Matthias Krüger [Thu, 13 Oct 2022 22:45:17 +0000 (00:45 +0200)]
Rollup merge of #103006 - WaffleLapkin:rustdoc_dont, r=compiler-errors
rustdoc: don't ICE on `TyKind::Typeof`
Fixes #102986
I'm not sure why rustdoc started seeing `TyKind::Typeof` all of a sudden (the code being editted was last touched 3 months ago), probably something to do with error recovery? idk.
Matthias Krüger [Thu, 13 Oct 2022 22:45:17 +0000 (00:45 +0200)]
Rollup merge of #103000 - wesleywiser:suggest_libname, r=compiler-errors
Add suggestion to the "missing native library" error
If we fail to locate a native library that we are linking with, it could be the case the user entered a complete file name like `foo.lib` or `libfoo.a` when we expect them to simply provide `foo`.
In this situation, we now detect that case and suggest the user only provide the library name itself.
bors [Thu, 13 Oct 2022 14:59:39 +0000 (14:59 +0000)]
Auto merge of #103009 - Dylan-DPC:rollup-9c2tng6, r=Dylan-DPC
Rollup of 6 pull requests
Successful merges:
- #102765 (Suggest `==` to the first expr which has `ExprKind::Assign` kind)
- #102854 (openbsd: don't reallocate a guard page on the stack.)
- #102904 (Print return-position `impl Trait` in trait verbosely if `-Zverbose`)
- #102947 (Sort elaborated existential predicates in `object_ty_for_trait`)
- #102956 (Use `full_res` instead of `expect_full_res`)
- #102999 (Delay `is_intrinsic` query until after we've determined the callee is a function)
Dylan DPC [Thu, 13 Oct 2022 12:49:20 +0000 (18:19 +0530)]
Rollup merge of #102947 - compiler-errors:sort-elaborated-existentials, r=cjgillot
Sort elaborated existential predicates in `object_ty_for_trait`
r? `@cjgillot`
I think that #102845 caused #102933. Depending on the order that we elaborate these existential projection predicates, there's no guarantee that they'll be sorted by def id, which is what is failing the assertion in the issue.
bors [Thu, 13 Oct 2022 12:03:46 +0000 (12:03 +0000)]
Auto merge of #102919 - luojia65:update-stdarch, r=Amanieu
library: update stdarch submodule
It has been one month since we update `stdarch` submodule into main branch Rust, it includes various fixes in code and more neat documents. This pull request also adds missing features to ensure we can build latest stdarch submodule.
Wesley Wiser [Thu, 13 Oct 2022 02:52:31 +0000 (22:52 -0400)]
Add suggestion to the "missing native library" error
If we fail to locate a native library that we are linking with, it could
be the case the user entered a complete file name like `foo.lib` or
`libfoo.a` when we expect them to simply provide `foo`.
In this situation, we now detect that case and suggest the user only
provide the library name itself.
bors [Thu, 13 Oct 2022 06:49:29 +0000 (06:49 +0000)]
Auto merge of #102655 - joboet:windows_tls_opt, r=ChrisDenton
Optimize TLS on Windows
This implements the suggestion in the current TLS code to embed the linked list of destructors in the `StaticKey` structure to save allocations. Additionally, locking is avoided when no destructor needs to be run. By using one Windows-provided `Once` per key instead of a global lock, locking is more finely-grained (this unblocks #100579).
bors [Thu, 13 Oct 2022 03:33:40 +0000 (03:33 +0000)]
Auto merge of #102995 - JohnTitor:rollup-yomkwge, r=JohnTitor
Rollup of 7 pull requests
Successful merges:
- #102641 (Support casting boxes to dyn*)
- #102836 (rustc_target: Fix json target specs using LLD linker flavors in link args)
- #102949 (should-skip-this: add missing backslash)
- #102967 (Add test for issue 102964)
- #102971 (tidy: error if a lang feature is already present)
- #102974 (Fix small word dupe typos)
- #102980 (rustdoc: merge separate `.item-info` CSS)
Yuki Okushi [Thu, 13 Oct 2022 00:41:27 +0000 (09:41 +0900)]
Rollup merge of #102971 - est31:tidy_duplicate_lang_features, r=jyn514
tidy: error if a lang feature is already present
If a lang feature gets declared twice, like for example as a result of a mistake during stabilization, emit an error in tidy. Library features already have this logic.
Inspired by a mistake done during `half_open_range_patterns` stabilization: https://github.com/rust-lang/rust/pull/102275/files#r991292215
The PR requires #102883 to be merged before CI turns green because the check is doing its job.
