mirror
/
rustc-dev-guide
mirror of https://github.com/rust-lang/rustc-dev-guide.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #19954 from lnicola/sync-from-rust 

minor: Sync from downstream
This commit is contained in:
Laurențiu Nicola 2025-06-09 12:55:47 +00:00 committed by GitHub
parent 968c5b5b8d a1f2e0c345
commit 92f36d9dae
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
37 changed files with 394 additions and 283 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
.mailmap
View File

@ -3,3 +3,4 @@ Jynn Nelson <github@jyn.dev> <joshua@yottadb.com>
Jynn Nelson <github@jyn.dev> <jyn.nelson@redjack.com>
Jynn Nelson <github@jyn.dev> <jnelson@cloudflare.com>
Jynn Nelson <github@jyn.dev>
Tshepang Mbambo <hopsi@tuta.io> <tshepang@gmail.com>

2
rust-version
View File

@ -1 +1 @@
414482f6a0d4e7290f614300581a0b55442552a3
c68032fd4c442d275f4daa571ba19c076106b490

2
src/SUMMARY.md
View File

@ -134,9 +134,9 @@
- [Command-line arguments](./cli.md)
- [rustc_driver and rustc_interface](./rustc-driver/intro.md)
- [Remarks on perma-unstable features](./rustc-driver/remarks-on-perma-unstable-features.md)
- [Example: Type checking](./rustc-driver/interacting-with-the-ast.md)
- [Example: Getting diagnostics](./rustc-driver/getting-diagnostics.md)
- [Remarks on perma-unstable features](./rustc-driver/remarks-on-perma-unstable-features.md)
- [Errors and lints](diagnostics.md)
- [Diagnostic and subdiagnostic structs](./diagnostics/diagnostic-structs.md)
- [Translation](./diagnostics/translation.md)

1
src/appendix/compiler-lecture.md
View File

@ -46,3 +46,4 @@ These are videos where various experts explain different parts of the compiler:
## Code Generation
- [January 2019: Cranelift](https://www.youtube.com/watch?v=9OIA7DTFQWU)
- [December 2024: LLVM Developers' Meeting - Rust ❤️ LLVM](https://www.youtube.com/watch?v=Kqz-umsAnk8)

2
src/autodiff/flags.md
View File

@ -16,7 +16,9 @@ LooseTypes // Risk incorrect derivatives instead of aborting when missing Type I
```
<div class="warning">
`LooseTypes` is often helpful to get rid of Enzyme errors stating `Can not deduce type of <X>` and to be able to run some code. But please keep in mind that this flag absolutely has the chance to cause incorrect gradients. Even worse, the gradients might be correct for certain input values, but not for others. So please create issues about such bugs and only use this flag temporarily while you wait for your bug to be fixed.
</div>
### Benchmark flags

27
src/backend/libs-and-metadata.md
View File

@ -28,8 +28,8 @@ format is specific to `rustc`, and may change over time. This file contains:
[`-C embed-bitcode=no`][embed-bitcode] CLI option to improve compile times
and reduce disk space if LTO is not needed.
* `rustc` [metadata], in a file named `lib.rmeta`.
* A symbol table, which is generally a list of symbols with offsets to the
object file that contain that symbol. This is pretty standard for archive
* A symbol table, which is essentially a list of symbols with offsets to the
object files that contain that symbol. This is pretty standard for archive
files.
[archive file]: https://en.wikipedia.org/wiki/Ar_(Unix)
@ -46,12 +46,11 @@ A `dylib` is a platform-specific shared library. It includes the `rustc`
### rmeta
An `rmeta` file is custom binary format that contains the [metadata] for the
crate. This file can be used for fast "checks" of a project by skipping all
code generation (as is done with `cargo check`), collecting enough information
for documentation (as is done with `cargo doc`), or for
[pipelining](#pipelining). This file is created if the
[`--emit=metadata`][emit] CLI option is used.
An `rmeta` file is a custom binary format that contains the [metadata] for the
crate. This file can be used for fast "checks" of a project by skipping all code
generation (as is done with `cargo check`), collecting enough information for
documentation (as is done with `cargo doc`), or for [pipelining](#pipelining).
This file is created if the [`--emit=metadata`][emit] CLI option is used.
`rmeta` files do not support linking, since they do not contain compiled
object files.
@ -60,8 +59,8 @@ object files.
## Metadata
The metadata contains a wide swath of different elements. This guide will not
go into detail of every field it contains. You are encouraged to browse the
The metadata contains a wide swath of different elements. This guide will not go
into detail about every field it contains. You are encouraged to browse the
[`CrateRoot`] definition to get a sense of the different elements it contains.
Everything about metadata encoding and decoding is in the [`rustc_metadata`]
package.
@ -122,9 +121,9 @@ much more.
By default, all Rust symbols are mangled and incorporate the stable crate id.
This allows multiple versions of the same crate to be included together. Cargo
automatically generates `-C metadata` hashes based on a variety of factors,
like the package version, source, and the target kind (a lib and test can have
the same crate name, so they need to be disambiguated).
automatically generates `-C metadata` hashes based on a variety of factors, like
the package version, source, and target kind (a lib and test can have the same
crate name, so they need to be disambiguated).
[`StableCrateId`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/def_id/struct.StableCrateId.html
[`StableCrateId::new`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/def_id/struct.StableCrateId.html#method.new
@ -154,7 +153,7 @@ will also look at the [sysroot] to find dependencies.
As crates are loaded, they are kept in the [`CStore`] with the crate metadata
wrapped in the [`CrateMetadata`] struct. After resolution and expansion, the
`CStore` will make its way into the [`GlobalCtxt`] for the rest of
`CStore` will make its way into the [`GlobalCtxt`] for the rest of the
compilation.
[name resolution]: ../name-resolution.md

2
src/borrow_check/two_phase_borrows.md
View File

@ -76,7 +76,7 @@ borrow.
[`AutoBorrow`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/adjustment/enum.AutoBorrow.html
[converted]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_mir_build/thir/cx/expr/trait.ToBorrowKind.html#method.to_borrow_kind
[`BorrowKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/enum.BorrowKind.html
[`GatherBorrows`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/visit/trait.Visitor.html#method.visit_local
[`GatherBorrows`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_borrowck/borrow_set/struct.GatherBorrows.html
[`BorrowData`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_borrowck/borrow_set/struct.BorrowData.html
## Checking two-phase borrows

89
src/building/bootstrapping/what-bootstrapping-does.md
View File

@ -45,13 +45,13 @@ compiler.
```mermaid
graph TD
s0c["stage0 compiler (1.63)"]:::downloaded -->|A| s0l("stage0 std (1.64)"):::with-s0c;
s0c["stage0 compiler (1.86.0-beta.1)"]:::downloaded -->|A| s0l("stage0 std (1.86.0-beta.1)"):::downloaded;
s0c & s0l --- stepb[ ]:::empty;
stepb -->|B| s0ca["stage0 compiler artifacts (1.64)"]:::with-s0c;
s0ca -->|copy| s1c["stage1 compiler (1.64)"]:::with-s0c;
s1c -->|C| s1l("stage1 std (1.64)"):::with-s1c;
stepb -->|B| s0ca["stage0 compiler artifacts (1.87.0-dev)"]:::with-s0c;
s0ca -->|copy| s1c["stage1 compiler (1.87.0-dev)"]:::with-s0c;
s1c -->|C| s1l("stage1 std (1.87.0-dev)"):::with-s1c;
s1c & s1l --- stepd[ ]:::empty;
stepd -->|D| s1ca["stage1 compiler artifacts (1.64)"]:::with-s1c;
stepd -->|D| s1ca["stage1 compiler artifacts (1.87.0-dev)"]:::with-s1c;
s1ca -->|copy| s2c["stage2 compiler"]:::with-s1c;
classDef empty width:0px,height:0px;
@ -62,19 +62,21 @@ graph TD
### Stage 0: the pre-compiled compiler
The stage0 compiler is usually the current _beta_ `rustc` compiler and its
The stage0 compiler is by default the very recent _beta_ `rustc` compiler and its
associated dynamic libraries, which `./x.py` will download for you. (You can
also configure `./x.py` to use something else.)
also configure `./x.py` to change stage0 to something else.)
The stage0 compiler is then used only to compile [`src/bootstrap`],
[`library/std`], and [`compiler/rustc`]. When assembling the libraries and
binaries that will become the stage1 `rustc` compiler, the freshly compiled
`std` and `rustc` are used. There are two concepts at play here: a compiler
(with its set of dependencies) and its 'target' or 'object' libraries (`std` and
`rustc`). Both are staged, but in a staggered manner.
The precompiled stage0 compiler is then used only to compile [`src/bootstrap`] and [`compiler/rustc`]
with precompiled stage0 std.
Note that to build the stage1 compiler we use the precompiled stage0 compiler and std.
Therefore, to use a compiler with a std that is freshly built from the tree, you need to
build the stage2 compiler.
There are two concepts at play here: a compiler (with its set of dependencies) and its
'target' or 'object' libraries (`std` and `rustc`). Both are staged, but in a staggered manner.
[`compiler/rustc`]: https://github.com/rust-lang/rust/tree/master/compiler/rustc
[`library/std`]: https://github.com/rust-lang/rust/tree/master/library/std
[`src/bootstrap`]: https://github.com/rust-lang/rust/tree/master/src/bootstrap
### Stage 1: from current code, by an earlier compiler
@ -84,16 +86,14 @@ The rustc source code is then compiled with the `stage0` compiler to produce the
### Stage 2: the truly current compiler
We then rebuild our `stage1` compiler with itself to produce the `stage2`
We then rebuild the compiler using `stage1` compiler with in-tree std to produce the `stage2`
compiler.
In theory, the `stage1` compiler is functionally identical to the `stage2`
compiler, but in practice there are subtle differences. In particular, the
`stage1` compiler itself was built by `stage0` and hence not by the source in
your working directory. This means that the ABI generated by the `stage0`
compiler may not match the ABI that would have been made by the `stage1`
compiler, which can cause problems for dynamic libraries, tests, and tools using
`rustc_private`.
The `stage1` compiler itself was built by precompiled `stage0` compiler and std
and hence not by the source in your working directory. This means that the ABI
generated by the `stage0` compiler may not match the ABI that would have been made
by the `stage1` compiler, which can cause problems for dynamic libraries, tests
and tools using `rustc_private`.
Note that the `proc_macro` crate avoids this issue with a `C` FFI layer called
`proc_macro::bridge`, allowing it to be used with `stage1`.
@ -101,9 +101,10 @@ Note that the `proc_macro` crate avoids this issue with a `C` FFI layer called
The `stage2` compiler is the one distributed with `rustup` and all other install
methods. However, it takes a very long time to build because one must first
build the new compiler with an older compiler and then use that to build the new
compiler with itself. For development, you usually only want the `stage1`
compiler, which you can build with `./x build library`. See [Building the
compiler](../how-to-build-and-run.html#building-the-compiler).
compiler with itself.
For development, you usually only want to use `--stage 1` flag to build things.
See [Building the compiler](../how-to-build-and-run.html#building-the-compiler).
### Stage 3: the same-result test
@ -114,10 +115,11 @@ something has broken.
### Building the stages
The script [`./x`] tries to be helpful and pick the stage you most likely meant
for each subcommand. These defaults are as follows:
for each subcommand. Here are some `x` commands with their default stages:
- `check`: `--stage 0`
- `doc`: `--stage 0`
- `check`: `--stage 1`
- `clippy`: `--stage 1`
- `doc`: `--stage 1`
- `build`: `--stage 1`
- `test`: `--stage 1`
- `dist`: `--stage 2`
@ -191,8 +193,8 @@ include, but are not limited to:
without building `rustc` from source ('build with `stage0`, then test the
artifacts'). If you're working on the standard library, this is normally the
test command you want.
- `./x build --stage 0` means to build with the beta `rustc`.
- `./x doc --stage 0` means to document using the beta `rustdoc`.
- `./x build --stage 0` means to build with the stage0 `rustc`.
- `./x doc --stage 0` means to document using the stage0 `rustdoc`.
#### Examples of what *not* to do
@ -208,9 +210,6 @@ include, but are not limited to:
### Building vs. running
Note that `build --stage N compiler/rustc` **does not** build the stage N
compiler: instead it builds the stage N+1 compiler _using_ the stage N compiler.
In short, _stage 0 uses the `stage0` compiler to create `stage0` artifacts which
will later be uplifted to be the stage1 compiler_.
@ -268,23 +267,6 @@ However, when cross-compiling, `stage1` `std` will only run on the host. So the
(See in the table how `stage2` only builds non-host `std` targets).
### Why does only libstd use `cfg(bootstrap)`?
For docs on `cfg(bootstrap)` itself, see [Complications of
Bootstrapping](#complications-of-bootstrapping).
The `rustc` generated by the `stage0` compiler is linked to the freshly-built
`std`, which means that for the most part only `std` needs to be `cfg`-gated, so
that `rustc` can use features added to `std` immediately after their addition,
without need for them to get into the downloaded `beta` compiler.
Note this is different from any other Rust program: `stage1` `rustc` is built by
the _beta_ compiler, but using the _master_ version of `libstd`!
The only time `rustc` uses `cfg(bootstrap)` is when it adds internal lints that
use diagnostic items, or when it uses unstable library features that were
recently changed.
### What is a 'sysroot'?
When you build a project with `cargo`, the build artifacts for dependencies are
@ -459,7 +441,6 @@ compiler itself uses to run. These aren't actually used by artifacts the new
compiler generates. This step also copies the `rustc` and `rustdoc` binaries we
generated into `build/$HOST/stage/bin`.
The `stage1/bin/rustc` is a fully functional compiler, but it doesn't yet have
any libraries to link built binaries or libraries to. The next 3 steps will
provide those libraries for it; they are mostly equivalent to constructing the
`stage1/bin` compiler so we don't go through them individually here.
The `stage1/bin/rustc` is a fully functional compiler built with stage0 (precompiled) compiler and std.
To use a compiler built entirely from source with the in-tree compiler and std, you need to build the
stage2 compiler, which is compiled using the stage1 (in-tree) compiler and std.

