require full validity when determining the discriminant of a value
This resolves (for now) the semantic question that came up in https://github.com/rust-lang/rust/pull/89764: arguably, reading the discriminant of a value is 'using' that value, so we are in our right to demand full validity. Reading a discriminant is somewhat special in that it works for values of *arbitrary* type; all the other primitive MIR operations work on specific types (e.g. `bool` or an integer) and basically implicitly require validity as part of just "doing their job".
The alternative would be to just require that the discriminant itself is valid, if any -- but then what do we do for types that do not have a discriminant, which kind of validity do we check? [This code](81117ff930/compiler/rustc_codegen_ssa/src/mir/place.rs (L206-L215)) means we have to at least reject uninhabited types, but I would rather not special case that.
I don't think this can be tested in CTFE (since validity is not enforced there), I will add a compile-fail test to Miri:
```rust
#[allow(enum_intrinsics_non_enums)]
fn main() {
let i = 2u8;
std::mem::discriminant(unsafe { &*(&i as *const _ as *const bool) }); // UB
}
```
(I tried running the check even on the CTFE machines, but then it runs during ConstProp and that causes all sorts of problems. We could run it for ConstEval but not ConstProp, but that simply does not seem worth the effort currently.)
r? ``@oli-obk``
This function parameter attribute was introduced in https://github.com/rust-lang/rust/pull/44866 as an intermediate step in implementing `impl Trait`, it's not necessary or used anywhere by itself.
Improve ManuallyDrop suggestion
closes https://github.com/rust-lang/rust/issues/90585
* Fixes the recommended change to use ManuallyDrop as per the issue
* Changes the note to a help
* improves the span so it only points at the type.
Remove workaround for the forward progress handling in LLVM
this workaround was only needed for LLVM < 12 and the minimum LLVM version was updated to 12 in #90175
Fix span for non-satisfied trivial trait bounds
The spans for "trait bound not satisfied" errors in trivial trait bounds referenced the entire item (fn, impl, struct) before.
Now they only reference the obligation itself (`String: Copy`)
Address #90869
Print escaped string if char literal has multiple characters, but only one printable character
Fixes#90857
I'm not sure about the error message here, it could get rather long and *maybe* using the names of characters would be better? That wouldn't help the length any, though.
Improve diagnostics when a static lifetime is expected
Makes progress towards https://github.com/rust-lang/rust/issues/90600
The diagnostics here were previously entirely removed due to giving a misleading suggestion but if we instead provide an informative label in that same location it should better help the user understand the situation.
I included the example from the issue as it demonstrates an area where the diagnostics are still lacking.
Happy to remove that if its just adding noise atm.
warn on must_use use on async fn's
As referenced in #78149
This only works on `async` fn's for now, I can also look into if I can get `Box<dyn Future>` and `impl Future` working at this level (hir)
Alphabetize language features
This should significantly reduce the frequency of merge conflicts.
r? ````@joshtriplett````
````@rustbot```` label: +A-contributor-roadblock +S-waiting-on-review
Fix await suggestion on non-future type
Remove a match block that would suggest to add `.await` in the case where the expected type's `Future::Output` equals the found type. We only want to suggest `.await`ing in the opposite case (the found type's `Future::Output` equals the expected type).
The code sample is here: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=6ba6b83d4dddda263553b79dca9f6bcb
Before:
```
➜ ~ rustc --edition=2021 --crate-type=lib test.rs
error[E0308]: `match` arms have incompatible types
--> test.rs:4:14
|
2 | let x = match 1 {
| _____________-
3 | | 1 => other(),
| | ------- this is found to be of type `impl Future`
4 | | 2 => other().await,
| | ^^^^^^^^^^^^^ expected opaque type, found enum `Result`
5 | | };
| |_____- `match` arms have incompatible types
|
= note: expected type `impl Future`
found enum `Result<(), ()>`
help: consider `await`ing on the `Future`
|
4 | 2 => other().await.await,
| ++++++
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
```
After:
```
➜ ~ rustc +stage1 --edition=2021 --crate-type=lib test.rs
error[E0308]: `match` arms have incompatible types
--> test.rs:4:14
|
2 | let x = match 1 {
| _____________-
3 | | 1 => other(),
| | ------- this is found to be of type `impl Future`
4 | | 2 => other().await,
| | ^^^^^^^^^^^^^ expected opaque type, found enum `Result`
5 | | };
| |_____- `match` arms have incompatible types
|
= note: expected type `impl Future`
found enum `Result<(), ()>`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
```
Fixes#90931
Remove `DropArena`.