For reviewers, I suggest [turning off whitespace changes](https://github.com/rust-lang/rust/pull/102971/files?w=1) in the diff by adding `?w=1` to the url, as a large part of the diff is just about removing one level of indentation.
Yuki Okushi [Thu, 13 Oct 2022 00:41:25 +0000 (09:41 +0900)]
Rollup merge of #102836 - petrochenkov:jsonspec, r=eholk
rustc_target: Fix json target specs using LLD linker flavors in link args
Fixes https://github.com/rust-lang/rust/pull/101988#issuecomment-1272407248 (a regression introduced by https://github.com/rust-lang/rust/pull/101988).
Yuki Okushi [Thu, 13 Oct 2022 00:41:25 +0000 (09:41 +0900)]
Rollup merge of #102641 - eholk:dyn-star-box, r=compiler-errors
Support casting boxes to dyn*
Boxes have a pointer type at codegen time which LLVM does not allow to be transparently converted to an integer. Work around this by inserting a `ptrtoint` instruction if the argument is a pointer.
bors [Thu, 13 Oct 2022 00:37:28 +0000 (00:37 +0000)]
Auto merge of #102372 - abrown:issue-102157, r=thomcc
Allow compiling the `wasm32-wasi` std library with atomics
The issue #102157 demonstrates how currently the `-Z build-std` option will fail when re-compiling the standard library with `RUSTFLAGS` like `RUSTFLAGS="-C target-feature=+atomics,+bulk-memory -C link-args=--shared-memory"`. This change attempts to resolve those build issues by depending on the the WebAssembly `futex` module and providing an implementation for `env_lock`. Fixes #102157.
est31 [Wed, 12 Oct 2022 15:57:05 +0000 (17:57 +0200)]
tidy: error if a lang feature is already present
If a lang feature gets declared twice, like for example as
a result of a mistake during stabilization, emit an error
in tidy. Library features already have this logic.
bors [Wed, 12 Oct 2022 21:03:47 +0000 (21:03 +0000)]
Auto merge of #101679 - compiler-errors:rpitit-default-body, r=nikomatsakis
Support default-body trait functions with return-position `impl Trait` in traits
Introduce a new `Trait` candidate kind for the `ImplTraitInTrait` projection candidate, which just projects an RPITIT down to its opaque type form.
This is a hack until we lower RPITITs to regular associated types, after which we will need to rework how these default bodies are type-checked, so comments are left in a few places for us to clean up later.
9 commits in a7cdac33ca7356ad49d5c2b5e2c5010889b33eee..f6ed74f582bddcec73f753eafaab3749c4f7df61
2022-09-19 17:39:58 -0700 to 2022-10-08 02:43:26 -0700
- Typo 'a' -> 'an' (rust-lang/reference#1280)
- One line one sentence for expressions and statements main chapters (rust-lang/reference#1277)
- Document let else statements (rust-lang/reference#1156)
- Document `label_break_value` in the reference (rust-lang/reference#1263)
- Document target_has_atomic (rust-lang/reference#1171)
- update 'unsafe' (rust-lang/reference#1278)
- Update tokens.md (rust-lang/reference#1276)
- One sentence, one line Patterns chapter (rust-lang/reference#1275)
- Use semver-compliant example version (rust-lang/reference#1272)
## rust-by-example
9 commits in 767a6bd9727a596d7cfdbaeee475e65b2670ea3a..5e7b296d6c345addbd748f242aae28c42555c015
2022-09-14 09:17:18 -0300 to 2022-10-05 08:24:45 -0300
- Make it clear that rustdoc uses the commonmark spec (rust-lang/rust-by-example#1622)
- Update defaults.md (rust-lang/rust-by-example#1615)
- added "see also" for the @ binding sigil (rust-lang/rust-by-example#1612)
- add more precision to the effects of --bin flag (rust-lang/rust-by-example#1607)
- create bar project in cargo/dependencies example (rust-lang/rust-by-example#1606)
- use consistent wording about type annotation (rust-lang/rust-by-example#1603)
- cast.md improvements (rust-lang/rust-by-example#1599)
- Fix typo in macros.md (rust-lang/rust-by-example#1598)
- Corrected mistaken "The" instead of "There" (rust-lang/rust-by-example#1617)
Dylan DPC [Wed, 12 Oct 2022 16:43:26 +0000 (22:13 +0530)]
Rollup merge of #102927 - compiler-errors:let, r=davidtwco
Fix `let` keyword removal suggestion in structs
(1.) Fixes a bug where, given this code:
```rust
struct Foo {
let x: i32,
}
```
We were parsing the field name as `let` instead of `x`, which causes issues later on in the type-checking phase.
