Do less work on the good path
This commit is contained in:
Michael Goulet
parent
f8f4d50aa3
commit
70641356dc
@ -264,130 +264,133 @@ fn visit_ty(&mut self, t: Ty<'tcx>) -> Self::Result {
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&& let hir::OpaqueTyOrigin::FnReturn(parent_def_id) = opaque.origin
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&& parent_def_id == self.parent_def_id
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{
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// Compute the set of args that are captured by the opaque...
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let mut captured = FxIndexSet::default();
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let mut captured_regions = FxIndexSet::default();
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let variances = self.tcx.variances_of(opaque_def_id);
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let mut current_def_id = Some(opaque_def_id.to_def_id());
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while let Some(def_id) = current_def_id {
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let generics = self.tcx.generics_of(def_id);
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for param in &generics.own_params {
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// A param is captured if it's invariant.
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if variances[param.index as usize] != ty::Invariant {
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continue;
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}
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let arg = opaque_ty.args[param.index as usize];
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// We need to turn all `ty::Param`/`ConstKind::Param` and
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// `ReEarlyParam`/`ReBound` into def ids.
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captured.insert(extract_def_id_from_arg(self.tcx, generics, arg));
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captured_regions.extend(arg.as_region());
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}
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current_def_id = generics.parent;
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}
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// Compute the set of in scope params that are not captured. Get their spans,
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// since that's all we really care about them for emitting the diagnostic.
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let mut uncaptured_args: FxIndexSet<_> = self
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.in_scope_parameters
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.iter()
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.filter(|&(def_id, _)| !captured.contains(def_id))
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.collect();
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// These are args that we know are likely fine to "overcapture", since they can be
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// contravariantly shortened to one of the already-captured lifetimes that they
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// outlive.
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let covariant_long_args: FxIndexSet<_> = uncaptured_args
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.iter()
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.copied()
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.filter(|&(def_id, kind)| {
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let Some(ty::Bivariant | ty::Contravariant) = self.variances.get(def_id) else {
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return false;
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};
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let DefKind::LifetimeParam = self.tcx.def_kind(def_id) else {
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return false;
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};
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let uncaptured = match *kind {
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ParamKind::Early(name, index) => ty::Region::new_early_param(
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self.tcx,
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ty::EarlyParamRegion { name, index },
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),
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ParamKind::Free(def_id, name) => ty::Region::new_late_param(
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self.tcx,
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self.parent_def_id.to_def_id(),
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ty::BoundRegionKind::BrNamed(def_id, name),
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),
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ParamKind::Late => return false,
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};
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// Does this region outlive any captured region?
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captured_regions.iter().any(|r| {
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self.outlives_env
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.free_region_map()
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.sub_free_regions(self.tcx, *r, uncaptured)
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})
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})
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.collect();
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// We don't care to warn on these args.
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uncaptured_args.retain(|arg| !covariant_long_args.contains(arg));
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let opaque_span = self.tcx.def_span(opaque_def_id);
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let new_capture_rules =
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opaque_span.at_least_rust_2024() || self.tcx.features().lifetime_capture_rules_2024;
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// If we have uncaptured args, and if the opaque doesn't already have
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// `use<>` syntax on it, and we're < edition 2024, then warn the user.
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if !new_capture_rules
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&& !opaque.bounds.iter().any(|bound| matches!(bound, hir::GenericBound::Use(..)))
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&& !uncaptured_args.is_empty()
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{
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let suggestion = if let Ok(snippet) =
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self.tcx.sess.source_map().span_to_snippet(opaque_span)
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&& snippet.starts_with("impl ")
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{
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let (lifetimes, others): (Vec<_>, Vec<_>) = captured
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.into_iter()
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.partition(|def_id| self.tcx.def_kind(*def_id) == DefKind::LifetimeParam);
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// Take all lifetime params first, then all others (ty/ct).
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let generics: Vec<_> = lifetimes
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.into_iter()
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.chain(others)
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.map(|def_id| self.tcx.item_name(def_id).to_string())
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.collect();
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// Make sure that we're not trying to name any APITs
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if generics.iter().all(|name| !name.starts_with("impl ")) {
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Some((
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format!(" + use<{}>", generics.join(", ")),
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opaque_span.shrink_to_hi(),
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))
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} else {
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None
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}
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} else {
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None
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};
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// Compute the set of args that are captured by the opaque...
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let mut captured = FxIndexSet::default();
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let mut captured_regions = FxIndexSet::default();
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let variances = self.tcx.variances_of(opaque_def_id);
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let mut current_def_id = Some(opaque_def_id.to_def_id());
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while let Some(def_id) = current_def_id {
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let generics = self.tcx.generics_of(def_id);
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for param in &generics.own_params {
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// A param is captured if it's invariant.