13
src/building/how-to-build-and-run.md
View File

@ -217,7 +217,6 @@ probably the best "go to" command for building a local compiler:
This may *look* like it only builds the standard library, but that is not the case.
What this command does is the following:
- Build `std` using the stage0 compiler
- Build `rustc` using the stage0 compiler
- This produces the stage1 compiler
- Build `std` using the stage1 compiler
@ -241,8 +240,7 @@ build. The **full** `rustc` build (what you get with `./x build
--stage 2 compiler/rustc`) has quite a few more steps:
- Build `rustc` with the stage1 compiler.
- The resulting compiler here is called the "stage2" compiler.
- Build `std` with stage2 compiler.
- The resulting compiler here is called the "stage2" compiler, which uses stage1 std from the previous command.
- Build `librustdoc` and a bunch of other things with the stage2 compiler.
You almost never need to do this.
@ -250,14 +248,14 @@ You almost never need to do this.
### Build specific components
If you are working on the standard library, you probably don't need to build
the compiler unless you are planning to use a recently added nightly feature.
Instead, you can just build using the bootstrap compiler.
every other default component. Instead, you can build a specific component by
providing its name, like this:
```bash
./x build --stage 0 library
./x build --stage 1 library
```
If you choose the `library` profile when running `x setup`, you can omit `--stage 0` (it's the
If you choose the `library` profile when running `x setup`, you can omit `--stage 1` (it's the
default).
## Creating a rustup toolchain
@ -271,7 +269,6 @@ you will likely need to build at some point; for example, if you want
to run the entire test suite).
```bash
rustup toolchain link stage0 build/host/stage0-sysroot # beta compiler + stage0 std
rustup toolchain link stage1 build/host/stage1
rustup toolchain link stage2 build/host/stage2
```

2
src/building/new-target.md
View File

@ -85,7 +85,7 @@ Look for existing targets to use as examples.
After adding your target to the `rustc_target` crate you may want to add
`core`, `std`, ... with support for your new target. In that case you will
probably need access to some `target_*` cfg. Unfortunately when building with
stage0 (the beta compiler), you'll get an error that the target cfg is
stage0 (a precompiled compiler), you'll get an error that the target cfg is
unexpected because stage0 doesn't know about the new target specification and
we pass `--check-cfg` in order to tell it to check.

69
src/building/suggested.md
View File

@ -59,6 +59,14 @@ always overrides the inner ones.
## Configuring `rust-analyzer` for `rustc`
### Checking the "library" tree
Checking the "library" tree requires a stage1 compiler, which can be a heavy process on some computers.
For this reason, bootstrap has a flag called `--skip-std-check-if-no-download-rustc` that skips checking the
"library" tree if `rust.download-rustc` isn't available. If you want to avoid putting a heavy load on your computer
with `rust-analyzer`, you can add the `--skip-std-check-if-no-download-rustc` flag to your `./x check` command in
the `rust-analyzer` configuration.
### Project-local rust-analyzer setup
`rust-analyzer` can help you check and format your code whenever you save a
@ -91,7 +99,7 @@ for two reasons:
additional rebuilds in some cases.
To avoid these problems:
- Add `--build-dir=build-rust-analyzer` to all of the custom `x` commands in
- Add `--build-dir=build/rust-analyzer` to all of the custom `x` commands in
your editor's rust-analyzer configuration.
(Feel free to choose a different directory name if desired.)
- Modify the `rust-analyzer.rustfmt.overrideCommand` setting so that it points
@ -100,10 +108,7 @@ To avoid these problems:
copy of `rust-analyzer-proc-macro-srv` in that other build directory.
Using separate build directories for command-line builds and rust-analyzer
requires extra disk space, and also means that running `./x clean` on the
command-line will not clean out the separate build directory. To clean the
separate build directory, run `./x clean --build-dir=build-rust-analyzer`
instead.
requires extra disk space.
### Visual Studio Code
@ -137,7 +142,7 @@ Task] instead:
### Neovim
For Neovim users there are several options for configuring for rustc. The
For Neovim users, there are a few options. The
easiest way is by using [neoconf.nvim](https://github.com/folke/neoconf.nvim/),
which allows for project-local configuration files with the native LSP. The
steps for how to use it are below. Note that they require rust-analyzer to
@ -310,51 +315,15 @@ lets you use `cargo fmt`.
[the section on vscode]: suggested.md#configuring-rust-analyzer-for-rustc
[the section on rustup]: how-to-build-and-run.md?highlight=rustup#creating-a-rustup-toolchain
## Faster builds with `--keep-stage`.
## Faster Builds with CI-rustc
Sometimes just checking whether the compiler builds is not enough. A common
example is that you need to add a `debug!` statement to inspect the value of
some state or better understand the problem. In that case, you don't really need
a full build. By bypassing bootstrap's cache invalidation, you can often get
these builds to complete very fast (e.g., around 30 seconds). The only catch is
this requires a bit of fudging and may produce compilers that don't work (but
that is easily detected and fixed).
The sequence of commands you want is as follows:
- Initial build: `./x build library`
- As [documented previously], this will build a functional stage1 compiler as
part of running all stage0 commands (which include building a `std`
compatible with the stage1 compiler) as well as the first few steps of the
"stage 1 actions" up to "stage1 (sysroot stage1) builds std".
- Subsequent builds: `./x build library --keep-stage 1`
- Note that we added the `--keep-stage 1` flag here
[documented previously]: ./how-to-build-and-run.md#building-the-compiler
As mentioned, the effect of `--keep-stage 1` is that we just _assume_ that the
old standard library can be re-used. If you are editing the compiler, this is
almost always true: you haven't changed the standard library, after all. But
sometimes, it's not true: for example, if you are editing the "metadata" part of
the compiler, which controls how the compiler encodes types and other states
into the `rlib` files, or if you are editing things that wind up in the metadata
(such as the definition of the MIR).
**The TL;DR is that you might get weird behavior from a compile when using
`--keep-stage 1`** -- for example, strange [ICEs](../appendix/glossary.html#ice)
or other panics. In that case, you should simply remove the `--keep-stage 1`
from the command and rebuild. That ought to fix the problem.
You can also use `--keep-stage 1` when running tests. Something like this:
- Initial test run: `./x test tests/ui`
- Subsequent test run: `./x test tests/ui --keep-stage 1`
### Iterating the standard library with `--keep-stage`
If you are making changes to the standard library, you can use `./x build
--keep-stage 0 library` to iteratively rebuild the standard library without
rebuilding the compiler.
If you are not working on the compiler, you often don't need to build the compiler tree.
For example, you can skip building the compiler and only build the `library` tree or the
tools under `src/tools`. To achieve that, you have to enable this by setting the `download-rustc`
option in your configuration. This tells bootstrap to use the latest nightly compiler for `stage > 0`
steps, meaning it will have two precompiled compilers: stage0 compiler and `download-rustc` compiler
for `stage > 0` steps. This way, it will never need to build the in-tree compiler. As a result, your
build time will be significantly reduced by not building the in-tree compiler.
## Using incremental compilation