(2.) Also, suggestions for `let: i32` as a field regressed, displaying this extra `help:` which is removed by this PR
```
help: remove the let, the `let` keyword is not allowed in struct field definitions
|
2 - let: i32,
2 + : i32,
```
(3.) Makes the suggestion text a bit more succinct, since we don't need to re-explain that `let` is not allowed in this position (since it's in a note that follows). This causes the suggestion to render inline as well.
cc `@gimbles,` this addresses a few nits I mentioned in your PR.
Dylan DPC [Wed, 12 Oct 2022 16:43:25 +0000 (22:13 +0530)]
Rollup merge of #102830 - compiler-errors:constness-parity, r=fee1-dead
Unify `tcx.constness` query and param env constness checks
The checks that we do in the `constness` query seem inconsistent with the checks that we do to determine if an item's param-env is const, so I merged them into the `constness` query and call that from the `param_env` query.
I'm not sure if this totally makes sense -- is there a case where `tcx.param_env()` would return a const param-env for an item whose `tcx.constness()` is `Constness::NotConst`? Because if not, it seems a bit dangerous that these two differ.
Luckily, not many places actually use `tcx.constness()`, and the checks in `tcx.param_env()` seem stricter than the checks in `tcx.constness()` (at least for the types of items we type-check).
Also, due to the way that `tcx.param_env()` is implemented, it _never_ used to return a const param-env for a item coming from a different crate, which also seems dangerous (though also probably not weaponizable currently, because we seldom actually compute the param-env for a non-local item).
Dylan DPC [Wed, 12 Oct 2022 16:43:24 +0000 (22:13 +0530)]
Rollup merge of #102719 - Nilstrieb:tidy-alphabetical, r=jackh726
Enforce alphabetical sorting with tidy
We have many places where things are supposed to be sorted alphabetically. For the smaller and more recent size assertions, this is mostly upheld, but in other more... alive places it's very messy.
This introduces a new tidy directive to check that a section of code is sorted alphabetically and fixes all places where sorting has gone wrong.
Dylan DPC [Wed, 12 Oct 2022 16:43:23 +0000 (22:13 +0530)]
Rollup merge of #102623 - davidtwco:translation-eager, r=compiler-errors
translation: eager translation
Part of #100717. See [Zulip thread](https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/.23100717.20lists!/near/295010720) for additional context.
- **Store diagnostic arguments in a `HashMap`**: Eager translation will enable subdiagnostics to be translated multiple times with different arguments - this requires the ability to replace the value of one argument with a new value, which is better suited to a `HashMap` than the previous storage, a `Vec`.
- **Add `AddToDiagnostic::add_to_diagnostic_with`**: `AddToDiagnostic::add_to_diagnostic_with` is similar to the previous `AddToDiagnostic::add_to_diagnostic` but takes a function that can be used by the caller to modify diagnostic messages originating from the subdiagnostic (such as performing translation eagerly). `add_to_diagnostic` now just calls `add_to_diagnostic_with` with an empty closure.
- **Add `DiagnosticMessage::Eager`**: Add variant of `DiagnosticMessage` for eagerly translated messages
(messages in the target language which don't need translated by the emitter during emission). Also adds `eager_subdiagnostic` function which is intended to be invoked by the diagnostic derive for subdiagnostic fields which are marked as needing eager translation.
- **Support `#[subdiagnostic(eager)]`**: Add support for `eager` argument to the `subdiagnostic` attribute which generates a call to `eager_subdiagnostic`.
- **Finish migrating `rustc_query_system`**: Using eager translation, migrate the remaining repeated cycle stack diagnostic.
- **Split formatting initialization and use in diagnostic derives**: Diagnostic derives have previously had to take special care when ordering the generated code so that fields were not used after a move.
This is unlikely for most fields because a field is either annotated with a subdiagnostic attribute and is thus likely a `Span` and copiable, or is a argument, in which case it is only used once by `set_arg`
anyway.
However, format strings for code in suggestions can result in fields being used after being moved if not ordered carefully. As a result, the derive currently puts `set_arg` calls last (just before emission), such as:
diag.set_arg("foo", __binding_0);
/* + other `set_arg` calls */
diag.emit();
For eager translation, this doesn't work, as the message being translated eagerly can assume that all arguments are available - so arguments _must_ be set first.