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if variances[param.index as usize] != ty::Invariant {
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continue;
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}
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let uncaptured_spans: Vec<_> = uncaptured_args
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.into_iter()
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.map(|(def_id, _)| self.tcx.def_span(def_id))
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let arg = opaque_ty.args[param.index as usize];
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// We need to turn all `ty::Param`/`ConstKind::Param` and
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// `ReEarlyParam`/`ReBound` into def ids.
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captured.insert(extract_def_id_from_arg(self.tcx, generics, arg));
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captured_regions.extend(arg.as_region());
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}
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current_def_id = generics.parent;
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}
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// Compute the set of in scope params that are not captured. Get their spans,
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// since that's all we really care about them for emitting the diagnostic.
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let mut uncaptured_args: FxIndexSet<_> = self
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.in_scope_parameters
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.iter()
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.filter(|&(def_id, _)| !captured.contains(def_id))
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.collect();
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self.tcx.emit_node_span_lint(
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IMPL_TRAIT_OVERCAPTURES,
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self.tcx.local_def_id_to_hir_id(opaque_def_id),
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opaque_span,
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ImplTraitOvercapturesLint {
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self_ty: t,
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num_captured: uncaptured_spans.len(),
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uncaptured_spans,
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suggestion,
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},
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);
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// These are args that we know are likely fine to "overcapture", since they can be
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// contravariantly shortened to one of the already-captured lifetimes that they
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// outlive.
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let covariant_long_args: FxIndexSet<_> = uncaptured_args
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.iter()
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.copied()
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.filter(|&(def_id, kind)| {
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let Some(ty::Bivariant | ty::Contravariant) = self.variances.get(def_id)
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else {
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return false;
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};
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let DefKind::LifetimeParam = self.tcx.def_kind(def_id) else {
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return false;
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};
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let uncaptured = match *kind {
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ParamKind::Early(name, index) => ty::Region::new_early_param(
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self.tcx,
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ty::EarlyParamRegion { name, index },
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),
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ParamKind::Free(def_id, name) => ty::Region::new_late_param(
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self.tcx,
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self.parent_def_id.to_def_id(),
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ty::BoundRegionKind::BrNamed(def_id, name),
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),
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ParamKind::Late => return false,
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};
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// Does this region outlive any captured region?
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captured_regions.iter().any(|r| {
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self.outlives_env
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.free_region_map()
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.sub_free_regions(self.tcx, *r, uncaptured)
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})
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})
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.collect();
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// We don't care to warn on these args.
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uncaptured_args.retain(|arg| !covariant_long_args.contains(arg));
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// If we have uncaptured args, and if the opaque doesn't already have
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// `use<>` syntax on it, and we're < edition 2024, then warn the user.
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if !uncaptured_args.is_empty() {
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let suggestion = if let Ok(snippet) =
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self.tcx.sess.source_map().span_to_snippet(opaque_span)
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&& snippet.starts_with("impl ")
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{
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let (lifetimes, others): (Vec<_>, Vec<_>) =
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captured.into_iter().partition(|def_id| {
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self.tcx.def_kind(*def_id) == DefKind::LifetimeParam
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});
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// Take all lifetime params first, then all others (ty/ct).
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let generics: Vec<_> = lifetimes
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.into_iter()
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.chain(others)
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.map(|def_id| self.tcx.item_name(def_id).to_string())
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.collect();
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// Make sure that we're not trying to name any APITs
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if generics.iter().all(|name| !name.starts_with("impl ")) {
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Some((
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format!(" + use<{}>", generics.join(", ")),
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opaque_span.shrink_to_hi(),
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))
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} else {
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None
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}
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} else {
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None
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};
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let uncaptured_spans: Vec<_> = uncaptured_args
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.into_iter()
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.map(|(def_id, _)| self.tcx.def_span(def_id))
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.collect();
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self.tcx.emit_node_span_lint(
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IMPL_TRAIT_OVERCAPTURES,
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self.tcx.local_def_id_to_hir_id(opaque_def_id),
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opaque_span,
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ImplTraitOvercapturesLint {
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self_ty: t,
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num_captured: uncaptured_spans.len(),
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uncaptured_spans,
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suggestion,
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},
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);
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}
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}
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// Otherwise, if we are edition 2024, have `use<>` syntax, and
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// have no uncaptured args, then we should warn to the user that
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// it's redundant to capture all args explicitly.
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else if new_capture_rules
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if new_capture_rules
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&& let Some((captured_args, capturing_span)) =
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opaque.bounds.iter().find_map(|bound| match *bound {
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hir::GenericBound::Use(a, s) => Some((a, s)),
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