Improve `Arc` and `Rc` documentation
This makes two changes (I can split the PR if necessary, but the changes are pretty small):
1. A bunch of trait implementations claimed to be zero cost; however, they use the `Arc<T>: From<Box<T>>` impl which is definitely not free, especially for large dynamically sized `T`.
2. The code in deferred initialization examples unnecessarily used excessive amounts of `unsafe`. This has been reduced.
Improve string concatenation suggestion
Before:
error[E0369]: cannot add `&str` to `&str`
--> file.rs:2:22
|
2 | let _x = "hello" + " world";
| ------- ^ -------- &str
| | |
| | `+` cannot be used to concatenate two `&str` strings
| &str
|
help: `to_owned()` can be used to create an owned `String` from a string reference. String concatenation appends the string on the right to the string on the left and may require reallocation. This requires ownership of the string on the left
|
2 | let _x = "hello".to_owned() + " world";
| ~~~~~~~~~~~~~~~~~~
After:
error[E0369]: cannot add `&str` to `&str`
--> file.rs:2:22
|
2 | let _x = "hello" + " world";
| ------- ^ -------- &str
| | |
| | `+` cannot be used to concatenate two `&str` strings
| &str
|
= note: string concatenation requires an owned `String` on the left
help: create an owned `String` from a string reference
|
2 | let _x = "hello".to_owned() + " world";
| +++++++++++
Improve error message for key="value" cfg arguments.
Hi, I ran into difficulties using the `--cfg` flag syntax, first hit when googling for the error was issue https://github.com/rust-lang/rust/issues/66450. Reading that issue, it sounded like the best way to improve the experience was to improve the error message, this is low risk and doesn't introduce any additional argument parsing.
The issue mentions that it is entirely dependent on the shell, while this may be true, I think guiding the the user into the realization that the quotes may need to be escaped is helpful. The two suggested escapings both work in Bash and in the Windows command prompt.
fyi `@ehuss`
Ensure that early-bound function lifetimes are always 'local'
During borrowchecking, we treat any free (early-bound) regions on
the 'defining type' as `RegionClassification::External`. According
to the doc comments, we should only have 'external' regions when
checking a closure/generator.
However, a plain function can also have some if its regions
be considered 'early bound' - this occurs when the region is
constrained by an argument, appears in a `where` clause, or
in an opaque type. This was causing us to incorrectly mark these
regions as 'external', which caused some diagnostic code
to act as if we were referring to a 'parent' region from inside
a closure.
This PR marks all instantiated region variables as 'local'
when we're borrow-checking something other than a
closure/generator/inline-const.
Add more granular `--exclude` in `x.py`
x.py has support for excluding some steps from the current invocation, but unfortunately that's not granular enough: some steps have the same name in different modules, and that prevents excluding only *some* of them.
As a practical example, let's say you need to run everything in `./x.py test` except for the standard library tests, as those tests require IPv6 and need to be executed on a separate machine. Before this commit, if you were to just run this:
./x.py test --exclude library/std
...the invocation would eventually fail, as that would not only exclude running the tests for the standard library (`library/std` in the `test` module), it would also exclude generating its documentation (`library/std` in the `doc` module), breaking linkchecker.
This commit adds support to the `--exclude` flag for prefixing paths with the name of the module their step is defined in, allowing the user to choose which module to exclude from:
./x.py test --exclude test::library/std
This maintains backward compatibility with existing invocations, while allowing more ganular exclusion. Examples of the behavior:
| `--exclude` | Docs | Tests |
| ------------------- | ------- | ------- |
| `library/std` | Skipped | Skipped |
| `doc::library/std` | Skipped | Run |
| `test::library/std` | Run | Skipped |
Note that this PR only changes the `--exclude` flag, and not in other `x.py` arguments or flags yet.
In the implementation I tried to limit the impact this would have with rustbuild as a whole as much as possible. The module name is extracted from the step by parsing the result of `std::any::type_name()`: unfortunately that output can change at any point in time, but IMO it's better than having to annotate all the existing and future `Step` implementations with the module name. I added a test to ensure the parsing works as expected, so hopefully if anyone makes changes to the output of `std::any::type_name()` they'll also notice they have to update rustbuild.
r? `@Mark-Simulacrum`
Update some rustc dependencies to deduplicate them
This PR updates `rand` and `itertools` in rustc (not the whole workspace) in order to deduplicate them (and hopefully slightly improve compile times).