Format strings for suggestion code are now separated into two parts - an initialization line that performs the formatting into a variable, and a usage in the subdiagnostic addition.
By separating these parts, the initialization can happen before arguments are set, preserving the desired order so that code compiles, while still enabling arguments to be set before subdiagnostics are added.
let diag = { /* create diagnostic */ };
let __code_0 = format!("{}", __binding_0);
/* + other formatting */
diag.set_arg("foo", __binding_0);
/* + other `set_arg` calls */
- **Remove field ordering logic in diagnostic derive:** Following the approach taken in earlier commits to separate formatting initialization from use in the subdiagnostic derive, simplify the diagnostic derive by removing the field-ordering logic that previously solved this problem.
bors [Wed, 12 Oct 2022 14:39:43 +0000 (14:39 +0000)]
Auto merge of #102732 - RalfJung:assert_unsafe_precondition2, r=bjorn3
nicer errors from assert_unsafe_precondition
This makes the errors shown by cargo-careful nicer, and since `panic_no_unwind` is `nounwind noreturn` it hopefully doesn't have bad codegen impact. Thanks to `@bjorn3` for the hint!
Would be nice if we could somehow supply our own (static) message to print, currently it always prints `panic in a function that cannot unwind`. But still, this is better than before.
Nilstrieb [Tue, 4 Oct 2022 20:34:07 +0000 (22:34 +0200)]
Add tidy directoy `tidy-alphabetical`
It can be used to ensure that a list of things is sorted alphabetically.
It goes off lines, but contains several heuristics to work with normal
Rust code (looking at indentation, ignoring comments and attributes).
bors [Wed, 12 Oct 2022 10:51:31 +0000 (10:51 +0000)]
Auto merge of #102460 - flba-eb:fix_85261_prevent_alloc_after_fork, r=thomcc
Prevent UB in child process after calling libc::fork
After calling libc::fork, the child process tried to access a TLS variable when processing a panic. This caused a memory allocation which is UB in the child.
To prevent this from happening, the panic handler will not access the TLS variable in case `panic::always_abort` was called before.
Fixes #85261 (not only on Android systems, but also on Linux/QNX with TLS disabled, see issue for more details)
Main drawbacks of this fix:
* Panic messages can incorrectly omit `core::panic::PanicInfo` struct in case several panics (of multiple threads) occur at the same time. The handler cannot distinguish between multiple panics in different threads or recursive ones in the same thread, but the message will contain a hint about the uncertainty.
* `panic_count::increase()` will be a bit slower as it has an additional `if`, but this should be irrelevant as it is only called in case of a panic.
Dylan DPC [Wed, 12 Oct 2022 05:41:27 +0000 (11:11 +0530)]
Rollup merge of #102924 - notriddle:notriddle/sidebar-link-class, r=GuillaumeGomez
rustdoc: remove unused classes from sidebar links
Since https://github.com/rust-lang/rust/commit/98f05a0282625a5fda6e90ebf3b05a4bd7608f65 removed separate colors from the currently-selected item, there's no need to have item classes on sidebar links.
While cleaning up the CSS to remove unneeded `.content` selectors, this PR changes the `h1.fqn a` CSS selector to just be `h1 a`, so that the header link color selector is less specific than the typed link at the end. Since https://github.com/rust-lang/rust/pull/89506 made docblocks start at `h2`, the main page link header should be the only h1 in the page now.
Dylan DPC [Wed, 12 Oct 2022 05:41:26 +0000 (11:11 +0530)]
Rollup merge of #102890 - camsteffen:adt-sized-representability, r=cjgillot
Check representability in adt_sized_constraint
Now that representability is a query, we can use it to preemptively avoid a cycle in `adt_sized_constraint`.
I moved the representability check into `check_mod_type_wf` to avoid a scenario where rustc quits before checking all the types for representability. This also removes the check from rustdoc, which is alright AFAIK.
Dylan DPC [Wed, 12 Oct 2022 05:41:25 +0000 (11:11 +0530)]
Rollup merge of #102811 - the8472:bufread-memset, r=m-ou-se
Use memset to initialize readbuf
The write loop was found to be slow in #102727
The proper fix is in #102760 but this might still help debug builds and code running under miri by using the write_bytes intrinsic instead of writing one byte at a time.
