For example:
enum Ty {
Unit,
List(Box<Ty>),
}
fn foo(x: Ty) -> Ty {
match x {
Ty::Unit => Ty::Unit,
Ty::List(elem) => foo(elem),
}
}
Before, the only suggestion was to rewrap `elem` with `Ty::List`,
which is unhelpful and confusing:
error[E0308]: mismatched types
--> src/test/ui/suggestions/boxed-variant-field.rs:9:31
|
9 | Ty::List(elem) => foo(elem),
| ^^^^
| |
| expected enum `Ty`, found struct `Box`
| help: try using a variant of the expected enum: `Ty::List(elem)`
|
= note: expected enum `Ty`
found struct `Box<Ty>`
Now, rustc will first suggest dereferencing the `Box`, which is most
likely what the user intended:
error[E0308]: mismatched types
--> src/test/ui/suggestions/boxed-variant-field.rs:9:31
|
9 | Ty::List(elem) => foo(elem),
| ^^^^ expected enum `Ty`, found struct `Box`
|
= note: expected enum `Ty`
found struct `Box<Ty>`
help: try dereferencing the `Box`
|
9 | Ty::List(elem) => foo(*elem),
| +
help: try using a variant of the expected enum
|
9 | Ty::List(elem) => foo(Ty::List(elem)),
| ~~~~~~~~~~~~~~
Append .0 to unsuffixed float if it would otherwise become int token
Previously the unsuffixed f32/f64 constructors of `proc_macro::Literal` would create literal tokens that are definitely not a float:
```rust
Literal::f32_unsuffixed(10.0) // 10
Literal::f32_suffixed(10.0) // 10f32
Literal::f64_unsuffixed(10.0) // 10
Literal::f64_suffixed(10.0) // 10f64
```
Notice that the `10` are actually integer tokens if you were to reparse them, not float tokens.
This diff updates `Literal::f32_unsuffixed` and `Literal::f64_unsuffixed` to produce tokens that unambiguously parse as a float. This matches longstanding behavior of the proc-macro2 crate's implementation of these APIs dating back at least 3.5 years, so it's likely an unobjectionable behavior.
```rust
Literal::f32_unsuffixed(10.0) // 10.0
Literal::f32_suffixed(10.0) // 10f32
Literal::f64_unsuffixed(10.0) // 10.0
Literal::f64_suffixed(10.0) // 10f64
```
Fixes https://github.com/dtolnay/syn/issues/1085.
Implementation of GATs outlives lint
See #87479 for background. Closes#87479
The basic premise of this lint/error is to require the user to write where clauses on a GAT when those bounds can be implied or proven from any function on the trait returning that GAT.
## Intuitive Explanation (Attempt) ##
Let's take this trait definition as an example:
```rust
trait Iterable {
type Item<'x>;
fn iter<'a>(&'a self) -> Self::Item<'a>;
}
```
Let's focus on the `iter` function. The first thing to realize is that we know that `Self: 'a` because of `&'a self`. If an impl wants `Self::Item` to contain any data with references, then those references must be derived from `&'a self`. Thus, they must live only as long as `'a`. Furthermore, because of the `Self: 'a` implied bound, they must live only as long as `Self`. Since it's `'a` is used in place of `'x`, it is reasonable to assume that any value of `Self::Item<'x>`, and thus `'x`, will only be able to live as long as `Self`. Therefore, we require this bound on `Item` in the trait.
As another example:
```rust
trait Deserializer<T> {
type Out<'x>;
fn deserialize<'a>(&self, input: &'a T) -> Self::Out<'a>;
}
```
The intuition is similar here, except rather than a `Self: 'a` implied bound, we have a `T: 'a` implied bound. Thus, the data on `Self::Out<'a>` is derived from `&'a T`, and thus it is reasonable to expect that the lifetime `'x` will always be less than `T`.
## Implementation Algorithm ##
* Given a GAT `<P0 as Trait<P1..Pi>>::G<Pi...Pn>` declared as `trait T<A1..Ai> for A0 { type G<Ai...An>; }` used in return type of one associated function `F`
* Given env `E` (including implied bounds) for `F`
* For each lifetime parameter `'a` in `P0...Pn`:
* For each other type parameter `Pi != 'a` in `P0...Pn`: // FIXME: this include of lifetime parameters too
* If `E => (P: 'a)`:
* Require where clause `Ai: 'a`
## Follow-up questions ##
* What should we do when we don't pass params exactly?