2
src/cli.md
View File

@ -28,6 +28,6 @@ adding a new command-line argument.
unstable-options` flag.
[cli-docs]: https://doc.rust-lang.org/rustc/command-line-arguments.html
[forge guide for new options]: https://forge.rust-lang.org/compiler/new_option.html
[forge guide for new options]: https://forge.rust-lang.org/compiler/proposals-and-stabilization.html#compiler-flags
[unstable book]: https://doc.rust-lang.org/nightly/unstable-book/
[`parse_bool`]: https://github.com/rust-lang/rust/blob/e5335592e78354e33d798d20c04bcd677c1df62d/src/librustc_session/options.rs#L307-L313

28
src/coroutine-closures.md
View File

@ -1,6 +1,10 @@
# Async closures/"coroutine-closures"
<!-- toc -->
Please read [RFC 3668](https://rust-lang.github.io/rfcs/3668-async-closures.html) to understand the general motivation of the feature. This is a very technical and somewhat "vertical" chapter; ideally we'd split this and sprinkle it across all the relevant chapters, but for the purposes of understanding async closures *holistically*, I've put this together all here in one chapter.
# Coroutine-closures -- a technical deep dive
## Coroutine-closures -- a technical deep dive
Coroutine-closures are a generalization of async closures, being special syntax for closure expressions which return a coroutine, notably one that is allowed to capture from the closure's upvars.
@ -8,9 +12,11 @@ For now, the only usable kind of coroutine-closure is the async closure, and sup
As a consequence of the code being somewhat general, this document may flip between calling them "async closures" and "coroutine-closures". The future that is returned by the async closure will generally be called the "coroutine" or the "child coroutine".
## HIR
### HIR
Async closures (and in the future, other coroutine flavors such as `gen`) are represented in HIR as a `hir::Closure` whose closure-kind is `ClosureKind::CoroutineClosure(_)`[^k1], which wraps an async block, which is also represented in HIR as a `hir::Closure`) and whose closure-kind is `ClosureKind::Closure(CoroutineKind::Desugared(_, CoroutineSource::Closure))`[^k2].
Async closures (and in the future, other coroutine flavors such as `gen`) are represented in HIR as a `hir::Closure`.
The closure-kind of the `hir::Closure` is `ClosureKind::CoroutineClosure(_)`[^k1], which wraps an async block, which is also represented in HIR as a `hir::Closure`.
The closure-kind of the async block is `ClosureKind::Closure(CoroutineKind::Desugared(_, CoroutineSource::Closure))`[^k2].
[^k1]: <https://github.com/rust-lang/rust/blob/5ca0e9fa9b2f92b463a0a2b0b34315e09c0b7236/compiler/rustc_ast_lowering/src/expr.rs#L1147>
@ -24,7 +30,7 @@ Like `async fn`, when lowering an async closure's body, we need to unconditional
[^l3]: <https://github.com/rust-lang/rust/blob/5ca0e9fa9b2f92b463a0a2b0b34315e09c0b7236/compiler/rustc_hir_typeck/src/upvar.rs#L250-L256>
## `rustc_middle::ty` Representation
### `rustc_middle::ty` Representation
For the purposes of keeping the implementation mostly future-compatible (i.e. with gen `|| {}` and `async gen || {}`), most of this section calls async closures "coroutine-closures".
@ -72,7 +78,7 @@ To most easily construct the `Coroutine` that a coroutine-closure returns, you c
Most of the args to that function will be components that you can get out of the `CoroutineArgs`, except for the `goal_kind: ClosureKind` which controls which flavor of coroutine to return based off of the `ClosureKind` passed in -- i.e. it will prepare the by-ref coroutine if `ClosureKind::Fn | ClosureKind::FnMut`, and the by-move coroutine if `ClosureKind::FnOnce`.
## Trait Hierarchy
### Trait Hierarchy
We introduce a parallel hierarchy of `Fn*` traits that are implemented for . The motivation for the introduction was covered in a blog post: [Async Closures](https://hackmd.io/@compiler-errors/async-closures).
@ -98,11 +104,11 @@ We mention above that "regular" callable types can implement `AsyncFn*`, but the
See the "follow-up: when do..." section below for an elaborated answer. The full answer describes a pretty interesting and hopefully thorough heuristic that is used to ensure that most async closures "just work".
## Tale of two bodies...
### Tale of two bodies...
When async closures are called with `AsyncFn`/`AsyncFnMut`, they return a coroutine that borrows from the closure. However, when they are called via `AsyncFnOnce`, we consume that closure, and cannot return a coroutine that borrows from data that is now dropped.
To work around around this limitation, we synthesize a separate by-move MIR body for calling `AsyncFnOnce::call_once` on a coroutine-closure that can be called by-ref.
To work around this limitation, we synthesize a separate by-move MIR body for calling `AsyncFnOnce::call_once` on a coroutine-closure that can be called by-ref.
This body operates identically to the "normal" coroutine returned from calling the coroutine-closure, except for the fact that it has a different set of upvars, since we must *move* the captures from the parent coroutine-closure into the child coroutine.
@ -120,7 +126,7 @@ Since we've synthesized a new def id, this query is also responsible for feeding
[^b3]: <https://github.com/rust-lang/rust/blob/5ca0e9fa9b2f92b463a0a2b0b34315e09c0b7236/compiler/rustc_mir_transform/src/lib.rs#L339-L342>
## Closure signature inference
### Closure signature inference
The closure signature inference algorithm for async closures is a bit more complicated than the inference algorithm for "traditional" closures. Like closures, we iterate through all of the clauses that may be relevant (for the expectation type passed in)[^deduce1].
@ -173,7 +179,7 @@ s.as_bytes();
So *instead*, we use this alias (in this case, a projection: `AsyncFnKindHelper::Upvars<'env, ...>`) to delay the computation of the *tupled upvars* and give us something to put in its place, while still allowing us to return a `TyKind::Coroutine` (which is a rigid type) and we may successfully confirm the built-in traits we need (in our case, `Future`), since the `Future` implementation doesn't depend on the upvars at all.
## Upvar analysis
### Upvar analysis
By and large, the upvar analysis for coroutine-closures and their child coroutines proceeds like normal upvar analysis. However, there are several interesting bits that happen to account for async closures' special natures:
@ -262,7 +268,7 @@ let c = async || {
If either of these cases apply, then we should capture the borrow with the lifetime of the parent coroutine-closure's env. Luckily, if this function is not correct, then the program is not unsound, since we still borrowck and validate the choices made from this function -- the only side-effect is that the user may receive unnecessary borrowck errors.
## Instance resolution
### Instance resolution
If a coroutine-closure has a closure-kind of `FnOnce`, then its `AsyncFnOnce::call_once` and `FnOnce::call_once` implementations resolve to the coroutine-closure's body[^res1], and the `Future::poll` of the coroutine that gets returned resolves to the body of the child closure.
@ -282,7 +288,7 @@ This is represented by the `ConstructCoroutineInClosureShim`[^i1]. The `receiver
[^i3]: <https://github.com/rust-lang/rust/blob/07cbbdd69363da97075650e9be24b78af0bcdd23/compiler/rustc_middle/src/ty/instance.rs#L841>
## Borrow-checking
### Borrow-checking
It turns out that borrow-checking async closures is pretty straightforward. After adding a new `DefiningTy::CoroutineClosure`[^bck1] variant, and teaching borrowck how to generate the signature of the coroutine-closure[^bck2], borrowck proceeds totally fine.

