolnay/aa9c34993dc051a4f344d1b10e4487e8).
With the list of files from the script in outstanding_files, the relevant commands were:
```
$ find src/libcore -name '*.rs' \
| xargs rustfmt --edition=2018 --unstable-features --skip-children
$ rg libcore outstanding_files | xargs git checkout --
```
To confirm no funny business:
```
$ git checkout $THIS_COMMIT^
$ git show --pretty= --name-only $THIS_COMMIT \
| xargs rustfmt --edition=2018 --unstable-features --skip-children
$ git diff $THIS_COMMIT # there should be no difference
```
r? @Dylan-DPC
These passes were buggy, MIR building is now responsible for
canonicalizing `ConstantIndex` projections and `MoveData` is responsible
for splitting `Subslice` projections.
* `min_length` is now exact for const index elements.
* const index elements are always from the start.
* make array `Subslice` `PlaceElems` count both `from` and `to` from the
start.
In which we implement illegal subset relations errors using Polonius
This PR is the rustc side of implementing subset errors using Polonius. That is, in
```rust
fn foo<'a, 'b>(x: &'a u32, y: &'b u32) -> &'a u32 {
y
}
```
returning `y` requires that `'b: 'a` but we have no evidence of that, so this is an error. (Evidence that the relation holds could come from explicit bounds, or via implied bounds).
Polonius outputs one such error per CFG point where the free region's placeholder loan unexpectedly flowed into another free region. While all these CFG locations could be useful in diagnostics in the future, rustc does not do that (and the duplication is only partially handled in the rest of the errors/diagnostics infrastructure, e.g. duplicate suggestions will be shown by the "outlives suggestions" or some of the `#[rustc_*]` NLL/MIR debug dumps), so I deduplicated the errors.
(The ordering also matters, otherwise some of the elided lifetime naming would change behaviour).
I've blessed a couple of tests, where the output is currently suboptimal:
- the `hrtb-perfect-forwarding` tests mix subset errors with higher-ranked subtyping, however the plan is for chalk to eventually take care of some of this to generate polonius constraints (i.e. it's not polonius' job). Until that happens, polonius will not see the error that NLL sees.
- some other tests have errors and diagnostics specific to `'static`, I _believe_ this to be because of it being treated as more "special" than in polonius. I believe the output is not wrong, but could be better, and appears elsewhere (I feel we'll need to look at polonius' handling of `'static` at some point in the future, maybe to match a bit more what NLL does when it produces errors)
I'll create a tracking issue in the polonius repo to record these 2 points (and a general "we'll need to go over the blessed output" issue, much like we did for NLLs)
The last blessed test is because it's an improvement: in this case, more errors/suggestions were computed, instead of the existing code path where this case apparently stops at the first error.
The `Naive` variant in Polonius computes those errors, so this PR also switches the default variant to that, as we're also in the process of temporarily deactivating all other variants (which exist mostly for performance considerations) until we have completed more work on completeness and correctness, before focusing on efficiency once again.
While most of the correctness in this PR is hidden in the polonius compare-mode (which of course passes locally), I've added a couple of smoke-tests to the existing ones, so that we have some confidence that it works (and keeps working) until we're in a position where we can run them on CI.
As mentioned during yesterday's wg-polonius meeting, @nikomatsakis has already read through most of this PR (and which is matching what they thought needed to be done [during the recent Polonius sprint](https://hackmd.io/CGMNjt1hR_qYtsR9hgdGmw#Compiler-notes-on-generating-the-placeholder-loans-support)), but Matthew was hopefully going to review (again, not urgent), so:
r? @matthewjasper
(This updates to the latest `polonius-engine` release, and I'm not sure whether `Cargo.lock` updates can easily be rolled up, but apart from that: this changes little that's tested on CI, so seems safe-ish to rollup ?)
Move clean types into their own file
This PR is just about moving clean types into their own files to make the code more clear and keep all `Clean` trait implementations on their own.
r? @kinnison
Update measureme crate to 0.5.0
This PR updates the `measureme` self-profiling crate to the latest release. Heads up, this version changes the trace file format, so the `summarize` tool on perf.rlo needs to be updated to 0.5 too.
r? @Mark-Simulacrum
cc @wesleywiser
This commit corrects the diagnostic note for `async move {}` so that
`await` is mentioned, rather than `yield`.
Signed-off-by: David Wood <david@davidtw.co>
