Fix invalid `mut T` suggestion for `&mut T` in missing lifetime error
close: rust-lang/rust#150077
When suggesting to return an owned value instead of a borrowed one, the diagnostic was only removing `&` instead of `&mut `, resulting in invalid syntax like `mut T`. This PR fixes the span calculation to properly cover the entire `&mut ` prefix.
remove the explicit error for old `rental` versions
This was converted to a hard error 20 months ago (in rust-lang/rust#125596). This seems like enough time for anyone still using it to notice, so remove the note entirely now.
In comparison, the explicit note for the more impactful `time` breakage was already removed after 6 months (rust-lang/rust#129343).
Closesrust-lang/rust#73933.
Closesrust-lang/rust#83125.
r? @petrochenkov
Rename dep node "fingerprints" to distinguish key and value hashes
In the query system's dependency graph, each node is associated with two *fingerprints*: one that is typically a hash of the query key, and one that is typically a hash of the query's return value when called with that key.
Unfortunately, many identifiers and comments fail to clearly distinguish between these two kinds of fingerprint, which have very different roles in dependency tracking. This is a frequent source of confusion.
This PR therefore tries to establish a clear distinction between:
- **Key fingerprints** that help to uniquely identify a node (along with its `DepKind`), and are typically a hash of the query key
- **Value fingerprints** that help to determine whether a node can be marked green (despite having red dependencies), and are typically a hash of the query value
There should be no change to compiler behaviour.
r? nnethercote (or compiler)
compiler: Don't mark `SingleUseConsts` MIR pass as "required for soundness"
I don't think this MIR pass is required for soundness. The reasons are:
* Something like it was not enabled by default before PR rust-lang/rust#107404 which was the precursor to `SingleUseConsts` (see rust-lang/rust#125910 for the switch).
* By following the advice from https://github.com/rust-lang/rust/pull/128657#discussion_r1705114015 we can conclude it is not required for soundness since it has only ever run on MIR opt level > 0.
* Its [`MirPass::can_be_overridden()`](0ee7d96253/compiler/rustc_mir_transform/src/pass_manager.rs (L98-L102)) is unchanged and thus returns `true`, indicating that it is not a required MIR pass.
* PR CI pass in rust-lang/rust#151426 which stops enabling it by default in non-optimized builds.
As shown in the updated test `tests/mir-opt/optimize_none.rs`, `#[optimize(none)]` functions become even less optimized, as expected and desired.
Unblocks https://github.com/rust-lang/rust/pull/151426.
tail calls: fix copying non-scalar arguments to callee
Alternative to https://github.com/rust-lang/rust/pull/144933: when invoking a tail call with a non-scalar argument, we need to delay freeing the caller's local variables until after the callee is initialized, so that we can copy things from the caller to the callee.
Fixes https://github.com/rust-lang/rust/issues/144820... but as the FIXMEs in the code show, it's not clear to me whether these are the right semantics.
r? @WaffleLapkin
Unify wording of resolve error
Remove "failed to resolve" from the main error message and use the same format we use in other resolution errors "cannot find `name`":
```
error[E0433]: cannot find `nonexistent` in `existent`
--> $DIR/custom_attr_multisegment_error.rs:5:13
|
LL | #[existent::nonexistent]
| ^^^^^^^^^^^ could not find `nonexistent` in `existent`
```
The intent behind this is to end up with all resolve errors eventually be on the form of
```
error[ECODE]: cannot find `{NAME}` in {SCOPE}
--> $DIR/file.rs:5:13
|
LL | #[existent::nonexistent]
| ^^^^^^^^^^^ {SPECIFIC LABEL}
```
A category of errors that is interest are those that involve keywords. For example:
```
error[E0433]: cannot find `Self` in this scope
--> $DIR/issue-97194.rs:2:35
|
LL | fn bget(&self, index: [usize; Self::DIM]) -> bool {
| ^^^^ `Self` is only available in impls, traits, and type definitions
```
and
```
error[E0433]: cannot find `super` in this scope
--> $DIR/keyword-super.rs:2:9
|
LL | let super: isize;
| ^^^^^ there are too many leading `super` keywords
```
For these the label provides the actual help, while the message is less informative beyond telling you "couldn't find `name`".