162
src/diagnostics.md
View File

@ -866,19 +866,17 @@ struct](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/json/struct
(and sub-structs) for the JSON serialization. Don't confuse this with
[`errors::Diag`](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_errors/struct.Diag.html)!
## `#[rustc_on_unimplemented(...)]`
## `#[rustc_on_unimplemented]`
The `#[rustc_on_unimplemented]` attribute allows trait definitions to add specialized
notes to error messages when an implementation was expected but not found.
You can refer to the trait's generic arguments by name and to the resolved type using `Self`.
For example:
This attribute allows trait definitions to modify error messages when an implementation was
expected but not found. The string literals in the attribute are format strings and can be
formatted with named parameters. See the Formatting
section below for what parameters are permitted.
```rust,ignore
#![feature(rustc_attrs)]
#[rustc_on_unimplemented="an iterator over elements of type `{A}` \
cannot be built from a collection of type `{Self}`"]
#[rustc_on_unimplemented(message = "an iterator over \
elements of type `{A}` cannot be built from a \
collection of type `{Self}`")]
trait MyIterator<A> {
fn next(&mut self) -> A;
}
@ -895,32 +893,26 @@ fn main() {
When the user compiles this, they will see the following;
```txt
error[E0277]: the trait bound `&[{integer}]: MyIterator<char>` is not satisfied
--> <anon>:14:5
error[E0277]: an iterator over elements of type `char` cannot be built from a collection of type `&[{integer}]`
--> src/main.rs:13:19
|
14 | iterate_chars(&[1, 2, 3][..]);
| ^^^^^^^^^^^^^ an iterator over elements of type `char` cannot be built from a collection of type `&[{integer}]`
13 | iterate_chars(&[1, 2, 3][..]);
| ------------- ^^^^^^^^^^^^^^ the trait `MyIterator<char>` is not implemented for `&[{integer}]`
| |
| required by a bound introduced by this call
|
= help: the trait `MyIterator<char>` is not implemented for `&[{integer}]`
= note: required by `iterate_chars`
note: required by a bound in `iterate_chars`
```
`rustc_on_unimplemented` also supports advanced filtering for better targeting
of messages, as well as modifying specific parts of the error message. You
target the text of:
You can modify the contents of:
- the main error message (`message`)
- the label (`label`)
- an extra note (`note`)
- the note(s) (`note`)
For example, the following attribute
```rust,ignore
#[rustc_on_unimplemented(
message="message",
label="label",
note="note"
)]
#[rustc_on_unimplemented(message = "message", label = "label", note = "note")]
trait MyIterator<A> {
fn next(&mut self) -> A;
}
@ -930,45 +922,61 @@ Would generate the following output:
```text
error[E0277]: message
--> <anon>:14:5
--> <file>:10:19
|
14 | iterate_chars(&[1, 2, 3][..]);
| ^^^^^^^^^^^^^ label
10 | iterate_chars(&[1, 2, 3][..]);
| ------------- ^^^^^^^^^^^^^^ label
| |
| required by a bound introduced by this call
|
= note: note
= help: the trait `MyIterator<char>` is not implemented for `&[{integer}]`
= note: required by `iterate_chars`
= note: note
note: required by a bound in `iterate_chars`
```
To allow more targeted error messages, it is possible to filter the
application of these fields based on a variety of attributes when using
`on`:
The functionality discussed so far is also available with
[`#[diagnostic::on_unimplemented]`](https://doc.rust-lang.org/nightly/reference/attributes/diagnostics.html#the-diagnosticon_unimplemented-attribute).
If you can, you should use that instead.
### Filtering
To allow more targeted error messages, it is possible to filter the
application of these fields with `on`.
You can filter on the following boolean flags:
- `crate_local`: whether the code causing the trait bound to not be
fulfilled is part of the user's crate. This is used to avoid suggesting
code changes that would require modifying a dependency.
- Any of the generic arguments that can be substituted in the text can be
referred by name as well for filtering, like `Rhs="i32"`, except for
`Self`.
- `_Self`: to filter only on a particular calculated trait resolution, like
`Self="std::iter::Iterator<char>"`. This is needed because `Self` is a
keyword which cannot appear in attributes.
- `direct`: user-specified rather than derived obligation.
- `from_desugaring`: usable both as boolean (whether the flag is present)
or matching against a particular desugaring. The desugaring is identified
with its variant name in the `DesugaringKind` enum.
- `direct`: whether this is an user-specified rather than derived obligation.
- `from_desugaring`: whether we are in some kind of desugaring, like `?`
or a `try` block for example. This flag can also be matched on, see below.
For example, the `Iterator` trait can be annotated in the following way:
You can match on the following names and values, using `name = "value"`:
- `cause`: Match against one variant of the `ObligationCauseCode`
enum. Only `"MainFunctionType"` is supported.
- `from_desugaring`: Match against a particular variant of the `DesugaringKind`
enum. The desugaring is identified by its variant name, for example
`"QuestionMark"` for `?` desugaring or `"TryBlock"` for `try` blocks.
- `Self` and any generic arguments of the trait, like `Self = "alloc::string::String"`
or `Rhs="i32"`.
The compiler can provide several values to match on, for example:
- the self_ty, pretty printed with and without type arguments resolved.
- `"{integral}"`, if self_ty is an integral of which the type is known.
- `"[]"`, `"[{ty}]"`, `"[{ty}; _]"`, `"[{ty}; $N]"` when applicable.
- references to said slices and arrays.
- `"fn"`, `"unsafe fn"` or `"#[target_feature] fn"` when self is a function.
- `"{integer}"` and `"{float}"` if the type is a number but we haven't inferred it yet.
- combinations of the above, like `"[{integral}; _]"`.
For example, the `Iterator` trait can be filtered in the following way:
```rust,ignore
#[rustc_on_unimplemented(
on(
_Self="&str",
note="call `.chars()` or `.as_bytes()` on `{Self}`"
),
message="`{Self}` is not an iterator",
label="`{Self}` is not an iterator",
note="maybe try calling `.iter()` or a similar method"
on(Self = "&str", note = "call `.chars()` or `.as_bytes()` on `{Self}`"),
message = "`{Self}` is not an iterator",
label = "`{Self}` is not an iterator",
note = "maybe try calling `.iter()` or a similar method"
)]
pub trait Iterator {}
```
@ -997,15 +1005,47 @@ error[E0277]: `&str` is not an iterator
= note: required by `std::iter::IntoIterator::into_iter`
```
If you need to filter on multiple attributes, you can use `all`, `any` or
`not` in the following way:
The `on` filter accepts `all`, `any` and `not` predicates similar to the `cfg` attribute:
```rust,ignore
#[rustc_on_unimplemented(
on(
all(_Self="&str", T="std::string::String"),
note="you can coerce a `{T}` into a `{Self}` by writing `&*variable`"
)
)]
pub trait From<T>: Sized { /* ... */ }
#[rustc_on_unimplemented(on(
all(Self = "&str", T = "alloc::string::String"),
note = "you can coerce a `{T}` into a `{Self}` by writing `&*variable`"
))]
pub trait From<T>: Sized {
/* ... */
}
```
### Formatting
The string literals are format strings that accept parameters wrapped in braces
but positional and listed parameters and format specifiers are not accepted.
The following parameter names are valid:
- `Self` and all generic parameters of the trait.
- `This`: the name of the trait the attribute is on, without generics.
- `Trait`: the name of the "sugared" trait. See `TraitRefPrintSugared`.
- `ItemContext`: the kind of `hir::Node` we're in, things like `"an async block"`,
`"a function"`, `"an async function"`, etc.
Something like:
```rust,ignore
#![feature(rustc_attrs)]
#[rustc_on_unimplemented(message = "Self = `{Self}`, \
T = `{T}`, this = `{This}`, trait = `{Trait}`, \
context = `{ItemContext}`")]
pub trait From<T>: Sized {
fn from(x: T) -> Self;
}
fn main() {
let x: i8 = From::from(42_i32);
}
```
Will format the message into
```text
"Self = `i8`, T = `i32`, this = `From`, trait = `From<i32>`, context = `a function`"
```

3
src/early_late_parameters.md
View File

@ -174,7 +174,8 @@ As mentioned previously, the distinction between early and late bound parameters
- When naming a function (early)
- When calling a function (late)
There currently is no syntax for explicitly specifying generic arguments for late bound parameters as part of the call step, only specifying generic arguments when naming a function. The syntax `foo::<'static>();`, despite being part of a function call, behaves as `(foo::<'static>)();` and instantiates the early bound generic parameters on the function item type.
There is currently no syntax for explicitly specifying generic arguments for late bound parameters during the call step; generic arguments can only be specified for early bound parameters when naming a function.
The syntax `foo::<'static>();`, despite being part of a function call, behaves as `(foo::<'static>)();` and instantiates the early bound generic parameters on the function item type.
See the following example:
```rust

24
src/fuzzing.md
View File

@ -73,21 +73,32 @@ To build a corpus, you may want to use:
- The rustc/rust-analyzer/clippy test suites (or even source code) --- though avoid
tests that are already known to cause failures, which often begin with comments
like `// failure-status: 101` or `// known-bug: #NNN`.
- The already-fixed ICEs in [Glacier][glacier] --- though avoid the unfixed
ones in `ices/`!
like `//@ failure-status: 101` or `//@ known-bug: #NNN`.
- The already-fixed ICEs in the archived [Glacier][glacier] repository --- though
avoid the unfixed ones in `ices/`!
[glacier]: https://github.com/rust-lang/glacier
## Extra credit
Here are a few things you can do to help the Rust project after filing an ICE.
- [Bisect][bisect] the bug to figure out when it was introduced
- [Bisect][bisect] the bug to figure out when it was introduced.
If you find the regressing PR / commit, you can mark the issue with the label
`S-has-bisection`. If not, consider applying `E-needs-bisection` instead.
- Fix "distractions": problems with the test case that don't contribute to
triggering the ICE, such as syntax errors or borrow-checking errors
- Minimize the test case (see below)
- Add the minimal test case to [Glacier][glacier]
- Minimize the test case (see below). If successful, you can label the
issue with `S-has-mcve`. Otherwise, you can apply `E-needs-mcve`.
- Add the minimal test case to the rust-lang/rust repo as a [crashes test].
While you're at it, consider including other "untracked" crashes in your PR.
Please don't forget to mark your issue with `S-bug-has-test` afterwards.
See also [applying and removing labels][labeling].
[bisect]: https://rust-lang.github.io/cargo-bisect-rustc/
[crashes test]: tests/compiletest.html#crashes-tests
[labeling]: https://forge.rust-lang.org/release/issue-triaging.html#applying-and-removing-labels
## Minimization
@ -143,7 +154,6 @@ ICEs that require debug assertions to reproduce should be tagged
- [tree-splicer][tree-splicer] generates new source files by combining existing
ones while maintaining correct syntax
[glacier]: https://github.com/rust-lang/glacier
[fuzz-rustc]: https://github.com/dwrensha/fuzz-rustc
[icemaker]: https://github.com/matthiaskrgr/icemaker/
[tree-splicer]: https://github.com/langston-barrett/tree-splicer/