~~Currently, `object` is still duplicated, but https://github.com/rust-lang/thorin/pull/15 and updating `thorin` in the future will remove the use of version 0.27.~~ Update: Thorin 0.2 has now been released, and this PR updates `rustc_codegen_ssa` to use it and deduplicate the `object` crate.
There's a final tiny rustc dependency, `cfg-if`, which will be left: as both versions 0.1.x and 1.0 looked to be heavily depended on, they will require a few cascading updates to be removed.
x.py has support for excluding some steps from the invocation, but
unfortunately that's not granular enough: some steps have the same name
in different modules, and that prevents excluding only *some* of them.
As a practical example, let's say you need to run everything in `./x.py
test` except for the standard library tests, as those tests require IPv6
and need to be executed on a separate machine. Before this commit, if
you were to just run this:
./x.py test --exclude library/std
...the execution would fail, as that would not only exclude running the
tests for the standard library, it would also exclude generating its
documentation (breaking linkchecker).
This commit adds support for an optional module annotation in --exclude
paths, allowing the user to choose which module to exclude from:
./x.py test --exclude test::library/std
This maintains backward compatibility, but also allows for more ganular
exclusion. More examples on how this works:
| `--exclude` | Docs | Tests |
| ------------------- | ------- | ------- |
| `library/std` | Skipped | Skipped |
| `doc::library/std` | Skipped | Run |
| `test::library/std` | Run | Skipped |
Note that the new behavior only works in the `--exclude` flag, and not
in other x.py arguments or flags yet.
Rollup of 17 pull requests
Successful merges:
- #91032 (Introduce drop range tracking to generator interior analysis)
- #92856 (Exclude "test" from doc_auto_cfg)
- #92860 (Fix errors on blanket impls by ignoring the children of generated impls)
- #93038 (Fix star handling in block doc comments)
- #93061 (Only suggest adding `!` to expressions that can be macro invocation)
- #93067 (rustdoc mobile: fix scroll offset when jumping to internal id)
- #93086 (Add tests to ensure that `let_chains` works with `if_let_guard`)
- #93087 (Fix src/test/run-make/raw-dylib-alt-calling-convention)
- #93091 (⬆ chalk to 0.76.0)
- #93094 (src/test/rustdoc-json: Check for `struct_field`s in `variant_tuple_struct.rs`)
- #93098 (Show a more informative panic message when `DefPathHash` does not exist)
- #93099 (rustdoc: auto create output directory when "--output-format json")
- #93102 (Pretty printer algorithm revamp step 3)
- #93104 (Support --bless for pp-exact pretty printer tests)
- #93114 (update comment for `ensure_monomorphic_enough`)
- #93128 (Add script to prevent point releases with same number as existing ones)
- #93136 (Backport the 1.58.1 release notes to master)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Add script to prevent point releases with same number as existing ones
This will hopefully prevent what happened today with #93110 and #93121, where we built point release artifacts without changing version numbers, thus requiring another PR to change the version number.
r? `@Mark-Simulacrum`
Support --bless for pp-exact pretty printer tests
I ran into this while working on the stack of PRs containing #93102. `x.py test src/test/pretty --bless` previously would `fatal` instead of blessing the input files.
Tested by making a silly pretty-printer tweak and running the above command: 98823c3929ebfe796786345c5ee713f63317d9c6
Pretty printer algorithm revamp step 3
This PR follows #93065 as a third chunk of minor modernizations backported from https://github.com/dtolnay/prettyplease into rustc_ast_pretty.
I've broken this up into atomic commits that hopefully are sensible in isolation. At every commit, the pretty printer is compilable and has runtime behavior that is identical to before and after the PR. None of the refactoring so far changes behavior.
This PR is the last chunk of non-behavior-changing cleanup. After this the **next PR** will begin backporting behavior changes from `prettyplease`, starting with block indentation:
```rust
macro_rules! print_expr {
($expr:expr) => {
println!("{}", stringify!($expr));
};
}
fn main() {
print_expr!(Struct { x: 0, y: 0 });
print_expr!(Structtttttttttttttttttttttttttttttttttttttttttttttttttt { xxxxxxxxx: 0, yyyyyyyyy: 0 });
}
```
Output currently on master (nowhere near modern Rust style):
```console
Struct{x: 0, y: 0,}
Structtttttttttttttttttttttttttttttttttttttttttttttttttt{xxxxxxxxx: 0,
yyyyyyyyy: 0,}
```
After the upcoming PR for block indentation (based on 401d60c042):
```console
Struct { x: 0, y: 0, }
Structtttttttttttttttttttttttttttttttttttttttttttttttttt {
xxxxxxxxx: 0,
yyyyyyyyy: 0,
}
```
And the PR after that, for intelligent trailing commas (based on e2a0297f17):
```console
Struct { x: 0, y: 0 }
Structtttttttttttttttttttttttttttttttttttttttttttttttttt {
xxxxxxxxx: 0,
yyyyyyyyy: 0,
}
```
rustdoc: auto create output directory when "--output-format json"
This PR allows rustdoc to automatically create output directory in case it does not exist (when run with `--output-format json`).
