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 `()`
```
Do not complain about unmentioned fields in recovered patterns
When the parser has to recover from malformed code in a pattern, do not
complain about missing fields.
Fix#59145.
Do not complain about non-existing fields after parse recovery
When failing to parse struct-like enum variants, the ADT gets recorded
as having no fields. Record that we have actually recovered during
parsing of this variant to avoid complaing about non-existing fields
when actually using it.
Fix#57361.
When failing to parse struct-like enum variants, the ADT gets recorded
as having no fields. Record that we have actually recovered during
parsing of this variant to avoid complaing about non-existing fields
when actually using it.