4
src/getting-started.md
View File

@ -89,7 +89,7 @@ filtering the search to areas you're interested in. For example:
Not all important or beginner work has issue labels.
See below for how to find work that isn't labelled.
[help-wanted-search]: https://github.com/issues?q=is%3Aopen+is%3Aissue+org%3Arust-lang+no%3Aassignee+label%3AE-easy%2C%22good+first+issue%22%2Cgood-first-issue%2CE-medium%2CEasy%2CE-help-wanted%2CE-mentor+-label%3AS-blocked+
[help-wanted-search]: https://github.com/issues?q=is%3Aopen+is%3Aissue+org%3Arust-lang+no%3Aassignee+label%3AE-easy%2C%22good+first+issue%22%2Cgood-first-issue%2CE-medium%2CEasy%2CE-help-wanted%2CE-mentor+-label%3AS-blocked+-linked%3Apr+
[Triage]: ./contributing.md#issue-triage
### Recurring work
@ -98,8 +98,6 @@ Some work is too large to be done by a single person. In this case, it's common
issues" to co-ordinate the work between contributors. Here are some example tracking issues where
it's easy to pick up work without a large time commitment:
- [Rustdoc Askama Migration](https://github.com/rust-lang/rust/issues/108868)
- [Diagnostic Translation](https://github.com/rust-lang/rust/issues/100717)
- [Move UI tests to subdirectories](https://github.com/rust-lang/rust/issues/73494)
If you find more recurring work, please feel free to add it here!

2
src/memory.md
View File

@ -63,7 +63,7 @@ represented as a slice `&'tcx [tcx.types.i32, tcx.types.u32]`).
[`mk_args`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TyCtxt.html#method.mk_args
[adtdefid]: ./ty_module/generic_arguments.md#adtdef-and-defid
[`Predicate`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Predicate.html
[`TraitRef`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TraitRef.html
[`TraitRef`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.TraitRef.html
[`ty::TyKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/sty/type.TyKind.html
[traits]: ./traits/resolution.md

11
src/normalization.md
View File

@ -166,7 +166,10 @@ In this example:
When interfacing with the type system it will often be the case that it's necessary to request a type be normalized. There are a number of different entry points to the underlying normalization logic and each entry point should only be used in specific parts of the compiler.
An additional complication is that the compiler is currently undergoing a transition from the old trait solver to the new trait solver. As part of this transition our approach to normalization in the compiler has changed somewhat significantly, resulting in some normalization entry points being "old solver only" slated for removal in the long-term once the new solver has stabilized.
<!-- date-check: May 2025 -->
An additional complication is that the compiler is currently undergoing a transition from the old trait solver to the new trait solver.
As part of this transition our approach to normalization in the compiler has changed somewhat significantly, resulting in some normalization entry points being "old solver only" slated for removal in the long-term once the new solver has stabilized.
The transition can be tracked via the [WG-trait-system-refactor](https://github.com/rust-lang/rust/labels/WG-trait-system-refactor) label in Github.
Here is a rough overview of the different entry points to normalization in the compiler:
- `infcx.at.structurally_normalize`
@ -262,13 +265,13 @@ Another problem was that it was not possible to normalize `ParamEnv`s correctly
Given a type such as `for<'a> fn(<?x as Trait<'a>::Assoc>)`, it is not possible to correctly handle this with the old solver's approach to normalization.
If we were to normalize it to `for<'a> fn(?y)` and register a goal to normalize `for<'a> <?x as Trait<'a>>::Assoc -> ?y`, this would result in errors in cases where `<?x as Trait<'a>>::Assoc` normalized to `&'a u32`. The inference variable `?y` would be in a lower [universe][universes] than the placeholders made when instantiating the `for<'a>` binder.
If we were to normalize it to `for<'a> fn(?y)` and register a goal to normalize `for<'a> <?x as Trait<'a>>::Assoc -> ?y`, this would result in errors in cases where `<?x as Trait<'a>>::Assoc` normalized to `&'a u32`. The inference variable `?y` would be in a lower [universe] than the placeholders made when instantiating the `for<'a>` binder.
Leaving the alias unnormalized would also be wrong as the old solver expects all aliases to be rigid. This was a soundness bug before the new solver was stabilized in coherence: [relating projection substs is unsound during coherence](https://github.com/rust-lang/rust/issues/102048).
Ultimately this means that it is not always possible to ensure all aliases inside of a value are rigid.
[universes]: https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference/placeholders_and_universes.html#what-is-a-universe
[universe]: borrow_check/region_inference/placeholders_and_universes.md#what-is-a-universe
[deeply_normalize]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_trait_selection/traits/normalize/trait.NormalizeExt.html#tymethod.deeply_normalize
## Handling uses of diverging aliases
@ -306,4 +309,4 @@ Const aliases differ from type aliases a bit here; well formedness of const alia
[^5]: Const aliases certainly wouldn't be *less* sound than type aliases if we stopped doing this
[const_evaluatable]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ClauseKind.html#variant.ConstEvaluatable
[const_evaluatable]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ClauseKind.html#variant.ConstEvaluatable

3
src/opaque-types-impl-trait-inference.md
View File

@ -13,13 +13,16 @@ it can work across functions and function bodies.
To help explain how it works, let's consider an example.
```rust
#![feature(type_alias_impl_trait)]
mod m {
pub type Seq<T> = impl IntoIterator<Item = T>;
#[define_opaque(Seq)]
pub fn produce_singleton<T>(t: T) -> Seq<T> {
vec![t]
}
#[define_opaque(Seq)]
pub fn produce_doubleton<T>(t: T, u: T) -> Seq<T> {
vec![t, u]
}

2
src/return-position-impl-trait-in-trait.md
View File

@ -356,7 +356,7 @@ trait Foo {
Failing because a down-stream impl could theoretically provide an
implementation for `RPITIT` without providing an implementation of
`foo`:
`bar`:
```text
error[E0308]: mismatched types

12
src/rustc-driver/intro.md
View File

@ -7,8 +7,8 @@ It acts as the glue for running the various phases of the compiler in the correc
using the interface defined in the [`rustc_interface`] crate. Where possible, using [`rustc_driver`] rather than [`rustc_interface`] is recommended.
The main entry point of [`rustc_driver`] is [`rustc_driver::run_compiler`][rd_rc].
This builder accepts the same command-line args as rustc as well as an implementation of [`Callbacks`][cb] and a couple of other optional options.
[`Callbacks`][cb] is a `trait` that allows for custom compiler configuration,
This builder accepts the same command-line args as rustc as well as an implementation of [`Callbacks`] and a couple of other optional options.
[`Callbacks`] is a `trait` that allows for custom compiler configuration,
as well as allowing custom code to run after different phases of the compilation.
## `rustc_interface`
@ -33,14 +33,8 @@ specifically [`rustc_driver_impl::run_compiler`][rdi_rc]
[`Compiler`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/interface/struct.Compiler.html
[`rustc_driver`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/
[`rustc_interface`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/index.html
[`Session`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_session/struct.Session.html
[`SourceMap`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/source_map/struct.SourceMap.html
[`TyCtxt`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TyCtxt.html
[Appendix A]: appendix/stupid-stats.html
[cb]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/trait.Callbacks.html
[`Callbacks`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/trait.Callbacks.html
[example]: https://github.com/rust-lang/rustc-dev-guide/blob/master/examples/rustc-interface-example.rs
[i_rc]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_interface/interface/fn.run_compiler.html
[rd_rc]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver/fn.run_compiler.html
[rdi_rc]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_driver_impl/fn.run_compiler.html
[stupid-stats]: https://github.com/nrc/stupid-stats
[`nightly-rustc`]: https://doc.rust-lang.org/nightly/nightly-rustc/

4
src/rustdoc-internals.md
View File

@ -281,10 +281,10 @@ using `XPath` notation to get a precise look at the output. The full
description of all the commands available to `rustdoc` tests (e.g. [`@has`] and
[`@matches`]) is in [`htmldocck.py`].
To use multiple crates in a `rustdoc` test, add `// aux-build:filename.rs`
To use multiple crates in a `rustdoc` test, add `//@ aux-build:filename.rs`
to the top of the test file. `filename.rs` should be placed in an `auxiliary`
directory relative to the test file with the comment. If you need to build
docs for the auxiliary file, use `// build-aux-docs`.
docs for the auxiliary file, use `//@ build-aux-docs`.
In addition, there are separate tests for the search index and `rustdoc`'s
ability to query it. The files in `tests/rustdoc-js` each contain a

