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Rollup merge of #106783 - WaffleLapkin:break-my-ident, r=wesleywiser

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Recover labels written as identifiers

This adds recovery for `break label expr` and `continue label`, as well as a test for `break label`.
This commit is contained in:
Matthias Krüger 2023-01-20 07:16:08 +01:00 committed by GitHub
commit df88f7e02c
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 93 additions and 7 deletions
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61
compiler/rustc_parse/src/parser/expr.rs
View File

@ -1353,9 +1353,6 @@ impl<'a> Parser<'a> {
err.span_label(sp, "while parsing this `loop` expression");
err
})
} else if self.eat_keyword(kw::Continue) {
let kind = ExprKind::Continue(self.eat_label());
Ok(self.mk_expr(lo.to(self.prev_token.span), kind))
} else if self.eat_keyword(kw::Match) {
let match_sp = self.prev_token.span;
self.parse_match_expr().map_err(|mut err| {
@ -1379,6 +1376,8 @@ impl<'a> Parser<'a> {
self.parse_try_block(lo)
} else if self.eat_keyword(kw::Return) {
self.parse_return_expr()
} else if self.eat_keyword(kw::Continue) {
self.parse_continue_expr(lo)
} else if self.eat_keyword(kw::Break) {
self.parse_break_expr()
} else if self.eat_keyword(kw::Yield) {
@ -1715,10 +1714,10 @@ impl<'a> Parser<'a> {
fn parse_break_expr(&mut self) -> PResult<'a, P<Expr>> {
let lo = self.prev_token.span;
let mut label = self.eat_label();
let kind = if label.is_some() && self.token == token::Colon {
let kind = if self.token == token::Colon && let Some(label) = label.take() {
// The value expression can be a labeled loop, see issue #86948, e.g.:
// `loop { break 'label: loop { break 'label 42; }; }`
let lexpr = self.parse_labeled_expr(label.take().unwrap(), true)?;
let lexpr = self.parse_labeled_expr(label, true)?;
self.sess.emit_err(LabeledLoopInBreak {
span: lexpr.span,
sub: WrapExpressionInParentheses {
@ -1730,8 +1729,8 @@ impl<'a> Parser<'a> {
} else if self.token != token::OpenDelim(Delimiter::Brace)
|| !self.restrictions.contains(Restrictions::NO_STRUCT_LITERAL)
{
let expr = self.parse_expr_opt()?;
if let Some(expr) = &expr {
let mut expr = self.parse_expr_opt()?;
if let Some(expr) = &mut expr {
if label.is_some()
&& matches!(
expr.kind,
@ -1749,7 +1748,19 @@ impl<'a> Parser<'a> {
BuiltinLintDiagnostics::BreakWithLabelAndLoop(expr.span),
);
}
// Recover `break label aaaaa`
if self.may_recover()
&& let ExprKind::Path(None, p) = &expr.kind
&& let [segment] = &*p.segments
&& let &ast::PathSegment { ident, args: None, .. } = segment
&& let Some(next) = self.parse_expr_opt()?
{
label = Some(self.recover_ident_into_label(ident));
*expr = next;
}
}
expr
} else {
None
@ -1758,6 +1769,23 @@ impl<'a> Parser<'a> {
self.maybe_recover_from_bad_qpath(expr)
}
/// Parse `"continue" label?`.
fn parse_continue_expr(&mut self, lo: Span) -> PResult<'a, P<Expr>> {
let mut label = self.eat_label();
// Recover `continue label` -> `continue 'label`
if self.may_recover()
&& label.is_none()
&& let Some((ident, _)) = self.token.ident()
{
self.bump();
label = Some(self.recover_ident_into_label(ident));
}
let kind = ExprKind::Continue(label);
Ok(self.mk_expr(lo.to(self.prev_token.span), kind))
}
/// Parse `"yield" expr?`.
fn parse_yield_expr(&mut self) -> PResult<'a, P<Expr>> {
let lo = self.prev_token.span;
@ -3046,6 +3074,25 @@ impl<'a> Parser<'a> {
false
}
/// Converts an ident into 'label and emits an "expected a label, found an identifier" error.
fn recover_ident_into_label(&mut self, ident: Ident) -> Label {
// Convert `label` -> `'label`,
// so that nameres doesn't complain about non-existing label
let label = format!("'{}", ident.name);
let ident = Ident { name: Symbol::intern(&label), span: ident.span };
self.struct_span_err(ident.span, "expected a label, found an identifier")
.span_suggestion(
ident.span,
"labels start with a tick",
label,
Applicability::MachineApplicable,
)
.emit();
Label { ident }
}
/// Parses `ident (COLON expr)?`.
fn parse_expr_field(&mut self) -> PResult<'a, ExprField> {
let attrs = self.parse_outer_attributes()?;

7
tests/ui/parser/recover-unticked-labels.fixed Normal file
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@ -0,0 +1,7 @@
// run-rustfix
fn main() {
'label: loop { break 'label }; //~ error: cannot find value `label` in this scope
'label: loop { break 'label 0 }; //~ error: expected a label, found an identifier
'label: loop { continue 'label }; //~ error: expected a label, found an identifier
}

7
tests/ui/parser/recover-unticked-labels.rs Normal file
View File

@ -0,0 +1,7 @@
// run-rustfix
fn main() {
'label: loop { break label }; //~ error: cannot find value `label` in this scope
'label: loop { break label 0 }; //~ error: expected a label, found an identifier
'label: loop { continue label }; //~ error: expected a label, found an identifier
}

25
tests/ui/parser/recover-unticked-labels.stderr Normal file
View File

@ -0,0 +1,25 @@
error: expected a label, found an identifier
--> $DIR/recover-unticked-labels.rs:5:26
|
LL | 'label: loop { break label 0 };
| ^^^^^ help: labels start with a tick: `'label`
error: expected a label, found an identifier
--> $DIR/recover-unticked-labels.rs:6:29
|
LL | 'label: loop { continue label };
| ^^^^^ help: labels start with a tick: `'label`
error[E0425]: cannot find value `label` in this scope
--> $DIR/recover-unticked-labels.rs:4:26
|
LL | 'label: loop { break label };
| ------ ^^^^^
| | |
| | not found in this scope
| | help: use the similarly named label: `'label`
| a label with a similar name exists
error: aborting due to 3 previous errors
For more information about this error, try `rustc --explain E0425`.