Tidy Python improvements
Fixes display of Python formatting diffs in tidy, and refactors the code to make it simpler and more robust. Also documents Python formatting and linting in the Rustc dev guide.
Fixes: https://github.com/rust-lang/rust/issues/135942
r? `@onur-ozkan`
Implement `needs-subprocess` directive, and cleanup a bunch of tests to use `needs-{subprocess,threads}`
### Summary
Closes#128295.
- Implements `//@ needs-subprocess` directive in compiletest as requested in #128295. However, compiletest is a host tool, so we can't just try to spawn process because that spawns the process on *host*, not the *target*, under cross-compilation scenarios.
- The short-term solution is to add *Yet Another* list of allow-list targets.
- The long-term solution is to first check if a `$target` supports std, then try to run a binary to do run-time capability detection *on the target*. But that is tricky because you have to build-and-run a binary *for the target*.
- This PR picks the short-term solution, because the long-term solution is highly non-trivial, and it's already an improvement over individual `ignore-*`s all over the place.
- Opened an issue about the long-term solution in #135928.
- Documents `//@ needs-subprocess` in rustc-dev-guide.
- Replace `ignore-{wasm,wasm32,emscripten,sgx}` with `needs-{subprocess,threads}` where suitable in tests.
- Some drive-by test changes as I was trying to figure out if I could use `needs-{subprocess,threads}` and found some bits needlessly distracting.
Count of tests that use `ignore-{wasm,wasm32,emscripten,sgx}` before and after this PR:
| State | `ignore-sgx` | `ignore-wasm` | `ignore-emscripten` |
| - | - | - | - |
| Before this PR | 96 | 88 | 207 |
| After this PR | 36 | 38 | 61 |
<details>
<summary>Commands used to find out locally</summary>
```
--- before
[17:40] Joe:rust (fresh) | rg --no-ignore -l "ignore-sgx" tests | wc -l
96
[17:40] Joe:rust (fresh) | rg --no-ignore -l "ignore-wasm" tests | wc -l
88
[17:40] Joe:rust (fresh) | rg --no-ignore -l "ignore-emscripten" tests | wc -l
207
--- after
[17:39] Joe:rust (needs-subprocess-thread) | rg --no-ignore -l "ignore-sgx" tests | wc -l
36
[17:39] Joe:rust (needs-subprocess-thread) | rg --no-ignore -l "ignore-wasm" tests | wc -l
38
[17:39] Joe:rust (needs-subprocess-thread) | rg --no-ignore -l "ignore-emscripten" tests | wc -l
61
```
</details>
### Review advice
- Best reviewed commit-by-commit.
- Non-trivial test changes (not mechanically simple replacements) are split into individual commits to help with review. Their individual commit messages give some basic description of the changes.
- I *could* split some test changes out into another PR, but I found that I needed to change some tests to `needs-threads`, some to `needs-subprocess`, and some needed to use *both*, so they might conflict and become very annoying.
---
r? ``@ghost`` (need to run try jobs)
try-job: x86_64-msvc-1
try-job: i686-msvc-1
try-job: i686-mingw
try-job: x86_64-mingw-1
try-job: x86_64-apple-1
try-job: aarch64-apple
try-job: aarch64-gnu
try-job: test-various
try-job: armhf-gnu
remove pointless allowed_through_unstable_modules on TryFromSliceError
This got added in https://github.com/rust-lang/rust/pull/132482 but the PR does not explain why. `@lukas-code` do you still remember? Also Cc `@Noratrieb` as reviewer of that PR.
If I understand the issue description correctly, all paths under which this type is exported are stable now: `core::array::TryFromSliceError` and `std::array::TryFromSliceError`. If that is the case, we shouldn't have the attribute; it's a terrible hack that should only be used when needed to maintain backward compatibility. Getting some historic information right is IMO *not* sufficient justification to risk accidentally exposing this type via more unstable paths today or in the future.
Get rid of RunCompiler
The various `set_*` methods that have been removed can be replaced by setting the respective fields in the `Callbacks::config` implementation. `set_using_internal_features` was often forgotten and it's equivalent is now done automatically.
This documents how to determine which settings are used in CI, since I
see this question come up regularly. We currently don't have a great way
to answer the question, but at least there is something.
许杰友 Jieyou Xu (Joe)
Matthias Krüger
Jakub Beránek
bjorn3
Noratrieb
Yuki Okushi
Patrick Oliveira
lcnr
Ryan Mehri
Noah Lev
Ralf Jung
onur-ozkan
Eric Huss
Max Heller
Boxy
Stuart Cook
Tshepang Mbambo
Martin Liška
clubby789
Marco Ieni
Chris Bloodsworth