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Rollup merge of #57779 - estebank:recover-struct-fields, r=davidtwco

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Recover from parse errors in literal struct fields and incorrect float literals

Fix #52496.
This commit is contained in:
Mazdak Farrokhzad 2019-01-24 00:19:53 +01:00 • committed by GitHub
commit 2dd63a2e10
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GPG key ID: 4AEE18F83AFDEB23
11 changed files with 225 additions and 44 deletions
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94
src/libsyntax/parse/parser.rs
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@ -100,6 +100,7 @@ pub enum PathStyle {
enum SemiColonMode {
Break,
Ignore,
Comma,
}
#[derive(Clone, Copy, PartialEq, Debug)]
@ -1988,6 +1989,44 @@ impl<'a> Parser<'a> {
result.unwrap()
}
token::Dot if self.look_ahead(1, |t| match t {
token::Literal(parse::token::Lit::Integer(_) , _) => true,
_ => false,
}) => { // recover from `let x = .4;`
let lo = self.span;
self.bump();
if let token::Literal(
parse::token::Lit::Integer(val),
suffix,
) = self.token {
let suffix = suffix.and_then(|s| {
let s = s.as_str().get();
if ["f32", "f64"].contains(&s) {
Some(s)
} else {
None
}
}).unwrap_or("");
self.bump();
let sp = lo.to(self.prev_span);
let mut err = self.diagnostic()
.struct_span_err(sp, "float literals must have an integer part");
err.span_suggestion_with_applicability(
sp,
"must have an integer part",
format!("0.{}{}", val, suffix),
Applicability::MachineApplicable,
);
err.emit();
return Ok(match suffix {
"f32" => ast::LitKind::Float(val, ast::FloatTy::F32),
"f64" => ast::LitKind::Float(val, ast::FloatTy::F64),
_ => ast::LitKind::FloatUnsuffixed(val),
});
} else {
unreachable!();
};
}
_ => { return self.unexpected_last(&self.token); }
};
@ -2656,8 +2695,24 @@ impl<'a> Parser<'a> {
break;
}
let mut recovery_field = None;
if let token::Ident(ident, _) = self.token {
if !self.token.is_reserved_ident() && self.look_ahead(1, |t| *t == token::Colon) {
// Use in case of error after field-looking code: `S { foo: () with a }`
let mut ident = ident.clone();
ident.span = self.span;
recovery_field = Some(ast::Field {
ident,
span: self.span,
expr: self.mk_expr(self.span, ExprKind::Err, ThinVec::new()),
is_shorthand: false,
attrs: ThinVec::new(),
});
}
}
let mut parsed_field = None;
match self.parse_field() {
Ok(f) => fields.push(f),
Ok(f) => parsed_field = Some(f),
Err(mut e) => {
e.span_label(struct_sp, "while parsing this struct");
e.emit();
@ -2666,19 +2721,28 @@ impl<'a> Parser<'a> {
// what comes next as additional fields, rather than
// bailing out until next `}`.
if self.token != token::Comma {
self.recover_stmt();
break;
self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
if self.token != token::Comma {
break;
}
}
}
}
match self.expect_one_of(&[token::Comma],
&[token::CloseDelim(token::Brace)]) {
Ok(()) => {}
Ok(()) => if let Some(f) = parsed_field.or(recovery_field) {
// only include the field if there's no parse error for the field name
fields.push(f);
}
Err(mut e) => {
if let Some(f) = recovery_field {
fields.push(f);
}
e.span_label(struct_sp, "while parsing this struct");
e.emit();
self.recover_stmt();
break;
self.recover_stmt_(SemiColonMode::Comma, BlockMode::Ignore);
self.eat(&token::Comma);
}
}
}
@ -4542,13 +4606,13 @@ impl<'a> Parser<'a> {
token::CloseDelim(token::DelimToken::Brace) => {
if brace_depth == 0 {
debug!("recover_stmt_ return - close delim {:?}", self.token);
return;
break;
}
brace_depth -= 1;
self.bump();
if in_block && bracket_depth == 0 && brace_depth == 0 {
debug!("recover_stmt_ return - block end {:?}", self.token);
return;
break;
}
}
token::CloseDelim(token::DelimToken::Bracket) => {
@ -4560,7 +4624,7 @@ impl<'a> Parser<'a> {
}
token::Eof => {
debug!("recover_stmt_ return - Eof");
return;
break;
}
token::Semi => {
self.bump();
@ -4568,7 +4632,17 @@ impl<'a> Parser<'a> {
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
return;
break;
}
}
token::Comma => {
if break_on_semi == SemiColonMode::Comma &&
brace_depth == 0 &&
bracket_depth == 0 {
debug!("recover_stmt_ return - Semi");
break;
} else {
self.bump();
}
}
_ => {