Add a check for swapped words when we can't find an identifier
Fixes#66968
Couple things here:
1. The matches take the precedence of case insensitive match, then levenshtein match, then swapped words match. Doing this allows us to not even check for swapped words unless the other checks return `None`.
2. I've assumed that the swapped words check is not held to the limits of the max levenshtein distance threshold (ie. we want to try and find a match even if the levenshtein distance is very high). This means that we cannot perform this check in the `fold` that occurs after the `filter_map` call, because the candidate will be filtered out. So, I've split this into two separate `fold` calls, and had to collect the original iterator into a vec so it can be copied (I don't think we want to change the function signature to take a vec or require the `Copy` trait). An alternative implemenation may be to remove the `filter_map`, `fold` over the entire iterator, and do a check against `max_dist` inside the relevant cases there.
r? @estebank
The idea here is to make a reusable library out of the existing
rust-lexer, by separating out pure lexing and rustc-specific concerns,
like spans, error reporting an interning.
So, rustc_lexer operates directly on `&str`, produces simple tokens
which are a pair of type-tag and a bit of original text, and does not
report errors, instead storing them as flags on the token.
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.
Adds support for .await under the existing async_await feature gate.
Moves macro-like await! syntax to the await_macro feature gate.
Removes support for `await` as a non-keyword under the `async_await`
feature.
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.