30
src/rustdoc.md
View File

@ -93,13 +93,13 @@ does is call the `main()` that's in this crate's `lib.rs`, though.)
interactivity. For information on how to write this form of test,
see [`tests/rustdoc-gui/README.md`][rustdoc-gui-readme]
as well as [the description of the `.goml` format][goml-script]
* Additionally, JavaScript type annotations are written using [TypeScript-flavored JSDoc]
comments and an external d.ts file. The code itself is plain, valid JavaScript; we only
use tsc as a linter.
* The tests on the structure of rustdoc HTML output are located in `tests/rustdoc`,
* Tests on the structure of rustdoc HTML output are located in `tests/rustdoc`,
where they're handled by the test runner of bootstrap and
the supplementary script `src/etc/htmldocck.py`.
[These tests have several extra directives available to them](./rustdoc-internals/rustdoc-test-suite.md).
* Additionally, JavaScript type annotations are written using [TypeScript-flavored JSDoc]
comments and an external d.ts file. The code itself is plain, valid JavaScript; we only
use tsc as a linter.
[TypeScript-flavored JSDoc]: https://www.typescriptlang.org/docs/handbook/jsdoc-supported-types.html
[rustdoc-gui-readme]: https://github.com/rust-lang/rust/blob/master/tests/rustdoc-gui/README.md
@ -116,6 +116,28 @@ Certain browser features that require secure origins, like `localStorage` and
Service Workers, don't work reliably. We can still use such features but we
should make sure pages are still usable without them.
Rustdoc [does not type-check function bodies][platform-specific docs].
This works by [overriding the built-in queries for typeck][override queries],
by [silencing name resolution errors], and by [not resolving opaque types].
This comes with several caveats: in particular, rustdoc *cannot* run any parts of the compiler that
require type-checking bodies; for example it cannot generate `.rlib` files or run most lints.
We want to move away from this model eventually, but we need some alternative for
[the people using it][async-std]; see [various][zulip stop accepting broken code]
[previous][rustdoc meeting 2024-07-08] [zulip][compiler meeting 2023-01-26] [discussion][notriddle rfc].
For examples of code that breaks if this hack is removed, see
[`tests/rustdoc-ui/error-in-impl-trait`].
[platform-specific docs]: https://doc.rust-lang.org/rustdoc/advanced-features.html#interactions-between-platform-specific-docs
[override queries]: https://github.com/rust-lang/rust/blob/52bf0cf795dfecc8b929ebb1c1e2545c3f41d4c9/src/librustdoc/core.rs#L299-L323
[silencing name resolution errors]: https://github.com/rust-lang/rust/blob/52bf0cf795dfecc8b929ebb1c1e2545c3f41d4c9/compiler/rustc_resolve/src/late.rs#L4517
[not resolving opaque types]: https://github.com/rust-lang/rust/blob/52bf0cf795dfecc8b929ebb1c1e2545c3f41d4c9/compiler/rustc_hir_analysis/src/check/check.rs#L188-L194
[async-std]: https://github.com/rust-lang/rust/issues/75100
[rustdoc meeting 2024-07-08]: https://rust-lang.zulipchat.com/#narrow/channel/393423-t-rustdoc.2Fmeetings/topic/meeting.202024-07-08/near/449969836
[compiler meeting 2023-01-26]: https://rust-lang.zulipchat.com/#narrow/channel/238009-t-compiler.2Fmeetings/topic/.5Bweekly.5D.202023-01-26/near/323755789
[zulip stop accepting broken code]: https://rust-lang.zulipchat.com/#narrow/stream/266220-rustdoc/topic/stop.20accepting.20broken.20code
[notriddle rfc]: https://rust-lang.zulipchat.com/#narrow/channel/266220-t-rustdoc/topic/Pre-RFC.3A.20stop.20accepting.20broken.20code
[`tests/rustdoc-ui/error-in-impl-trait`]: https://github.com/rust-lang/rust/tree/163cb4ea3f0ae3bc7921cc259a08a7bf92e73ee6/tests/rustdoc-ui/error-in-impl-trait
## Multiple runs, same output directory
Rustdoc can be run multiple times for varying inputs, with its output set to the

4
src/solve/coinduction.md
View File

@ -237,14 +237,14 @@ Alternatively, we could simply always treat the equate branch of `normalizes_to`
Any cycles should result in infinite types, which aren't supported anyways and would only
result in overflow when deeply normalizing for codegen.
experimentation and examples: https://hackmd.io/-8p0AHnzSq2VAE6HE_wX-w?view
experimentation and examples: <https://hackmd.io/-8p0AHnzSq2VAE6HE_wX-w?view>
Another attempt at a summary.
- in projection eq, we must make progress with constraining the rhs
- a cycle is only ok if while equating we have a rigid ty on the lhs after norm at least once
- cycles outside of the recursive `eq` call of `normalizes_to` are always fine
[^1]: related: https://coq.inria.fr/refman/language/core/coinductive.html#top-level-definitions-of-corecursive-functions
[^1]: related: <https://coq.inria.fr/refman/language/core/coinductive.html#top-level-definitions-of-corecursive-functions>
[perfect derive]: https://smallcultfollowing.com/babysteps/blog/2022/04/12/implied-bounds-and-perfect-derive
[ex1]: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=0a9c3830b93a2380e6978d6328df8f72

4
src/solve/opaque-types.md
View File

@ -1,8 +1,10 @@
# Opaque types in the new solver
The way opaque types are handled in the new solver differs from the old implementation.
The way [opaque types] are handled in the new solver differs from the old implementation.
This should be a self-contained explanation of the behavior in the new solver.
[opaque types]: ../opaque-types-type-alias-impl-trait.md
## opaques are alias types
Opaque types are treated the same as other aliases, most notabily associated types,

26
src/tests/ci.md
View File

@ -66,9 +66,9 @@ kinds of builds (sets of jobs).
### Pull Request builds
After each push to a pull request, a set of `pr` jobs are executed. Currently,
these execute the `x86_64-gnu-llvm-X`, `x86_64-gnu-tools`, `mingw-check` and
`mingw-check-tidy` jobs, all running on Linux. These execute a relatively short
(~30 minutes) and lightweight test suite that should catch common issues. More
these execute the `x86_64-gnu-llvm-X`, `x86_64-gnu-tools`, `mingw-check-1`, `mingw-check-2`
and `mingw-check-tidy` jobs, all running on Linux. These execute a relatively short
(~40 minutes) and lightweight test suite that should catch common issues. More
specifically, they run a set of lints, they try to perform a cross-compile check
build to Windows mingw (without producing any artifacts) and they test the
compiler using a *system* version of LLVM. Unfortunately, it would take too many
@ -100,8 +100,8 @@ Most platforms only run the build steps, some run a restricted set of tests,
only a subset run the full suite of tests (see Rust's [platform tiers]).
Auto jobs are defined in the `auto` section of [`jobs.yml`]. They are executed
on the `auto` branch under the `rust-lang-ci/rust` repository[^rust-lang-ci] and
their results can be seen [here](https://github.com/rust-lang-ci/rust/actions),
on the `auto` branch under the `rust-lang/rust` repository and
their results can be seen [here](https://github.com/rust-lang/rust/actions),
although usually you will be notified of the result by a comment made by bors on
the corresponding PR.
@ -110,9 +110,6 @@ more [here](#merging-prs-serially-with-bors).
[platform tiers]: https://forge.rust-lang.org/release/platform-support.html#rust-platform-support
[^rust-lang-ci]: The `auto` and `try` jobs run under the `rust-lang-ci` fork for
historical reasons. This may change in the future.
### Try builds
Sometimes we want to run a subset of the test suite on CI for a given PR, or
@ -179,8 +176,8 @@ the pattern as Markdown.
> that are exercised this way.
Try jobs are defined in the `try` section of [`jobs.yml`]. They are executed on
the `try` branch under the `rust-lang-ci/rust` repository[^rust-lang-ci] and
their results can be seen [here](https://github.com/rust-lang-ci/rust/actions),
the `try` branch under the `rust-lang/rust` repository and
their results can be seen [here](https://github.com/rust-lang/rust/actions),
although usually you will be notified of the result by a comment made by bors on
the corresponding PR.
@ -189,9 +186,11 @@ Note that if you start the default try job using `@bors try`, it will skip build
Multiple try builds can execute concurrently across different PRs.
<div class="warning">
bors identify try jobs by commit hash. This means that if you have two PRs
Bors identifies try jobs by commit hash. This means that if you have two PRs
containing the same (latest) commits, running `@bors try` will result in the
*same* try job and it really confuses `bors`. Please refrain from doing so.
</div>
[rustc-perf]: https://github.com/rust-lang/rustc-perf
@ -355,7 +354,7 @@ invalidated if one of the following changes:
- Files copied into the Docker image in the Dockerfile
- The architecture of the GitHub runner (x86 or ARM)
[ghcr.io]: https://github.com/rust-lang-ci/rust/pkgs/container/rust-ci
[ghcr.io]: https://github.com/rust-lang/rust/pkgs/container/rust-ci
[Docker registry caching]: https://docs.docker.com/build/cache/backends/registry/
### LLVM caching with sccache
@ -446,7 +445,7 @@ particular job, it is probably easiest to just look at the build log. To do
this:
1. Go to
<https://github.com/rust-lang-ci/rust/actions?query=branch%3Aauto+is%3Asuccess>
<https://github.com/rust-lang/rust/actions?query=branch%3Aauto+is%3Asuccess>
to find the most recently successful build, and click on it.
2. Choose the job you are interested in on the left-hand side.
3. Click on the gear icon and choose "View raw logs"
@ -458,7 +457,6 @@ this:
[`jobs.yml`]: https://github.com/rust-lang/rust/blob/master/src/ci/github-actions/jobs.yml
[`.github/workflows/ci.yml`]: https://github.com/rust-lang/rust/blob/master/.github/workflows/ci.yml
[`src/ci/citool`]: https://github.com/rust-lang/rust/blob/master/src/ci/citool
[rust-lang-ci]: https://github.com/rust-lang-ci/rust/actions
[bors]: https://github.com/bors
[homu]: https://github.com/rust-lang/homu
[merge queue]: https://bors.rust-lang.org/queue/rust

