It's like `Symbol` but for byte strings. The interner is now used for
both `Symbol` and `ByteSymbol`. E.g. if you intern `"dog"` and `b"dog"`
you'll get a `Symbol` and a `ByteSymbol` with the same index and the
characters will only be stored once.
The motivation for this is to eliminate the `Arc`s in `ast::LitKind`, to
make `ast::LitKind` impl `Copy`, and to avoid the need to arena-allocate
`ast::LitKind` in HIR. The latter change reduces peak memory by a
non-trivial amount on literal-heavy benchmarks such as `deep-vector` and
`tuple-stress`.
`Encoder`, `Decoder`, `SpanEncoder`, and `SpanDecoder` all get some
changes so that they can handle normal strings and byte strings.
This change does slow down compilation of programs that use
`include_bytes!` on large files, because the contents of those files are
now interned (hashed). This makes `include_bytes!` more similar to
`include_str!`, though `include_bytes!` contents still aren't escaped,
and hashing is still much cheaper than escaping.
Insert checks for enum discriminants when debug assertions are enabled
Similar to the existing null-pointer and alignment checks, this checks for valid enum discriminants on creation of enums through unsafe transmutes. Essentially this sanitizes patterns like the following:
```rust
let val: MyEnum = unsafe { std::mem::transmute<u32, MyEnum>(42) };
```
An extension of this check will be done in a follow-up that explicitly sanitizes for extern enum values that come into Rust from e.g. C/C++.
This check is similar to Miri's capabilities of checking for valid construction of enum values.
This PR is inspired by saethlin@'s PR
https://github.com/rust-lang/rust/pull/104862. Thank you so much for keeping this code up and the detailed comments!
I also pair-programmed large parts of this together with vabr-g@.
r? `@saethlin`
Similar to the existing nullpointer and alignment checks, this checks
for valid enum discriminants on creation of enums through unsafe
transmutes. Essentially this sanitizes patterns like the following:
```rust
let val: MyEnum = unsafe { std::mem::transmute<u32, MyEnum>(42) };
```
An extension of this check will be done in a follow-up that explicitly
sanitizes for extern enum values that come into Rust from e.g. C/C++.
This check is similar to Miri's capabilities of checking for valid
construction of enum values.
This PR is inspired by saethlin@'s PR
https://github.com/rust-lang/rust/pull/104862. Thank you so much for
keeping this code up and the detailed comments!
I also pair-programmed large parts of this together with vabr-g@.
This centralizes the placeholder type error reporting in one location, but it also exposes the granularity at which we convert things from hir to ty more. E.g. previously infer types in where bounds were errored together with the function signature, but now they are independent.
Introduce the `MetaSized` and `PointeeSized` traits as supertraits of
`Sized` and initially implement it on everything that currently
implements `Sized` to isolate any changes that simply adding the
traits introduces.
Reduce precedence of expressions that have an outer attr
Previously, `-Zunpretty=expanded` would expand this program as follows:
```rust
#![feature(stmt_expr_attributes)]
macro_rules! repro {
($e:expr) => {
#[allow(deprecated)] $e
};
}
#[derive(Default)]
struct Thing {
#[deprecated]
field: i32,
}
fn main() {
let thing = Thing::default();
let _ = repro!(thing).field;
}
```
```rs
#![feature(prelude_import)]
#![feature(stmt_expr_attributes)]
#[prelude_import]
use std::prelude::rust_2021::*;
#[macro_use]
extern crate std;
struct Thing {
#[deprecated]
field: i32,
}
#[automatically_derived]
impl ::core::default::Default for Thing {
#[inline]
fn default() -> Thing {
Thing { field: ::core::default::Default::default() }
}
}
fn main() {
let thing = Thing::default();
let _ = #[allow(deprecated)] thing.field;
}
```
This is not the correct expansion. The correct output would have `(#[allow(deprecated)] thing).field` with the attribute applying only to `thing`, not to `thing.field`.
