Specifically, change `Ty` from this:
```
pub type Ty<'tcx> = &'tcx TyS<'tcx>;
```
to this
```
pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
```
There are two benefits to this.
- It's now a first class type, so we can define methods on it. This
means we can move a lot of methods away from `TyS`, leaving `TyS` as a
barely-used type, which is appropriate given that it's not meant to
be used directly.
- The uniqueness requirement is now explicit, via the `Interned` type.
E.g. the pointer-based `Eq` and `Hash` comes from `Interned`, rather
than via `TyS`, which wasn't obvious at all.
Much of this commit is boring churn. The interesting changes are in
these files:
- compiler/rustc_middle/src/arena.rs
- compiler/rustc_middle/src/mir/visit.rs
- compiler/rustc_middle/src/ty/context.rs
- compiler/rustc_middle/src/ty/mod.rs
Specifically:
- Most mentions of `TyS` are removed. It's very much a dumb struct now;
`Ty` has all the smarts.
- `TyS` now has `crate` visibility instead of `pub`.
- `TyS::make_for_test` is removed in favour of the static `BOOL_TY`,
which just works better with the new structure.
- The `Eq`/`Ord`/`Hash` impls are removed from `TyS`. `Interned`s impls
of `Eq`/`Hash` now suffice. `Ord` is now partly on `Interned`
(pointer-based, for the `Equal` case) and partly on `TyS`
(contents-based, for the other cases).
- There are many tedious sigil adjustments, i.e. adding or removing `*`
or `&`. They seem to be unavoidable.
In particular, there's now more protection against incorrect usage,
because you can only create one via `Interned::new_unchecked`, which
makes it more obvious that you must be careful.
There are also some tests.
Generator drop tracking: improve break and continue handling
This PR fixes two related issues.
One, sometimes break or continue have a block target instead of an expression target. This seems to mainly happen with try blocks. Since the drop tracking analysis only works on expressions, if we see a block target for break or continue, we substitute the last expression of the block as the target instead.
Two, break and continue were incorrectly being treated as the same, so continue would also show up as an exit from the loop or block. This patch corrects the way continue is handled by keeping a stack of loop entry points and uses those to find the target of the continue.
Fixes#93197
r? `@nikomatsakis`
make `find_similar_impl_candidates` even fuzzier
continues the good work of `@BGR360` in #92223. I might have overshot a bit and we're now slightly too fuzzy 😅
with this we can now also simplify `simplify_type`, which is nice :3
Make `Res::SelfTy` a struct variant and update docs
I found pattern matching on a `(Option<DefId>, Option<(DefId, bool)>)` to not be super readable, additionally the doc comments on the types in a tuple variant aren't visible anywhere at use sites as far as I can tell (using rust analyzer + vscode)
The docs incorrectly assumed that the `DefId` in `Option<(DefId, bool)>` would only ever be for an impl item and I also found the code examples to be somewhat unclear about which `DefId` was being talked about.
r? `@lcnr` since you reviewed the last PR changing these docs
Remove Config::stderr
1. It captured stdout and not stderr
2. It isn't used anywhere
3. All error messages should go to the DiagnosticOutput instead
4. It modifies thread local state
Marking as blocked as it will conflict a bit with https://github.com/rust-lang/rust/pull/93936.
rustc_target: Remove compiler-rt linking hack on Android
`compiler-rt` did some significant work last year trying to eliminate this kind of duplicated symbols, so the flag may be no longer necessary.
Tested locally with AArch64 Android, seems to work, CI will check the rest of the targets.
Update dist-(arm|armv7|armhf)-linux to Ubuntu 20.04
I believe this should be safe, as actual artifacts will be produced by a cross toolchain. The build ran through cleanly locally.
This came up in https://github.com/rust-lang/rust/pull/93577, where the host GCC ICEd during the LLD build. (Though I wonder why we build LLD for the host at all...)
r? `@Mark-Simulacrum`
Drop time dependency from bootstrap
This was only used for the inclusion of 'current' dates into our manpages, but
it is not clear that this is practically necessary. The manpage is essentially
never updated, and so we can likely afford to keep a manual date in these files.
It also seems possible to just omit it, but that may cause other tools trouble,
so avoid doing that for now.
