Test conditional initialization validation in async fns
r? @cramertj
Per [paper doc](https://paper.dropbox.com/doc/async.await-Call-for-Tests--AiWF2Nt8tgDiA70qFI~oiLOOAg-nMyZGrra7dz9KcFRMLKJy) calling for async/.await tests, tests are desired for conditionally initialized local variables. This PR hopes to provide tests for that.
#63294 seems to be tracking the items from the paper doc that this PR is related to
#62121 is an open issue asking for more async/.await tests that this relates to
---
👍 executed 2 new tests
👍 tidy
pretty-pretty extremal constants!
(A resurrection of the defunct #57073.)
While many programmers may intuitively appreciate the significance of "magic numbers" like −2147483648, Rust is about empowering everyone to build reliable and efficient software! It's a bit more legible to print the constant names (even noisy fully-qualified-paths thereof).
The bit-manipulation methods mirror those in `librustc_mir::hair::pattern::_match::all_constructors`; thanks to the immortal Varkor for guidance.
Resolves#56393.
r? @varkor
redox: convert to target_family unix
This is the second step to supporting rust-lang/rust#60139.
In order to have a smooth transition, there will need to be a change made in liblibc at the same time, switching Redox over to the unix target family. See https://github.com/rust-lang/libc/pull/1332
While many programmers may intuitively appreciate the significance of
"magic numbers" like −2147483648, Rust is about empowering everyone to
build reliable and efficient software! It's a bit more legible to
print the constant names (even noisy fully-qualified-paths thereof).
The bit-manipulation methods mirror those in
`librustc_mir::hair::pattern::_match::all_constructors`; thanks to the
immortal Varkor for guidance.
Resolves#56393.
Rollup of 9 pull requests
Successful merges:
- #63034 (Fix generator size regressions due to optimization)
- #63035 (Use MaybeUninit to produce more correct layouts)
- #63163 (add a pair of whitespace after remove parentheses)
- #63294 (tests for async/await drop order)
- #63307 (don't ignore mir_dump folder)
- #63308 (PlaceRef's base is already a reference)
- #63310 (Tests around moving parts of structs and tuples across await points)
- #63314 (doc: the content has since been moved to the guide)
- #63333 (Remove unnecessary features from compiler error code list)
Failed merges:
r? @ghost
don't ignore mir_dump folder
I dumped some MIR and wondered why `git status` wouldn't show the tree as dirty, reminding me to clean up after myself. Turns out this folder was explicitly gitignored. I don't think it should be.
If someone doesn't want to clean up that way, they can add it to `.git/info/exclude`.
(That file seems like it could need some general cleanup, honestly, but that's for another day.)
tests for async/await drop order
This is just me helping out with https://github.com/rust-lang/rust/issues/62121 where I can.
I'm also going to use this as a public place to collect my thoughts about what has already been done and what hasn't (adding comments to the dropbox paper doc was quickly getting spammy).
I've tried to keep my commit messages similar to the line items on https://paper.dropbox.com/doc/async.await-Call-for-Tests--AiKouT0L41mSnK1741s~TiiRAg-nMyZGrra7dz9KcFRMLKJy as possible.
A bunch of my tests are likely to be either redundant with other tests, or lower quality than other tests that people are writing. A reasonable approach might be to tell me which commits you want to keep and I'll throw away the rest of them.
The part from the dropbox paper doc that I'm concentrating on here is:
(items marked with `?` are ones that I can't immediately think of how to test, so I will leave for other people. Items with checkboxes are things that I have done or will try to do next)
### Dynamic semantics
- `async`/`await` with unusual locals:
- ? partially uninhabited
- ? conditionally initialized
- ~drop impls~ already done in src/test/ui/async-await/drop-order/*
- ? nested drop impls
- ~partially moved (e.g., `let x = (vec![], vec![]); drop(x.0); foo.await; drop(x.1);`)~ see https://github.com/rust-lang/rust/pull/63310
- Control flow:
- basic
- complex
- [x] `.await` while holding variables of different sizes
- (possibly) drop order
- [x] including drop order for locals when a future is dropped part-way through execution
- Parameters' drop order is covered in my commit f40190a
- ~An async fn version of `dynamic-drop.rs`~
- already done by matthewjasper in https://github.com/rust-lang/rust/pull/62193/files
- ? interaction with const eval, promoteds, and temporaries
- [x] drop the resulting future and check that local variables and parameters are dropped in the expected order (interaction with cancellation, in other words)
- also in f40190a
Explanation of commits:
* 0a1bdd4 is the simplest place I could think of to explicitly test `.await` while holding variables of different sizes. I'm pretty sure that this will end up being redundant with something else, so I'm happy to drop it.
* f40190a is a copy-paste from `drop-order-for-async-fn-parameters.rs` with `NeverReady.await` dumped on the end of each testcase.
* Normally I don't like copy-paste-based tests, but `drop-order-for-async-fn-parameters-by-ref-binding.rs` is also copy-paste, so I thought it might be okay.
* [x] I'm a bit sad that this doesn't cover non-parameter locals, but I think it should be easy enough to extend in that direction, so I might have a crack at that tomorrow.
* c4940e0f90 makes a bunch of local variables and moves them into either `{}` blocks or `async move {}` blocks, checking for any surprising differences.
* I have tried to give the test functions descriptive names
* I have not duplicated the tests for methods with/without self.
* I think that all of these tests could be rewritten to be clearer if I could write down the expected drop order next to each test.
Fix generator size regressions due to optimization
I tested the generator optimizations in #60187 and #61922 on the Fuchsia
build, and noticed that some small generators (about 8% of the async fns
in our build) increased in size slightly.
This is because in #60187 we split the fields into two groups, a
"prefix" non-overlap region and an overlap region, and lay them out
separately. This can introduce unnecessary padding bytes between the two
groups.
In every single case in the Fuchsia build, it was due to there being
only a single variant being used in the overlap region. This means that
we aren't doing any overlapping, period. So it's better to combine the
two regions into one and lay out all the fields at once, which is what
this change does.
r? @cramertj
cc @eddyb @Zoxc
I tested the generator optimizations in #60187 and #61922 on the Fuchsia
build, and noticed that some small generators (about 8% of the async fns
in our build) increased in size slightly.
This is because in #60187 we split the fields into two groups, a
"prefix" non-overlap region and an overlap region, and lay them out
separately. This can introduce unnecessary padding bytes between the two
groups.
In every single case in the Fuchsia build, it was due to there being
only a single variant being used in the overlap region. This means that
we aren't doing any overlapping, period. So it's better to combine the
two regions into one and lay out all the fields at once, which is what
this change does.