Add a new `mismatched-lifetime-syntaxes` lint
The lang-team [discussed this](https://hackmd.io/nf4ZUYd7Rp6rq-1svJZSaQ) and I attempted to [summarize](https://github.com/rust-lang/rust/pull/120808#issuecomment-2701863833) their decision. The summary-of-the-summary is:
- Using two different kinds of syntax for elided lifetimes is confusing. In rare cases, it may even [lead to unsound code](https://github.com/rust-lang/rust/issues/48686)! Some examples:
```rust
// Lint will warn about these
fn(v: ContainsLifetime) -> ContainsLifetime<'_>;
fn(&'static u8) -> &u8;
```
- Matching up references with no lifetime syntax, references with anonymous lifetime syntax, and paths with anonymous lifetime syntax is an exception to the simplest possible rule:
```rust
// Lint will not warn about these
fn(&u8) -> &'_ u8;
fn(&'_ u8) -> &u8;
fn(&u8) -> ContainsLifetime<'_>;
```
- Having a lint for consistent syntax of elided lifetimes will make the [future goal](https://github.com/rust-lang/rust/issues/91639) of warning-by-default for paths participating in elision much simpler.
---
This new lint attempts to accomplish the goal of enforcing consistent syntax. In the process, it supersedes and replaces the existing `elided-named-lifetimes` lint, which means it starts out life as warn-by-default.
Rollup of 11 pull requests
Successful merges:
- rust-lang/rust#141890 (Add link to correct documentation in htmldocck.py)
- rust-lang/rust#141932 (Fix for async drop inside async gen fn)
- rust-lang/rust#141960 (Use non-2015 edition paths in tests that do not test for their resolution)
- rust-lang/rust#141968 (Run wfcheck in one big loop instead of per module)
- rust-lang/rust#141969 (Triagebot: Remove `assign.users_on_vacation`)
- rust-lang/rust#141985 (Ensure query keys are printed with reduced queries)
- rust-lang/rust#141999 (Visit the ident in `PreciseCapturingNonLifetimeArg`.)
- rust-lang/rust#142005 (Change `tag_field` to `FieldIdx` in `Variants::Multiple`)
- rust-lang/rust#142017 (Fix incorrect use of "recommend" over "recommended")
- rust-lang/rust#142024 (Don't refer to 'this tail expression' in expansion.)
- rust-lang/rust#142025 (Don't refer to 'local binding' in extern macro.)
r? `@ghost`
`@rustbot` modify labels: rollup
This adds an `iter!` macro that can be used to create movable
generators.
This also adds a yield_expr feature so the `yield` keyword can be used
within iter! macro bodies. This was needed because several unstable
features each need `yield` expressions, so this allows us to stabilize
them separately from any individual feature.
Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de>
Co-authored-by: Jieyou Xu <jieyouxu@outlook.com>
Co-authored-by: Travis Cross <tc@traviscross.com>
Deconstruct values in the THIR visitor
I continue to add deconstruction for task rust-lang/rust#141849
The changes concern a more complex part of the task `compiler/rustc_hir/src/intravisit.rs`
r? `@nnethercote`
Don't declare variables in `ExprKind::Let` in invalid positions
Handle `let` expressions in invalid positions specially during resolve in order to avoid making destructuring-assignment expressions that reference (invalid) variables that have not yet been delcared yet.
See further explanation in test and comment in the source.
Fixesrust-lang/rust#141844
`UsePath` contains a `SmallVec<[Res; 3]>`. This holds up to three `Res`
results, one per namespace (type, value, or macro). `lower_import_res`
takes a `PerNS<Option<Res<NodeId>>>` result and lowers it into the
`SmallVec`. This is pretty weird. The input `PerNS` makes it clear which
`Res` belongs to which namespace, but the `SmallVec` throws that
information away.
And code that operates on the `SmallVec` tends to use iteration (or even
just grabbing the first entry!) without knowing which namespace the
`Res` belongs to. Even weirder! Also, `SmallVec` is an overly flexible
type to use here, because it can contain any number of elements (even
though it's optimized for 3 in this case).
