Implements "gaps" in string literals. These are escape sequences of the
form `"\" newline whitespace+` that have the interpretation of an empty
string. For example,
```
"this is \
a string"
```
is equivalent to `"this is a string"`. These are modeled after string
continuations in
[Rust](https://doc.rust-lang.org/beta/reference/tokens.html#string-literals).
Implements RFC #2838
1 line
85 B
Text
1 line
85 B
Text
string_gaps_err_newline.lean:8:0: error: unexpected additional newline in string gap
|