for `~str`/`~[]`.
Note that `~self` still remains, since I forgot to add support for
`Box<self>` before the snapshot.
How to update your code:
* Instead of `~EXPR`, you should write `box EXPR`.
* Instead of `~TYPE`, you should write `Box<Type>`.
* Instead of `~PATTERN`, you should write `box PATTERN`.
[breaking-change]
Commits for details.
This shouldn't change the generated code at all (except for switching to `LitBinary` from an explicit ExprVec of individual ExprLit bytes for `prefix_bytes`).
char literals now work in a quotation.
There were several instances of duplicated functionality in regex_macros
compared to AstBuilder so refactor those out.
The AST doesn't need ~s everywhere, so we can save allocations this way
& the enum isn't particularly large (~4 words) nor are regexes
long (normally), so the space saved in the `Cat` vector is unlikely to
be very much.
