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Auto merge of #43716 - MaloJaffre:_-in-literals, r=petrochenkov

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Accept underscores in unicode escapes

Fixes #43692.

I don't know if this need an RFC, but at least the impl is here!
This commit is contained in:
bors
2017-09-12 01:25:23 +00:00
parent 07d950f38f d4e0e52281
commit 11f64d8f88
8 changed files with 102 additions and 57 deletions
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89
src/libsyntax/parse/lexer/mod.rs
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@@ -963,60 +963,67 @@ impl<'a> StringReader<'a> {
true
}
/// Scan over a \u{...} escape
/// Scan over a `\u{...}` escape
///
/// At this point, we have already seen the \ and the u, the { is the current character. We
/// will read at least one digit, and up to 6, and pass over the }.
/// At this point, we have already seen the `\` and the `u`, the `{` is the current character.
/// We will read a hex number (with `_` separators), with 1 to 6 actual digits,
/// and pass over the `}`.
fn scan_unicode_escape(&mut self, delim: char) -> bool {
self.bump(); // past the {
let start_bpos = self.pos;
let mut count = 0;
let mut accum_int = 0;
let mut valid = true;
while !self.ch_is('}') && count <= 6 {
let c = match self.ch {
Some(c) => c,
if let Some('_') = self.ch {
// disallow leading `_`
self.err_span_(self.pos,
self.next_pos,
"invalid start of unicode escape");
valid = false;
}
let count = self.scan_digits(16, 16);
if count > 6 {
self.err_span_(start_bpos,
self.pos,
"overlong unicode escape (must have at most 6 hex digits)");
valid = false;
}
loop {
match self.ch {
Some('}') => {
if valid && count == 0 {
self.err_span_(start_bpos,
self.pos,
"empty unicode escape (must have at least 1 hex digit)");
valid = false;
}
self.bump(); // past the ending `}`
break;
},
Some(c) => {
if c == delim {
self.err_span_(self.pos,
self.pos,
"unterminated unicode escape (needed a `}`)");
valid = false;
break;
} else if valid {
self.err_span_char(start_bpos,
self.pos,
"invalid character in unicode escape",
c);
valid = false;
}
},
None => {
panic!(self.fatal_span_(start_bpos,
self.pos,
"unterminated unicode escape (found EOF)"));
}
};
accum_int *= 16;
accum_int += c.to_digit(16).unwrap_or_else(|| {
if c == delim {
panic!(self.fatal_span_(self.pos,
self.next_pos,
"unterminated unicode escape (needed a `}`)"));
} else {
self.err_span_char(self.pos,
self.next_pos,
"invalid character in unicode escape",
c);
}
valid = false;
0
});
}
self.bump();
count += 1;
}
if count > 6 {
self.err_span_(start_bpos,
self.pos,
"overlong unicode escape (can have at most 6 hex digits)");
valid = false;
}
if valid && (char::from_u32(accum_int).is_none() || count == 0) {
self.err_span_(start_bpos,
self.pos,
"invalid unicode character escape");
valid = false;
}
self.bump(); // past the ending }
valid
}