Recover keywords in trait bounds
(_this pr was inspired by [this tweet](https://twitter.com/Azumanga/status/1552982326409367561)_)
Recover keywords in trait bound, motivational example:
```rust
fn f(_: impl fn()) {} // mistyped, meant `Fn`
```
<details><summary>Current nightly (3 needless and confusing errors!)</summary>
<p>
```text
error: expected identifier, found keyword `fn`
--> ./t.rs:1:15
|
1 | fn _f(_: impl fn()) {}
| ^^ expected identifier, found keyword
|
help: escape `fn` to use it as an identifier
|
1 | fn _f(_: impl r#fn()) {}
| ++
error: expected one of `:` or `|`, found `)`
--> ./t.rs:1:19
|
1 | fn _f(_: impl fn()) {}
| ^ expected one of `:` or `|`
error: expected one of `!`, `(`, `)`, `,`, `?`, `for`, `~`, lifetime, or path, found keyword `fn`
--> ./t.rs:1:15
|
1 | fn _f(_: impl fn()) {}
| -^^ expected one of 9 possible tokens
| |
| help: missing `,`
error: at least one trait must be specified
--> ./t.rs:1:10
|
1 | fn _f(_: impl fn()) {}
| ^^^^
```
</p>
</details>
This PR:
```text
error: expected identifier, found keyword `fn`
--> ./t.rs:1:15
|
1 | fn _f(_: impl fn()) {}
| ^^ expected identifier, found keyword
|
help: escape `fn` to use it as an identifier
|
1 | fn _f(_: impl r#fn()) {}
| ++
error[E0405]: cannot find trait `r#fn` in this scope
--> ./t.rs:1:15
|
1 | fn _f(_: impl fn()) {}
| ^^ help: a trait with a similar name exists (notice the capitalization): `Fn`
|
::: /home/waffle/projects/repos/rust/library/core/src/ops/function.rs:74:1
|
74 | pub trait Fn<Args>: FnMut<Args> {
| ------------------------------- similarly named trait `Fn` defined here
```
It would be nice to have suggestion in the first error like "have you meant `Fn` trait", instead of a separate error, but the recovery is deep inside ident parsing, which makes it a lot harder to do.
r? `@compiler-errors`
implied bounds: explicitly state which types are assumed to be wf
Adds a new query which maps each definition to the types which that definition assumes to be well formed. The intent is to make it easier to reason about implied bounds.
This change should not influence the user-facing behavior of rustc. Notably, `borrowck` still only assumes that the function signature of associated functions is well formed while `wfcheck` assumes that the both the function signature and the impl trait ref is well formed. Not sure if that by itself can trigger UB or whether it's just annoying.
As a next step, we can add `WellFormed` predicates to `predicates_of` of these items and can stop adding the wf bounds at each place which uses them. I also intend to move the computation from `assumed_wf_types` to `implied_bounds` into the `param_env` computation. This requires me to take a deeper look at `compare_predicate_entailment` which is currently somewhat weird wrt implied bounds so I am not touching this here.
r? `@nikomatsakis`
Use `AttrVec` more
In some places we use `Vec<Attribute>` and some places we use
`ThinVec<Attribute>` (a.k.a. `AttrVec`). This results in various points
where we have to convert between `Vec` and `ThinVec`.
This commit changes the places that use `Vec<Attribute>` to use
`AttrVec`. A lot of this is mechanical and boring, but there are
some interesting parts:
- It adds a few new methods to `ThinVec`.
- It implements `MapInPlace` for `ThinVec`, and introduces a macro to
avoid the repetition of this trait for `Vec`, `SmallVec`, and
`ThinVec`.
Overall, it makes the code a little nicer, and has little effect on
performance. But it is a precursor to removing
`rustc_data_structures::ThinVec` and replacing it with
`thin_vec::ThinVec`, which is implemented more efficiently.
r? `@spastorino`
Rework "point at arg" suggestions to be more accurate
Fixes#100560
Introduce a new set of `ObligationCauseCode`s which have additional bookeeping for what expression caused the obligation, and which predicate caused the obligation. This allows us to look at the _unsubstituted_ signature to find out which parameter or generic type argument caused an obligaton to fail.
This means that (in most cases) we significantly improve the likelihood of pointing out the right argument that causes a fulfillment error. Also, since this logic isn't happening in just the `select_where_possible_and_mutate_fulfillment()` calls in the argument checking code, but instead during all trait selection in `FnCtxt`, we are also able to point out the correct argument even if inference means that we don't know whether an obligation has failed until well after a call expression has been checked.
r? `@ghost`
In some places we use `Vec<Attribute>` and some places we use
`ThinVec<Attribute>` (a.k.a. `AttrVec`). This results in various points
where we have to convert between `Vec` and `ThinVec`.
