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Use identifier's span in unused lint

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This commit is contained in:
Giacomo Stevanato 2021-02-28 20:44:54 +01:00
parent 573a697a61
commit 2f8fa012ca
1 changed files with 65 additions and 42 deletions
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107
compiler/rustc_passes/src/liveness.rs
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@ -1494,12 +1494,13 @@ impl<'tcx> Liveness<'_, 'tcx> {
// bindings, and we also consider the first pattern to be the "authoritative" set of ids.
// However, we should take the ids and spans of variables with the same name from the later
// patterns so the suggestions to prefix with underscores will apply to those too.
let mut vars: FxIndexMap<Symbol, (LiveNode, Variable, Vec<(HirId, Span)>)> = <_>::default();
let mut vars: FxIndexMap<Symbol, (LiveNode, Variable, Vec<(HirId, Span, Span)>)> =
<_>::default();
pat.each_binding(|_, hir_id, pat_sp, ident| {
let ln = entry_ln.unwrap_or_else(|| self.live_node(hir_id, pat_sp));
let var = self.variable(hir_id, ident.span);
let id_and_sp = (hir_id, pat_sp);
let id_and_sp = (hir_id, pat_sp, ident.span);
vars.entry(self.ir.variable_name(var))
.and_modify(|(.., hir_ids_and_spans)| hir_ids_and_spans.push(id_and_sp))
.or_insert_with(|| (ln, var, vec![id_and_sp]));
@ -1508,7 +1509,8 @@ impl<'tcx> Liveness<'_, 'tcx> {
for (_, (ln, var, hir_ids_and_spans)) in vars {
if self.used_on_entry(ln, var) {
let id = hir_ids_and_spans[0].0;
let spans = hir_ids_and_spans.into_iter().map(|(_, sp)| sp).collect();
let spans =
hir_ids_and_spans.into_iter().map(|(_, _, ident_span)| ident_span).collect();
on_used_on_entry(spans, id, ln, var);
} else {
self.report_unused(hir_ids_and_spans, ln, var);
@ -1516,7 +1518,12 @@ impl<'tcx> Liveness<'_, 'tcx> {
}
}
fn report_unused(&self, hir_ids_and_spans: Vec<(HirId, Span)>, ln: LiveNode, var: Variable) {
fn report_unused(
&self,
hir_ids_and_spans: Vec<(HirId, Span, Span)>,
ln: LiveNode,
var: Variable,
) {
let first_hir_id = hir_ids_and_spans[0].0;
if let Some(name) = self.should_warn(var).filter(|name| name != "self") {
@ -1530,7 +1537,10 @@ impl<'tcx> Liveness<'_, 'tcx> {
self.ir.tcx.struct_span_lint_hir(
lint::builtin::UNUSED_VARIABLES,
first_hir_id,
hir_ids_and_spans.into_iter().map(|(_, sp)| sp).collect::<Vec<_>>(),
hir_ids_and_spans
.into_iter()
.map(|(_, _, ident_span)| ident_span)
.collect::<Vec<_>>(),
|lint| {
lint.build(&format!("variable `{}` is assigned to, but never used", name))
.note(&format!("consider using `_{}` instead", name))
@ -1538,54 +1548,67 @@ impl<'tcx> Liveness<'_, 'tcx> {
},
)
} else {
self.ir.tcx.struct_span_lint_hir(
lint::builtin::UNUSED_VARIABLES,
first_hir_id,
hir_ids_and_spans.iter().map(|(_, sp)| *sp).collect::<Vec<_>>(),
|lint| {
let mut err = lint.build(&format!("unused variable: `{}`", name));
let (shorthands, non_shorthands): (Vec<_>, Vec<_>) =
hir_ids_and_spans.iter().copied().partition(|(hir_id, _, ident_span)| {
let var = self.variable(*hir_id, *ident_span);
self.ir.variable_is_shorthand(var)
});
let (shorthands, non_shorthands): (Vec<_>, Vec<_>) =
hir_ids_and_spans.into_iter().partition(|(hir_id, span)| {
let var = self.variable(*hir_id, *span);
self.ir.variable_is_shorthand(var)
});
let mut shorthands = shorthands
.into_iter()
.map(|(_, span)| (span, format!("{}: _", name)))
.collect::<Vec<_>>();
// If we have both shorthand and non-shorthand, prefer the "try ignoring
// the field" message, and suggest `_` for the non-shorthands. If we only
// have non-shorthand, then prefix with an underscore instead.
if !shorthands.is_empty() {
shorthands.extend(
non_shorthands
.into_iter()
.map(|(_, span)| (span, "_".to_string()))
.collect::<Vec<_>>(),
);
// If we have both shorthand and non-shorthand, prefer the "try ignoring
// the field" message, and suggest `_` for the non-shorthands. If we only
// have non-shorthand, then prefix with an underscore instead.
if !shorthands.is_empty() {
let shorthands = shorthands
.into_iter()
.map(|(_, pat_span, _)| (pat_span, format!("{}: _", name)))
.chain(
non_shorthands
.into_iter()
.map(|(_, pat_span, _)| (pat_span, "_".to_string())),
)
.collect::<Vec<_>>();
self.ir.tcx.struct_span_lint_hir(
lint::builtin::UNUSED_VARIABLES,
first_hir_id,
hir_ids_and_spans
.iter()
.map(|(_, pat_span, _)| *pat_span)
.collect::<Vec<_>>(),
|lint| {
let mut err = lint.build(&format!("unused variable: `{}`", name));
err.multipart_suggestion(
"try ignoring the field",
shorthands,
Applicability::MachineApplicable,
);
} else {
err.emit()
},
);
} else {
let non_shorthands = non_shorthands
.into_iter()
.map(|(_, _, ident_span)| (ident_span, format!("_{}", name)))
.collect::<Vec<_>>();
self.ir.tcx.struct_span_lint_hir(
lint::builtin::UNUSED_VARIABLES,
first_hir_id,
hir_ids_and_spans
.iter()
.map(|(_, _, ident_span)| *ident_span)
.collect::<Vec<_>>(),
|lint| {
let mut err = lint.build(&format!("unused variable: `{}`", name));
err.multipart_suggestion(
"if this is intentional, prefix it with an underscore",
non_shorthands
.into_iter()
.map(|(_, span)| (span, format!("_{}", name)))
.collect::<Vec<_>>(),
non_shorthands,
Applicability::MachineApplicable,
);
}
err.emit()
},
);
err.emit()
},
);
}
}
}
}