This is largely done to reduce bootstrap complexity; the time crate is not particularly
small and in #92480 would have started pulling in num-threads, which does runtime
thread count detection. I would prefer to avoid that, so filing this to just drop the nearly
unused dependency entirely.
r? `@pietroalbini`
1. It captured stdout and not stderr
2. It isn't used anywhere
3. All error messages should go to the DiagnosticOutput instead
4. It modifies thread local state
Rollup of 9 pull requests
Successful merges:
- #89926 (make `Instant::{duration_since, elapsed, sub}` saturating and remove workarounds)
- #90532 (More informative error message for E0015)
- #93810 (Improve chalk integration)
- #93851 (More practical examples for `Option::and_then` & `Result::and_then`)
- #93885 (bootstrap.py: Suggest disabling download-ci-llvm option if url fails to download)
- #93886 (Stabilise inherent_ascii_escape (FCP in #77174))
- #93930 (add link to format_args! when mention it in docs)
- #93936 (Couple of driver cleanups)
- #93944 (Don't relabel to a team if there is already a team label)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Don't relabel to a team if there is already a team label
Should prevent cases like #93628, where teams have been manually assigned, but changes are pushed. We give up adding new labels on *new* changes; but I feel like that is less frequent.
r? `@Mark-Simulacrum`
Couple of driver cleanups
* Remove the `RustcDefaultCalls` struct, which hasn't been necessary since the introduction of `rustc_interface`.
* Move the `setup_callbacks` call around for a tiny code deduplication.
* Remove the `SPAN_DEBUG` global as it isn't actually necessary.
Stabilise inherent_ascii_escape (FCP in #77174)
Implements #77174, which completed its FCP.
This does *not* deprecate any existing methods or structs, as that is tracked in #93887. That stated, people should prefer using `u8::escape_ascii` to `std::ascii::escape_default`.
bootstrap.py: Suggest disabling download-ci-llvm option if url fails to download
I got an error when trying to build the compiler using an old commit, and it turns out it was because the option `download-ci-llvm` was implicitly set to true. So this pull request tries to add a help message for other people that may run into the same problem.
To reproduce my error:
```
git checkout 8d7707f3c4
./x.py test
[...]
spurious failure, trying again
downloading https://ci-artifacts.rust-lang.org/rustc-builds/db002a06ae9154a35d410550bc5132df883d7baa/rust-dev-nightly-x86_64-unknown-linux-gnu.tar.xz
curl: (22) The requested URL returned error: 404
failed to run: curl -# -y 30 -Y 10 --connect-timeout 30 --retry 3 -Sf -o /tmp/tmp8g13rb4n https://ci-artifacts.rust-lang.org/rustc-builds/db002a06ae9154a35d410550bc5132df883d7baa/rust-dev-nightly-x86_64-unknown-linux-gnu.tar.xz
Build completed unsuccessfully in 0:00:46
```
This is my `config.toml`:
```
# Includes one of the default files in src/bootstrap/defaults
profile = "compiler"
changelog-seen = 2
[rust]
debug = true
```
To reproduce an error with this branch:
Change line 618 of bootstrap.py to
```
url = "rustc-builds-error404/{}".format(llvm_sha)
```
Delete llvm and cached tarball, and set `llvm.download-ci-llvm=true` in config.toml.
```
./x.py test
[...]
spurious failure, trying again
downloading https://ci-artifacts.rust-lang.org/rustc-builds-error404/719b04ca99be0c78e09a8ec5e2eda082a5d8ccae/rust-dev-nightly-x86_64-unknown-linux-gnu.tar.xz
curl: (22) The requested URL returned error: 404
failed to run: curl -# -y 30 -Y 10 --connect-timeout 30 --retry 3 -Sf -o /tmp/tmpesl1ydvo https://ci-artifacts.rust-lang.org/rustc-builds-error404/719b04ca99be0c78e09a8ec5e2eda082a5d8ccae/rust-dev-nightly-x86_64-unknown-linux-gnu.tar.xz
error: failed to download llvm from ci
help: old builds get deleted after a certain time
help: if trying to compile an old commit of rustc, disable `download-ci-llvm` in config.toml:
[llvm]
download-ci-llvm = false
Build completed unsuccessfully in 0:00:01
```
Regarding the implementation, I expected to be able to use a try/catch block in `_download_ci_llvm`, but the `run` function calls `sys.exit` instead of raising an exception so that's not possible. Also, suggestions for better wording of the help message are welcome.
More practical examples for `Option::and_then` & `Result::and_then`
To be blatantly honest, I think the current example given for `Option::and_then` is objectively terrible. (No offence to whoever wrote them initially.)