This commit changes the places that use `Vec<Attribute>` to use
`AttrVec`. A lot of this is mechanical and boring, but there are
some interesting parts:
- It adds a few new methods to `ThinVec`.
- It implements `MapInPlace` for `ThinVec`, and introduces a macro to
avoid the repetition of this trait for `Vec`, `SmallVec`, and
`ThinVec`.
Overall, it makes the code a little nicer, and has little effect on
performance. But it is a precursor to removing
`rustc_data_structures::thin_vec::ThinVec` and replacing it with
`thin_vec::ThinVec`, which is implemented more efficiently.
rustdoc: Merge source code pages HTML elements together v2
This is the follow-up of https://github.com/rust-lang/rust/pull/100429.
I strongly recommend to review it one commit at a time because otherwise it's a lot at once.
For these ones, on each page, I run this JS: `document.getElementsByTagName('*').length`. The goal is to count the number of DOM elements. I took some pages that seemed big, but don't hesitate to check some others. I also added the "starting point" because it's quite nice to see how much the page was reduced thanks to these two PRs.
| file name | before #100429 | before this PR | with this PR | diff |
|-|-|-|-|-|
| std/lib.rs.html (source link on std crate page) | 3455 | 2332 | 1772 | 24% |
| alloc/vec/mod.rs.html (source on Vec type page) | 11012 | 5982 | 5833 | 2.5% |
| alloc/string.rs.html (source on String type page) | 10800 | 6010 | 5822 | 3.2% |
| std/sync/mutex.rs.html (source on Mutex type page) | 2953 | 2041 | 2038 | 0.1% |
So unsurprisingly, the more attributes you have, the bigger the difference.
You can test it [here](https://rustdoc.crud.net/imperio/reduce-span-v2/src/std/lib.rs.html).
cc ``````@jsha``````
r? ``````@notriddle``````
Clamp Function for f32 and f64
I thought the clamp function could use a little improvement for readability purposes. The function now returns early in order to skip the extra bound checks.
If there was a reason for binding `self` to `x` or if this code is incorrect, please correct me :)
Deriving SessionDiagnostic on a type no longer forces that diagnostic to
be one of warning, error, or fatal. The level is instead decided when
the struct is passed to the respective Handler::emit_*() method.
I couldn't find where exactly it's documented, but apperantly pointers to void
type are invalid in llvm - void is only allowed as a return type of functions.
Refactor: remove unnecessary string searchings
This patch removes unnecessary string searchings for checking if function arguments have `&` and `&mut`.
Reenable disabled early syntax gates as future-incompatibility lints
- MCP: https://github.com/rust-lang/compiler-team/issues/535
The approach taken by this PR is
- Introduce a new lint, `unstable_syntax_pre_expansion`, and reenable the early syntax gates to emit it
- Use the diagnostic stashing mechanism to stash warnings the early warnings
- When the hard error occurs post expansion, steal and cancel the early warning
- Don't display any stashed warnings if errors are present to avoid the same noise problem that hiding type ascription errors is avoiding
Commits are working commits, but in a coherent steps-to-implement manner. Can be squashed if desired.
The preexisting `soft_unstable` lint seems like it would've been a good fit, but it is deny-by-default (appropriate for `#[bench]`) and these gates should be introduced as warn-by-default.
It may be desirable to change the stash mechanism's behavior to not flush lint errors in the presence of other errors either (like is done for warnings here), but upgrading a stash-using lint from warn to error perhaps is enough of a request to see the lint that they shouldn't be hidden; additionally, fixing the last error to get new errors thrown at you always feels bad, so if we know the lint errors are present, we should show them.
Using a new flag/mechanism for a "weak diagnostic" which is suppressed by other errors may also be desirable over assuming any stashed warnings are "weak," but this is the first user of stashing warnings and seems an appropriate use of stashing (it follows the "know more later to refine the diagnostic" pattern; here we learn that it's in a compiled position) so we get to define what it means to stash a non-hard-error diagnostic.
cc `````@petrochenkov````` (seconded MCP)
Add LLVM15-specific codegen test for `try`/`?`s that now optimize away
These still generated a bunch of code back in Rust 1.63 (<https://rust.godbolt.org/z/z31P8h6rz>), but with LLVM 15 merged they no longer do 🎉
Make `same_type_modulo_infer` a proper `TypeRelation`
Specifically, this fixes#100690 because we no longer consider a `ReLateBound` and a `ReVar` to be equal. `ReVar` can only be equal to free regions or static.
