When encountering `pub ident`, attempt to identify the code that comes
afterwards, wether it is a brace block (assume it is a struct), a paren
list followed by a colon (assume struct) or a paren list followed by a
block (assume a fn). Consume those blocks to avoid any further parser
errors and return a `Placeholder` item in order to allow the parser to
continue. In the case of unenclosed blocks, the behavior is the same as
it is currently: no further errors are processed.
Add error for `...` in expressions
Follow-up to https://github.com/rust-lang/rust/pull/44709
Tracking issue: https://github.com/rust-lang/rust/issues/28237
* Using `...` in expressions was a warning, now it's an error
* The error message suggests using `..` or `..=` instead, and explains the difference
* Updated remaining occurrences of `...` to `..=`
r? petrochenkov
Detect `=` -> `:` typo in let bindings
When encountering a let binding type error, attempt to parse as
initializer instead. If successful, it is likely just a typo:
```rust
fn main() {
let x: Vec::with_capacity(10);
}
```
```
error: expected type, found `10`
--> file.rs:3:31
|
3 | let x: Vec::with_capacity(10, 20);
| -- ^^
| ||
| |help: did you mean assign here?: `=`
| while parsing the type for `x`
```
Fix#43703.
Add a nicer error message for missing in for loop, fixes#40782.
As suggested by @estebank in issue #40782, this works in the same way as #42578: if the in keyword is missing, we continue parsing the expression and if this works correctly an adapted error message is produced. Otherwise we return the old error.
A specific test case has also been added.
This is my first PR on rust-lang/rust so any feedback is very welcome.
When encountering a let binding type error, attempt to parse as
initializer instead. If successful, it is likely just a typo:
```rust
fn main() {
let x: Vec::with_capacity(10);
}
```
```
error: expected type, found `10`
--> file.rs:3:31
|
3 | let x: Vec::with_capacity(10, 20);
| -- ^^
| ||
| |help: did you mean assign here?: `=`
| while parsing the type for `x`
```
DefaultImpl is a highly confusing name for what we now call auto impls,
as in `impl Send for ..`. The name auto impl is not formally decided
but for sanity anything is better than `DefaultImpl` which refers
neither to `default impl` nor to `impl Default`.
This multiline string literal was missing a backslash, leaving an awkward
newline and 35 spaces in the middle of the message.
But while we're here, the existing message seems kind of long in comparison to
similar notes: to cut it down, we excise the mentions of doc comments, which
seems sensible because we know that this erroneous attribute is not a doc
comment (notice the `is_sugared_doc: false` at the end of the function; if it
had been a doc comment, that error would get set in the `token::DocComment`
match branch of `parse_outer_attributes`).
Implement RFC 1861: Extern types
A few notes :
- Type parameters are not supported. This was an unresolved question from the RFC. It is not clear how useful this feature is, and how variance should be treated. This can be added in a future PR.
- `size_of_val` / `align_of_val` can be called with extern types, and respectively return 0 and 1. This differs from the RFC, which specified that they should panic, but after discussion with @eddyb on IRC this seems like a better solution.
If/when a `DynSized` trait is added, this will be disallowed statically.
- Auto traits are not implemented by default, since the contents of extern types is unknown. This means extern types are `!Sync`, `!Send` and `!Freeze`. This seems like the correct behaviour to me.
Manual `unsafe impl Sync for Foo` is still possible.
- This PR allows extern type to be used as the tail of a struct, as described by the RFC :
```rust
extern {
type OpaqueTail;
}
#[repr(C)]
struct FfiStruct {
data: u8,
more_data: u32,
tail: OpaqueTail,
}
```
However this is undesirable, as the alignment of `tail` is unknown (the current PR assumes an alignment of 1). Unfortunately we can't prevent it in the general case as the tail could be a type parameter :
```rust
#[repr(C)]
struct FfiStruct<T: ?Sized> {
data: u8,
more_data: u32,
tail: T,
}
```
Adding a `DynSized` trait would solve this as well, by requiring tail fields to be bound by it.
- Despite being unsized, pointers to extern types are thin and can be casted from/to integers. However it is not possible to write a `null<T>() -> *const T` function which works with extern types, as I've explained here : https://github.com/rust-lang/rust/issues/43467#issuecomment-321678621
- Trait objects cannot be built from extern types. I intend to support it eventually, although how this interacts with `DynSized`/`size_of_val` is still unclear.
- The definition of `c_void` is unmodified
Improve diagnostics when list of tokens has incorrect separators
Make `parse_seq_to_before_tokens` more resilient to error conditions. Where possible it is better if it can consume up to the final bracket before returning. This change improves the diagnostics in a couple of situations:
```
struct S(pub () ()); // omitted separator
use std::{foo. bar}; // used a similar but wrong separator
```
Fixes#44339
r? @petrochenkov