This commit changes `UsePath` so it also contains a
`PerNS<Option<Res<HirId>>>`. This type preserves more information and is
more self-documenting. The commit also changes a lot of the use sites to
access the result for a particular namespace. E.g. if you're looking up
a trait, it will be in the `Res` for the type namespace if it's present;
it's silly to look in the `Res` for the value namespace or macro
namespace. Overall I find the new code much easier to understand.
However, some use sites still iterate. These now use `present_items`
because that filters out the `None` results.
Also, `redundant_pub_crate.rs` gets a bigger change. A
`UseKind:ListStem` item gets no `Res` results, which means the old `all`
call in `is_not_macro_export` would succeed (because `all` succeeds on
an empty iterator) and the `ListStem` would be ignored. This is what we
want, but was more by luck than design. The new code detects `ListStem`
explicitly. The commit generalizes the name of that function
accordingly.
Finally, the commit also removes the `use_path` arena, because
`PerNS<Option<Res>>` impls `Copy` (unlike `SmallVec`) and it can be
allocated in the arena shared by all `Copy` types.
Specifically `TyAlias`, `Enum`, `Struct`, `Union`. So the fields match
the textual order in the source code.
The interesting part of the change is in
`compiler/rustc_hir/src/hir.rs`. The rest is extremely mechanical
refactoring.
All uses have been removed. And it's nonsensical: an identifier by
definition has at least one char.
The commits adds an is-non-empty assertion to `Ident::new` to enforce
this, and converts some `Ident` constructions to use `Ident::new`.
Adding the assertion requires making `Ident::new` and
`Ident::with_dummy_span` non-const, which is no great loss.
The commit amends a couple of places that do path splitting to ensure no
empty identifiers are created.
Remove global `next_disambiguator` state and handle it with a `DisambiguatorState` type
This removes `Definitions.next_disambiguator` as it doesn't guarantee deterministic def paths when `create_def` is called in parallel. Instead a new `DisambiguatorState` type is passed as a mutable reference to `create_def` to help create unique def paths. `create_def` calls with distinct `DisambiguatorState` instances must ensure that that the def paths are unique without its help.
Anon associated types did rely on this global state for uniqueness and are changed to use (method they're defined in + their position in the method return type) as the `DefPathData` to ensure uniqueness. This also means that the method they're defined in appears in error messages, which is nicer.
`DefPathData::NestedStatic` is added to use for nested data inside statics instead of reusing `DefPathData::AnonConst` to avoid conflicts with those.
cc `@oli-obk`
Simplify `LazyAttrTokenStream`
`LazyAttrTokenStream` is an unpleasant type: `Lrc<Box<dyn ToAttrTokenStream>>`. Why does it look like that?
- There are two `ToAttrTokenStream` impls, one for the lazy case, and one for the case where we already have an `AttrTokenStream`.
- The lazy case (`LazyAttrTokenStreamImpl`) is implemented in `rustc_parse`, but `LazyAttrTokenStream` is defined in `rustc_ast`, which does not depend on `rustc_parse`. The use of the trait lets `rustc_ast` implicitly depend on `rustc_parse`. This explains the `dyn`.
- `LazyAttrTokenStream` must have a `size_of` as small as possible, because it's used in many AST nodes. This explains the `Lrc<Box<_>>`, which keeps it to one word. (It's required `Lrc<dyn _>` would be a fat pointer.)
This PR moves `LazyAttrTokenStreamImpl` (and a few other token stream things) from `rustc_parse` to `rustc_ast`. This lets us replace the `ToAttrTokenStream` trait with a two-variant enum and also remove the `Box`, changing `LazyAttrTokenStream` to `Lrc<LazyAttrTokenStreamInner>`. Plus it does a few cleanups.
r? `@petrochenkov`
This commit does the following.
- Changes it from `Lrc<Box<dyn ToAttrTokenStream>>` to
`Lrc<LazyAttrTokenStreamInner>`.
- Reworks `LazyAttrTokenStreamImpl` as `LazyAttrTokenStreamInner`, which
is a two-variant enum.
- Removes the `ToAttrTokenStream` trait and the two impls of it.
The recursion limit must be increased in some crates otherwise rustdoc
aborts.
