Allow attributes in formal function parameters
Implements https://github.com/rust-lang/rust/issues/60406.
This is my first contribution to the compiler and since this is a large and complex project, I am not fully aware of the consequences of the changes I have made.
**TODO**
- [x] Forbid some built-in attributes.
- [x] Expand cfg/cfg_attr
lexer: Disallow bare CR in raw byte strings
Handles bare CR ~but doesn't translate `\r\n` to `\n` yet in raw strings yet~ and translates CRLF to LF in raw strings.
As a side-note I think it'd be good to change the `unescape_` to return plain iterators to reduce some boilerplate (e.g. `has_error` could benefit from collecting `Result<T>` and aborting early on errors) but will do that separately, unless I missed something here that prevents it.
@matklad @petrochenkov thoughts?
Mention that `self` is only valid on "associated functions"
```
error: unexpected `self` argument in function
--> $DIR/self-in-function-arg.rs:1:15
|
LL | fn foo(x:i32, self: i32) -> i32 { self }
| ^^^^ not valid as function argument
|
= note: `self` is only valid as the first argument of an associated function
```
When it is a method, mention it must be first
```
error: unexpected `self` argument in function
--> $DIR/trait-fn.rs:4:20
|
LL | fn c(foo: u32, self) {}
| ^^^^ must be the first associated function argument
```
- Add detail on origin of current parser when reaching EOF and stop
saying "found <eof>" and point at the end of macro calls
- Handle empty `cfg_attr` attribute
- Reword empty `derive` attribute error
Remove `ObsoleteInPlace`
The in place syntax has been deprecated for over a year. As it is, this is accumulated cruft: the error messages are unlikely to be helpful any more and it conflicts with some useful syntax (e.g. const generics in some instances).
It may be that removing `Token::LArrow` is backwards-incompatible. We should do a crater run to check.
cc @eddyb
tweak discriminant on non-nullary enum diagnostic
Adds notes pointing at the non-nullary variants, and uses "custom
discriminant" language to be consistent with the Reference.
Fixes#61039.
r? @estebank
Identify when a stmt could have been parsed as an expr
There are some expressions that can be parsed as a statement without
a trailing semicolon depending on the context, which can lead to
confusing errors due to the same looking code being accepted in some
places and not others. Identify these cases and suggest enclosing in
parenthesis making the parse non-ambiguous without changing the
accepted grammar.
Fix#54186, cc #54482, fix#59975, fix#47287.
Currently, we deal with escape sequences twice: once when we lex a
string, and a second time when we unescape literals. This PR aims to
remove this duplication, by introducing a new `unescape` mode as a
single source of truth for character escaping rules
There are some expressions that can be parsed as a statement without
a trailing semicolon depending on the context, which can lead to
confusing errors due to the same looking code being accepted in some
places and not others. Identify these cases and suggest enclosing in
parenthesis making the parse non-ambiguous without changing the
accepted grammar.
Fix#58270, fix off-by-one error in error diagnostics.
This fixes#58270 by checking if two diagnostics overlap completely when we're calculating the line offset for each message.
When encountering one of a few keywords when a semicolon was
expected, suggest the semicolon and recover:
```
error: expected one of `.`, `;`, `?`, or an operator, found `let`
--> $DIR/recover-missing-semi.rs:4:5
|
LL | let _: usize = ()
| - help: missing semicolon here
LL |
LL | let _ = 3;
| ^^^
error[E0308]: mismatched types
--> $DIR/recover-missing-semi.rs:2:20
|
LL | let _: usize = ()
| ^^ expected usize, found ()
|
= note: expected type `usize`
found type `()`
```