This is an off-shoot of https://github.com/rust-lang/rust/pull/126810 and https://github.com/rust-lang/rust/pull/128086, a subset of the intended changes there with review comments applied.
r? @petrochenkov
Remove "failed to resolve" and use the same format we use in other resolution errors "cannot find `name`".
```
error[E0433]: cannot find `nonexistent` in `existent`
--> $DIR/custom_attr_multisegment_error.rs:5:13
|
LL | #[existent::nonexistent]
| ^^^^^^^^^^^ could not find `nonexistent` in `existent`
```
remove `#![allow(stable_features)]` from most tests
The only remaining usages are tests that specifically deal with feature gates.
This also deletes the very weird `#![feature(issue_5723_bootstrap)]`, a 13 year old "temporary fix" (rust-lang/rust#5723).
Remove `QueryCtxt` and trait `HasDepContext`
- Follow-up to https://github.com/rust-lang/rust/pull/152636.
- Potentially waiting on https://github.com/rust-lang/rust/pull/152703 to reduce conflicts.
---
With the `QueryContext` trait removed, wrapper struct `QueryCtxt` no longer serves a purpose and can be replaced with `TyCtxt` everywhere.
After that, the only obstacle to removing trait `HasDepContext` is `DepGraph::with_task`, which uses the trait to allow passing both a `TyCtxt` and a query vtable through the context argument. But we can achieve the same result by passing the vtable through the other argument instead, in a tuple alongside the query key.
r? nnethercote
Install LLVM DLL in the right place on Windows
Continuation of https://github.com/rust-lang/rust/pull/151795 towards https://github.com/rust-lang/rust/issues/151774.
Unlike other systems, Windows requires runtime libraries to be present in `PATH` or right next to the binary.
So, we copy the library next to the binary as the easier solution.
Tested building `rust-openssl` in debug and release modes, but the difference is within noise margin.
Revert "Fix an ICE in the vtable iteration for a trait reference"
The ICE fix appears to be unsound, causing a miscompilation involving `dyn Trait` and `async {}` which induces segfaults in safe Rust code. As the patch only hid an ICE, it does not seem worth the risk.
This addresses the problem in rust-lang/rust#152735 but it may still merit team discussion even if this PR is merged.
This reverts commit 8afd63610b, reversing changes made to 19122c03c7.
This struct was only wrapping `TyCtxt` in order to implement traits that
were removed by RUST-152636.
This commit also slightly simplifies the signature of `execute_job_incr`, by
having it call `tcx.dep_graph.data()` internally.
Because:
* Something like it did not exist before PR 107404
* That it is not run our mir-opt-level 0 indicates that it is not
required for soundness
* Its `MirPass::can_be_overridden()` is unchanged and thus returns true,
indicating that it is not a required MIR pass.
* No test fails in PR 151426 that stops enabling by default in non-optimized builds
As can be seen from the updated test `tests/mir-opt/optimize_none.rs`,
this means that `#[optimize(none)]` functions become even less
optimized. As expected and as desired.
Suppress unstable-trait notes under `-Zforce-unstable-if-unmarked`
- Fixes https://github.com/rust-lang/rust/issues/152692.
---
https://github.com/rust-lang/rust/pull/151036 adds extra diagnostic text (“the nightly-only, unstable trait”) to note when a not-implemented trait is unstable.
However, that extra text is usually unhelpful when building a crate graph with `-Zforce-unstable-if-unmarked` (such as the compiler or stdlib), because *any* trait not explicitly marked stable will be treated as unstable.
(For typical compiler contributors using the stage0 compiler, this fix won't take effect until the next bootstrap beta bump.)
Avoid ICE in From/TryFrom diagnostic under -Znext-solver
Fixesrust-lang/rust#152518.
Under `-Znext-solver=globally`, `trait_ref.args` may contain fewer
elements than expected. The diagnostic logic in
`fulfillment_errors.rs` assumed at least two elements and
unconditionally called `type_at(1)`, which could lead to an
index out-of-bounds panic during error reporting.
This change adds a defensive check before accessing the second
argument to avoid the ICE. A UI regression test has been added.
Implement RFC 3678: Final trait methods
Tracking: https://github.com/rust-lang/rust/issues/131179
This PR is based on rust-lang/rust#130802, with some minor changes and conflict resolution.
Futhermore, this PR excludes final methods from the vtable of a dyn Trait.
