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Avoid double lowering of idents #138588

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Merged
merged 4 commits into from
Mar 17, 2025
Merged

Avoid double lowering of idents #138588

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87457f6
Inline and remove `LoweringContext::new_named_lifetime_with_res`.
nnethercote Mar 17, 2025
fe4d144
Avoid double lowering of lifetime identifiers.
nnethercote Mar 17, 2025
6496d69
Make the `match` in `new_named_lifetime` exhaustive.
nnethercote Mar 17, 2025
adf2bb7
Avoid double lowering of generic identifiers.
nnethercote Mar 17, 2025
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3 changes: 1 addition & 2 deletions compiler/rustc_ast_lowering/src/item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1720,7 +1720,6 @@ impl<'hir> LoweringContext<'_, 'hir> {

let bounds = self.lower_param_bounds(bounds, itctx);

let ident = self.lower_ident(ident);
let param_span = ident.span;

// Reconstruct the span of the entire predicate from the individual generic bounds.
Expand All @@ -1739,6 +1738,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
let def_id = self.local_def_id(id).to_def_id();
let hir_id = self.next_id();
let res = Res::Def(DefKind::TyParam, def_id);
let ident = self.lower_ident(ident);
let ty_path = self.arena.alloc(hir::Path {
span: param_span,
res,
Expand All @@ -1757,7 +1757,6 @@ impl<'hir> LoweringContext<'_, 'hir> {
})
}
GenericParamKind::Lifetime => {
let ident = self.lower_ident(ident);
let lt_id = self.next_node_id();
let lifetime = self.new_named_lifetime(id, lt_id, ident);
hir::WherePredicateKind::RegionPredicate(hir::WhereRegionPredicate {
Expand Down
28 changes: 8 additions & 20 deletions compiler/rustc_ast_lowering/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1769,17 +1769,17 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
}

fn lower_lifetime(&mut self, l: &Lifetime) -> &'hir hir::Lifetime {
let ident = self.lower_ident(l.ident);
self.new_named_lifetime(l.id, l.id, ident)
self.new_named_lifetime(l.id, l.id, l.ident)
}

#[instrument(level = "debug", skip(self))]
fn new_named_lifetime_with_res(
fn new_named_lifetime(
&mut self,
id: NodeId,
new_id: NodeId,
ident: Ident,
res: LifetimeRes,
) -> &'hir hir::Lifetime {
let res = self.resolver.get_lifetime_res(id).unwrap_or(LifetimeRes::Error);
let res = match res {
LifetimeRes::Param { param, .. } => hir::LifetimeName::Param(param),
LifetimeRes::Fresh { param, .. } => {
Expand All @@ -1789,31 +1789,19 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
LifetimeRes::Infer => hir::LifetimeName::Infer,
LifetimeRes::Static { .. } => hir::LifetimeName::Static,
LifetimeRes::Error => hir::LifetimeName::Error,
res => panic!(
"Unexpected lifetime resolution {:?} for {:?} at {:?}",
res, ident, ident.span
),
LifetimeRes::ElidedAnchor { .. } => {
panic!("Unexpected `ElidedAnchar` {:?} at {:?}", ident, ident.span);
}
};

debug!(?res);
self.arena.alloc(hir::Lifetime {
hir_id: self.lower_node_id(id),
hir_id: self.lower_node_id(new_id),
ident: self.lower_ident(ident),
res,
})
}

#[instrument(level = "debug", skip(self))]
fn new_named_lifetime(
&mut self,
id: NodeId,
new_id: NodeId,
ident: Ident,
) -> &'hir hir::Lifetime {
let res = self.resolver.get_lifetime_res(id).unwrap_or(LifetimeRes::Error);
self.new_named_lifetime_with_res(new_id, ident, res)
}

fn lower_generic_params_mut(
&mut self,
params: &[GenericParam],
Expand Down
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