19
src/tests/compiletest.md
View File

@ -438,7 +438,9 @@ To work around this when working on a particular test, temporarily create a
with these contents:
<div class="warning">
Be careful not to add this `Cargo.toml` or its `Cargo.lock` to your actual PR!
</div>
```toml
@ -546,10 +548,10 @@ only running the main `coverage` suite.
[`tests/crashes`] serve as a collection of tests that are expected to cause the
compiler to ICE, panic or crash in some other way, so that accidental fixes are
tracked. This was formally done at <https://github.com/rust-lang/glacier> but
tracked. Formerly, this was done at <https://github.com/rust-lang/glacier> but
doing it inside the rust-lang/rust testsuite is more convenient.
It is imperative that a test in the suite causes rustc to ICE, panic or crash
It is imperative that a test in the suite causes rustc to ICE, panic, or
crash in some other way. A test will "pass" if rustc exits with an exit status
other than 1 or 0.
@ -560,9 +562,12 @@ If you want to see verbose stdout/stderr, you need to set
$ COMPILETEST_VERBOSE_CRASHES=1 ./x test tests/crashes/999999.rs --stage 1
```
When adding crashes from <https://github.com/rust-lang/rust/issues>, the issue
number should be noted in the file name (`12345.rs` should suffice) and also
inside the file include a `//@ known-bug: #4321` directive.
Anyone can add ["untracked" crashes] from the issue tracker. It's strongly
recommended to include test cases from several issues in a single PR.
When you do so, each issue number should be noted in the file name (`12345.rs`
should suffice) and also inside the file by means of a `//@ known-bug: #12345`
directive. Please [label][labeling] the relevant issues with `S-bug-has-test`
afterwards.
If you happen to fix one of the crashes, please move it to a fitting
subdirectory in `tests/ui` and give it a meaningful name. Please add a doc
@ -585,6 +590,8 @@ a subset first. The issue numbers can be found in the file name or the `//@
known-bug` directive inside the test file.
[`tests/crashes`]: https://github.com/rust-lang/rust/tree/master/tests/crashes
["untracked" crashes]: https://github.com/rust-lang/rust/issues?q=is%3Aissue+state%3Aopen+label%3AI-ICE%2CI-crash+label%3AT-compiler+label%3AS-has-mcve+-label%3AS-bug-has-test
[labeling]: https://forge.rust-lang.org/release/issue-triaging.html#applying-and-removing-labels
## Building auxiliary crates
@ -614,7 +621,7 @@ file). The `-L` flag is used to find the extern crates.
`aux-crate` is very similar to `aux-build`. However, it uses the `--extern` flag
to link to the extern crate to make the crate be available as an extern prelude.
That allows you to specify the additional syntax of the `--extern` flag, such as
renaming a dependency. For example, `// aux-crate:foo=bar.rs` will compile
renaming a dependency. For example, `//@ aux-crate:foo=bar.rs` will compile
`auxiliary/bar.rs` and make it available under then name `foo` within the test.
This is similar to how Cargo does dependency renaming.

4
src/tests/directives.md
View File

@ -59,7 +59,7 @@ not be exhaustive. Directives can generally be found by browsing the
| `aux-crate` | Like `aux-build` but makes available as extern prelude | All except `run-make` | `<extern_prelude_name>=<path/to/aux/file.rs>` |
| `aux-codegen-backend` | Similar to `aux-build` but pass the compiled dylib to `-Zcodegen-backend` when building the main file | `ui-fulldeps` | Path to codegen backend file |
| `proc-macro` | Similar to `aux-build`, but for aux forces host and don't use `-Cprefer-dynamic`[^pm]. | All except `run-make` | Path to auxiliary proc-macro `.rs` file |
| `build_aux_docs` | Build docs for auxiliaries as well | All except `run-make` | N/A |
| `build-aux-docs` | Build docs for auxiliaries as well | All except `run-make` | N/A |
[^pm]: please see the Auxiliary proc-macro section in the
[compiletest](./compiletest.md) chapter for specifics.
@ -248,11 +248,13 @@ ignoring debuggers.
| `no-prefer-dynamic` | Don't use `-C prefer-dynamic`, don't build as a dylib via a `--crate-type=dylib` preset flag | `ui`, `crashes` | N/A |
<div class="warning">
Tests (outside of `run-make`) that want to use incremental tests not in the
incremental test-suite must not pass `-C incremental` via `compile-flags`, and
must instead use the `//@ incremental` directive.
Consider writing the test as a proper incremental test instead.
</div>
### Rustdoc

2
src/tests/minicore.md
View File

@ -7,9 +7,11 @@ ui/codegen/assembly test suites. It provides `core` stubs for tests that need to
build for cross-compiled targets but do not need/want to run.
<div class="warning">
Please note that [`minicore`] is only intended for `core` items, and explicitly
**not** `std` or `alloc` items because `core` items are applicable to a wider
range of tests.
</div>
A test can use [`minicore`] by specifying the `//@ add-core-stubs` directive.

4
src/tests/running.md
View File

@ -8,6 +8,7 @@ development because it takes a really long time. For local development, see the
subsection after on how to run a subset of tests.
<div class="warning">
Running plain `./x test` will build the stage 1 compiler and then run the whole
test suite. This not only include `tests/`, but also `library/`, `compiler/`,
`src/tools/` package tests and more.
@ -16,6 +17,7 @@ You usually only want to run a subset of the test suites (or even a smaller set
of tests than that) which you expect will exercise your changes. PR CI exercises
a subset of test collections, and merge queue CI will exercise all of the test
collection.
</div>
```text
@ -116,8 +118,10 @@ By listing which test suites you want to run,
you avoid having to run tests for components you did not change at all.
<div class="warning">
Note that bors only runs the tests with the full stage 2 build; therefore, while
the tests **usually** work fine with stage 1, there are some limitations.
</div>
### Run all tests using a stage 2 compiler

9
src/tests/ui.md
View File

@ -192,7 +192,7 @@ They have several forms, but generally are a comment with the diagnostic level
to write out the entire message, just make sure to include the important part of
the message to make it self-documenting.
The error annotation needs to match with the line of the diagnostic. There are
Most error annotations need to match with the line of the diagnostic. There are
several ways to match the message with the line (see the examples below):
* `~`: Associates the error level and message with the *current* line
@ -205,9 +205,6 @@ several ways to match the message with the line (see the examples below):
* `~v`: Associates the error level and message with the *next* error
annotation line. Each symbol (`v`) that you add adds a line to this, so `~vvv`
is three lines below the error annotation line.
* `~?`: Used to match error levels and messages with errors not having line
information. These can be placed on any line in the test file, but are
conventionally placed at the end.
Example:
@ -222,6 +219,10 @@ The space character between `//~` (or other variants) and the subsequent text is
negligible (i.e. there is no semantic difference between `//~ ERROR` and
`//~ERROR` although the former is more common in the codebase).
`~? <diagnostic kind>` (example being `~? ERROR`)
is used to match diagnostics without line information.
These can be placed on any line in the test file, but are conventionally placed at the end.
### Error annotation examples
Here are examples of error annotations on different lines of UI test source.

9
src/ty_module/binders.md
View File

@ -1,6 +1,6 @@
# `Binder` and Higher ranked regions
Sometimes we define generic parameters not on an item but as part of a type or a where clauses. As an example the type `for<'a> fn(&'a u32)` or the where clause `for<'a> T: Trait<'a>` both introduce a generic lifetime named `'a`. Currently there is no stable syntax for `for<T>` or `for<const N: usize>` but on nightly `feature(non_lifetime_binders)` feature can be used to write where clauses (but not types) using `for<T>`/`for<const N: usize>`.
Sometimes we define generic parameters not on an item but as part of a type or a where clause. As an example the type `for<'a> fn(&'a u32)` or the where clause `for<'a> T: Trait<'a>` both introduce a generic lifetime named `'a`. Currently there is no stable syntax for `for<T>` or `for<const N: usize>` but on nightly `feature(non_lifetime_binders)` can be used to write where clauses (but not types) using `for<T>`/`for<const N: usize>`.
The `for` is referred to as a "binder" because it brings new names into scope. In rustc we use the `Binder` type to track where these parameters are introduced and what the parameters are (i.e. how many and whether the parameter is a type/const/region). A type such as `for<'a> fn(&'a u32)` would be
represented in rustc as:
@ -13,8 +13,9 @@ Binder(
Usages of these parameters is represented by the `RegionKind::Bound` (or `TyKind::Bound`/`ConstKind::Bound` variants). These bound regions/types/consts are composed of two main pieces of data:
- A [DebruijnIndex](../appendix/background.md#what-is-a-de-bruijn-index) to specify which binder we are referring to.
- A [`BoundVar`] which specifies which of the parameters the `Binder` introduces we are referring to.
- We also sometimes store some extra information for diagnostics reasons via the [`BoundTyKind`]/[`BoundRegionKind`] but this is not important for type equality or more generally the semantics of `Ty`. (omitted from the above example)
- A [`BoundVar`] which specifies which of the parameters that the `Binder` introduces we are referring to.
We also sometimes store some extra information for diagnostics reasons via the [`BoundTyKind`]/[`BoundRegionKind`] but this is not important for type equality or more generally the semantics of `Ty`. (omitted from the above example)
In debug output (and also informally when talking to each other) we tend to write these bound variables in the format of `^DebruijnIndex_BoundVar`. The above example would instead be written as `Binder(fn(&'^0_0), &[BoundVariableKind::Region])`. Sometimes when the `DebruijnIndex` is `0` we just omit it and would write `^0`.
@ -43,7 +44,7 @@ Binder(
&[BoundVariableKind::Region(...)],
)
```
This would cause all kinds of issues as the region `'^1_0` refers to a binder at a higher level than the outermost binder i.e. it is an escaping bound var. The `'^1` region (also writeable as `'^0_1`) is also ill formed as the binder it refers to does not introduce a second parameter. Modern day rustc will ICE when constructing this binder due to both of those regions, in the past we would have simply allowed this to work and then ran into issues in other parts of the codebase.
This would cause all kinds of issues as the region `'^1_0` refers to a binder at a higher level than the outermost binder i.e. it is an escaping bound var. The `'^1` region (also writeable as `'^0_1`) is also ill formed as the binder it refers to does not introduce a second parameter. Modern day rustc will ICE when constructing this binder due to both of those reasons, in the past we would have simply allowed this to work and then ran into issues in other parts of the codebase.
[`Binder`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.Binder.html
[`BoundVar`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.BoundVar.html