And some excerpt from the original PR description:
> Implements the surface part of https://github.com/rust-lang/rfcs/pull/3678.
>
> I'm using the word "method" in the title, but in the diagnostics and the feature gate I used "associated function", since that's more accurate.
cc @joshtriplett
The ICE fix appears to be unsound, causing a miscompilation involving
`dyn Trait` and `async {}` which induces segfaults in safe Rust code.
As the patch only hid an ICE, it does not seem worth the risk.
This reverts commit 8afd63610b, reversing
changes made to 19122c03c7.
replace box_new with lower-level intrinsics
The `box_new` intrinsic is super special: during THIR construction it turns into an `ExprKind::Box` (formerly known as the `box` keyword), which then during MIR building turns into a special instruction sequence that invokes the exchange_malloc lang item (which has a name from a different time) and a special MIR statement to represent a shallowly-initialized `Box` (which raises [interesting opsem questions](https://github.com/rust-lang/rust/issues/97270)).
This PR is the n-th attempt to get rid of `box_new`. That's non-trivial because it usually causes a perf regression: replacing `box_new` by naive unsafe code will incur extra copies in debug builds, making the resulting binaries a lot slower, and will generate a lot more MIR, making compilation measurably slower. Furthermore, `vec!` is a macro, so the exact code it expands to is highly relevant for borrow checking, type inference, and temporary scopes.
To avoid those problems, this PR does its best to make the MIR almost exactly the same as what it was before. `box_new` is used in two places, `Box::new` and `vec!`:
- For `Box::new` that is fairly easy: the `move_by_value` intrinsic is basically all we need. However, to avoid the extra copy that would usually be generated for the argument of a function call, we need to special-case this intrinsic during MIR building. That's what the first commit does.
- `vec!` is a lot more tricky. As a macro, its details leak to stable code, so almost every variant I tried broke either type inference or the lifetimes of temporaries in some ui test or ended up accepting unsound code due to the borrow checker not enforcing all the constraints I hoped it would enforce. I ended up with a variant that involves a new intrinsic, `fn write_box_via_move<T>(b: Box<MaybeUninit<T>>, x: T) -> Box<MaybeUninit<T>>`, that writes a value into a `Box<MaybeUninit<T>>` and returns that box again. In exchange we can get rid of somewhat similar code in the lowering for `ExprKind::Box`, and the `exchange_malloc` lang item. (We can also get rid of `Rvalue::ShallowInitBox`; I didn't include that in this PR -- I think @cjgillot has a commit for this somewhere [around here](https://github.com/rust-lang/rust/pull/147862/commits).)
See [here](https://github.com/rust-lang/rust/pull/148190#issuecomment-3457454814) for the latest perf numbers. Most of the regressions are in deep-vector which consists entirely of an invocation of `vec!`, so any change to that macro affects this benchmark disproportionally.
This is my first time even looking at MIR building code, so I am very low confidence in that part of the patch, in particular when it comes to scopes and drops and things like that.
I also had do nerf some clippy tests because clippy gets confused by the new expansion of `vec!` so it makes fewer suggestions when `vec!` is involved.
### `vec!` FAQ
- Why does `write_box_via_move` return the `Box` again? Because we need to expand `vec!` to a bunch of method invocations without any blocks or let-statements, or else the temporary scopes (and type inference) don't work out.
- Why is `box_assume_init_into_vec_unsafe` (unsoundly!) a safe function? Because we can't use an unsafe block in `vec!` as that would necessarily also include the `$x` (due to it all being one big method invocation) and therefore interpret the user's code as being inside `unsafe`, which would be bad (and 10 years later, we still don't have safe blocks for macros like this).
- Why does `write_box_via_move` use `Box` as input/output type, and not, say, raw pointers? Because that is the only way to get the correct behavior when `$x` panics or has control effects: we need the `Box` to be dropped in that case. (As a nice side-effect this also makes the intrinsic safe, which is imported as explained in the previous bullet.)
- Can't we make it safe by having `write_box_via_move` return `Box<T>`? Yes we could, but there's no easy way for the intrinsic to convert its `Box<MaybeUninit<T>>` to a `Box<T>`. Transmuting would be unsound as the borrow checker would no longer properly enforce that lifetimes involved in a `vec!` invocation behave correctly.
- Is this macro truly cursed? Yes, yes it is.
