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Feb 25, 2022
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1 change: 1 addition & 0 deletions compiler/rustc_ast/src/lib.rs
Original file line number Diff line number Diff line change
@@ -16,6 +16,7 @@
#![feature(min_specialization)]
#![recursion_limit = "256"]
#![feature(slice_internals)]
#![feature(stmt_expr_attributes)]

#[macro_use]
extern crate rustc_macros;
39 changes: 22 additions & 17 deletions compiler/rustc_ast/src/util/literal.rs
Original file line number Diff line number Diff line change
@@ -56,25 +56,30 @@ impl LitKind {
// new symbol because the string in the LitKind is different to the
// string in the token.
let s = symbol.as_str();
let symbol =
if s.contains(&['\\', '\r']) {
let mut buf = String::with_capacity(s.len());
let mut error = Ok(());
unescape_literal(&s, Mode::Str, &mut |_, unescaped_char| {
match unescaped_char {
Ok(c) => buf.push(c),
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
let symbol = if s.contains(&['\\', '\r']) {
let mut buf = String::with_capacity(s.len());
let mut error = Ok(());
// Force-inlining here is aggressive but the closure is
// called on every char in the string, so it can be
// hot in programs with many long strings.
unescape_literal(
&s,
Mode::Str,
&mut #[inline(always)]
|_, unescaped_char| match unescaped_char {
Ok(c) => buf.push(c),
Err(err) => {
if err.is_fatal() {
error = Err(LitError::LexerError);
}
}
});
error?;
Symbol::intern(&buf)
} else {
symbol
};
},
);
error?;
Symbol::intern(&buf)
} else {
symbol
};
LitKind::Str(symbol, ast::StrStyle::Cooked)
}
token::StrRaw(n) => {
45 changes: 22 additions & 23 deletions compiler/rustc_lexer/src/unescape.rs
Original file line number Diff line number Diff line change
@@ -159,26 +159,8 @@ impl Mode {
}
}

fn scan_escape(first_char: char, chars: &mut Chars<'_>, mode: Mode) -> Result<char, EscapeError> {
if first_char != '\\' {
// Previous character was not a slash, and we don't expect it to be
// an escape-only character.
return match first_char {
'\t' | '\n' => Err(EscapeError::EscapeOnlyChar),
'\r' => Err(EscapeError::BareCarriageReturn),
'\'' if mode.in_single_quotes() => Err(EscapeError::EscapeOnlyChar),
'"' if mode.in_double_quotes() => Err(EscapeError::EscapeOnlyChar),
_ => {
if mode.is_bytes() && !first_char.is_ascii() {
// Byte literal can't be a non-ascii character.
return Err(EscapeError::NonAsciiCharInByte);
}
Ok(first_char)
}
};
}

// Previous character is '\\', try to unescape it.
fn scan_escape(chars: &mut Chars<'_>, mode: Mode) -> Result<char, EscapeError> {
// Previous character was '\\', unescape what follows.

let second_char = chars.next().ok_or(EscapeError::LoneSlash)?;

@@ -270,9 +252,24 @@ fn scan_escape(first_char: char, chars: &mut Chars<'_>, mode: Mode) -> Result<ch
Ok(res)
}

#[inline]
fn ascii_check(first_char: char, mode: Mode) -> Result<char, EscapeError> {
if mode.is_bytes() && !first_char.is_ascii() {
// Byte literal can't be a non-ascii character.
Err(EscapeError::NonAsciiCharInByte)
} else {
Ok(first_char)
}
}

fn unescape_char_or_byte(chars: &mut Chars<'_>, mode: Mode) -> Result<char, EscapeError> {
let first_char = chars.next().ok_or(EscapeError::ZeroChars)?;
let res = scan_escape(first_char, chars, mode)?;
let res = match first_char {
'\\' => scan_escape(chars, mode),
'\n' | '\t' | '\'' => Err(EscapeError::EscapeOnlyChar),
'\r' => Err(EscapeError::BareCarriageReturn),
_ => ascii_check(first_char, mode),
}?;
if chars.next().is_some() {
return Err(EscapeError::MoreThanOneChar);
}
@@ -303,12 +300,14 @@ where
skip_ascii_whitespace(&mut chars, start, callback);
continue;
}
_ => scan_escape(first_char, &mut chars, mode),
_ => scan_escape(&mut chars, mode),
}
}
'\n' => Ok('\n'),
'\t' => Ok('\t'),
_ => scan_escape(first_char, &mut chars, mode),
'"' => Err(EscapeError::EscapeOnlyChar),
'\r' => Err(EscapeError::BareCarriageReturn),
_ => ascii_check(first_char, mode),
};
let end = initial_len - chars.as_str().len();
callback(start..end, unescaped_char);