4
src/ty_module/instantiating_binders.md
View File

@ -105,7 +105,8 @@ the `RePlaceholder` for the `'b` parameter is in a higher universe to track the
## Instantiating with `ReLateParam`
As discussed in a previous chapter, `RegionKind` has two variants for representing generic parameters, `ReLateParam` and `ReEarlyParam`. `ReLateParam` is conceptually a `Placeholder` that is always in the root universe (`U0`). It is used when instantiating late bound parameters of functions/closures while inside of them. Its actual representation is relatively different from both `ReEarlyParam` and `RePlaceholder`:
As discussed in [the chapter about representing types][representing-types], `RegionKind` has two variants for representing generic parameters, `ReLateParam` and `ReEarlyParam`.
`ReLateParam` is conceptually a `Placeholder` that is always in the root universe (`U0`). It is used when instantiating late bound parameters of functions/closures while inside of them. Its actual representation is relatively different from both `ReEarlyParam` and `RePlaceholder`:
- A `DefId` for the item that introduced the late bound generic parameter
- A [`BoundRegionKind`] which either specifies the `DefId` of the generic parameter and its name (via a `Symbol`), or that this placeholder is representing the anonymous lifetime of a `Fn`/`FnMut` closure's self borrow. There is also a variant for `BrAnon` but this is not used for `ReLateParam`.
@ -133,6 +134,7 @@ Generally whenever we have a `Binder` for late bound parameters on a function/cl
As a concrete example, accessing the signature of a function we are type checking will be represented as `EarlyBinder<Binder<FnSig>>`. As we are already "inside" of these binders, we would call `instantiate_identity` followed by `liberate_late_bound_regions`.
[`liberate_late_bound_regions`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TyCtxt.html#method.liberate_late_bound_regions
[representing-types]: param_ty_const_regions.md
[`BoundRegionKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/enum.BoundRegionKind.html
[`enter_forall`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_trait_selection/infer/struct.InferCtxt.html#method.enter_forall
[ch_placeholders_universes]: ../borrow_check/region_inference/placeholders_and_universes.md

12
src/ty_module/param_ty_const_regions.md
View File

@ -11,15 +11,15 @@ TyKind::Ref(
There are three separate ways we represent usages of generic parameters:
- [`TyKind::Param`]/[`ConstKind::Param`]/[`RegionKind::EarlyParam`] for early bound generic parameters (note: all type and const parameters are considered early bound, see the [chapter on early vs late bound parameters][ch_early_late_bound] for more information)
- [`TyKind::Bound`]/[`ConstKind::Bound`]/[`RegionKind::Bound`] for references to parameters introduced via higher ranked bounds or higher ranked types i.e. `for<'a> fn(&'a u32)` or `for<'a> T: Trait<'a>`. This will be discussed in the [chapter on `Binder`s][ch_binders].
- [`RegionKind::LateParam`] for late bound lifetime parameters, `LateParam` will be discussed in the [chapter on instantiating `Binder`s][ch_instantiating_binders].
- [`TyKind::Bound`]/[`ConstKind::Bound`]/[`RegionKind::Bound`] for references to parameters introduced via higher ranked bounds or higher ranked types i.e. `for<'a> fn(&'a u32)` or `for<'a> T: Trait<'a>`. This is discussed in the [chapter on `Binder`s][ch_binders].
- [`RegionKind::LateParam`] for late bound lifetime parameters, `LateParam` is discussed in the [chapter on instantiating `Binder`s][ch_instantiating_binders].
This chapter will only cover `TyKind::Param` `ConstKind::Param` and `RegionKind::EarlyParam`.
This chapter only covers `TyKind::Param` `ConstKind::Param` and `RegionKind::EarlyParam`.
## Ty/Const Parameters
As `TyKind::Param` and `ConstKind::Param` are implemented identically this section will only refer to `TyKind::Param` for simplicity. However
you should keep in mind that everything here also is true of `ConstKind::Param`
As `TyKind::Param` and `ConstKind::Param` are implemented identically this section only refers to `TyKind::Param` for simplicity.
However you should keep in mind that everything here also is true of `ConstKind::Param`
Each `TyKind::Param` contains two things: the name of the parameter and an index.
@ -83,7 +83,7 @@ fn foo<'a, 'b, T: 'a>(one: T, two: &'a &'b u32) -> &'b u32 {
}
```
`RegionKind::LateParam` will be discussed more in the chapter on [instantiating binders][ch_instantiating_binders].
`RegionKind::LateParam` is discussed more in the chapter on [instantiating binders][ch_instantiating_binders].
[ch_early_late_bound]: ../early_late_parameters.md
[ch_binders]: ./binders.md

7
src/typing_parameter_envs.md
View File

@ -32,7 +32,7 @@ where
<T as Trait>::Assoc: Clone,
{}
```
If we were conceptually inside of `foo` (for example, type-checking or linting it) we would use this `ParamEnv` everywhere that we interact with the type system. This would allow things such as normalization (TODO: write a chapter about normalization and link it), evaluating generic constants, and proving where clauses/goals, to rely on `T` being sized, implementing `Trait`, etc.
If we were conceptually inside of `foo` (for example, type-checking or linting it) we would use this `ParamEnv` everywhere that we interact with the type system. This would allow things such as [normalization], evaluating generic constants, and proving where clauses/goals, to rely on `T` being sized, implementing `Trait`, etc.
A more concrete example:
```rust
@ -70,6 +70,7 @@ fn foo2<T>(a: T) {
[predicates_of]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir_analysis/collect/predicates_of/fn.predicates_of.html
[method_pred_entailment]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_hir_analysis/check/compare_impl_item/fn.compare_method_predicate_entailment.html
[query]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/context/struct.TyCtxt.html#method.param_env
[normalization]: normalization.md
### Acquiring a `ParamEnv`
@ -199,8 +200,8 @@ In the next-gen trait solver the requirement for all where clauses in the `Param
Depending on what context we are performing type system operations in, different behaviour may be required. For example during coherence there are stronger requirements about when we can consider goals to not hold or when we can consider types to be unequal.
Tracking which "phase" of the compiler type system operations are being performed in is done by the [`TypingMode`][tenv] enum. The documentation on the `TypingMode` enum is quite good so instead of repeating it here verbatim we would recommend reading the API documentation directly.
Tracking which "phase" of the compiler type system operations are being performed in is done by the [`TypingMode`][tmode] enum. The documentation on the `TypingMode` enum is quite good so instead of repeating it here verbatim we would recommend reading the API documentation directly.
[penv]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.ParamEnv.html
[tenv]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_type_ir/infer_ctxt/enum.TypingMode.html
[tenv]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TypingEnv.html
[tmode]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.TypingMode.html

76
triagebot.toml
View File

@ -1,18 +1,82 @@
[assign]
# This file's format is documented at
# https://forge.rust-lang.org/triagebot/pr-assignment.html#configuration
[autolabel."needs-triage"]
new_issue = true
exclude_labels = [
"A-diagnostics",
"C-tracking-issue",
]
[review-submitted]
# This label is added when a "request changes" review is submitted.
reviewed_label = "S-waiting-on-author"
# These labels are removed when a "request changes" review is submitted.
review_labels = ["S-waiting-on-review"]
[review-requested]
# Those labels are removed when PR author requests a review from an assignee
remove_labels = ["S-waiting-on-author"]
# Those labels are added when PR author requests a review from an assignee
add_labels = ["S-waiting-on-review"]
# Enable shortcuts like `@rustbot ready`
# Documentation at: https://forge.rust-lang.org/triagebot/shortcuts.html
[shortcut]
[autolabel."S-waiting-on-review"]
new_pr = true
# Enable issue transfers within the org
# Documentation at: https://forge.rust-lang.org/triagebot/transfer.html
[transfer]
[relabel]
allow-unauthenticated = [
"waiting-on-review",
"waiting-on-author",
"blocked",
"-Z*",
"A-*",
"C-*",
"D-*",
"E-*",
"F-*",
"I-*",
"L-*",
"O-*",
"PG-*",
"S-*",
"T-*",
"WG-*",
"needs-triage",
]
# Enable `@rustbot note` functionality
# Documentation at: https://forge.rust-lang.org/triagebot/note.html
[note]
# Prevents mentions in commits to avoid users being spammed
# Documentation at: https://forge.rust-lang.org/triagebot/no-mentions.html
[no-mentions]
[canonicalize-issue-links]
# Canonicalize issue numbers to avoid closing the wrong issue
# when commits are included in subtrees, as well as warning links in commits.
# Documentation at: https://forge.rust-lang.org/triagebot/issue-links.html
[issue-links]
# Automatically close and reopen PRs made by bots to run CI on them
[bot-pull-requests]
[behind-upstream]
days-threshold = 7
days-threshold = 7
# Enable triagebot (PR) assignment.
# Documentation at: https://forge.rust-lang.org/triagebot/pr-assignment.html
[assign]
# Keep members alphanumerically sorted.
[assign.adhoc_groups]
rustc-dev-guide = [
"@BoxyUwU",
"@jieyouxu",
"@jyn514",
"@tshepang",
]