This fixes rustdoc crash:
````
$ rustdoc --output-format json -Z unstable-options src/main.rs
error: couldn't generate documentation: No such file or directory (os error 2)
|
= note: failed to create or modify "doc/main.json"
error: aborting due to previous error
````
With this fix behavior of `rustdoc --output-format json` becomes consistent with `rustdoc --output-format html` (which already auto-creates output directory if it's missing)
Show a more informative panic message when `DefPathHash` does not exist
This should hopefully make it easier to debug incremental compilation
bugs like #93096 without affecting performance.
src/test/rustdoc-json: Check for `struct_field`s in `variant_tuple_struct.rs`
The presence of `struct_field`s is being checked for already in
`variant_struct.rs`. We should also check for them in `variant_tuple_struct.rs`.
This PR is one small step towards resolving #92945.
Fix src/test/run-make/raw-dylib-alt-calling-convention
Fix the test headers so that the test now runs on all intended platforms; it is currently ignored on all platforms because the headers are incorrect. Also comment out a couple of function calls that fail because of an unrelated problem, described in issue #91167.
Add tests to ensure that `let_chains` works with `if_let_guard`
The current machinery already makes such combination possible but lacks tests.
cc `@matthewjasper`
rustdoc mobile: fix scroll offset when jumping to internal id
Followup to #92692. The semantics of `scroll-margin-top` are a little surprising - the attribute needs to be applied to the element that gets scrolled into the viewport, not the scrolling element.
This fixes an issue where clicking on a method (or other item) from the sidebar takes you to a scroll position where the topbar covers up the method name.
I'm interested in ideas for how to test this with browser-ui-test, but I think it doesn't yet have what I need. What I need is an assert that `<element>.getBoundingClientRect().y` is > 45.
Demo: https://rustdoc.crud.net/jsha/fix-scroll-padding-top/std/string/struct.String.html#method.extend_from_within
r? `@GuillaumeGomez`
Fix star handling in block doc comments
Fixes#92872.
Some extra explanation about this PR and why https://github.com/rust-lang/rust/pull/92357 created this regression: when we merge doc comment kinds for example in:
```rust
/// he
/**
* hello
*/
#[doc = "boom"]
```
We don't want to remove the empty lines between them. However, to correctly compute the "horizontal trim", we still need it, so instead, I put back a part of the "vertical trim" directly in the "horizontal trim" computation so it doesn't impact the output buffer but allows us to correctly handle the stars.
r? ``@camelid``
Fix errors on blanket impls by ignoring the children of generated impls
Related to #83718
We can safely skip the children, as they don't contain any new info, and may be subtly different for reasons hard to track down, in ways that are consistently worse than the actual generic impl.
Introduce drop range tracking to generator interior analysis
This PR addresses cases such as this one from #57478:
```rust
struct Foo;
impl !Send for Foo {}
let _: impl Send = || {
let guard = Foo;
drop(guard);
yield;
};
```
Previously, the `generator_interior` pass would unnecessarily include the type `Foo` in the generator because it was not aware of the behavior of `drop`. We fix this issue by introducing a drop range analysis that finds portions of the code where a value is guaranteed to be dropped. If a value is dropped at all suspend points, then it is no longer included in the generator type. Note that we are using "dropped" in a generic sense to include any case in which a value has been moved. That is, we do not only look at calls to the `drop` function.
There are several phases to the drop tracking algorithm, and we'll go into more detail below.
1. Use `ExprUseVisitor` to find values that are consumed and borrowed.
2. `DropRangeVisitor` uses consume and borrow information to gather drop and reinitialization events, as well as build a control flow graph.
3. We then propagate drop and reinitialization information through the CFG until we reach a fix point (see `DropRanges::propagate_to_fixpoint`).
4. When recording a type (see `InteriorVisitor::record`), we check the computed drop ranges to see if that value is definitely dropped at the suspend point. If so, we skip including it in the type.