Most arena-allocate types that impl `Drop` get their own `TypedArena`, but a
few infrequently used ones share a `DropArena`. This sharing adds complexity
but doesn't help performance or memory usage. Perhaps it was more effective in
the past prior to some other improvements to arenas.
This commit removes `DropArena` and the sharing of arenas via the `few`
attribute of the `arena_types` macro. This change removes over 100 lines of
code and nine uses of `unsafe` (one of which affects the parallel compiler) and
makes the remaining code easier to read.
Rollup of 8 pull requests
Successful merges:
- #86455 (check where-clause for explicit `Sized` before suggesting `?Sized`)
- #90801 (Normalize both arguments of `equate_normalized_input_or_output`)
- #90803 (Suggest `&str.chars()` on attempt to `&str.iter()`)
- #90819 (Fixes incorrect handling of TraitRefs when emitting suggestions.)
- #90910 (fix getting the discriminant of a zero-variant enum)
- #90925 (rustc_mir_build: reorder bindings)
- #90928 (Use a different server for checking clock drift)
- #90936 (Add a regression test for #80772)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
rustc_mir_build: reorder bindings
No functional changes intended.
I'm playing around with building compiler components using nightly rust
(2021-11-02) in a non-standard way. I encountered the following error while
trying to build rustc_mir_build:
```
error[E0597]: `wildcard` does not live long enough
--> rust/src/nightly/compiler/rustc_mir_build/src/build/matches/mod.rs:1767:82
|
1767 | let mut otherwise_candidate = Candidate::new(expr_place_builder.clone(), &wildcard, false);
| ^^^^^^^^^ borrowed value does not live long enough
...
1799 | }
| -
| |
| `wildcard` dropped here while still borrowed
| borrow might be used here, when `guard_candidate` is dropped and runs the destructor for type `Candidate<'_, '_>`
|
= note: values in a scope are dropped in the opposite order they are defined
```
I believe this flags an issue that may become an error in the future.
Swapping the order of `wildcard` and `guard_candidate` resolves it.
Fixes incorrect handling of TraitRefs when emitting suggestions.
Closes#90804 , although there were more issues here that were hidden by the thing that caused this ICE.
Underlying problem was that substitutions were being thrown out, which not only leads to an ICE but also incorrect diagnostics. On top of that, in some cases the self types from the root obligations were being mixed in with those from derived obligations.
This makes a couple diagnostics arguable worse ("`B<C>` does not implement `Copy`" instead of "`C` does not implement `Copy`") but the worse diagnostics are at least still correct and that downside is in my opinion clearly outweighed by the benefits of fixing the ICE and unambiguously wrong diagnostics.
check where-clause for explicit `Sized` before suggesting `?Sized`
Fixes#85945.
Based on #86454.
``@rustbot`` label +A-diagnostics +A-traits +A-typesystem +D-papercut +T-compiler
Address performance regression introduced by #90218
As part of the changes in #90218 , the `adt_drop_tys` and friends code stopped recursing through the query system, meaning that intermediate computations did not get cached. This change adds the recursions back in without re-introducing any of the old issues.
On local benchmarks this fixes the 5% regressions in #90504 ; the wg-grammar regressions didn't seem to move too much. I may take some time later to look into those.
Not sure who to request for review here, so will leave it up to whoever gets it.
