bjoernager/rust
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Tweak error for invalid break expr

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Point at loop head on invalid `break expr`.
Suggest removing `expr` or using label if available.
This commit is contained in:
Esteban Küber 2021-01-20 17:25:27 -08:00
parent 060dba67b7
commit 8a13abba1d
6 changed files with 180 additions and 80 deletions
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76
compiler/rustc_passes/src/loops.rs
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@ -90,47 +90,83 @@ impl<'a, 'hir> Visitor<'hir> for CheckLoopVisitor<'a, 'hir> {
};
if let Some(Node::Block(_)) = loop_id.and_then(|id| self.hir_map.find(id)) {
return;
}
return;
}
if opt_expr.is_some() {
let loop_kind = if let Some(loop_id) = loop_id {
Some(match self.hir_map.expect_expr(loop_id).kind {
hir::ExprKind::Loop(_, _, source) => source,
if let Some(break_expr) = opt_expr {
let (head, label, loop_kind) = if let Some(loop_id) = loop_id {
match self.hir_map.expect_expr(loop_id).kind {
hir::ExprKind::Loop(_, label, source, sp) => {
(Some(sp), label, Some(source))
}
ref r => {
span_bug!(e.span, "break label resolved to a non-loop: {:?}", r)
}
})
}
} else {
None
(None, None, None)
};
match loop_kind {
None | Some(hir::LoopSource::Loop) => (),
Some(kind) => {
struct_span_err!(
let mut err = struct_span_err!(
self.sess,
e.span,
E0571,
"`break` with value from a `{}` loop",
kind.name()
)
.span_label(
);
err.span_label(
e.span,
"can only break with a value inside \
`loop` or breakable block",
)
.span_suggestion(
"can only break with a value inside `loop` or breakable block",
);
if let Some(head) = head {
err.span_label(
head,
&format!(
"you can't `break` with a value in a `{}` loop",
kind.name()
),
);
}
err.span_suggestion(
e.span,
&format!(
"instead, use `break` on its own \
without a value inside this `{}` loop",
kind.name()
"use `break` on its own without a value inside this `{}` loop",
kind.name(),
),
"break".to_string(),
Applicability::MaybeIncorrect,
)
.emit();
);
if let Some(label) = label {
match break_expr.kind {
hir::ExprKind::Path(hir::QPath::Resolved(
None,
hir::Path {
segments: [segment],
res: hir::def::Res::Err,
..
},
)) if label.ident.to_string()
== format!("'{}", segment.ident) =>
{
// This error is redundant, we will have already emitted a
// suggestion to use the label when `segment` wasn't found
// (hence the `Res::Err` check).
err.delay_as_bug();
}
_ => {
err.span_suggestion(
break_expr.span,
"alternatively, you might have meant to use the \
available loop label",
label.ident.to_string(),
Applicability::MaybeIncorrect,
);
}
}
}
err.emit();
}
}
}