Dylan DPC [Wed, 12 Oct 2022 05:41:24 +0000 (11:11 +0530)]
Rollup merge of #102187 - b-naber:inline-const-source-info, r=eholk
Use correct location for type tests in promoted constants
Previously we forgot to remap the location in a type test collected when visiting the body of a promoted constant back to the usage location, causing an ICE when trying to get span information for that type test.
Dylan DPC [Wed, 12 Oct 2022 05:41:23 +0000 (11:11 +0530)]
Rollup merge of #102110 - CleanCut:migrate_rustc_passes_diagnostics, r=davidtwco
Migrate rustc_passes diagnostics
Picks up abandoned work from https://github.com/rust-lang/rust/pull/100870
I would like to do this collaboratively, as there is a lot of work! Here's the process:
- Comment below that you are willing to help and I will add you as a collaborator to my `rust` fork (that gives you write access)
- Indicate which file/task you would like to work on (so we don't duplicate work) from the list below
- Do the work, push up a commit, comment that you're done with that file/task
- Repeat until done 😄
### Files to Migrate (in `compiler/rustc_passes/src/`)
- [x] Rebase on current `master` ``@CleanCut``
- [x] Review work from [the earlier PR](https://github.com/rust-lang/rust/pull/100870) and make sure it all looks good
- [x] compiler/rustc_error_messages/locales/en-US/passes.ftl ``@CleanCut``
- [x] compiler/rustc_passes/src/check_attr.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/errors.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/lang_items.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/lib.rs ``@CleanCut``
- [x] compiler/rustc_passes/src/weak_lang_items.rs ``@CleanCut``
- Add more doc comments for three modules (rust-lang/cargo#11207)
- docs: fix (rust-lang/cargo#11208)
- Add completions for `cargo remove` (rust-lang/cargo#11204)
- Config file loaded via CLI takes priority over env vars (rust-lang/cargo#11077)
- Use `#[default]` when possible (rust-lang/cargo#11197)
- Implement RFC 3289: source replacement ambiguity (rust-lang/cargo#10907)
- Use correct version of cargo in test (rust-lang/cargo#11193)
- Check empty input for login (rust-lang/cargo#11145)
- Add retry support to sparse registries (rust-lang/cargo#11069)
- Add more doc comments for three modules (rust-lang/cargo#11207)
- docs: fix (rust-lang/cargo#11208)
- Add completions for `cargo remove` (rust-lang/cargo#11204)
- Config file loaded via CLI takes priority over env vars (rust-lang/cargo#11077)
- Use `#[default]` when possible (rust-lang/cargo#11197)
- Implement RFC 3289: source replacement ambiguity (rust-lang/cargo#10907)
- Use correct version of cargo in test (rust-lang/cargo#11193)
- Check empty input for login (rust-lang/cargo#11145)
- Add retry support to sparse registries (rust-lang/cargo#11069)
Matthias Krüger [Tue, 11 Oct 2022 16:59:49 +0000 (18:59 +0200)]
Rollup merge of #102685 - nbdd0121:unwind, r=m-ou-se
Interpret EH actions properly
The EH actions stored in the LSDA follows the format of GCC except table (even for LLVM-generated code). An missing action in the table is the encoding for `Terminate`, see https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/libsupc%2B%2B/eh_personality.cc#L522-L526.
The currently code interprets it as `None`, as a workaround for #35011, an issue that seems to occur in LLVM 3.7 and not after 3.9. These are very old versions of LLVM and we don't support them anymore, so remove this workaround and interpret them properly.
Note that LLVM currently does not emit any `Terminate` actions, but GCC does. Although GCC backend currently doesn't do unwinding, removing it preemptively would prevent future developers from wasting time to figure out what's wrong.
Matthias Krüger [Tue, 11 Oct 2022 16:59:48 +0000 (18:59 +0200)]
Rollup merge of #102612 - JhonnyBillM:migrate-codegen-ssa-to-diagnostics-structs, r=davidtwco
Migrate `codegen_ssa` to diagnostics structs - [Part 1]
Initial migration of `codegen_ssa`. Going to split this crate migration in at least two PRs in order to avoid a huge PR and to quick off some questions around:
1. Translating messages from "external" crates.
2. Interfacing with OS messages.
3. Adding UI tests while migrating diagnostics.
Matthias Krüger [Tue, 11 Oct 2022 16:59:46 +0000 (18:59 +0200)]
Rollup merge of #101774 - Riolku:atomic-update-aba, r=m-ou-se
Warn about safety of `fetch_update`
Specifically as it relates to the ABA problem.