## 1. Use `ExprUseVisitor` to find values that are consumed and borrowed.
We use `ExprUseVisitor` to identify the places where values are consumed. We track both the `hir_id` of the value, and the `hir_id` of the expression that consumes it. For example, in the expression `[Foo]`, the `Foo` is consumed by the array expression, so after the array expression we can consider the `Foo` temporary to be dropped.
In this process, we also collect values that are borrowed. The reason is that the MIR transform for generators conservatively assumes anything borrowed is live across a suspend point (see `rustc_mir_transform::generator::locals_live_across_suspend_points`). We match this behavior here as well.
## 2. Gather drop events, reinitialization events, and control flow graph
After finding the values of interest, we perform a post-order traversal over the HIR tree to find the points where these values are dropped or reinitialized. We use the post-order index of each event because this is how the existing generator interior analysis refers to the position of suspend points and the scopes of variables.
During this traversal, we also record branching and merging information to handle control flow constructs such as `if`, `match`, and `loop`. This is necessary because values may be dropped along some control flow paths but not others.
## 3. Iterate to fixed point
The previous pass found the interesting events and locations, but now we need to find the actual ranges where things are dropped. Upon entry, we have a list of nodes ordered by their position in the post-order traversal. Each node has a set of successors. For each node we additionally keep a bitfield with one bit per potentially consumed value. The bit is set if we the value is dropped along all paths entering this node.
To compute the drop information, we first reverse the successor edges to find each node's predecessors. Then we iterate through each node, and for each node we set its dropped value bitfield to the intersection of all incoming dropped value bitfields.
If any bitfield for any node changes, we re-run the propagation loop again.
## 4. Ignore dropped values across suspend points
At this point we have a data structure where we can ask whether a value is guaranteed to be dropped at any post order index for the HIR tree. We use this information in `InteriorVisitor` to check whether a value in question is dropped at a particular suspend point. If it is, we do not include that value's type in the generator type.
Note that we had to augment the region scope tree to include all yields in scope, rather than just the last one as we did before.
r? `@nikomatsakis`
Rollup of 13 pull requests
Successful merges:
- #89747 (Add MaybeUninit::(slice_)as_bytes(_mut))
- #89764 (Fix variant index / discriminant confusion in uninhabited enum branching)
- #91606 (Stabilize `-Z print-link-args` as `--print link-args`)
- #91694 (rustdoc: decouple stability and const-stability)
- #92183 (Point at correct argument when async fn output type lifetime disagrees with signature)
- #92582 (improve `_` constants in item signature handling)
- #92680 (intra-doc: Use the impl's assoc item where possible)
- #92704 (Change lint message to be stronger for &T -> &mut T transmute)
- #92861 (Rustdoc mobile: put out-of-band info on its own line)
- #92992 (Help optimize out backtraces when disabled)
- #93038 (Fix star handling in block doc comments)
- #93108 (⬆️ rust-analyzer)
- #93112 (Fix CVE-2022-21658)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Fix star handling in block doc comments
Fixes#92872.
Some extra explanation about this PR and why https://github.com/rust-lang/rust/pull/92357 created this regression: when we merge doc comment kinds for example in:
```rust
/// he
/**
* hello
*/
#[doc = "boom"]
```
We don't want to remove the empty lines between them. However, to correctly compute the "horizontal trim", we still need it, so instead, I put back a part of the "vertical trim" directly in the "horizontal trim" computation so it doesn't impact the output buffer but allows us to correctly handle the stars.
r? `@camelid`
Help optimize out backtraces when disabled
The comment in `rust_backtrace_env` says:
> // If the `backtrace` feature of this crate isn't enabled quickly return
> // `None` so this can be constant propagated all over the place to turn
> // optimize away callers.
but this optimization has regressed, because the only caller of this function had an alternative path that unconditionally (and pointlessly) asked for a full backtrace, so the disabled state couldn't propagate.
I've added a getter for the full format that respects the feature flag, so that the caller will now be able to really optimize out the disabled backtrace path. I've also made `rust_backtrace_env` trivially inlineable when backtraces are disabled.
Rustdoc mobile: put out-of-band info on its own line
Before this, the item name and the stability, source link, and "collapse
all docs" would compete for room on a single line, resulting in awkward
wrapping behavior on mobile. This gives a separate line for that
out-of-band information. It also removes the "copy path" icon on mobile
to make a little more room.