Android is not GNU
For a long time, the Android targets had `target_env=""`, but this changed to `"gnu"` in Rust 1.49.0. I tracked this down to #77729 which started setting `"gnu"` in the `linux_base` target options, and this was inherited by `android_base`. Then #78929 split the env into `linux_gnu_base`, but `android_base` was also changed to follow that. Android was not specifically mentioned in either pull request, so I believe this was an accident. Moving it back to `linux_base` will use an empty `env` again.
r? ````@Mark-Simulacrum````
cc ````@petrochenkov````
Assoc item cleanup Part 2
- Remove `AssocItem` from `RegionVariableOrigin::AutoRef`
- Use the `associated_item_def_ids` query instead of the `associated_items` query when possible
The change to `ObligationCauseCode` from #90639 is omitted because it caused a perf regression.
r? `@cjgillot`
stabilize format args capture
Works as expected, and there are widespread reports of success with it, as well as interest in it.
RFC: rust-lang/rfcs#2795
Tracking issue: https://github.com/rust-lang/rust/issues/67984
Addressing items from the tracking issue:
- We don't support capturing arguments from a non-literal format string like `format_args!(concat!(...))`. We could add that in a future enhancement, or we can decide that it isn't supported (as suggested in https://github.com/rust-lang/rust/issues/67984#issuecomment-801394736 ).
- I've updated the documentation.
- `panic!` now supports capture as well.
- There are potentially opportunities to further improve diagnostics for invalid usage, such as if it looks like the user tried to use an expression rather than a variable. However, such cases are all already caught and provide reasonable syntax errors now, and we can always provided even friendlier diagnostics in the future.
No functional changes intended.
I'm playing around with building compiler components using nightly rust
(2021-11-02) in a non-standard way. I encountered the following error while
trying to build rustc_mir_build:
```
error[E0597]: `wildcard` does not live long enough
--> rust/src/nightly/compiler/rustc_mir_build/src/build/matches/mod.rs:1767:82
|
1767 | let mut otherwise_candidate = Candidate::new(expr_place_builder.clone(), &wildcard, false);
| ^^^^^^^^^ borrowed value does not live long enough
...
1799 | }
| -
| |
| `wildcard` dropped here while still borrowed
| borrow might be used here, when `guard_candidate` is dropped and runs the destructor for type `Candidate<'_, '_>`
|
= note: values in a scope are dropped in the opposite order they are defined
```
I believe this flags an issue that may become an error in the future.
Swapping the order of `wildcard` and `guard_candidate` resolves it.
Fix ld64 flags
- The `-exported_symbols_list` argument appears to be malformed for `ld64` (if you are not going through `clang`).
- The `-dynamiclib` argument isn't support for `ld64`. It should be guarded behind a compiler flag.
These problems are fixed by these changes. I have also refactored the way linker arguments are generated to be ld/compiler agnostic and therefore less error prone.
These changes are necessary to support cross-compilation to darwin targets.
Leave -Z strip available temporarily as an alias, to avoid breaking
cargo until cargo transitions to using -C strip. (If the user passes
both, the -C version wins.)
Tweak the `options!` macro to allow for -Z and -C options with the same
name without generating conflicting internal parsing functions.
Split out of the commit stabilizing -Z strip as -C strip.
Most arena-allocate types that impl `Drop` get their own `TypedArena`, but a
few infrequently used ones share a `DropArena`. This sharing adds complexity
but doesn't help performance or memory usage. Perhaps it was more effective in
the past prior to some other improvements to arenas.
This commit removes `DropArena` and the sharing of arenas via the `few`
attribute of the `arena_types` macro. This change removes over 100 lines of
code and nine uses of `unsafe` (one of which affects the parallel compiler) and
makes the remaining code easier to read.
Implement diagnostic for String conversion
This is my first real contribution to rustc, any feedback is highly appreciated.
This should fix https://github.com/rust-lang/rust/issues/89856
Thanks to `@estebank` for guiding me.
check if `String` or `&String` or `&str`
Update compiler/rustc_typeck/src/check/method/suggest.rs
Co-authored-by: Esteban Kuber <estebank@users.noreply.github.com>
remove some trailing whitespace