```rust
fn sq(x: u32) -> Option<u32> { Some(x * x) }
fn nope(_: u32) -> Option<u32> { None }
assert_eq!(Some(2).and_then(sq).and_then(sq), Some(16));
assert_eq!(Some(2).and_then(sq).and_then(nope), None);
assert_eq!(Some(2).and_then(nope).and_then(sq), None);
assert_eq!(None.and_then(sq).and_then(sq), None);
```
Current example:
- does not demonstrate that `and_then` converts `Option<T>` to `Option<U>`
- is far removed from any realistic code
- generally just causes more confusion than it helps
So I replaced them with two blocks:
- the first one shows basic usage (including the type conversion)
- the second one shows an example of typical usage
Same thing with `Result::and_then`.
Hopefully this helps with clarity.
Improve chalk integration
- Support subtype bounds in chalk lowering
- Handle universes in canonicalization
- Handle type parameters in chalk responses
- Use `chalk_ir::LifetimeData::Empty` for `ty::ReEmpty`
- Remove `ignore-compare-mode-chalk` for tests that no longer hang (they may still fail or ICE)
This is enough to get a hello world program to compile with `-Zchalk` now. Some of the remaining issues that are needed to get Chalk integration working on larger programs are:
- rust-lang/chalk#234
- rust-lang/chalk#548
- rust-lang/chalk#734
- Generators are handled differently in chalk and rustc
r? `@jackh726`
make `Instant::{duration_since, elapsed, sub}` saturating and remove workarounds
This removes all mutex/atomic-based workarounds for non-monotonic clocks and makes the previously panicking methods saturating instead. Additionally `saturating_duration_since` becomes deprecated since `duration_since` now fills that role.
Effectively this moves the fixup from `Instant` construction to the comparisons.
This has some observable effects, especially on platforms without monotonic clocks:
* Incorrectly ordered Instant comparisons no longer panic in release mode. This could hide some programming errors, but since debug mode still panics tests can still catch them.
* `checked_duration_since` will now return `None` in more cases. Previously it only happened when one compared instants obtained in the wrong order or manually created ones. Now it also does on backslides.
* non-monotonic intervals will not be transitive, i.e. `b.duration_since(a) + c.duration_since(b) != c.duration_since(a)`
The upsides are reduced complexity and lower overhead of `Instant::now`.
## Motivation
Currently we must choose between two poisons. One is high worst-case latency and jitter of `Instant::now()` due to explicit synchronization; see #83093 for benchmarks, the worst-case overhead is > 100x. The other is sporadic panics on specific, rare combinations of CPU/hypervisor/operating system due to platform bugs.
Use-cases where low-overhead, fine-grained timestamps are needed - such as syscall tracing, performance profiles or sensor data acquisition (drone flight controllers were mentioned in a libs meeting) in multi-threaded programs - are negatively impacted by the synchronization.
The panics are user-visible (program crashes), hard to reproduce and can be triggered by any dependency that might be using Instants for any reason.
A solution that is fast _and_ doesn't panic is desirable.
----
closes#84448closes#86470
Apply noundef attribute to &T, &mut T, Box<T>, bool
This doesn't handle `char` because it's a bit awkward to distinguish it from `u32` at this point in codegen.
Note that this _does not_ change whether or not it is UB for `&`, `&mut`, or `Box` to point to undef. It only applies to the pointer itself, not the pointed-to memory.
Fixes (partially) #74378.
r? `@nikic` cc `@RalfJung`
This removes all mutex/atomics based workarounds for non-monotonic clocks and makes the previously panicking methods saturating instead.
Effectively this moves the monotonization from `Instant` construction to the comparisons.
This has some observable effects, especially on platforms without monotonic clocks:
* Incorrectly ordered Instant comparisons no longer panic. This may hide some programming errors until someone actually looks at the resulting `Duration`
* `checked_duration_since` will now return `None` in more cases. Previously it only happened when one compared instants obtained in the wrong order or
manually created ones. Now it also does on backslides.
The upside is reduced complexity and lower overhead of `Instant::now`.
Inherit lifetimes for async fn instead of duplicating them.
The current desugaring of `async fn foo<'a>(&usize) -> &u8` is equivalent to
```rust
fn foo<'a, '0>(&'0 usize) -> foo<'static, 'static>::Opaque<'a, '0, '_>;
type foo<'_a, '_0>::Opaque<'a, '0, '1> = impl Future<Output = &'1 u8>;
```
following the RPIT model.
Duplicating all the inherited lifetime parameters and setting the inherited version to `'static` makes lowering more complex and causes issues like #61949. This PR removes the duplication of inherited lifetimes to directly use
```rust
fn foo<'a, '0>(&'0 usize) -> foo<'a, '0>::Opaque<'_>;
type foo<'a, '0>::Opaque<'1> = impl Future<Output = &'1 u8>;
```
following the TAIT model.
Fixes https://github.com/rust-lang/rust/issues/61949