For this example:
```rust
trait Des {
type Out<'x, D>;
fn des<'z, T>(&self, data: &'z Wrap<T>) -> Self::Out<'z, Wrap<T>>;
}
```
Should we be requiring a `D: 'x` clause? We pass `Wrap<T>` as `D` and `'z` as `'x`, and should be able to prove that `Wrap<T>: 'z`.
r? `@nikomatsakis`
Rollup of 5 pull requests
Successful merges:
- #89942 (Reorder `widening_impl`s to make the doc clearer)
- #90569 (Fix tests using `only-i686` to use the correct `only-x86` directive)
- #90597 (Warn for variables that are no longer captured)
- #90623 (Remove more checks for LLVM < 12)
- #90626 (Properly register text_direction_codepoint_in_comment lint.)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Properly register text_direction_codepoint_in_comment lint.
This makes it known to the compiler so it can be configured like with `#![allow(text_direction_codepoint_in_comment)]`.
Fixes#90614.
Fix ICE when rustdoc is scraping examples inside of a proc macro
This PR provides a clearer semantics for how --scrape-examples interacts with macros. If an expression's span AND it's enclosing item's span both are not `from_expansion`, then the example will be scraped. The added test case `rustdoc-scrape-examples-macros` shows a variety of situations.
* A macro-rules macro that takes a function call as input: good
* A macro-rules macro that generates a function call as output: bad
* A proc-macro that generates a function call as output: bad
* An attribute macro that generates a function call as output: bad
* An attribute macro that takes a function call as input: good, if the proc macro is designed to propagate the input spans
I ran this updated rustdoc on pyo3 and confirmed that it successfully scrapes examples from inside a proc macro, eg
<img width="1013" alt="Screen Shot 2021-11-04 at 1 11 28 PM" src="https://user-images.githubusercontent.com/663326/140412691-81a3bb6b-a448-4a1b-a293-f7a795553634.png">
(cc `@mejrs)`
Additionally, this PR fixes an ordering bug in the highlighting logic.
Fixes https://github.com/rust-lang/rust/issues/90567.
r? `@jyn514`
Clean up some `-Z unstable-options` in tests.
Several of these tests were for features that have been stabilized, or otherwise don't need `-Z unstable-options`.
Add beginner friendly lifetime elision hint to E0623
Address #90170
Suggest adding a new lifetime parameter when two elided lifetimes should match up but don't.
Example:
```
error[E0623]: lifetime mismatch
--> $DIR/issue-90170-elision-mismatch.rs:2:35
|
LL | fn foo(slice_a: &mut [u8], slice_b: &mut [u8]) {
| --------- --------- these two types are declared with different lifetimes...
LL | core::mem::swap(&mut slice_a, &mut slice_b);
| ^^^^^^^^^^^^ ...but data from `slice_b` flows into `slice_a` here
|
= note: each elided lifetime in input position becomes a distinct lifetime
help: explicitly declare a lifetime and assign it to both
|
LL | fn foo<'a>(slice_a: &'a mut [u8], slice_b: &'a mut [u8]) {
| ++++ ++ ++
```
for
```rust
fn foo(slice_a: &mut [u8], slice_b: &mut [u8]) {
core::mem::swap(&mut slice_a, &mut slice_b);
}
```
Suggest adding a new lifetime parameter when two elided lifetimes should match up but don't
Issue #90170
This also changes the tests introduced by the previous commits because of another rustc issue (#90258)
The exact set of permissions granted when forming a raw reference is
currently undecided https://github.com/rust-lang/rust/issues/56604.
To avoid presupposing any particular outcome, adjust the const
qualification to be compatible with decision where raw reference
constructed from `addr_of!` grants mutable access.
Split doc_cfg and doc_auto_cfg features
Part of #90497.
With this feature, `doc_cfg` won't pick up items automatically anymore.
cc `@Mark-Simulacrum`
r? `@jyn514`
Collect `panic/panic_bounds_check` during monomorphization
This would prevent link time errors if these functions are `#[inline]` (e.g. when `panic_immediate_abort` is used).
Fix#90405Fixrust-lang/cargo#10019
`@rustbot` label: T-compiler A-codegen