`fetch_update` is a useful function, and one that isn't provided by, say, C++. However, this does not mean the function is magic. It is implemented in terms of `compare_exchange_weak`, and in particular, suffers from the ABA problem. See the following code, which is a naive implementation of `pop` in a lock-free queue:
This code is unsound if called from multiple threads because of the ABA problem. Specifically, suppose nodes are allocated with `Box`. Suppose the following sequence happens:
```
Initial: Queue is X -> Y.
Thread A: Starts popping, is pre-empted.
Thread B: Pops successfully, twice, leaving the queue empty.
Thread C: Pushes, and `Box` returns X (very common for allocators)
Thread A: Wakes up, sees the head is still X, and stores Y as the new head.
```
But `Y` is deallocated. This is undefined behaviour.
Adding a note about this problem to `fetch_update` should hopefully prevent users from being misled, and also, a link to this common problem is, in my opinion, an improvement to our docs on atomics.
Matthias Krüger [Tue, 11 Oct 2022 16:59:45 +0000 (18:59 +0200)]
Rollup merge of #100387 - cjgillot:hygiene-trait-impl, r=petrochenkov
Check uniqueness of impl items by trait item when applicable.
When checking uniqueness of item names in impl blocks, we currently use the same definition of hygiene as for toplevel items. This means that a plain item and one generated by a macro 2.0 do not collide.
This hygiene rule does not match with how impl items resolve to associated trait items. As a consequence, we misdiagnose the trait impls.
This PR proposes to consider that trait impl items are uses of the corresponding trait items during resolution, instead of checking for duplicates later. An error is emitted when a trait impl item is used twice.
There should be no stable breakage, since macros 2.0 are still unstable.
This commit does have to change `h1.fqn a` to just be `h1 a`, so that the
header link color selector is less specific than the typed link at the end.
Since #89506 made docblocks start at `h2`, the main page link header should
be the only h1 in the page now.
Yuki Okushi [Tue, 11 Oct 2022 09:37:55 +0000 (18:37 +0900)]
Rollup merge of #102859 - cjgillot:collect-lifetimes, r=oli-obk
Move lifetime resolution module to rustc_hir_analysis.
Now that lifetime resolution has been removed from it, this file has nothing to do in `rustc_resolve`. It's purpose is to compute Debruijn indices for lifetimes, so let's put it in type collection.
Yuki Okushi [Tue, 11 Oct 2022 09:37:54 +0000 (18:37 +0900)]
Rollup merge of #102589 - RalfJung:scoped-threads-dangling, r=m-ou-se
scoped threads: pass closure through MaybeUninit to avoid invalid dangling references
The `main` function defined here looks roughly like this, if it were written as a more explicit stand-alone function:
```rust
// Not showing all the `'lifetime` tracking, the point is that
// this closure might live shorter than `thread`.
fn thread(control: ..., closure: impl FnOnce() + 'lifetime) {
closure();
control.signal_done();
// A lot of time can pass here.
}
```
Note that `thread` continues to run even after `signal_done`! Now consider what happens if the `closure` captures a reference of lifetime `'lifetime`:
- The type of `closure` is a struct (the implicit unnameable closure type) with a `&'lifetime mut T` field. References passed to a function are marked with `dereferenceable`, which is LLVM speak for *this reference will remain live for the entire duration of this function*.
- The closure runs, `signal_done` runs. Then -- potentially -- this thread gets scheduled away and the main thread runs, seeing the signal and returning to the user. Now `'lifetime` ends and the memory the reference points to might be deallocated.
- Now we have UB! The reference that as passed to `thread` with the promise of remaining live for the entire duration of the function, actually got deallocated while the function still runs. Oops.
Long-term I think we should be able to use `ManuallyDrop` to fix this without `unsafe`, or maybe a new `MaybeDangling` type. I am working on an RFC for that. But in the mean time it'd be nice to fix this so that Miri with `-Zmiri-retag-fields` (which is needed for "full enforcement" of all the LLVM flags we generate) stops erroring on scoped threads.
bors [Tue, 11 Oct 2022 08:09:41 +0000 (08:09 +0000)]
Auto merge of #102755 - pcc:data-local-tmp, r=Mark-Simulacrum
tools/remote-test-{server,client}: Use /data/local/tmp on Android
The /data/tmp directory does not exist, at least not on recent versions of Android, which currently leads to test failures on that platform. I checked a virtual device running AOSP master and a Nexus 5 running Android Marshmallow and on both devices the /data/tmp directory does not exist and /data/local/tmp does, so let's switch to /data/local/tmp.
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