Demo: https://rustdoc.crud.net/jsha/mobile-column-flex/std/string/struct.String.html
r? `@GuillaumeGomez`
Change lint message to be stronger for &T -> &mut T transmute
The old message implied that it's only UB if you use the reference to mutate, which (as far as I know) is not true. As in, the following program has UB, and a &T -> &mut T transmute is effectively an `unreachable_unchecked`.
```rust
fn main() {
#[allow(mutable_transmutes)]
unsafe {
let _ = std::mem::transmute::<&i32, &mut i32>(&0);
}
}
```
In the future, it might be a good idea to use the edition system to make this a hard error, since I don't think it is *ever* defined behaviour? Unless we rule that `&UnsafeCell<i32> -> &mut i32` is fine. (That, and you always could just use `.get()`, so you're not losing anything)
intra-doc: Use the impl's assoc item where possible
Before, the trait's associated item would be used. Now, the impl's
associated item is used. The only exception is for impls that use
default values for associated items set by the trait. In that case,
the trait's associated item is still used.
As an example of the old and new behavior, take this code:
trait MyTrait {
type AssocTy;
}
impl MyTrait for String {
type AssocTy = u8;
}
Before, when resolving a link to `String::AssocTy`,
`resolve_associated_trait_item` would return the associated item for
`MyTrait::AssocTy`. Now, it would return the associated item for
`<String as MyTrait>::AssocTy`, as it claims in its docs.
r? `@petrochenkov`
improve `_` constants in item signature handling
removing the "type" from the error messages does slightly worsen the error messages for types, but figuring out whether the placeholder is for a type or a constant and correctly dealing with that seemed fairly difficult to me so I took the easy way out ✨ Imo the error message is still clear enough.
r? `@BoxyUwU` cc `@estebank`
Point at correct argument when async fn output type lifetime disagrees with signature
Fixes most of #74256.
## Problems fixed
This PR fixes a couple of related problems in the error reporting code.
### Highlighting the wrong argument
First, the error reporting code was looking at the desugared return type of an `async fn` to decide which parameter to highlight. For example, a function like
```rust
async fn async_fn(self: &Struct, f: &u32) -> &u32
{ f }
```
desugars to
```rust
async fn async_fn<'a, 'b>(self: &'a Struct, f: &'b u32)
-> impl Future<Output = &'a u32> + 'a + 'b
{ f }
```
Since `f: &'b u32` is returned but the output type is `&'a u32`, the error would occur when checking that `'a: 'b`.
The reporting code would look to see if the "offending" lifetime `'b` was included in the return type, and because the code was looking at the desugared future type, it was included. So it defaulted to reporting that the source of the other lifetime `'a` (the `self` type) was the problem, when it was really the type of `f`. (Note that if it had chosen instead to look at `'a` first, it too would have been included in the output type, and it would have arbitrarily reported the error (correctly this time) on the type of `f`.)
Looking at the actual future type isn't useful for this reason; it captures all input lifetimes. Using the written return type for `async fn` solves this problem and results in less confusing error messages for the user.
This isn't a perfect fix, unfortunately; writing the "manually desugared" form of the above function still results in the wrong parameter being highlighted. Looking at the output type of every `impl Future` return type doesn't feel like a very principled approach, though it might work. The problem would remain for function signatures that look like the desugared one above but use different traits. There may be deeper changes required to pinpoint which part of each type is conflicting.
### Lying about await point capture causing lifetime conflicts
The second issue fixed by this PR is the unnecessary complexity in `try_report_anon_anon_conflict`. It turns out that the root cause I suggested in https://github.com/rust-lang/rust/issues/76547#issuecomment-692863608 wasn't really the root cause. Adding special handling to report that a variable was captured over an await point only made the error messages less correct and pointed to a problem other than the one that actually occurred.
Given the above discussion, it's easy to see why: `async fn`s capture all input lifetimes in their return type, so holding an argument across an await point should never cause a lifetime conflict! Removing the special handling simplified the code and improved the error messages (though they still aren't very good!)
## Future work
* Fix error reporting on the "desugared" form of this code
* Get the `suggest_adding_lifetime_params` suggestion firing on these examples
* cc #42703, I think
r? `@estebank`
rustdoc: decouple stability and const-stability
This PR tweaks the stability rendering code to consider stability and const-stability separately. This fixes two issues:
- Stabilities that match the enclosing item are now always omitted, even if the item has const-stability as well (#90552)
- Const-stable unstable functions will now have their (const-) stability rendered.
Fixes#90552.
